Modular and Flexible Payload Arrangements for Surface Ships with Reconfigurable Floors and Sliding Bulkheads

Master of Science in Mechanical Engineering June 2021

Modular and flexible payload arrangements for surface ships with reconfigurable floors and sliding bulkheads

Haris Hodzic Liban Mohamed Hassan

Faculty of Mechanical Engineering, Blekinge Institute of Technology, 371 79 Karlskrona, Sweden

This thesis is submitted to the Faculty of Mechanical Engineering at Blekinge Institute of Technology to fulfill the requirements for the degree of Master of Science in Mechanical Engineering. The thesis was done in cooperation with Saab Kockums, Karlskrona.

The authors declare that they are the sole authors of this thesis and that they have not used any sources other than those listed in the bibliography and identified as references. They further declare that they have not submitted this thesis at any other institution to obtain a degree.

Contact Information: Authors: Haris Hodzic E-mail: [email protected]

Liban Mohamed Hassan E-mail: [email protected]

University advisor: Ph.D. Student Raj Jiten Machchhar Department of Mechanical engineering

Faculty of Mechanical Engineering Internet: www.bth.se Blekinge Institute of Technology Phone: +46 455 38 50 00 SE–371 79 Karlskrona, Sweden Fax: +46 455 38 50 57

Abstract Background The shipbuilding trends have changed from being single purpose ships only to using modular and flexible parts or systems to carry out multiple missions with as few ships as possible to minimize the ecological and economic impact. A flotilla can become smaller by having multiple ships capable of carrying out various missions instead of single-purpose ships. Objectives The objectives throughout the thesis are to provide an insight into how the trends today are affecting the market of surface ships and to study how a reconfigurable floor can be combined with a sliding bulkhead to be implemented into the cargo space. The developed concept needs to meet the regulations set by DNV-GL, which are an international classification society that is experts in risk management and quality assurance. This master’s thesis focuses on how to implement modularity and flexibility in payload arrangement for surface ships. Method The work process is based on the methodology design thinking’s four phases, which are initiation, inspiration, ideation, and implementation. Throughout the project, a trendwatching was conducted to determine the most impactful trends on the naval market. Using semi-structured interviews, techwatching and brainstorming iterations, a requirements list was defined to support the concept development. The concepts were weighed against each other, and the highest scoring was developed into a parametric CAD model. The model was later compared to the DNV-GL regulations to see whether the developed concept affects existing systems such as HVAC. Results Some of the top trends that have been affecting the naval market lately is modularity, flexibility, and unmanned surface vessels. The developed concept was a combination of a pallet loading floor and cargo floor rollers for reconfigurable floors and garage door-inspired bulkhead. The concept was visualized in Autodesk Inventor Professional 2020 to be further analyzed and display how the concept operates, its functions and how the system compares to DNV-GL regulations. Conclusions The top trends affecting the naval market are modularity, flexibility, and unmanned surface vessels to mention a few. Some of the regulations from DNV-GL that need to be considered when implementing a modular and flexible payload arrangement are fire protection and tightness requirements. However, the regulations can be stricter or changed depending on the role, design, and placement of the payload arrangement.

Keywords: Trendwatching, DNV-GL, Parametric CAD model, Concept development, Cargo management

Sammanfattning Bakgrund Användning av modulära och flexibla system eller delar är några trender inom skeppsbyggeri som har fått uppmärksamhet. En av anledningarna är den minskade ekonomiska samt ekologiska påverkan av att kunna utföra olika typer av uppdrag med så få fartyg som möjligt. Modulära och flexibla system kan leda till att en flottilj kan bestå av färre fartyg utan att påverka dess möjlighet till att genomföra uppdrag. Syfte Syftet med examensarbetet är att skapa en inblick i hur dagens trender påverkar ytfartygsmarknaden och hur en kombinerad lösning av konfigurerbara golv och glidande skott kan bli implementerat i lastutrymmet. Det utvecklade konceptet måste möta föreskrifterna satta av DNV-GL, som är ett internationellt klassificeringssällskap som är experter inom riskhantering och kvalitetsförsäkran. Detta examensarbete fokuserar på hur man kan implementera modularitet och flexibilitet i lastutrymmet för att kunna frakta diverse last samt utrustning. Metod Arbetsprocessen är baserat på metodiken Design Thinkings fyra faser, vilka är uppstart, inspiration, tankegång och implementering. För bättre förståelse utfördes en trendwatching för att definiera de trender som påverkar marinmarknaden. Med hjälp av semi-strukturerade intervjuer, techwatching och brainstorming iterationer, skapades en lista med krav för de genererade koncepten. Koncepten blev jämförda med varandra och det koncept med högst poäng blev vidareutvecklat till en parametrisk CAD modell. Den utvecklade modellen jämfördes senare gentemot regelverken från DNV-GL och huruvida den påverkar existerande system som till exempel uppvärmning, ventilation och luftkonditionering. Resultat Några av topptrenderna som har påverkat den marina marknaden på senaste tiden är modularitet, flexibilitet och obemannade ytfartyg. Det utvecklade konceptet var en kombination av lastpallsinspirerat golv och rullande lastgolv för konfigurerbart golv samt skott som inspirerade av garagedörrar. Konceptet visualiserades i Autodesk Inventor Professional 2020 för att utföra ytterligare analyser och demonstrera dess funktioner och hur systemet förhåller sig till DNV-GLs föreskrifter. Slutsatser De största trenderna som påverkar ytfartygsmarknaden är bland annat modularitet, flexibilitet och obemannade ytfartyg. Några föreskrifter som är ett krav från DNV-GL när ett modulärt och flexibelt lasthantering system ska implementeras är eldskydd och täthetskrav. Dessa förskrifter kan vara striktare eller bli förändrade beroende på typen, designen och placering av lasthanterings systemet.

Nyckelord: Trendwatching. DNV-GL, Parametrisk CAD modell, Konceptutveckling, Lasthantering

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Acknowledgments

We would like to thank Joakim Hill, Isabel Dreveborn, Magnus Olsson, Mårten Hansson, and other workers from Saab Kockums for helping us with excellent guidance on what aspects are essential, giving us feedback whenever necessary, and for helping us with supervision throughout this project.

We would also like to thank our supervisor Raj Jiten Machchhar from Blekinge Institute of Technology, who helped us understand the importance of the master thesis and took the time to meet with us when we needed guidance.

Contents

List of figures ix List of tables x 1 Introduction 1 1.1 Background 1 1.1.1 Saab Group 1 1.1.2 Surface ships 1 1.2 Problem statement & objectives 2 1.3 Scope and aim 2 1.4 Delimitations 3 1.5 Thesis questions 3 1.6 Thesis outline 4 2 Theoretical backgrounds 5 2.1 Definition of Modularity & Flexibility 5 2.2 Design thinking 5 2.3 PDCA 6 2.4 Evaluation Matrix 6 2.5 Multi-purpose ships 8 2.5.1 MPS Life cycle costs 8 2.6 Bulkheads 9 2.7 Reconfiguration 9 2.8 Parametric CAD modeling 9 2.9 DNV-GL 10 2.9.1 DNV-GL Regulations 10 3 Method 12 3.2 Inspiration 12 3.2.1 Information gathering 12 3.2.2 Trendwatching 12 3.2.3 Techwatching 13 3.2.4 Semi-structured interviews and presentations 13 3.3 Ideation 13 3.3.1 Idea generation phase 13 3.3.2 Requirement list 14

3.3.3 Evaluation matrix 14 3.3.4 Pre-totypes 14 3.4 Implementation 15 3.4.1 Parametric CAD modeling 15 4 Results 17 4.1 Trendwatching 17 4.1.1 System trends 17 4.1.2 Design trends 18 4.2 Techwatching 20 4.2.1 HSwMS Visby-class corvette 20 4.2.2 Littoral combat ships 22 4.2.3 Mine Countermeasure ship 23 4.2.4 SAM 3 Minesweeping USV 23 4.2.5 Existing solutions 24 4.3 Ideation 25 4.3.1 Requirements list 25 4.3.2 Reconfigurable floor concepts 27 4.3.3 Sliding bulkheads concepts 30 4.3.4 Lifting mechanisms 31 4.3.5 Evaluation matrix 32 4.3.6 Combination of concepts 33 4.4 Implementation 34 4.4.1 Parametric CAD model 35 4.4.2 DNV-GL regulations 39 5 Discussion 40 5.1 Design thinking 40 5.2 Trendwatching 40 5.3 Techwatching 41 5.4 Ideation 42 5.5 Parametric CAD modeling 42 5.6 DNV-GL regulations 43 5.7 Analyzation of developed idea 44 5.7.1 Advantages 44 5.7.2 Disadvantages 44 6 Conclusion and future work 46 6.1 Conclusions 46

6.2 Future work 47 References 48

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Terminology

1. S.B. - Sliding bulkheads 2. Bulkhead - A bulkhead is an upright wall within the hull of a ship or container. It can also work to resist pressure or shut off water, fire, and gas. 3. R.F. - Reconfigurable floors 4. MPS - Multi-purpose ships 5. SPS - Single-purpose ships 6. DNV-GL - An international classification society that are experts in risk management and quality assurance. 7. ASW - Anti-submarine warfare 8. MCM - Mine countermeasures 9. LCS - Littoral combat ships 10. ASuW - Anti-surface warfare 11. HVAC - Heating, ventilation, and air condition 12. CAD - Computer Aided Design 13. PDCA - Plan, do, check, and act. 14. MPCV - Multi-purpose cargo vessel 15. CBO - Congressional Budget Office 16. W.T - Watertight 17. Pre-totypes - A pre-totype is a simplified version of an early prototype where it explains the functions in an overview description or a hand drawn sketch. 18. QFD - Quality Function Deployment 19. HoQ - House of Quality 20. USV - Unmanned surface vehicle 21. SAM - Self-propelled Acoustic Magnetic 22. SW - surface warfare 23. HSwMS - His Swedish Majesty’s ship 24. MCMV - Mine countermeasure vessel 25. MIW - Mine warfare 26. SUW - Surface warfare

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List of figures [1] Visby-class corvette | Saab’, Start. https://www.saab.com/products/visby-class-corvette (accessed May 31, 2021). [2-3] Adapted from, ‘Att se utan att synas – korvett typ Visby – Del 1’, IDG.se. https://www.idg.se/2.1085/1.567321/att-se-utan-att-synas--korvett-typ-visby--del-1 (accessed Jan 31, 2021). [4] MCMV | Saab’, Start. https://www.saab.com/products/mine-counter-measure-vessels (accessed Jan 31, 2021). [5] ‘Minesweeping USV SAM 3 | Saab’, Start. https://www.saab.com/products/minesweeping-usv- sam-3 (accessed Jan 31, 2021) [6] Figure 6. In the figure, the physical model of a generalized cargo space is visualized. [7] Figure 7. In the figure, a pre-totype of the pallet loading floor is visualized in a sketch. [8] Figure 8. In the figure a pre-totype of the active load plate is visualized in a sketch. [9] Figure 9. In the figure a pre-totype of the cargo floor rollers is visualized in a sketch. [10] Figure 10. In the figure a pre-totype of the “garage door” is visualized in a sketch. [11] Figure 11. In the figure a pre-totype of the “Pillow bulkhead” is visualized in a sketch. [12] Figure 12. In the figure, the Pugh matrix used for evaluating the different concepts of R.F. is shown. [13] Figure 13. In the figure, the Pugh matrix used for evaluating the different concepts of S.B. is shown. [14] Figure 14. The new Pugh matrix with the additional concepts. [15-16] Figure 15 & 16. In the figure to the left, the S.B is visualized with the pathway and to the right the R.F is seen with the integrated lifting mechanism. [17] Figure 17. An overview over the complete cargo space with three compartments and an opening to the upper deck. [18] Figure 18. The manual handle to reposition the S.B is shown as well as the connector from the bulkhead to the railway. [19-20] Figure 19 & 20. An overview over the movement of the bulkhead. The bulkhead is marked in blue in the left picture and shows the upper position on the right picture. [21] Figure 21. In the figure the lifting mechanism can be seen as it is raised with the R.F to reach the upper deck. [22] Figure 22. In the figure the R.F is seen with the cargo floor and an implementation of a standardized fastening mechanism called twistlock. [23] Figure 23. A possibility to attach a generalized twistlock fastening mechanism is shown in the figure.

List of tables [1] Table 1: The number of bulkheads in a ship depending on its length 5 placement of machinery. Adapted from, D. J. Eyres and G. J. Bruce, ‘Ship construction’, 2012, pp. 207–223. doi: 10.1016/B978-0-08-097239-8.00018-0. [2] Table 2. In the table the different classes for fire protection are shown [3] Table 3. The requirements for the reconfigurable floors [4] Table 4. The requirements for the sliding bulkheads [5] Table 5. The table shows all the trends that have been studied during this master thesis.

