MARITIME RESEARCH NEWS 2 Vol. 12/ISSN 0784-6010 1998

List of Contents Page:

Petri Varsta Automatic Editor’s Corner...... 2

Göran Granholm Improving safety with the Identification System...... 2

Kaj Riska Requirements for Ship Performance in Ice....4

Kari Marttila Evacuation from a Listing Passenger Cabin..6

Harri Soininen A Propeller-Ice Contact Model...... 7

Jorma Rytkönen Maritime Operations and the Environment.9 . Ilkka Saisto Modernization of the Towing Carriage...... 10 ...... 11...... 12 News

Recent Publications

Cower Photo: Pentti Tuononen

Maritime Institute of Finland

1 EDITOR’S CORNER we be more rational and analyze the research it is difficult to see answer that southern Europe work itself. Among the research community of would be interested in the winter navigation Petri Varsta Professor the industry the idea of innovation process has problems in the Baltic, but for the national Helsinki University of Technology been launched, where the aim is to produce new economy of Finland it is a crucial question. An solutions for the ship markets by stepped often used concept related to EU research is that SHIP RESEARCH IN scientific and technical innovations. The general the research must have a European dimension, time based lay-out of the innovation process which can be interpreted as some kind of added EUROPE consists of three blocks: fundamental marine value. What does it mean in practice? The most research at selected top knowledge subjects, direct or pragmatic answer is that modern applied ship research at basic knowledge subjects maritime research needs expensive research WHAT IS NEW ? and the third one, the product development itself. equipment that cannot be developed and This approach of co-operation is possible to purchased on the national basis, but with co- Today’s R&D work in European shipbuilding follow in EU research programs and I am sure operation the cost efficiency increases to an faces new challenges. During this year the that it offers several possibilities to get new acceptable level. An example of this could be European shipbuilding industry has developed research results and new products. efficient information technology instrumentation the Thematic Networks for the co-ordination of The European research resources in marine needed onboard marine expeditions to remote the implementation of the Master Plan to the technology are large counted on the basis of areas. Another example from an on-going project EU 5th Framework programme. The two number of organizations and also employees, is the powerful laser equipment existing in networks for research priorities are Product but this is an illusion. The organizations are not France, which is used in an EU research project Innovation (PRODIS) and Production in the creative element, but the researchers aimed at developing new closed steel structures. Shipbuilding (CEPS). The processing of the themselves. Here we have the key problem. The research topics has been very similar to that we marine industry as a whole does not attract in Finland have applied in two research programs, young people, but they are more interested in THE WORK IN THE Shipyard 2000 and SeaTech. The thematic information and computer industry. This NEAR FUTURE working groups represent current trends in situation can be improved by joint research work, which in itself is more transparent than international and European marine research giving The European marine industry has defined the the overall direction to the research. in-house research. But also the results of the research change the work content in the industry; main research areas and the targets for joint EU we will have more effective and automated design research forum. At the next stage the research THE PROBLEMS TO and production in shipyards controlled by project proposals must be developed and this computers and less hard labour by human beings. happens in the near future. There the role of the OVERCOME By research results we can also change the work European research organizations will be crucial content of the young naval architects in line with and the question can be put: are we capable of What is the general structure of European modern European industry. this? This means work in co-operation with the marine research? In the political slogans the aim What is the content of EU marine research? It industry to process the defined subjects and goals of the European research is defined as the can not surely be interpreted to cover all the into research entities which are composed of commercial battle against other big industrial research activities in this field. We must have workable packages so that the results from the blocks of the globe. One can ask is this single national research, which aims to the specific project will be according to the aims and at the idea relevant in the historical perspective? Should problems that every country has. For instance same time truthful. IMPROVING SAFETY WITH THE AUTOMATIC IDENTIFICATION SYSTEM