1 Introduction Declining fleet numbers in today’s navies combined with rapidly evolving technologies are demanding more flexible ships that easily can be reconfigured. A multi-purpose ship (MPS), i.e., a ship that can perform different roles or a wide range of missions, is seen as an attractive ship in most flotillas. There are several reasons why the MPS is gaining market shares, such as economic and environmental aspects. One of the reasons is that customers are looking for flexible ships instead of single-purpose ships (SPS) to perform different missions. Saab Kockums, a shipbuilding company located in Malmö and Karlskrona, is therefore interested in gaining more insight into the domain of MPSs. This is to better understand how they can be arranged, especially when it comes to flexible and modular payload arrangements to continue being at the forefront of the development of technology and shipbuilding.

1.1 Background The background presents Saab Group, as well as SPS and MPS. Due to the significant changes in trends today, most flotillas are changed from a larger number of ships to smaller numbers as MPS are better fitted.

1.1.1 Saab Group Saab Group consists of approximately 17,420 workers worldwide, and operates in over 30 countries. The vision of the company is to keep the society and people safe through systems and solutions that increase security. From a product life cycle perspective Saab Group is working towards creating more environmentally sustainable products. Their product portfolio consists of airplanes, surface ships, submarines, and other technologies such as combat systems. The surface ships and submarines are developed and manufactured by its branch Saab Kockums, located in Karlskrona and Malmö. Saab Kockums is one of the world’s leading companies with its surface ships and submarines technologies. The company is at the forefront of technology with its various systems, and continuously work to develop, adapt, and improve new technologies to meet its customer needs. Saab Kockums has, during recent years, noticed an increased demand in the MPS market segment. [1]

1.1.2 Surface ships Single purpose surface ships have been used for various missions such as anti-submarine warfare (ASW), mine countermeasure (MCM) or surface warfare. As trends are changing towards naval ships being more modular and flexible to perform various missions, older ships are becoming outdated due to fulfilling only one specific task. For example, older aircraft carriers were not used to deploy unmanned submarines or surface vessels, instead only used for airplanes to land and take off. Therefore, a disadvantage with the SPS is that the lead-time to reconfigure the ship to a new mission is extensive and more navies are searching for solutions that help reconfigure the ship to minimize the lead-time. One key advantage of SPSs usage is that the personnel are specialized within a certain area they are used to, compared to the personnel on a MPS who possesses a more general knowledge.

As a result of the trends, a new type of surface ship has been developed called MPS. The ship is a modular-based ship and is built with an empty hull, where the previously integrated systems are installed as modular pieces. This approach helps the MPS to adapted to complete different missions such as ASW or MCM. It also helps to reduce the lead-time to reconfigure the ship and economic

impacts such as costs for operations, since the navy can use one ship to assist in various missions. Some examples of MPS are the Visby-class corvette and the littoral combat ship (LCS). One of the advantages of having MPS is that they can function with a smaller crew by having specific modules and operators. The ship can also be reconfigured depending on what equipment the mission requires.

1.2 Problem statement & objectives Today's naval ships are mostly single purpose, for example an SPS is built for ASW or anti-surface warfare (ASuW), but not both, which limits the usage. This makes the life cycle hard to extend since these ships were designed with a purpose in mind that can be obsolete due to technological advances. A ship that can be reconfigured for different missions could minimize the environmental & economic impacts by using less raw material. That is why costumers today want a broader possibility to change the purpose of their ships while using one hull without having to order a new naval ship for specific missions.

This master’s thesis intends to innovate multi-role naval ships by creating practical ways of reconfiguring cargo space. Traditionally ships have been designed with their capabilities built-in and integrated onboard. The fundamental issues with today’s ships are the financial strains, environmental impact, and the lead-time required to change their purpose. For example, a naval ship might be used for a certain type of mission, and then change the mission modules, which might require an extensive lead-time to prepare with today's SPS. The changes in the environment during missions can cause damages to the ship. Examples of damages that can occur are moisture that creates corrosion or contaminating the air with sand particles which harms the ventilation system and the personnel’s health.

Objectives with the master’s thesis is to study the trends affecting the naval ship market and investigate the aspects of sliding bulkheads (S.B) and its requirements, as well as how it will affect existing systems such as heating, ventilation, and air conditioning (HVAC). The thesis also includes a study of how reconfigurable floors (R.F) can be used for relocating cargo. The reason for focusing on S.B as well as R.F is due to stakeholder's directive. A developed concept needs to be compared with the DNV-GL classifications to ensure that the solution follows all necessary regulations to provide a safe work environment. It is also critical for a developed solution to meet the regulations to be implemented into surface ships. Some of the requirements that are crucial for the compartments are fire-, dust- and smoke-proofing. DNV-GL has different regulations depending on how long the fire and smoke should be contained in the compartment, and there are different regulations depending on the categories.

1.3 Scope and aim

The scope of this thesis is to find a holistic solution to increase flexibility and decrease lead-time in the harbor for ship reconfiguration while maintaining high standards regarding safety. The purpose is to further develop flexible handling systems and measures to create a configurable payload arrangement onboard naval ship. Another aim is to increase the life cycle of existing and future ships by using modular parts to change the ship’s purpose. This helps to minimize the economic costs for companies and lowers the environmental impacts from producing new ships.

This thesis focuses on creating a modular and flexible system that can be arranged depending on the payload. The idea was to create a solution that gave the user the possibility to decide how to partition the cargo area. A combination of a R.F and S.B is explored in this thesis to understand how such a partitioning wall can improve the segmentation of the cargo space. Today, there are no existing examples of sliding bulkheads used for naval ships, but instead only stationary bulkheads or bulkheads with a sliding door.

To increase the ship’s flexibility and enable the use of different mission modules, the payload arrangement should be able to be adapted, for example by using S.B and R.F. Typical design limitations and challenges to be addressed are ship dimensions, structural integrity, a subdivision in fire zones, decks, bulkheads, and infrastructure interfaces such as HVAC. After a solution is generated, the concept will be compared to the DNV-GL classifications to assess safety compliances. The developed concepts will be created with the help of computer aided design (CAD) to analyze and visualize the solutions with suitable stakeholders.

1.4 Delimitations During this master’s thesis, a delimitation was that no physical prototypes will be manufactured due to the ongoing Covid-19 pandemic and the limited access to 3D printers or workshops. The pandemic also made it difficult to visit ships to see the cargo space in real life. Knowing what dimensions and the layout can make the solution more specialized or adapted to the requirements for future work. Instead, the focus was on creating a digital prototype with help of Autodesk Inventor Professional 2020. Another delimitation is that the concept development focused on surface ships with an opening to the cargo space from upper deck. When the concepts were generated and further developed, the choice of material was not a crucial aspect since it can change depending on the ship. Another limitation with the concept development is that the system will integrate an already existing lifting mechanism instead of developing one. Due to limited information about reconfigurable floors, the theoretical background focuses more on general reconfiguration.

With the focus of modularity and flexibility, the aim has been limited, and the literature study is narrowed down when searching for information that is related to the research questions. However, it also helps to see how the generated ideas can be perceived from the stakeholder’s view. A delimitation during the information gathering, tech-& trendwatching is that the development of technologies is mainly conducted by Navies, which have a restricted access. This means that some of the information available for the public might not be fully up to date.

1.5 Thesis questions 1. How are today’s trends affecting the development of new naval ships in a payload arrangement aspect?

2. How can a modular and flexible payload arrangement be implemented in existing surface ships without changing the ship's interior structure?

3. What regulations from DNV-GL need to be asserted onto a flexible and modular system that is implemented in the cargo space?

1.6 Thesis outline In chapter two, relevant theory for the thesis is presented, such as information about the methodology design thinking and the three phases. This section also presents numerous tools, MPS and the lifecycle costs, bulkheads, reconfiguration, DNV-GL and what a parametric CAD model is. Chapter three describes what was conducted in this study and why it was conducted. Within chapter four, the results from the inspiration, ideation, and implementation phases are presented. The later parts of chapter four show the implementation phase in which the highest scoring concepts from the three evaluation matrices are visualized with the help of a CAD model. The concepts are added together to create a more extensive system that shows the functions and design choices. In chapter five, there will be an analysis of the methodology used to reach the aim of the thesis and the work process of the development. It will also show how the literature study and results are connected and provide solid support to the various claims on why the developed concept can solve the research questions.

2 Theoretical backgrounds In this chapter of the thesis, a study of the methodology design thinking is presented, as well as numerous tools such as plan do check and act (PDCA) and Pugh matrix. This section also includes relevant background about MPS, life cycle costs, bulkheads, reconfiguration, parametric CAD models and DNV-GL. The information presented is later used in concept development and the discussion.

2.1 Definition of Modularity & Flexibility According to the Cambridge dictionary, the definition of modularity is “Consisting of separate parts that, when combined, form a complete whole” [2]. One of the pros of using a modular system is that if one part breaks down, the damage can be contained to that specific part. It also makes it easier to replace or upgrade parts. Manufacturers can also create a standardized product and give an option of customization by using modularity when creating products.

According to the Cambridge dictionary, the definition of flexibility is “the quality of being able to change or be changed easily according to the situation” [2]. Modularity and flexibility contribute to the adaptation of a surface ship. A modular design has a certain degree of flexibility but fixed boundaries. Schank explains [3] that flexibility allows the boundaries to change to adapt to different missions. One of the pros of a flexible system is that it is adaptable when conducting service or modifying the properties of the system.

2.2 Design thinking According to a study conducted by Greene et al., [4] Design thinking is a methodology in which technical and business-focused innovation activities are focused on a human-centered design philosophy. The goal of design thinking is to improve products by translating observations into insights. The innovation process is divided into four parts, which are gathering inspiration, generating ideas, making ideas tangible and sharing your story. Another study made about Design thinking is conducted by R. F. Dam and T. Y. Siang [5] where they explain that the methodology can be used in five stages. The five stages are Empathize, Define the problem, Ideation, Prototype and testing. The work process presented is outlined as direct and linear process, but is in practice carried out in a non- linear process. This means that different teams can work on different steps at the same time. An advantage with the Design thinking methodology is that it is an iterative approach which allows the user to test and redo concepts before doing the implementation.

Inspiration K. Tschimmel [6] describes that a project is framed in the first phase, where the objectives are specified with a challenge to ensure that there is an end goal. The planning is continuously updated due to new findings throughout the project, but the milestones and expectations are set early in the project to minimize miscommunications and reduce the risks of misinterpretations. The inspiration phase is where a group gains an insight into the project by gathering information through observing, literature studies, or semi-structured interviews. As well as gathering information through a tech- and trendwatching, to see what is affecting the market or product today. Due to the information being gathered from studying existing solutions, conducting interviews, and observing different scenarios,

the data is seen as qualitative. The gathered data is later translated into requirements to ensure that a user is satisfied and will be used as a baseline when evaluating possible concepts.

Ideation The insights done in the previous steps are translated in the ideation phase into possible solutions and ideas that can meet the requirements. Ideation is where methods and tools are used to expand the range of options, evaluate, and select concepts to be further developed. It is in this phase that tools such as brainstorming, divergence and convergence are used to further develop ideas. The ideation phase also focuses on being visual and to work in an iterative manner, so it is encouraged to come up with as many ideas as possible. [6]

Implementation In the implementation phase, the generated concepts are further developed either physically or virtually to showcase functions. The result of this phase is that the final concepts should solve the problem and meet the requirements of the stakeholder. This phase can also include things such as testing the product and be used to gather feedback about the developed concept, as well be used in a benchmarking against similar concepts. [6]

2.3 PDCA The PDCA tool explained by E. Lodgaard et al., [7], is an iterative method that was made popular by W. Edwards Deming but further developed by the Japanese to use as a systematic continuous problem-solving approach. The improvement method is used to help increase product quality. They further explain that there is an increased need for focus on continuous implementation. With the tool, it becomes clearer what type of outcomes are expected in each phase and how the time frame is planned for present and future work. As a method for further development, it is primarily applied to manufacturing departments rather than product development. The reason is that during product development, it is necessary to create a balance between formal processes and creative freedom. Some factors that are important when implementing the PDCA method are the following:

● Management commitment ● Knowledge on how to use the method PDCA. ● When to apply PDCA ● Efficient performance ● Internal marketing activities

The key factors are essential for successfully using the method during product development.

2.4 Evaluation Matrix The idea of the matrix is to help provide visual information about each concept and how it will perform in different scenarios where the requirements from the brainstorming are met. The tool is used to help provide information that helps the decision-making of concepts that should be further analyzed and developed, with the possibility of combining concepts. That means it is used to create credible information which can be presented and to create a better insight into the way of thinking about the generated concepts and how they meet the requirements. The purpose of the Pugh matrix is to separate the concepts so that it becomes easier to see which solutions are more important than

others, to eliminate “weaker” concepts. Pugh Matrix is a criteria-based matrix in which the scores are assigned relative to a baseline. The Pugh matrix does not require quantitative data, making it easy to use in the early phases of concept generation. [8]

H. F. Cervone [9], explains that a Pugh matrix analysis is a tool used for complex decision-making situations. It is used to provide support to help determine a course of action and gain concrete information. The Pugh matrix is based on multiple criteria bases which become easier to study. The usage of the tool is straightforward and involves the following seven steps:

1. Developing or choosing criteria for comparison During this step of preparation for the product development the criteria are defined through various work processes. An example that Cervone is discussing is that if a website is redesigned, it will result in several prototypes and each of the prototypes can be used as a criterion for the comparison. The criteria development process includes a wide variety of inputs based on the insights.

2. Selecting the factors to be compared When selecting the factors that are used during the comparison of concepts, the factors are all reframed to become more generalized. After that, the list of all factors is identified and studied to see if it is necessary to include all the factors or if some can be excluded. Lastly, the list of factors is reduced to the most crucial factors if the list is extensive, and an analysis of the factors is conducted to identify the ones that affect the decision-making process the most.

3. Draw the matrix Once the criteria and factors have been chosen, a matrix can be created. The matrix is often drawn with the criteria in the x-axis, while the factors are in the y-axis. Columns for various totals that will be generated during the analysis are also included into the matrices, as well as a row for weighting factors.

4. Assigning weights to factors Weights are assigned to the factors depending on how important they are deemed to be. This step is critical in the usage of the Pugh matrix to determine the relative importance of the factors. This step is often done in groups in which the members will assign how important they deem the factor to be. The weights that the groups come up with need to be averaged to be used in the final matrix, however if the weights that were distributed differentiate by a lot, the group needs to discuss how they reached their conclusion.

5. Define a baseline Next step is to define a baseline used for the comparison and in many cases the baseline is an already existing product. If there is no existing product to be used as baseline, it is defined as one of the identified criteria. When comparing the products to the factors it is important to keep the baseline in mind, and then rate it from 1 if it is an improvement, 0 if it is the same and −1 if it is inferior. The scale of the ratings can be changed to be more refined, for example it can be from − 3 to 3.

6. Generating factor scores The factor scores are added together to calculate a final value for the different factors. The scores that are calculated are the overall total scores which were multiplied with the weighted totals.

7. Computing criteria scores 7

When the comparison is completed, it is time to study the highest scoring products, so that it can be analyzed and further developed.

2.5 Multi-purpose ships According to Kalajdzic M. and Momcilovic N., [10] the preliminary design procedure for multi- purpose cargo vessels (MPCV) is one of the most critical stages. The designer can estimate the vessel’s length, breadth, height, and draught within this procedure. The information is gathered in a database which allows the designer to collaborate with the figures and simulate a model. This was later used in the preliminary design procedure where a designer can see the required general information. An example is that the overall length creates restrictions for the distance between the perpendiculars, breadth, and ship’s height. With this database, the designer can easily see if the measurements will meet the requirements and if every necessary system will fit.

2.5.1 MPS Life cycle costs The cost of an MPS is divided into initial fees, operation costs, maintenance, and end-of-life costs. The initial cost includes design, construction, and material purchase. The operation cost includes labor, management, and fuel cost, while the maintenance cost includes maintenance and repairs. According to the Congressional Budget Office (CBO [11] in the US, operations and support make up 49 to 56 percent of the life-cycle cost of four ships, in which personnel was the most expensive part of the cost. The analyzed ships were the MCM-1 Avenger class, FFG -6 Oliver Hazard Perry-class guided-missile frigates, DDg-51 flight Arleigh Burke-class guided-missile destroyers, and CG-47 Ticonderoga class guided-missile cruisers. The cost for acquiring the ships, research, development, and procurement, covers most of the remaining percentage, ranging from 43-50 percent of the lifecycle costs. The disposal phase of the life cycle is often dependent on if the ships are fully functional since the US Navy has sold or given them away to other countries. These numbers are based on the research and development costs among the ships divided by the number of ships purchased for each category. Using MPS, the total costs per ship would decrease since the ships are no longer bound to only one mission. When a new naval ship is manufactured, it also affects the environment with emissions by extracting natural resources, transportation, production, and delivery. A way to lower both the economic and environmental effects would then be to use MPS.

One way of lowering MPS costs according to B. Beauchamps and V. Bertram [12], is to take advantage of a modular approach, where fewer crews are needed due to the ships being pushed towards being more autonomous. This would lower the cost in both the initial as well as the operational phase. Another way of reducing the costs for the life-cycles would be to reuse salvageable materials. However, A. Largiadér [13] explains how the design of modular based surface ships faces decreasing budgets while the production costs are increased. Therefore, navies are striving to reduce costs associated with naval ship designs, production, acquisition of resources, operation, and reconfiguration of existing naval ships. Implementing modularity during the early stages of development and construction has shown that costs can be lowered while still offering design variety to the customer.

2.6 Bulkheads D. J. Eyres and G. J. Bruce [14] explains that a bulkhead is a vertical partition in a ship, which divides the ship into several rooms and watertight (W.T) compartments. It can also be used as a protection against radar systems when used on the exterior. The main hull bulkheads are made to contain any flooding that might occur in the event of a compartment on one side of the bulkhead being breached. They also carry some of the ship's vertical loading and prevent deformation of the ship. The minimum number of possible W.T bulkheads for a vessel with machinery in the middle is four. These four are a collision bulkhead fitted forward, a peak bulkhead fitted at the stern, and watertight bulkheads fitted at each side of the machinery space. This number can be reduced to three if the machinery is directed towards or in the stern, with the peak bulkhead being at the end of the machinery space. Table 1 below, is adapted from Lloyd’s Register, the oldest and largest classification organization for ships. It shows how the number of bulkheads can change depending on the ship’s length and the placement of the machinery.

Table 1: The number of bulkheads in a ship depending on its length 5 placement of machinery. Length of ship (meters) Total number of bulkheads Above Not exceeding Machinery midships Machinery after 65 4 3 65 85 4 4 8 105 5 5 105 115 6 5 115 125 6 6 125 145 7 6 145 165 8 7 165 190 9 8 190 To be considered individually

2.7 Reconfiguration Configuration of a product is done before sales, while reconfiguration refers to the configuration done on an existing product. The need for reconfiguration can be due to new requirements from customers or keeping the products up to date. Reconfiguration is more complex than configuration due to the difficulties of matching existing components to new components and functions while keeping costs down. The factors that influence the possibility of reconfiguration are product type, product cost, customer requirements, and technological changes. Nevertheless, to make reconfiguration possible, the product has to be designed in a way that makes disassembly possible. This can be done by creating modular systems instead of larger systems as a whole. [15]

2.8 Parametric CAD modeling Reusability in CAD often refers to how much CAD data can be altered to be used in different applications or designs with minimal effort. In a parametric model, the geometry of a design is made up of dimensional, geometric, or algebraic constraints. If the parameters are used correctly, the existing models can easily be altered just by editing the values of the parameters. All the features in a model are connected, which creates a network where every node represents a feature and every connection is the dependency between two features, which is known as the design tree. When feature dependencies are defined correctly, any alteration done to a node will automatically affect the bigger picture. [16]

E. J. Reddy and V. P. Rangadu [17] explains how advanced CAD modeling techniques like parametric modeling can help trim down the design time. This type of system is used to create and develop new types of spur gear designs and how it provides support from work that could take up to 150-200 hours of development. This shows how knowledge-based parametric modeling techniques provide support for users who are not experienced with the software. The developed system is easy to use, trouble-free, handy, and capable of improving the design quality and efficiency. They further explain that when using a parametric CAD modeling approach, it becomes more time effective, and the quality can be easily improved over time.

2.9 DNV-GL DNV-GL is an independent classification organization and an advisor that works with companies in maritime, oil & gas, business assurance, and digital solutions. They act as advisors and evaluate risks and quality assurance by providing testing and certifications to companies. The organization’s purpose is to safeguard life, property, and the environment by setting industry benchmarks while inventing and inspiring solutions [18]. In the maritime sector, DNV-GL provides a classification of ships and mobile offshore units, materials, and components. DNV-GL develops technical solutions and establishes regulations, rules, and verification methods to enable remote shore-based operation of ship machinery. A project in development since 2016 is the Zero-Fire Engine Room, to improve fire prevention in engine rooms. DNV-GL has since introduced a new class notation that focuses on processes and people to enhance safety barriers to prevent fires in machinery spaces. The new standards and procedures focus on preventing, detecting, and containing oil leakage, system shutdown, and ignition prevention [19].

DNV-GL classifications are used on fundamental assumptions that the other parties involved fulfill their obligations, which includes ensuring compliance with the rules. With naval authorities, the vessel’s arrangement and equipment shall comply with requirements given by DNV-GL, which are customized depending on the ship. For these requirements to be verified by the society, they need authorization from naval authorities. The work process determines the specific class request. Later on, the design process is initiated, and if all is according to the rules and classification, a plan of execution is approved. [20]

2.9.1 DNV-GL Regulations There are no fundamental regulations when it comes to S.B, the closest regulation would be sliding doors/hatches in the DNV-GL regulations. The regulation states that sliding doors should move and be supported by track-way grooves with a mechanical lock. The doors need to be designed to withstand pressure from both sides, and the thickness should be no less than the minimum bulkhead thickness. [21]

The DNV-GL regulations state that the bulkheads must be constructed to prevent the passage of smoke and fire from 0 to 60 minutes, which is described as A0 to A60 as seen in table 2. The bulkheads should also be insulated with non-combustible materials to maintain low temperature in the unexposed area. The temperature on the unexposed side is not allowed to rise more than 140℃, nor rise over 180℃ above the original temperature in the room within 60 minutes. [22]

Table 2. In the table the different classes for fire protection are shown. A60 60 min

A30 30 min

A15 15 min

A0 0 min

For the electrical installations in naval ships, the regulations state that there needs to be a ventilation system to ensure that the temperature does not exceed a certain limit. These limits are different depending on the purpose of the room. For example, in a dry cargo holding location, the temperature range should be between −25 to 45℃. Other regulations are that the arrangement of the electrical installations should not affect machinery or equipment and that there is continuous service on all electrical parts. [23]

3 Method During this master’s thesis, the work process has been based on the methodology design thinking’s three phases [6]. The method provides support to analyze the importance of each phase throughout the project processes and the focus has been to collect and present visual data to stakeholders to gather feedback on possible solutions. Design thinking was used due to the familiarity with the process and that it is a solution-based method. Another reason for using the methodology as explained by Greene et al. [4]. is because it focuses on taking a user-centric perspective, embracing ambiguity, and creating tangible abstract concepts.

3.2 Inspiration During the inspiration phase, the aim was to work in three more extensive fields. Firstly, a literature study was conducted to create a theoretical background for the research questions. Secondly semi- structured interviews were conducted with stakeholders, to plan and frame the work process in the thesis. Lastly during the inspiration phase information was gathered through a trend- and a techwatching process.

3.2.1 Information gathering The information gathering was done with BTH Summon [24] and Google Scholar to collect relevant information to answer the research questions. Information acquired during the thesis are based on reports and information surrounding the progress of the US Navy that was made public. Additional information was obtained from thesis works that have been relevant for the research questions. The critical factor was that the information was related to the research questions presented in this thesis and also had reliable sources that the information was built upon. Before any literature was used, the contents were studied to see if it was relevant to the research questions and to gain an insight to existing theory.

To reassure that the literature study provides answers to the research questions, it was studied and compared with the delimitations made during the initiation phase. The data collected was based on qualitative information and not on quantitative, because most of the data used are published from reliable sources such as researchers for the US navy, Saab Kockums, or peer-reviewed articles. The qualitative data gathered was used to provide context for the trend- and techwatching and as basis for background information.

3.2.2 Trendwatching During the trendwatching, possible trends were studied to understand what their effects on the naval ship´s market. The trendwatching helps to gain a broader insight into how a developed solution can be adapted on older ships to extend the life cycle. To better understand the requirement from the stakeholders, it was essential to understand what types of mission’s naval ships can conduct and how they affect the naval ship market. Trendwatching was one of the bigger areas during the inspiration phase. This is because of the significant impact trends have on the development of new naval ships and their systems.