Göran Granholm, VTT Manufacturing According to some experts, the Automatic individual transmission time slots. The objective Technology Identification System, or AIS for short, will is to incorporate the Universal AIS in SOLAS change the way we look at maritime Chapter 5, making this equipment mandatory The new functional specifications of a communication. It may also become the most on ships exceeding a certain size. The current Universal AIS, as approved by the IMO, offers important safety improving technology since the proposal would affect approximately 40,000 a whole range of new possibilities when it comes introduction of radar. ships, owned/managed by shipping companies to improving the safety of maritime traffic. The system works on a dedicated VHF radio resident in countries that have accepted the frequency on which a communication link is SOLAS convention. The Finnish and Swedish established completely Maritime Administrations have been working autonomously without user hard to promote this technology and to make it involvement and without the the new standard internationally. need of a land based station to The core function is the basic position report co-ordinate the radio traffic. containing identification, position, speed and This makes the communication heading broadcast from each vessel and available services available both shore-to- to all others within the reach of VHF radio. This ship and directly between ships message is updated with an interval of a few where ever they meet. The seconds to produce an accurate and up-to-date underlying technology called traffic image in the VTS or onboard other ships. SOTDMA (Self Organised Time In addition to the position report a number of Division Multiple Access) uses other predefined messages have been defined. accurate GPS time as a common The possibility to construct new message time reference for allocating structures based on free format binary data or text strings provides an attractive base for AIS transponder and ECDIS terminal with AIS targets displayed. developing totally new services.

2 support a multilingual service in which the user can output a message in the chosen language. • Onboard AIS data recording and play- back. AIS data can easily be recorded and reproduced onboard or on shore, enabling e.g. a simple shore based black box.

The second day of the presentation was arranged together with Helsinki VTS and showedsome VTS oriented services including:

• Transmitting targets under radar surveillance using the AIS system. Being a permanent radar installation, a VTS radar network can provide unbroken and wide coverage of the VTS area. AIS offers some major advantages that can be used to enhance radar based traffic monitoring onboard. With this function, the location Passenger ferry navigating through the and identification data of the objects archipelago (photo Jorma Rytkönen). services. The new functions were presented and recognised in radar monitoring will be evaluated at an on-site demonstration 1-2 transmitted by the system just as if they THE POSEIDON September this year as a part of the Poseidon were AIS subjects. As a result, objects need project. The presentation started onboard ms to be identified only once and other parties PROJECT Silja Serenade on a trip from Stockholm to will be able to receive the object with their Helsinki and continued the next day in Helsinki. identification attached. VTT has participated in the international The event attracted some thirty experts from • Transmitting differential corrections on research project ‘POSEIDON’ sponsored by the Scandinavia and the EU. the AIS network. This is a function built European Commission and locally by the Finnish into the system, by which a GPS correction Maritime Administration. The project deals with The first part of the demonstration was devoted signal can be transmitted on the AIS VTS (Vessel Traffic Services) integration and to ship-to-ship communication services. network. A DGPS-level positioning can data networks and provides a logical basis for Onboard Silja Serenade the simultaneous thus be achieved on vessels without a evaluating new communication systems such as departure of the ship and ms Mariella as an AIS differential receiver of their own. This the AIS. target was followed in real time. Demonstrated correction signal, which is transmitted on features were: VHF, is also insensitive to weather The research work has focused on responding • interference, so it can be used as a backup to a range of user requirements collected at specific AIS tracking and identification. on vessels which normally use other user meetings organised within the project. The Tracking and identification was differential receivers. key message of these events was the need to demonstrated with a chart display based • Transmitting wind data. A mathematical reduce the overall work load of the VTS operators navigation software. This software directly model has earlier been made of the Helsinki performing their routine task of identifying and supports the necessary AIS messages and harbour area based on wind tunnel tracking vessels in the area. These tasks should produces a data base of all received measurements at VTT. With this model messages. be automated to allow the operator to concentrate • single wind measurement can be used to on the developing of the traffic situation and to Path prediction. The path prediction estimate the spatial distribution of wind ensure safe transits. This could to a great extent function is a display option intended to speed and direction in the harbour area. The be done by reducing VHF voice communication produce a more informative traffic image system is in use at the Helsinki VTS station and automating identification and improving on a chart display. It consists of a trajectory and data can be obtained by vessels either tracking functions. By introducing AIS forecast based on onboard measured speed, by fax or over a separate radio link. Within technology these problems can be solved and at course, heading and turning rate values. The the project the same data was transferred the same time the services can be made available frequently updated position broadcasts to the AIS, eliminating the need for further directly onboard as well. from each vessel makes it possible to data transfer channels. In a similar way produce such predictions some 1 or 2 other meteorological data can be minutes ahead Within the Poseidon project a number of AIS • transmitted. installations were made. Two passenger car Passage plan exchange, ship-to-ship. ferries, ms Silja Serenade and ms Mariella were The passage plan exchange function equipped with AIS sets connected to their consists of a set of way points picked from integrated bridge systems and to an ECDIS a predefined route plan and broadcast in a THE FUTURE software. Helsinki VTS got an AIS configured AIS message to be visualised on a chart as a base station and the service ferry ms display. The purpose of this function is to Although the standardisation of the AIS Suomenlinna was equipped with a stand-alone transmit data to other ships on the route technology has advanced, many of the problems AIS. Two AIS sets were installed within the plan currently in use on the vessel, so that still remain to be solved before the vast Archipelago VTS. Additionally a land based the vessel’s intentions are known to others possibilities can be fully exploited. Regional unit was installed at VTT. The equipment was in advance and encounter situations, for differences concerning traffic structure, delivered by GP&C Sweden. example, can be planned in more detail ahead environmental conditions etc. will call for of time different kinds of solutions and services. • Exchange of text messages. This function Regardless of the level of sophistication a is based directly on the text message minimum performance is ensured if a common RESULTS ON DISPLAY transmission capability of the AIS. In the standard can be agreed upon. The current plans future it is intended to put together a aim at making AIS a requirement by the year To make further use of the AIS possibilities, communication protocol based on 2002. How this will be achieved remains to be VTT took the task of developing new additional standardised short messages, which will seen in the near future. 3 REQUIREMENTS FOR SHIP PERFORMANCE IN ICE