3.2.3 Techwatching The techwatching is performed to gain a deeper understanding before conducting the brainstorming sessions. The focus of the techwatching were different types of technologies used in payload arrangement as well as existing MPS. The analysis of the existing technologies was focused on how cargo is handled without endangering the personnel. Some techs are not adapted for naval ships and are used in various cargo transportation systems, such as airplanes or trucks. The purpose was to collect as much relevant technology to be studied, to bring tangible information when later conducting brainstorming sessions. As it is difficult to always be at the forefront of technology, techwatching was one of the most important steps conducted during this master’s thesis, as was trendwatching. This is because the trends that are affecting the market are also affecting the technology developed and used in the naval industries. Therefore, techwatching was a constant process where existing solutions are studied.

3.2.4 Semi-structured interviews and presentations H. Kallio et al., [25] explains that a semi-structured interview requires a certain knowledge of the subject beforehand. The questions are determined before the interview and are used as guidelines for the participants to know what to talk about. A semi-structured interview offers structure for discussion but should not be followed strictly and enables the interviewer to improvise follow-up questions based on the other person's response.

To gather knowledge about the subject and gain more information about the issue at hand, key persons were giving presentations, and later interviewed in a semi-structured fashion. The purpose of the interviews and presentations are because the speakers are familiar with today’s problems, existing solutions, how today’s naval ships are functioning, and how the cargo space is designed. The interviews were conducted simultaneously as the weekly meetings with supervisors. The interviews started with a description of the progress done weekly and turned into discussions about the work done so far and possible next steps. When using the semi-structured interviews, a positive outcome from the conversation between the participants becomes more fluent and the discussions are not equally strict. A negative aspect of this type of interview is that some aspects are easily neglected if the interviewee does not have enough knowledge about the subject.

3.3 Ideation At the start of the ideation phase, brainstorming sessions were conducted to generate a requirement list. In the later stages of ideation, sketches of concepts and pre-totypes were generated based on the requirements to be visualized and presented for the stakeholders. A pre-totype in this thesis is defined as a simplified version of an early prototype where it explains the functions in an overview description or a sketch.

3.3.1 Idea generation phase When starting the idea generation phase, a tool called PDCA was used, where the solutions gathered from the techwatching are studied and analyzed. This helps gather factual information during the techwatching stage and provides inspiration for the generated concepts during the brainstorming sessions. The brainstorming was done in multiple iterations, first individually and then in a group. It took place at the office assigned by Saab, which meant that no photos of the sessions were allowed due to security reasons. To help create more concepts during the idea generation, a generalized cargo space was 3D printed. The model was used as an inspiration for the brainstorming sessions as well as

to demonstrate the concepts. During these iterations, each individual had a set time to develop concepts and, after the set time, present their ideas. After each session, a pre-totypes was created, with a short description of how the idea could work or a simplified sketch. So that when sharing the idea, it was easier to explain in a simple way to the other participants of the session so that they could understand what it is and its functions. With the help of these sessions, multiple concepts were generated and can be combined into an improved concept that can meet the stakeholder’s requirements. After multiple concepts had been generated, the most beneficial concepts that meet the requirements are analyzed in an evaluation matrix.

3.3.2 Requirement list After the conducted interviews and trend- and techwatching, a requirement list was created with three different categories. Its purpose was to provide support during the idea generation and to show what was most crucial from the phases that have been processed. The different categories created are critical, good-to-have, and nice-to-have. When the idea generation was initiated, it was easier to see what requirements were satisfied and where there were flaws. This helped to show if there was a need for more analysis and redesigning of the concepts. The defined requirements explain what the solution should involve and how it can solve the most crucial aspects. Therefore, the requirement list was constructed with the help of the analyzed information collected during the literature study, semi- structured interviews, and presentations. These requirements were altered and rearranged throughout the project since more and more information were gathered and analyzed. It helped provide information about how the different requirements affect the existing systems and what was most crucial for them.

3.3.3 Evaluation matrix When the idea generation had been conducted and numerous concepts were developed, they were compared in an evaluation matrix known as the Pugh matrix. The different concepts were put into the three categories: bulkheads, reconfigurable floors, and lifting mechanisms. The concepts were graded from -1 to 1, where 1 is an improvement, and -1 is inferior or can be harmful compared to the baseline. A grade 0 means that the solution was not an improvement or inferior when compared to the baseline. In some cases, the grade 0 also had to be put due to not having enough information to make a fair grading. The highest scorer in each group was designed and put together with the two other winners to create a more extensive system.

The concepts were given a weight that corresponds to how vital the requirements were according to the stakeholders. The weights were graded from 1 to 3, where 3 is a critical requirement. Grade 2 is a good-to-have requirement, while grade 1 corresponds to a nice-to-have requirement. The evaluation matrix was done once more after getting the highest scorer in the first phase. This was to try to create the optimal concept by combining the concepts with the largest scores with each other.

Positive aspects of using a Pugh matrix were that it is focused on developing concepts in early stages while comparing to the requirements. It was easy to understand the outcomes and how it was meant to be used. A negative aspect was that the concepts were not evaluated in detail as it could be using another tool such as Quality Function Deployment (QFD) or House of Quality (HoQ).

3.3.4 Pre-totypes When the concepts had been generated from the brainstorming sessions, various pre-totypes were made. A pre-totype in this thesis was defined as quick sketch or simplified description. The pre-

totypes were created of the highest scoring concepts, the purpose was to gain an insight into what flaws could be found during the concept development. Pre-totype is a way to provide information in a visualized way by creating a simplified sketch or using physical material to provide a visual presentation. This helped to give essential information if the idea did not meet the requirements and brings forth the flaws early in the product development to be redesigned before an actual prototype is created.

The main idea of creating pre-totypes was to understand how they could be used to create modular and flexible functions in naval ships. When a concept is shown in a visual presentation, it helps to provide information that can be missed from a short description or a simplified visualization of the concept. This working method benefits the early stages of development due to the risks of having to redesign the whole concept if the requirements are not met. This shows that when creating a pre- totype, it can visualize the flaws before a prototype is constructed, which saves time, money and gives new knowledge on what can go wrong. The negative aspects of creating pre-totypes is that it can lead to attachments to the idea, instead of seeing flaws that need to be redesigned. Because of this a concept that does not solve the issue could be developed too much and waste time.

3.4 Implementation During the implementation phase, the idea was to further develop the chosen concept that meets most requirements. It was analyzed and then further developed with the help of Autodesk Inventor Professional, to visualize the concept and its functions.

3.4.1 Parametric CAD modeling A more complex visualization of the concept that had the highest score from the evaluation matrix, was developed and modeled by using parametric CAD modeling. The concepts were created in different 3D models and assembled with the help of the tool in the software called Assembly. When using this tool, requirements must be detailed and easy to understand. So, when the idea is further developed, it was easy to understand how each aspect is helped meeting the set requirements that are “crucial”, “good-to-have", or “nice-to-have".

When a model had been developed in Autodesk, it was easier to analyze the functions that were not equally detailed in a simplified sketch or a brief description. This process helped to generate essential information to study any possible flaws. Later the model was analyzed by comparing the specifications to the requirements found in the requirement list to provide tangible data on what needed to be redesigned. The purpose of parametric CAD modeling was to provide complex visualizations of each part connected to the solution. Due to each part being modeled separately, it became more apparent if there were critical flaws that needed to be redesigned or if the application did not match with the other parts created. Therefore, this method helped provide data and complex models that could be used during tests and presentations to stakeholders, where they could see the functions of the solution.

A positive aspect of using the work method parametric CAD modeling is that if there is a need to make changes during early stages of the development, it automatically updates the complete product by changing parameters. But if the changes are done in final development stages it takes more time to update the full model. Another advantage is that it is easier to capture design intentions of how the model should behave when the parameters of parts are changed. The difference between parametric

CAD models and direct modeling is that with a parametric CAD model the designer is building the product piece by piece, and in a direct modeling method the product is built as one part.

4 Results

4.1 Trendwatching This section shows the top trends that are affecting the naval market today, these trends are divided into system and design trends.

4.1.1 System trends In this section, the focus is on analyzing trends affecting today’s naval ship purposes and the design for modularity. The reason for the system changes is the development of existing technology, such as electrical-powered ships and unmanned surface vehicles. These changes use different designs without creating a demand to redesign the ship’s interior or the hull.

All-electric ship Today's ships are driven by primary diesel, gas turbines, or nuclear engines, which generate electricity used for all ship functions such as turning a propeller, driving pumps, and opening and closing W.T doors. One vision for the future is that they are entirely autonomous and filled with sensors connected to external computers to monitor the internal conditions of the ship. The main reason for changing the conventional ships to become more electric powered is because the propeller shafts connected to the prime movers and propellers take up about a third or more of the total length of the ship. If there would be any damage to that part of the ship, that affects the shaft, it would immobilize the ship. An all-electric ship can instead have several alternative paths to carry electric power from the engine to the propellers. [26]

Beauchamps and Bertram [12] explain that a possible trend for the future is high-powered fuel cells, which can operate at low temperatures and eliminate the optical signatures that ships currently create. This new operating system can be driven on hydrogen and oxygen if the oil has been abandoned as a fuel. If this were implemented, it would require a complete redesign of existing ships, and a lot of conventional ships would be almost impossible to modify for this purpose. Furthermore, according to N. Friedman [26], there is a potential adaptation with these electric ships for electric weapons. The vision is to create more advanced weapon systems powered on electricity and combined with the ship’s driving systems. The disadvantage with the present electric motors and transmission cables is the weight and size. The transmission is also less efficient than mechanical transmission when it comes to propulsion, while vibrations due to high power transmission are still a problem.

Unmanned surface vehicle Due to wars today being fought primarily in coastal regions worldwide against adversaries who possess increasingly more effective systems that place people in harm's way. Creating unmanned surface vehicles (USV) has therefore become one of the more critical research areas for militaries. Significant research has been conducted on unmanned underwater and aerial vehicles, but few efforts have examined USVs. Within the U.S. Navy, a “Master plan” has been developed where the idea is to create a flotilla of the USVs. These USVs have different application areas such as MCM, ASW, maritime security, surface warfare (SW), special operations force support, electronic warfare, and maritime interdiction operations support. Within the “Master Plan,” four different USV classes are defined: X-class, Harbor-class, Snorkeler-class, and Fleet-class. The thought behind using USVs is the capability to execute an independent operation, so it is essential to research how artificial

intelligence can be improved. It is believed that soon the level of intelligence of the USVs will enter a new phase, where the vessel can be used in more applications, both in the military and the civilian service. [27]

Z. Liu et al. [28] explains how the interest in USVs has grown worldwide in commercial, scientific, and military aspects. The development of fully autonomous USVs uses different technologies such as guidance systems, navigation, and environment perception. Beauchamps and Bertram [12] further explains that unmanned ships have been a vision for circa three decades. However, due to the complexity of naval ships, companies are trying to decrease the amount of personnel instead of creating an utterly unmanned ship. One example that shows how much automation helps to reduce the number of sailors is the French frigates from the 1960s, where the personnel consisted of 250 sailors. The modern Lafayette frigate has 150 personnel, and for the future frigates, their vision is to decrease the personnel needed down to 100 onboard for their multi-mission frigates. The need for personnel on board is because some applications cannot be controlled by computerization. Some examples of these applications are collision avoidance, target identification, combat guidance, and damage control.

4.1.2 Design trends According to Friedman [26], the trends for designing warships have been affected primarily after the Cold War. The ships were either operating against land targets or imposing maritime interdiction far from home. One developed trend after the cold war is ASW, where ships deal with diesel-electric submarines operating in relatively shallow water. While the trend to create countermeasures against mines has changed from detecting the mines to clearing or building a home defense. These trends are affecting the interior and the exterior of these naval ships where in some cases, whole sections have to be added or remodeled so that they can work properly. The article helps to understand the meaning of the trends, how they have affected older naval ships, and how it affects todays and future naval ships.

Atkinson and Skinner [29] explains that there was an inadequacy in equipment that needed to be compensated by having better-trained personnel onboard. Because of this, there has been a need to move away from the trend “crewing the equipment” to “equipping the crew”. Equipping the crew would change the training and education but help the personnel to think through and solve problems tactically for example in warfighting and logistics support.

Stealth Another significant trend that Friedman explains [27] is the stealth function, which affect today’s naval ships to make detection more difficult for radars. The design of naval ships has been remodeled so that the hull makes an angle with the water and forms a corner reflector, as shown in figures 2 and 3. The radar system has to catch the reflection from the same angle as it bounces from for it to be visible on the radar. Therefore, some equipment that cannot be re-designed and moved from the deck, are shielded by bulkheads or screens, to create an angle which prevents radar systems picking up reflections. The first prominent example of these types of ship designs came in the late 1990s, and it was the French Lafayette class frigate.