Kaj Riska Professor, Arctic Marine Technology Helsinki University of Technology

A decision to keep a number of ports along the whole coastline open throughout the year was made in Finland in the 70's. As all the Finnish ports are ice bound for at least a part of the year, this decision must be accompanied by decisions about winter navigation support. The principle of winter navigation is that all vessels are offered icebreaker assistance into and out of these winter ports by offering icebreaker escort. In order to ensure safe and continuous navigation, the authorities issue rules for ship strength and performance. These are the Finnish-Swedish Ice Class rules issued and maintained by the Finnish and Swedish maritime administrations. The background of the performance requirements is that once icebreaker escort is offered, the vessels should be able to follow icebreakers with adequate speed so that vessel delays and icebreaker waiting times are minimized. These performance requirements in the rules have been Fig 2. Photograph from MT Sotka navigating in an old channel (photo M. Wilhelmson). under revision and Helsinki University of Technology, Ship Laboratory has carried out a winter. The number of annual ice days in the project to supply the basis of this revision. north is about 120 and along the coast of southern Finland it varies between two and three months THE OPERATIONAL THE BALTIC WINTER (60 to 90 days). The first ice forms at the beginning of November and sometimes there are PROFILE OF VESSELS still some ice floes in the north in June. During an average winter the whole northern The ice thickness in the Gulf of Bothnia may Baltic is ice covered from the line Stockholm - The limits set for the performance of merchant reach 1.2 m in the fast ice but out at sea the Hiiumaa island in Estonia northwards. Even in a vessels in the Baltic must be based on the most thickness of level ice seldom exceeds 0.8 m. The mild winter the Gulf of Finland and the Gulf of frequently encountered ice conditions and also corresponding figures for the Gulf of Finland are Bothnia are ice covered. Thus only the port of on the operational profile in ice. As background 0.8 m and 0.5 m. The thickness of level ice is a Hanko and the ports Rauma and Pori on the work for the Finnish-Swedish ice rules, an good general indication of the severity of the Bothnian Sea are relatively ice free in a mild extensive field campaign to gather data about the winter but for ship navigation the amount of encountered ice conditions and operational modes FREQUECY OF ICE CONDITIONS 100

] ridged ice must be taken into account in judging 90 was carried out during years 1990-94. The 80 the severity of the winter. Ridging occurs when observations were done by sending observers 70 60 winds and currents break the ice cover and push onboard ships navigating mainly in the 50 it against the fixed ice next to a coast line. Ridging 40 northernmost Baltic. Ten vessels in IA Super 30 in the Baltic is mostly cotrolled by winds and and IA ice class were selected for observation. A 20

freguency of ice conditions thus, as westerly winds prevail, the Finnish coast [% of total voyage observed 10 plot of the velocity and encountered ice profile 0 WINDEN NA JA DEN FINNFIGHTER BORDEN SOTKA is heavily ridged outside the northernmost ports was made from each voyage observed and these

chanel drift level open water (Kemi, Oulu, Raahe). Likewise the ice is pushed were matched with the operational events like towards the end of the Gulf of Finland and the icebreaker assistance, towing, getting stopped Fig. 1a. The observed frequency of encountered entrance of the ports of Kotka and Hamina are by ice, waiting for icebreaker escort etc. ice conditions in winter 1994 (Lehtinen 1994). thus heavily ridged. The summary of the observations show that The ice cover closer to land i.e. inland from the by far the most frequent ice condition encountered 15 m isobath is stationary throughout the winter. is an old channel and the most frequent FREQUENCY OF OPERATION MODES This inmovable ice is called the fast ice zone. As operational mode is navigation assisted by an 100 the Finnish coast is quite shallow, this zone can icebreaker. These results are shown 80 be extensive in places. Thus the ship fairways quantitatively in Fig. 1. It is noticeable is that 60 40 leading to and from ports must go through this the relative distance navigated independently in modes observed) 20 zone. The ice in the fairways is repeatedly the pack ice in the middle of the sea basins is (% of total voyage total of (% 0 Frequency of operation operation of Frequency GRANÖ LARGO SOLANO KEMIRA HAMNÖ MINISTAR OUTOKUMPU broken and through this thermo-mechanic action small. Only MT Sotka and MS Finnfighter independent assisted towed the rubble ice cover in the fairways grows. The navigated in the pack ice, the former because of thickest rubble ice occurs usually in the fairways her exceptional icegoing capabilities and the latter Fig. 1b. The observed operational modes used in into the ports of Oulu and Kemi; there the average because her voyage started from the Gulf of winter 1993 (Lehtinen 1993). thickness across the width can be in excess of 2 m. Finland and thus light ice conditions were

4 included in the beginning of the icebound part of shown in Fig. 4. The test results the voyage. MT Hamnö was the only vessel were used to develop an navigating independently during the 1993 equation for the pure channel observations. This was partly because she tried resistance. Finally the result was to reach the sea independently going out from validated with full scale Oulu harbour but was later stopped by ice and observations at zero speed, see had to wait for an icebreaker. Other vessels waited Fig. 5. A detailed description of for an icebreaker in the harbour. the derivation is to be found in Riska et al. (1997). DEVELOPMENT OF THE ICE RESISTANCE THE FORMULATION FORMULATION OF THE Fig. 4. MT Tervi in model tests (photo M. Wilhelmson). The ship observations showed that the most PERFORMANCE frequently encountered ice condition is an old navigation channel. The ice in these channels can REQUIREMENTS be described as brash ice.The ship performance in ice is often described by determining the speed The final task in developing the powering obtained in certain ice conditions using the requirements to be included in the Finnish- propulsion power as a parameter. If the ice Swedish ice class rules is to determine the condition is level ice then the resulting plot is required shaft power PS from the ice resistance. called hi-v curve. The approach of setting the For this purpose the resistance was first divided power level directly was not chosen in into two parts, one due to the consolidated layer formulating the performance requirements but forming on top of the brash ice in the channel rather the approach of starting from the ice (Rcon(hcon,v)) and one due to the pure channel resistance leading to the propulsion power. resistance (Rch(HM,v)), where hcon is the The decision to base the performance thickness of the consolidated layer, HM the requirements on resistance requires a formulation channel thickness at the middle of the channel for the channel resistance as it was decided that and v ship speed. The resistance due to the this would be the design ice condition for the ice consolidated layer is assumed to be equal to the strengthened merchant vessels in the Baltic. In level ice resistance of the same thickness and the order to improve the existing formulations of formulation for it is developed based on earlier Fig. 5. The calculated low speed channel resistance for two vessels with some full scale results plotted versus the channel thickness at the centerline of the channel HM (Riska et al. 1997).