The stealth designs are more frequently found with the future combatant designs where it involves geometries with larger flat areas so that the angles are inclined. But with the development of these hulls, the radar systems are also getting more intelligent in filtering weak radar signals caused by waves. It is a race between stealth technology and radar systems. Therefore, the future naval ships must include more advanced stealth features to “stay in the game” during their life cycle. While it is

easy to develop and change the equipment of naval ships, many existing ships have to be re- manufactured to achieve the stealth function. [12]

Modularity A general trend that has been developed to decrease the production of naval ships is modularity, that more ships should become usable in larger varieties of missions during their life cycle. The advantages of creating modular designs are that it decreases the initial cost and lowers operational costs. However, the effort during the initial design process is increased, as is the training and reconfiguring of the naval ships. The idea behind the trend is to design naval ships to be more modular for different operations, to extend the life cycle of the ship. This makes designers push for naval ships to be more modular, which requires that it is considered early in the development phase. [12]

According to Friedman [27], the trend of modularity is affecting the market, as it is a way to reduce the number of ships and to force costs down by using modularity. One application of the modularity idea is to create a hull machinery combination that can be used for various purposes, e.g., German MEKO naval ship. The hull and machinery are adapted to a wide variety of containerized weapons and sensors. Thus, the naval ship does not need to be redesigned for each customer. Another implementation of modularity is what the Royal Danish Navy found during the 1980s where they had to replace numerous fleets of small ships commissioned during the early Cold war. They realized that the same ship could be used for multiple missions by changing containers on board, because wars in the future would be fought in phases. For example, coastal surveillance would proceed with a phase of minelaying, missile, and torpedo combat.

While in the U.S., the LCS is a different version of how modularity has been implemented in ships. The idea behind the LCS is a “plug and play” combat system that creates an alternative modular payload system, which generates the modularity functions. Typically, the LCS operates to support unmanned vehicles such as air, surface, and underwater. An example of a modular process with the LCS is the supporting function of using sensors, creating an acoustic array laid on the seabed. These sensors announce if a submarine passes over it and can register the course and speed, which results in a track that can be followed. The advantage of separating these modules from the hull is that it will make it possible to design a cheaper hull that can be manufactured on larger scales. The cost of ships is one of the most challenging aspects to estimate of ship manufacturing. Naval ships need expensive technology to deal with advanced threats, which led to the manufacturing of LCS. The LCS combines advanced technology with a lower cost by separating the cost of the ship´s combat system from the ship. It has large open spaces for modular combat systems, which led to a cheaper cost for manufacturing an “empty” shell. The LCS combines high speed with modularity, which offers various roles and makes it possible for different missions such as MCM. [27]

One reason that modularity has been developed according to Largiader [13], is due to purely standardized products failing to meet customer’s requirements. This shows that today's customers no longer want a standard mass production, because they are easy to duplicate compared to a customized product. Some of the reasons for not wanting mass productions is that it could affect the quality and increase the competition for shipbuilders since a duplicate can go for a lower cost. The best method for achieving modularity is by creating modular components that can be resized into various end products and systems.

Flexibility R. Adland, et al., [30] describe cargo flexibility as creating a more significant customer value. An example shown by them is how a seaborne oil transportation market is distributed by two different vessels, crude oil tankers and product tankers. The design of the product tankers is to transport refined oil products, yet there is a possibility that they can transport “dirtier” products, such as crude and heavy oil. If the product tanker is transporting the “dirtier” products, there is a need for the customer to pay for the cleaning of the tank so that when it is transporting the refined oil, it does not get contaminated. They explain further that when an oil tanker can transport various types of oil products, the estimated value is increasing. The market has some periods when the “dirtier” products are more appealing than the refined oil. This shows that the value of using existing ships flexibly to transport different oil products has increased over time.

S. Garver and J. Abbott [31] explain that flexible naval ships are often described as plug-n-play or Lego. They further explain and compare the flexibility of these naval ships with the features of a desktop computer. The comparison is based on the fact that a computers software and hardware interfaces enable the possibility to change the capabilities depending on what is added or removed. The challenge they present with flexible ship design is creating the simplistic concepts of Lego and plug-n-play to make them work in a real-world system as complex as a naval ship. Furthermore, they explain how a flexible naval ship can be changed to adapt to various missions and be eligible for upgraded equipment. The benefit of a flexible naval ship is the improved mission effectiveness at a lower cost.

M. Choi and S. O. Erikstad [32] addresses how a single modular ship can create an affordable reconfiguration for different operations, leading to flexibility. This provides the stakeholders with an option to delay investments until the specific technology is available. An example of the flexibility with modular ships is that a cable laying vessel can be used as support during diving operations by replacing particular modules. With these modular ships, operational flexibility has received growing attention in maritime industries due to the economic benefits. It helps stakeholders track technology development and use one hull for more than one purpose.

A flexible infrastructure also permits a reconfiguration of spaces during ship construction, reducing construction costs by eliminating hot works such as welding. Flexible spaces are an effective way to lower costs and add adaptability to some areas of a ship. Flexible spaces would reduce labor costs during construction and reconstruction during the life cycle [4].

4.2 Techwatching Some examples of how modularity and flexibility are implemented to existing surface ship is His Swedish Majesty’s ship (HSwMS) Visby-class corvette, LCS, mine countermeasure vessel (MCMV), and USV. The information gathered on these surface ships is used to gain an insight in today's ships and to provide support for the concept development.

4.2.1 HSwMS Visby-class corvette One of the more known surface ships that Saab has today is the HSwMS Visby-class corvette. The Visby corvette was first launched 20 years ago and is still one of the best in naval signature reduction across the full signature spectrum, including infrared, radar, acoustic, and magnetic design. The Visby-class corvette is flexible and designed for an extensive range of missions such as ASuW, ASW,

MCM, and patrolling coastal regions. The ship has an all-composite carbon fiber hull, which can be seen in figure 1, that provides some certain advantages such as speed and lower weight than a steel ship. The carbon fiber composite is superior to steel and aluminum from a fatigue perspective. The corrosion resistance also reduces the platform lifecycle cost. [33]

Figure 1. Two of the Visby-class corvettes are shown with the stealth adapted hull.

J. Städje, [34] explains in his article that the HSwMS Visby corvette has so many usage areas such as ASuW, ASW, MCM, sea monitoring, maritime security, and support to civil society in the events of, e.g., accidents at sea. What makes the Visby corvette unique is the developed stealth properties and the flexible opportunities for different mission assignments. As seen in figure 2, the left ship has surfaces that send back the reflections in the same direction as it came, while in figure 3, the reflections change direction and make it harder to read with a radar system. The hull is a sandwich construction of carbon fiber reinforced plastic, with a carbon fiber laminate outside the hull. The material of the hull is what makes it possible for the Visby corvette to minimize the magnetic signatures and not reveal its position to radar systems.

Figure 2 & 3. The figure shows how radar systems can see ships, the left is a conventional ship, and the right is the HSwMS Visby-corvette. Adaptation from the source of image [2].

Furthermore, J. Städje, [35] explains that the HSwMS Visby corvette is a naval ship at the forefront of technology. It can be compared with state-of-the-art technology in the Swedish airplane JAS 39 Gripen or the reaction engine 12, a Swedish-developed jet engine. The ship's development includes adaptable ventilation systems, preparing the ship to conduct missions worldwide and a modular weapon system so that the ship can be used in different missions against submarines, minesweeping, and surface warfare.

4.2.2 Littoral combat ships According to R. O. Work [36], the LCS is a fast and stealthy warship designed by the U.S Navy in 2001. It was designed for operations in shallow coastal waters to combat diesel submarines, mines, and smaller boats by alternating the operational modules. For example, it is supposed to provide coastal support for land troops or clear coastal regions from submarines or USVs. The LCS can be reconfigured for different missions in a short time due to its flexibility and the design for the ship is based on six principles:

1. Be fast 2. Get connected 3. Modularity 4. Off-board 5. Unmanned 6. Reconfigurable

To minimize the costs of the LCS, it is developed to be operated with minimal crew thanks to the ship being highly automated. The reconfiguration process is done faster by designing the ship’s hull around modular mission stations. A modular mission station is done by separating the ship’s mission capability from its hull form and dividing the crew into core and specific mission crews. So that only the necessary personnel for the different missions are onboard during the voyage.

Furthermore, Work [36] explains that the visions for the LCS is to be a component in a more extensive fleet that provides support during missions, which explains the ship's design. The design of the ships is to be fast and reach speeds of 45-46 knots, and it will be capable of operating in high- speed naval tasks, such as clearing mines and keeping up with fast amphibious vessels. The goal with the LCS is to make them more modular so that the payload can be changed, and the volume can be increased/decreased if necessary. The initial LCS prototype designs made it possible to carry three different mission packages: shallow water ASW, MCM, and one for anti-ship warfare. One key aspect that became vital was to create the LCS autonomous, because the most expensive component of a ship's life cycle is the personnel. The numbers of officers and personnel needed to sail the LCS will be approximately 75 sailors, while for a carrier combatant, it could be more than 350 sailors. With the LCS design being so modular, it can operate a wide array of unmanned aerial, surface, and underwater vehicles, where all are designed for autonomous or semi-autonomous operations. The last key aspect is that the ships are designed around modular mission packages, where the crew is divided into core and mission crews. Because of this, the lead time to reconfigure an LCS ship will take no more than four days which is a rapid process, and it allows a single hull to be used in multiple missions since the LCS is much smaller and easier to handle than other Navy ships. It also has a high-bandwidth command and control system, which connects the ship to the broader battle network sensor set. To accomplish the required missions, the LCS serves as a mothership for off-board systems and sensors.

The LCSs constitute a new class of fast, agile, and networked warships designed to overcome different threats in coastal and shallow regions. The dangers that the ships are supposed to overcome are mines, diesel-electric submarines, fast-attack craft, and fast inshore attack crafts. The three primary missions that the LCS are planned to be used for is Mine Warfare (MIW), ASW, and surface warfare (SUW). The heart of the concept with the LCS is modularity and consists of two elements. One element is the sea frame which includes the platform and inherent combat capabilities, another element is interchangeable modular plug and fight mission’s packages, which allows the ship to be reconfigured for ASW, MIW, or SUW missions. This allows the ship to become more flexible and usable for multi-purpose tasks [37].

4.2.3 Mine Countermeasure ship Since the development of the mines in the 19th century, it has been a valuable and cost-effective weapon against warships. This has led to new and higher demands on MCM systems. The MCMV 47 in figure 4 is one of seven ships that have been delivered to the Royal Swedish Navy. The primary role of the ship is mine-hunting, while minesweeping is the secondary role. It was designed as a multi- purpose ship that could perform various MIW tasks and participate in ASW. Some of the requirements for a MCMV is [38]:

● High resistance to explosions underwater ● Low signatures, such as acoustic and magnetic outputs ● Excellent maneuverability ● Electromagnetic compatibility

Figure 4. The MCMV 47, is shown in the figure.

4.2.4 SAM 3 Minesweeping USV Saab Kockums has developed a new type of construction where the vessel is an autonomous surface ship. The purpose of the SAM 3 minesweeping USV is to use an accurate imitation of the magnetic and acoustic signatures from a surface ship. It can detonate mines without placing personnel or naval ships in harm's way, due to it being either remote or autonomous controlled, which is one of the significant features provided. Therefore, it can be used from safe distances and provide intel. It is also equipped with a developed software, where it is possible to change the signature of the outputs to detonate new intelligent mines while at the same time being extremely resilient to shockwaves. Due to

its size, it needs to be separated into two parts when transported in the designated containers by land, sea, or air. This gives the possibility of connecting two separate vessels, which creates a flexibility function. The flexibility and modularity of the ship provide a fast launching, swift deployment, due to it being able to be mounted/dismounted within 24 hours. The SAM 3 can be seen in figure 5 [39].

Figure 5. The figure shows the SAM 3 vessel that is developed from Saab Kockums.

4.2.5 Existing solutions Loadmaster - Vanloda The company Loadmaster [40] has developed a product which is used with smaller vehicles and can load and unload three to four pallets up to 1000 kilos. The system is operated by a pneumatic system to raise and lower a roller bed which provides support when loading and unloading the cargo. It is powered by connecting the system to the cigarette lighter sockets of the vehicle, so that the roller bed can be controlled by the driver. This is an example of a reconfigurable floor in which the user can add or remove modules depending on how much space is needed for cargo management.

Keith Walking Floor - Walking floor Keith Walking floor [41] is a company that developed a horizontal loading and unloading system used in trucks. The walking floor consists of a series of slats powered by hydraulic drive, which functions as the flooring of the cargo space. When the walking floor is activated it “walks” out or in the load automatically. This kind of system provides unloading options in spaces where tippers and dump trailers cannot access such as inside buildings and tunnels.

Actiw - LoadPlate The product Loadplate is a system developed by the company Actiw [42]. The product is a semi- automated loading machine that is used for container and non-modified trucks to load and unload complex or long cargo, examples of cargo is steel or lumber. When using the LoadPlate, the truck can be loaded with 30 tons of cargo in only five minutes, it also improves the work safety and prevents handling damage of cargo.

The lifting mechanism used most frequently was the scissor lift and some examples of airlifts. An example of companies that used airlifts was Airfloat [43]. Their solution uses a pneumatic system to provide support to rearrange heavy cargo. It uses the same principle as a hovercraft in that the device forms a lubricating film of air between the load and floor surface. A flexible urethane diaphragm is inflated by compressed air and lifts structure off its rest pads. Another example of a lifting mechanism

is the hydraulic lift table developed by Align Production Systems [44]. The lift table is easily integrated with existing systems, and it is able to be customized for various needs.

4.3 Ideation Here the requirement list, concept generation and the evaluation matrices are presented. The generated concepts from the brainstorming sessions are presented for the different parts, the R.F. and S.B. The model in figure 6 was used during the brainstorming sessions for the concept generation and then used to present how and where ideas can be implemented in a cargo space.

Figure 6. In the figure, the physical model of a generalized cargo space is visualized.

4.3.1 Requirements list During discussions with personnel from Saab Kockums, the requirements were clarified through semi-structured interviews. Some requirements are more important for the solutions, which are the critical requirements. There are also good-to-have and nice-to-have requirements. Each part is divided during this section to be analyzed before combined as a complete system.

Reconfigurable floors The requirement list for the R.F can be seen in table 3 below, the needs are divided into three categories. The most critical requirements are shown in the first category, which has to be included within the solution. The reason for the critical requirements was to create a solution that is safe to use for the personnel. Then there are the good-to-have requirements which give easier usage and provide support to the personnel and then some requirements are nice-to-have.

Table 3. The requirements for the reconfigurable floors. Critical requirements Good-to-have requirements Nice-to-have Requirements

It should not affect the W.T Easy to maintain. Plug & play for more bulkheads. straightforward adaptation to different ships

HVAC, piping, and cables It should be time-effective to The R.F should be divided into should not be affected by the move cargo or adapt the R.F different segments so that the usage of R.F. for more/new equipment. cargo space can be used for more than one purpose at a time

The R.F should not obstruct the The reconfiguring of the floor fastening of cargo should not need a large crew

The R.F should be corrosion Minimal safety risk for resistant personnel working close to R.F.

The R.F should be safe to use The R.F should be during voyage, loading, or deformation-resistant unloading cargo for the personnel.

Easy to maneuver the cargo on the R.F.

DNV-GL classifications (Fire-, water, dust-proof) for the R.F.

Sliding bulkheads Some critical requirements for the sliding bulkhead are that it should not affect the watertight bulkhead, the placement of the R.F, and that it should not obstruct the fastening of cargo. These requirements had to be included in the solution because without them, there are risks that the naval ship’s interior could be harmed. Thus, some requirements are more of a good-to-have character rather than being critical. For example, one of the requirements is minimal safety risks for the personnel, the reason for it not being a critical requirement was that it could be prevented if the personnel are following the guidelines included with the solution. And for the nice-to-have requirements is that the S.B. should be time-effective when rearranging it in the hull, which is not necessary for how the solution is supposed to be designed or function. Table 3 can be seen below, where all the requirements can be seen.

Table 4. The requirements for the sliding bulkheads. Critical requirements Good-to-have requirements Nice-to-have Requirements

Should not affect the W.T Easy to maintain The S.B should be time- bulkheads effective to rearrange and adapt for different purposes.

HVAC, piping, and cables The S.B should not need a should not be affected by the large crew to reposition usage of S.B.

The S.B should not affect the Minimal safety risk for placement of R.F. personnel working close to S.B.

The S.B should not obstruct the fastening of cargo.

Possible to maneuver the S.B without damaging cargo

The S.B should be corrosion resistant

The S.B should be deformation-resistant

The S.B should be fastened during a voyage

DNV-GL classifications (Fire-, water, dust- and tight proof) for the S.B.

4.3.2 Reconfigurable floor concepts Concept 1: Pallet Loading floor With the pallet loading floor, the idea was to create modules where each section is built when needed. The idea was that the cargo area is installed after what type of cargo/equipment was supposed to be loaded into the naval ship. The floor can later be reconfigured by the personnel on the ship and attach more modules to expand the space, if needed. It is supposed to be powered by a pneumatic system or electrical system to keep each module attached during the voyage, loading, and unloading of cargo. How the modules are attached can be seen in figure 7.

Figure 7. In the figure, a pre-totype of the pallet loading floor is visualized in a sketch.

Concept 2: Walking floor The walking floor concept was based on an already existing solution that is available for trucks and often used when delivering large amounts of goods. The walking floor is made out of different segments which are placed vertically along the length of the cargo space. Using a hydraulic system, each piece of the floor moves forward and back individually until the cargo gets pushed to the edge. This simplifies the loading and unloading of the cargo since the hydraulic system does all the work of pushing the cargo.

Concept 3: Load plate The idea behind the active load plate was that there is a platform where cargo is placed with the help of an overhead crane or a forklift in the cargo space. The platform was designed as a large table which is able to be raised and lowered, using an electric installation. There is a combination of different systems such as a walking floor and conveyor systems that keep the cargo in place on the platform. By having different systems combined on one large platform it becomes easier to move cargo onboard the ship without having to use an external machine. The rollers that push the cargo on and off the platform are flexible and can be adapted to different cargo sizes, e.g., if it is a large container or if it is many smaller boxes. With the combination of conveyor systems and walking floor, a more robust feeling is created when moving cargo between different segments of the floor. To see the combination of the different systems, see figure 8.

Figure 8. In the figure a pre-totype of the active load plate is visualized in a sketch.

Concept 4: Cargo floor rollers The cargo floor rollers are made up of smaller segments with roller wheels on them. By separating the floor into smaller segments, the maintenance becomes much more accessible if something is not functioning correctly. The floor also includes a fastening mechanism that can be pulled up from the floor to hold the cargo in place. The fastening mechanism will be placed between the segments with regular intervals and moved depending on the size of the cargo. A sketch with the rollers and the fasteners can be seen in figure 9.

Figure 9. In the figure a pre-totype of the cargo floor rollers is visualized in a sketch.

Concept 5: Conveyor system The fifth concept was to use a caterpillar conveyor system to load and unload the cargo. The conveyor system is made up of one larger segment and smaller segments. The cargo is first loaded onto the large segment which will transport it further in and then pushes it into smaller segments that branch

out. The segments should be able to rotate to maximize the area available but also depending on the shape and size of the cargo.

Concept 6: Pillar system with sensors This concept is based on using pillars with small wheels that can be raised and pushed down with help from pneumatic systems to ease cargo relocation. For easier maneuvering with the system, each pillar is equipped with sensors to identify if the wheels need to be raised or pushed down. When working with this system, the personnel can be decreased, and there is no need to use much force. Later, when the cargo is supposed to be fastened, the complete rollers can be raised to create a barrier in each direction. This minimizes the work needed around the cargo and saves area for more cargo because it does not need to be fastened to the walls or floor using tensioning belts.

4.3.3 Sliding bulkheads concepts Concept 1: Garage door-inspired bulkhead This concept was inspired by a garage door system, where the bulkhead can be pulled down from above. By having tracks at the roof, the bulkhead can be moved throughout the whole cargo space. There are also tracks alongside the walls of the cargo space with regular intervals depending on how much space is needed. The bulkhead uses an electric system to move along the cargo space and to move up and down. The garage door system can be seen in figure 10.

Figure 10. In the figure a pre-totype of the “garage door” is visualized in a sketch.

Concept 2: Pillow bulkhead The concept of a pillow bulkhead system is that the bulkhead corners are covered by an inflatable rubber which is adaptable to the surface. To inflate the rubber, a compressor system is used. The complete bulkhead is moved by using an electric engine to help provide movement through the entire cargo space. The idea behind using inflatable rubber is that it provides specific functions such as high friction so that it can be fastened anywhere without damaging the personnel, floor, HVAC, piping, or cables. The sketch of the pillow bulkhead can be seen in figure 11.

Figure 11. In the figure a pre-totype of the “Pillow bulkhead” is visualized in a sketch.

Concept 3: Foldable bulkhead Vertical system In concept 3, the idea was to create a foldable bulkhead from the ceiling, which is driven by an electrical engine to move forward/backward along the cargo space. It would provide more space and easier access to the cargo when loading and unloading the ship. By having the bulkhead folded on the ceiling, it is easy to fasten to attachments on the floor, but it also brings risk and issues during maintenance of each section. There are safety hazards with the system, such as if the locking mechanism does not work, and unfolds at the wrong place and hurts personnel, floor, cargo, or the interior of the ship.

Concept 4: Foldable bulkhead Horizontal system Foldable bulkhead from walls which is driven by an electrical engine to move forward/backward. The bulkheads are built like a gate and divided into two parts in the middle. The two sides fold up to the sides when not in use and can act as a wall. By having tracks alongside the cargo floor, the doors can be moved throughout the whole space. It can be operated by an electric system that closes the doors whenever a segment needs to be separated.

4.3.4 Lifting mechanisms For the lifting mechanism, the purpose is to adapt an already existing solution to be integrated with the highest scoring concept from R.F and S.B. The solution is not newly generated, but an existing solution commonly used in areas such as the transportation industry and production facilities. The solution that is adapted to the system is a scissor lift which can elevate the R.F to the upper deck. The reason for choosing the scissor lift is that multiple scissor lifts together can create a floor segment.

4.3.5 Evaluation matrix The analysis of the concepts as well as the weight for each requirement is validated by semi- structured interviews, together with the stakeholders. The matrices were created by using the seven steps explained by Cervone [9]. The scores were generated to determine which concept should be further analyzed and developed. The scores are marked in green for positive properties, red for negative and yellow if equal to baseline. The color scheme for the total scores is blue if larger than 10 and red if equal or lower to 10.

Reconfigurable floor evaluation In figure 12 is the evaluation matrix for the R.F and the highest scorer of the group was concept one which was the pallet loading floor. Runner up was the cargo floor rollers at 15 points. The concept with the least points was the walking floor, and this is because the usage of the walking floor affects a lot of its surroundings. One of these reasons is that the full length of the plates works together to make the floor “walk”, which means that all the cargo needs to be lifted out in one round. This makes taking out specific cargo without moving the rest of the shipment difficult.

Figure 12. In the figure, the Pugh matrix used for evaluating the different concepts of R.F. is shown.

As it is seen in figure 12, the pallet loading floor scored a 0 on not affecting HVAC, piping, and cables. The reason for that is that it depends a lot on how it is installed into the existing cargo space. The system has a positive score on the requirement “Should not affect the W.T bulkheads” due to the system having a low height and weight depending on the choice of material as well as the installation. While for the active load plate where there is no tangible information for how it will affect either the W.T bulkheads or existing systems installed. The pallet loading floor also provides easier

maneuvering of the cargo in two dimensions compared to the active load plate which can only maneuver the cargo in one dimension.

Sliding bulkhead evaluation Figure 13 below is the evaluation matrix for the S.B, where the garage door concept scored the highest. The concept that scored the lowest was concept 3, the vertical folding bulkhead.

Figure 13. In the figure, the Pugh matrix used for evaluating the different concepts of S.B. is shown.

The garage door concept provides a system where it is possible to integrate the HVAC, piping, and cables to the railways where the bulkhead is relocated but it was graded as 0 because there was no information about the installation aspect. One of the reasons for the low scoring of the vertical system is that it is not robust compared to the other solutions. The solution's movement is similar to a folding wall, which means that the robustness of the concept is low. There is also the aspect of keeping the folds up when the bulkhead is in function, any damage to the fastening mechanism could result in major accidents to personnel or cargo. Another important aspect for the bulkheads is the implementation of the DNV-GL regulations. As it can be seen in figure 13, most of the concepts were graded 0 because there is no tangible information that can be applied to the systems. But the garage door bulkhead follows the regulations for a moving door or wall.

4.3.6 Combination of concepts In figure 14 below, two new concepts were added to the reconfigurable floor matrix. The concepts are combinations of the pallet loading floor and cargo floor rollers and the active load plate with cargo

floor rollers. The highest scoring of the new concepts is a combination of concepts 1 and 4 while the combination of concepts 3 and 4 was inferior compared to the original scores. The reason for choosing these concepts to combine was to improve the highest scoring concepts. Since both pallet loading and active load plate are larger systems that can cover a larger area, the cargo floor rollers were added to improve the management of cargo and safety concerns.

Figure 14. The new Pugh matrix with the combined concepts.

The reason for the combination of concepts 1 and 4 having a positive score in DNV-GL compared to the original concepts is due to the function of moving the roller balls up or down depending on if they are in use or not. After the analysis of the combination of concepts 3 and 4 which scored lower, was because the cargo floor rollers were hard to integrate due to safety concerns such as the cargo being unstable during movement inside the cargo area.

4.4 Implementation The concept chosen for further development was discussed and approved through a semi-structured interview with stakeholders where each concept along with the evaluation matrices were presented. The concepts chosen was the decorative garage door bulkhead which can be seen in figure 15 with the railways used for positioning. In figure 16 is the combination of concepts 1 and 4 with the integrated lifting mechanism. The generated concept can also be applied to other transportation methods such as trains, trucks, and planes. If applicable, this could also be a way to store different cargo in warehouses.

Figure 15 & 16. In the figure to the left, the S.B is visualized with the pathway and to the right the R.F is seen with the integrated lifting mechanism.

4.4.1 Parametric CAD model The different concepts were developed with the parametric CAD model method, in order to enable modification in the development stages. The purpose behind the model was to show the different functions and movements. It was also used for reworking modules sent between group members since the modelling was done on two different computers. As shown in figure 17, the complete system is shown in an overview perspective with an opening to the upper deck and two bulkheads creating three different compartments.

Figure 17. An overview over the complete cargo space with three compartments and an opening to the upper deck.

Figure 18 shows the connector to the railway from the bulkhead which is powered by an electrical engine to ease the workload on the personnel. A handle, shown in the same figure, was added due to design requirements from DNV-GL regulations, which states that there needs to be a manual way to operate electrical systems. The movement of the S.B can be seen in figure 19 and the upper position is seen in figure 20. This provides the possibility to divide the cargo area and separate equipment. The S.B can help contain fire or smoke from spreading by containing it in smaller compartments. When the S.B is being moved in the railway, it is not supposed to affect the equipment that is fastened on the R.F. To provide visual information to the personnel working inside the cargo space there is a warning light installed in case the bulkhead is repositioned or if there is an ongoing fire. The reason for the electrical engine not being a part of the CAD models is because a standardized engine can be used in various naval ships.

Figure 18. The manual handle to reposition the S.B is shown as well as the connector from the bulkhead to the railway.

Figure 19 & 20. An overview over the movement of the bulkhead. The bulkhead is marked in blue in the left picture and shows the upper position on the right picture.

In figure 21, it is also possible to see an implementation of the lifting mechanism. The lifting mechanism is based on scissor lifts to provide robustness for heavier objects. The lifting area was placed beneath the cargo opening to the upper deck. Cargo needs to be positioned to the marked area used for lifts since it is a smaller segment of the cargo space. The S.B needs to be positioned vertically to use the lifting mechanism, to not interrupt the lift. On the scissor lift, there is a segment of the R.F which helps to keep the equipment fastened while being raised to be unloaded from the ship. In the figure a lamp is installed, which is visualized as the yellow bar. The DNV-GL regulations state that there needs to be enough light in the working area, and the S.B can block off some ceiling light depending on its positioning. The rollers on the R.F are also shown on the lifting mechanism. Their function is to minimize the need for a lot of force to relocate equipment. The rollers are able to move up and down with the help of an electric system. This was done to minimize the wear and tear on the bearing balls and give users the possibility to adapt the system after the cargo.

Figure 21. In the figure the lifting mechanism can be seen as it is raised with the R.F to reach the upper deck.

Figure 22 shows a closer view of the R.F together with the bearing balls. The bearing balls can be raised up and down depending on if cargo is moved or not, with the help of an electric system. This feature is added to extend the life cycle of the bearing balls since it can be hidden whenever it is not in use. The smaller holes in the figure are used for the standardized twistlock mechanism to fasten cargo. There are multiple available positions for the twistlock depending on the size of the cargo.

Figure 22. In the figure the R.F is seen with the cargo floor and an implementation of a standardized fastening mechanism called twistlock.

Figure 23 shows placements for the twistlock located at the edge of the R.F. The reason these were added was due to the fact that cargo can be different shapes. This provides the user with another option of fastening the cargo.

Figure 23. A possibility to attach a generalized twistlock fastening mechanism is shown in the figure.

Implementing the standardized fastening mechanism was because this system can be used by various industries and it simplifies the adaptation of cargo. The purpose of the solution was to develop a modular and flexible solution which the S.B provides when combined with the R.F. Therefore, the solution grants an opportunity to adapt to different circumstances and provide support to change a SPS to become an MPS. The development of the solution was based on the fact that the cargo space had a door to the deck above. The cargo space was divided into smaller compartments, where one of the compartments was placed under the opening to upper deck. By dividing all of the cargo space into smaller segments, the user can use the necessary space. This gives the option of changing the cargo space depending on what the cargo is.

Most of the floor inside the cargo space was made with rolling floors to ease the moving of cargo. One of the compartments is fitted with a scissor lift to transport the cargo to the upper deck. By having a specific area for the lifting mechanism, the crew will be aware that they need to approach the area with extra caution if the bulkhead has been repositioned to a vertical position. This will help increase the awareness of the crew when operating in the cargo space.

4.4.2 DNV-GL regulations The generated solution was compared with the regulations from DNV-GL to meet requirements such as fire protection and tight proof. Through a meeting with a representative from DNV-GL it became clear that the solution could be implemented with minor changes such as integrating a fastening mechanism to keep the S.B in the desired position. The concept was discussed to study the possible ways of fastening the S.B, and a solution was to implement a mechanism that used spring pins to ensure that it would not move during voyage or relocating of cargo. The idea is to integrate the pins into the bulkhead sides and the railways so that it can be positioned in lower and upper sections. With this type of solution for fastening the S.B, the dimension tolerances are refined to ensure the tightness requirements.

The upper deck needs to be opened when the bulkhead is rearranged due to its size. This was because the bulkhead needs to fit the space in a certain way to provide fire protection according to the regulations. According to the regulations the door needs to be able withstand a fire for 0-60 minutes, depending on its classification. One aspect that is controlling the classification of the S.B is how it is defined, if it is a bearing or nonbearing bulkhead. If it is a bearing bulkhead, the requirements are stricter, for example it should not be able to be relocated. An important factor that needed to be considered was the fact the bulkhead blocked out the lights from the ceiling inside the cargo space. This is countered by having lights on the walls under the rails for the bulkhead to compensate for the blocked light when the bulkhead is in a horizontal position.

5 Discussion This master’s thesis contributes to laying a foundation for future work in the subject of payload arrangement. The results from this thesis are consistent with existing literature in that the studied trends have been proven to have the largest impact on the naval market. The concept developed included specific parts requested by the stakeholders, but studies done in payload arrangement can differ greatly depending on what the aim is. This study also generated a new way of implementing a S.B into a cargo area, which is a subject that has not been studied closely prior to this thesis. An example of how modularity and flexibility can be implemented into general cargo spaces has been shown but depending on if the cargo space has been specified, the solution could have been designed differently.

5.1 Design thinking The methodology design thinking provided support for analyzing the different phases that occurred throughout the thesis. Because of the three different phases used with the methodology, the timeline became clearer, and the work processes could be conducted more efficiently. This way, the early stages of the master’s thesis was focused on studying relevant information for the theoretical background and the trend- and techwatching. The gathered information was used as a basis for the requirements list and during the brainstorming session for concept generation, as well as to define the functions of the final solution. Since Design thinking is an iterative process, functions and prototypes can be altered and improved based on feedback from stakeholders.

A different methodology that could have been used as a work process is the Systems engineering process. The reason that design thinking was used is because it is a solution-based methodology and the stakeholders informed that the aim was to develop a solution that included a S.B and a R.F. Therefore, the work process was less focused on finding problems and more on concept development.

5.2 Trendwatching One system trend that has been driving the development of naval ships is the usage and research of USVs. There is both a social and an economic reason for this. When looking at the life cycle costs for a MPS, the most expensive part is operations and support. By creating more USVs, the costs for operations could be lowered since a crew is not needed. Most of the existing USVs are used as MCM or support to other missions, but there has been an increase in autonomous vessels due to technological advances.

On one hand, the trend of using USVs aims to minimize dangerous situations for crews and to reduce costs. As one of the higher costs today is the crew’s cost, as shown in the trendwatching, the cost of operations is approximately 49-56% [11]. Nevertheless, since today's USVs are not suitable to operate without a crew completely, it is hard to reduce the cost entirely. The aim with these ships is to reduce the lead-time of the reconfiguration process and the total life cycle costs. An example of how the trends of flexibility, modularity, and USVs can be combined to develop a surface ship is the SAM 3. An image of the vessel can be seen in figure 5, and just as it is explained, it can be separated into two different parts so that it becomes easier during transportation [39]. Because of its functions and use, it shows that there are possibilities of developing vessels that reduce the need for crew onboard completely when executing specific missions.

Another design trend is the usage of modularity to decrease the production of naval ships. The reason for the advancement of modularity in ship constructions is both ecological and economical. The advantage of modular design is that it decreases the initial cost by creating a hull that can be modified depending on the mission it needs to fulfill. By having an empty hull that can be modified later on, there is a minor need for producing different kinds of ships since one ship can be modified to complete different missions. Modularity also extends the life cycle since parts can be exchanged if they are not functional or need to be updated after a couple of years. As long as the main hull is intact, the ship can be used for different missions depending on its capabilities. Therefore, it is more appealing for navies to search for a multi-purpose vessel rather than a single-purpose vessel due to economic benefits such as using a hull for numerous missions. This provides the possibility to reconfigure one hull for various scenarios, on the other hand, if the hull is damaged, it may lead to longer service times.

Another reason for the increase in MPS is that it has an economic benefit due to the lowered total cost for the active ships. A key factor that shows the advantages of a modular approach with surface ships is that it helps to lower the need for personnel. Thus, the development is pushed towards surface ships becoming more and more autonomous which leads to modular stations being deployed. A disadvantage with the MPS is that in the early phases the cost is increased to adapt every module specification after the hull.

These trends have contributed to an increase in the research and development of MPS, which can be seen in navies. Another trend that can be observed is that the newer ships often have similarities in the geometrical hull design, due to the stealth trend. The difference between the US navy LCS and the Swedish HSwMS Visby corvette is that the LCS is more focused on automation while the Visby corvette has state of the art stealth technology. Both of the surface ships show how the trends of modularity and flexibility have been implemented due to their possibilities to conduct various missions.

One crucial factor that needs to be pointed out is that the information accessible to the public is often a bit old. This is because most of the technological advances are within the government agencies and defense forces, which makes it harder to access information since a lot of it can be restricted due to classification. Therefore, the information gathered in both trends &- techwatching might be a bit outdated but still relevant since it shows the progress that is accessible to the public.

5.3 Techwatching The existing solutions that were gathered and studied during the techwatching phase gave inspiration for the development of the modular and flexible solution for the payload arrangement. An issue during the techwatching was that there are not many existing solutions that include a S.B, because of that the technology that was analyzed became more widespread and various solutions were studied.

The various technologies studied during the techwatching showed that the different transportation systems did not use similar solutions. For example, the cargo in airplanes was placed using a rolling floor which provided support to the crew to relocate various cargo/equipment inside of the cargo space. While for trucks the cargo is placed on a “walking floor” or a loading plate which was later pushed inside the cargo space. For the cargo to be placed on the walking floor or the loading plate

there is a need for a forklift, crane, or similar external machine. This shows that the solutions are more focused on creating a smoother transition for relocating the cargo.

As one of the major trends for naval ships today is modularity and flexibility, the need for these types of solutions has grown over time. However, the main focus was on trying to find and study various technologies used today by the different transportations systems. To see if there is a possibility to redesign, combine or adapt the solutions so that they would be more suitable for naval ships. During the techwatching, it became clear that the solutions found could be used as an inspiration to generate concepts. This provided enough background support to make a justified claim on why modularity was so important and why it was the main focus. With every technology found, it showed that the modular and flexibility aspect was a part of the development, but due to it becoming simplified during usage it was neglected. Because the modular and flexible aspect is of great importance with the developed solution during the thesis, the technologies found inspired during the ideation phase.

5.4 Ideation The purpose of dividing the requirement list was to focus on each part individually. Therefore, the requirement list acted as a guide to provide support and to visualize what the requirements were, as well as to help generate the various concepts in the brainstorming sessions. The first parts of the sessions were done individually and later discussed, where the concepts were explained. The reason for doing separate brainstorming at first was to not influence each other. The concepts were then sorted based on how well they fulfilled the requirements. The pre-totypes were done as a sketch to explain the functions, and the reason for this was to simply visualize the concepts. With these sketches, it became easier to conduct the following evaluation matrix, the Pugh matrix. The reason for using Pugh matrices was because it is mainly used for concept development and there is no existing solution which the concepts could be compared to as a baseline. Therefore, the baseline was defined after findings from the techwatching and semi-structured interviews with stakeholders. Another reason for choosing the Pugh matrix over for example HoQ, is that the criterions for Pugh matrix can be created by conducting brainstorming sessions. The HoQ requires customer needs and criteria, while the Pugh matrix is more focused on comparing how well concepts can perform against various requirements.

5.5 Parametric CAD modeling To better explain how the idea could be used and how each different part can be designed, a CAD model was created. The model was developed to show the more complex parts and functions of the easily neglected idea in a pre-totype sketch. The CAD model became clearer about how the modular functions worked as a complete system in the cargo space and how it could be easily adapted to various surface ships or similar transportation systems. As explained in the theoretical background, a parametric CAD model helps to adapt various parts to different scenarios. Just as Reddy and Rangadu [17] explained, advanced CAD models will not take a long time if there is a possibility to use a parametric CAD system. Therefore, the developed CAD model aimed to create a solution that could be easily adapted, upscaled, or rearranged to be used on a larger scale, such as a warehouse or downscaled and used with a truck. The possibilities of a parametric CAD model create a broader perspective, and it can provide support for further development of a product's functions.

The idea was to use the simplified sketches of the highest scoring concept made during the brainstorming sessions and develop them further to a parametric CAD model. With the model, it became easier to visualize functions and details with the ideas that were neglected in the sketches. Furthermore, the CAD model helped provide support to various claims, e.g., that it would be easy to separate the cargo space into different compartments and how it would help change a SPS to become an MPS.

The most important aspect during the development of the solution was to develop a modular and flexible system that could be adapted to various surface ships. As shown during the trendwatching, modular and flexible systems are something that costumers are expressing is necessary for the future. Therefore, the solution is created as a modular and flexible system in a parametric CAD model. On one hand, it helps to show the flexibility of how the model can be used in various ships, but on the other hand, it can be hard to visualize how it is supposed to be redesigned to be suitable for other ships.

5.6 DNV-GL regulations With surface ships, some rules and classifications are mandatory to follow so that the environment, personnel, and the ships are protected against various dangers. The solution developed during this master thesis includes a S.B, R.F, and a scissor lift powered by electricity. There is also a requirement that can be seen in the requirement list that says that the solution should be able to prevent fire and be tight proof. For example, it has to protect against fire or smoke from spreading to the rest of the compartments inside of the ship. When analyzing the DNV-GL regulations about fire protection, it becomes clear that when a bulkhead can be moved inside of the hull, it should be classified somewhere between A0 to A60 [22]. If the developed solution shall be implemented into a naval ship it has meet the requirements set by DNV-GL, without any approval from the society it cannot be implemented.

Furthermore, because the R.F, S.B, and the lifting mechanism are powered by electricity, the electrical installations need to be constructed to have enough space. Due to it needing a ventilation system so that it does not overheat and raising the ambient air temperature beyond 45℃ [23]. With these classifications, it becomes clear that the developed concept can be helpful to create a modular and flexible system to transform an SPS to become an MPS. The vital aspect that will decide if the solution follows the different regulations provided by DNV-GL is the material selection which is a delimitation of this thesis.

The DNV-GL classification states that a moveable bulkhead needs to provide support against fire and smoke from spreading to the adjacent compartments. The regulations state that a moveable bulkhead should move by using an electrical installation or using manual force. Because if there is an accident and the electricity stops working the personnel needs to have the possibility to move the bulkhead. Therefore, the solution presented in the thesis can be used by moving it with manual labor or an electric-powered engine to relocate it and change the cargo space area.

The need to fasten the cargo is based on the area of usage of the surface ship. For example, in a freighter, the cargo has to be fastened, but if the ship is classed as a service and maintenance ship the cargo is not necessarily required to be fastened during the voyage. While for naval surface ships, there

are specific rules for the fastening of cargo. If the cargo will be used continuously during the voyage, there is no need to fasten it.

5.7 Analyzation of developed idea After the concept was created using Autodesk Inventor, it was time to analyze it with the DNV-GL regulations, the modularity and flexibility, and how it can be adapted to various ships. The solution is also studied, and the advantages and disadvantages are discussed on how they can be improved or be redesigned.

5.7.1 Advantages The main advantage of this concept is that it creates a modular and flexible cargo space. With help of the S.B the cargo can be separated so that it is adapted to various missions or cargo transports. This provides the possibility to gain a flexible rearrangement of the ship's purpose. Due to the floor being built in various segments, it becomes easier to adapt the cargo space floor to the cargo. This can simplify the work conducted during loading and unloading from the surface ship.

One clear advantage is that the user controls how the layout of the cargo space will be, depending on the cargo. The user also has the option of reconfiguring the layout of the floor due to the modularity. The separation of segments can also be helpful if the cargo is sensitive and needs to be isolated. The segments also include a lifting area, which was placed under the opening from the upper deck and having a section specific for the loading from the upper deck can make the management of cargo easier.

The fire regulations from DNV-GL have been taken into consideration when developing the S.B to provide protection, the regulations show that it needs to keep the fire/smoke contained without affecting the surroundings. Another requirement for the S.B was that it also needed to be moved by hand as well, which has been addressed by adding the handle seen in figure 18. The purpose is to give the user a firm handle to move the S.B to the lower or upper position. The S.B also has a lock mechanism to help keep it in place during voyage, and the fastening mechanism is placed in between the bulkhead and the railway, to ensure that the personnel’s safety is not compromised.

The R.F also provides a way to secure the cargo by having an integrated standardized fastening mechanism in multiple fastening locations. This provides the flexibility to adapt to different kinds of cargo depending on the size or geometry. The rolling floors also provide some extra assistance for the personnel to make the loading and unloading easier, as well to rearrange the cargo once it has been loaded. To ensure that the S.B does not interfere with the fastening of cargo on the R.F, there are small areas between each segment.

This solution is adaptable to transportation systems such as trains, trucks, and surface ships. The design is square-shaped, which means that it can be adapted to be used in regular warehouses. The S.B and the R.F can be implemented both together and independently since neither requires the others to function.

5.7.2 Disadvantages The developed concept is not suitable for oval-shaped areas because the S.B cannot protect against fire or smoke due to it not having a suitable shape. As can be seen in figure 17, it is most suitable for

areas that are shaped like a square. This disadvantage shows that the idea developed in this master’s thesis is mainly focused on surface ships. It could be used for other transportations systems also, but in that case, there would be a need to reshape the inside so that the S.B and the railways can be fastened correctly. The need for having a square space is because the S.B is designed after the general cargo space seen in figure 6.

Another disadvantage with the concept is that the S.B covers the light from the ceiling if it is implemented into an existing surface ship. However, as shown in figure 21, there is a possible installation of lamps on the side of the cargo space below the railway. As light is one of the most crucial aspects in cargo spaces, the S.B generates various difficulties. On one hand, if the S.B is locked in the lower position of the railway, there is a possibility to use the lamps from the ceiling. But on the other hand, if the upper deck is supposed to be opened to remove or add cargo, the installation of these lamps is getting affected by the moving parts. Therefore, existing ships will need to install more lamps that are placed on the walls to provide enough light so that the personnel can work without endangering themselves or the cargo.

For this concept to be implemented, a ship would need to have the possibility to open the upper cargo deck. Therefore, it will be hard to implement the idea on already existing ships if there is no existing opening to the cargo. The need to open up the deck is to load the necessary cargo to the surface ships cargo space on the R.F, using the lifting mechanism from figure 21. This is a disadvantage of the idea because if there is a need to redesign the entirety of the surface ship’s cargo space, the costs will vary from each ship.

Another disadvantage is that the R.F is heavily dependent on electric power to ensure that the cargo can be relocated inside the cargo space. Because the rollers on the R.F are powered by electricity to raise and lower the balls that are used to ease the workload for the personnel, suppose the electricity would be damaged during the voyage or loading/unloading of cargo. In that case, there is a possibility that the balls are stuck in a raised position that can expose dangers to both cargo and personnel. However, there is a possible power installation to provide support for raising and lowering the balls, which is a pneumatic solution. It provides security that the balls will not be stuck in a specific position however it can result in more disadvantages such as the S.B can lose the possibility to prevent fire and smoke from spreading due to more systems taking up space for installations.

6 Conclusion and future work

6.1 Conclusions 1. How are today’s trends affecting the development of new naval ships in a payload arrangement aspect?

The trends that are affecting the naval market are separated into system and design trends and are shown in table 5. These trends were studied during this thesis because they have the largest impact on the future development of various surface ships. Today's customers of surface ships are searching for alternatives that can provide support during several missions. With that said, it becomes clearer that customers want to have a flotilla that consists of MPS instead of SPS. This is because there is an economical benefit that helps to reduce the total life cost of the surface ships if they are designed to be an MPS. These trends seen in figure 5, has led to the increase of development for MPS in general when it comes to surface ships.

Table 5. The table shows all the trends that have been studied during this master thesis. System Trends Design Trends

All-electric ships Modularity

Unmanned surface vessel Flexibility

Stealth

The difference between the system and design trends is that the trends are either affecting the design of the hull or various stations found onboard the surface ship. One ship that has implemented both design trends modularity and flexibility as well as the system trend USV, is the LCS developed by the US navy. The purpose of these surface ships is to help troops in combat by coastal regions, ASuW and ASW. While in Sweden, the navy has developed the HSwMS Visby corvette that can be used in ASuW, ASW, MCM, and sea monitoring.

2. How can a modular and flexible payload arrangement be implemented in existing surface ships without changing the ship's interior structure?

The biggest issue when implementing modular and flexible payload arrangement into an existing surface ship is to consider systems such as HVAC. The installation of cables and necessary electric compartments will take up space which needs to be taken into consideration when designing a concept. Another thing that needs to be taken into consideration is what the space is used for and if there are any bearing walls or other objects that cannot be moved from that specific space. One important aspect of developing a modular and flexible payload arrangement is to consider if a concept should be generalized or more niched to a certain kind of ship. The methodology and process shown in this thesis is just one of many ways that a modular and flexible payload arrangement can be designed.

The concept that was developed is an example of how to implement a modular and flexible payload arrangement that does not affect the W.T bulkheads or interior structure. The design is based on

adding the tracks for the S.B, while the R.F can be placed in any area in the cargo space. Installation of the S.B and R.F will require new cables added to provide power to the parts. The S.B moves only within the tracks and has a fastening mechanism along the tracks to ensure that it does not interfere with the R.F or any other interior structure. The developed concept was based on the fact that the ship needs an opening to the upper deck since the full movement of the S.B needs space to be repositioned. However, the solution can be easily modified to be adapted to various ships. One thing that needed to be changed when applying the S.B was to add a new section of lights below the railways for the S.B. This was done to ensure that there would be enough light in the room even when the S.B is in the upper position, since it might block off the lamps on the ceiling. However, it can also be solved by having a light function on the sliding bulkhead itself that activates automatically when it is relocated from lower to upper position.

3. What regulations from DNV-GL need to be asserted onto a flexible and modular system that is implemented in the cargo space?

DNV-GL has regulations that depend on what system it is and the construction of the system. If a system is implemented in the cargo space, the main regulation of the system is fire protection. With the fire regulations comes tightness regulations as well, which can enable the suppression of fire by minimizing air pockets. Other regulations that need to be taken into consideration is if the system is supposed to be moveable or integrated into the cargo space. If the system is movable, DNV-GL states that it needs to have a fastening mechanism to keep it in a certain position if it is not operating. Without any approval by DNV-GL, a system cannot be implemented into a naval ship.

When it comes to the regulations for the developed concept, the main focus is that it needs to contain fire or smoke from spreading to other areas. The S.B is purely decorative and not a bearing wall which means that it does not have the same strict regulations as a bearing wall. The fire protection requirement is also affected by material choice, which is a delimitation that this thesis does not focus on, but a standard material that DNV-GL often recommends is stainless steel.

6.2 Future work Since this thesis was mainly focused on the concept generation and research of existing trends, there has not been a great insight into critical electronic systems. For future work, cooperation with DNV- GL is necessary to cover some of the regulations for the installation of electric systems. The electric systems that are necessary for this solution are the moving system of the S.B and the rollerballs. The electric systems can also be used together with a pneumatic system to ensure a backup plan if something happens to either of the systems. With the help of DNV-GL, it becomes clearer what the requirements are on a S.B, R.F, and the choice of material. It is necessary to analyze the system with strength theory to specify the dimensions, tensile and stress analysis.

For future work, the concepts need to be tested with suitable users such as constructors, sailors or technicians that work in similar areas. This is to analyze the developed concept so that their feedback can help define problems before it is manufactured and implemented into surface ships or other transportation systems. The testing would also show how long a S.B can contain fire in an area and get a classification based on their scale, which can be seen in table 2.

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Faculty of Mechanical Engineering, Blekinge Institute of Technology, 371 79 Karlskrona, Sweden