Fig. 6. The proposed power requirement divided Fig. 3. The old channel produced in model scale (photo M. Wilhelmson). by the installed one and plotted against the dead weight calculated for a set of existing vessels (Riska et al. 1997). the channel resistance, an extensive model test research results, see e.g. Lindqvist (1989). The series was carried out. The first task in the model total ice resistance in these low speeds; i.e. tests was to develop a method to model the old ignoring the open water component, is assumed navigating channels. The challenge here is to to be: produce in model scale fine enough brash ice - =+ where vow is the open water speed of the the ice pieces are typically round and about 25 Rhi(, con H M ,) v R con (,)(,). h con v R ch H M v vessel. The speed dependency is assumed here cm in diameter in full scale. This leads to ice to be of parabolic form. The propulsive power pieces of 1 - 2 cm diameter in model scale with The net thrust available to overcome the ice required at the bollard pull condition is the commonly used scales. Also the cross section resistance is sometimes called the net thrust. This approximated as: of natural channels was to be reconstructed. The net thrust T at any speed can be related to NET = 23/ method developed produces very natural the bollard pull thrust T by an approximate TCPDBP*( S P ) BP channels, see Fig. 3. equation: The model test series was carried out for the v where D is the propeller diameter and the Tf= ()*T P basic model of MT Tervi with a variation of NET vBP constant C is the so called quality factor of the length and depth. A photograph from the tests is ow bollard pull. Finally, the required propulsion 5 power is obtained from these approximate IA Super PS,Req = PS(10 cm, 1 m, 5 knots) team is very grateful for their unflinching relationships involving the bollard pull power IA PS,Req = PS(0, 1 m, 5 knots). encouragement. The team consisted of Ms. Päivi and the net power available to overcome the ice Lehtinen, Dr. Pentti Kujala, Mr. Max resistance as The result of these requirements for existing Wilhelmson, Kim Englund and Topi Leiviskä. vessels was checked. The result is shown in Fig.6 −32/ 1v 2v  where the result of the proposal is divided by Ph(, H ,) v=−− K (1 ()2 * SconM C3v 3v  the actual installed propulsive power of existing ow ow REFERENCES: vessels and plotted against the dead RhHv32/(, ,) iconM weight of the vessels. It is noted that for some D Lehtinen, P. 1993: Performance of Ice-Navigating P of the smaller vessels, dead weight less than 4000 Ships in the Northern Baltic in Winter 1993. t, an increase in the propulsive power is foreseen. Helsinki University of Technology, Arctic where Ke is a constant which depends on the This, however, is already foreseen in the Offshore Research Centre, Rpt M-182, number of propellers and type of machinery navigational practice where restrictions to Otaniemi, 50 p. and propeller (e.g. lower for diesel-electric navigation are placed for IA vessels. These Lehtinen, P. 1994: Observations on Ice machinery or CP propeller). restrictions depend on the vessel dead weight Navigation Performance of Ships in the Baltic in It was decided that the design situation for the and usually the limit goes at 4000 tdw, smaller Winter 1994. Helsinki University of Technology, ice class IASuper is a channel the thickness of vessels are not assisted into the ports. Arctic Offshore Research Centre, Rpt M-187, which is 1 m with a consolidated layer of 10 cm Otaniemi, 35 p. on top of it. IASuper vessels are assumed to be Riska, K., Wilhelmson, M., Englund, K., able to proceed in heavy channels which have ACKNOWLEDGEMENTS Leiviskä, T: Performance of Merchant Vessels not been navigated during the previous two days in Ice in the Baltic. Winter Navigation Research (this allows the consolidated layer to grow) with The work to update the powering requirements Board, Research Report No 52, The Finnish 5 knots speed. IA class vessels shall be able to was a team effort with the Finnish and Swedish Maritime Administration & the Swedish proceed in old channels of 1 m thickness with a maritime authorities and especially Mr. Gunnar Administration of Shipping and Navigation, speed of 5 knots. These channels have not been Edelmann, Captains Jan Stenberg and Anders Helsinki, 73 p. consolidated i.e. a ship has navigated just before Backman acting as supervisors. The research breaking the consolidated layer. Thus the proposed power requirements are: EVACUATION FROM A LISTING PASSENGER CABIN Kari Marttila, VTT Manufacturing Technology videotape and the evacuation time was measured. A prefabricated self-supporting cabin The evacuation process was repeated the same manufactured by Kvaerner Masa-Yards Inc way at various list conditions. The aim of the evacuation tests was to find Piikkiö Works was received for the tests. The The evacuation times during the test sequenses out possibilities of different passengers to test cabin is a complete mock-up with all the were influenced by the learned techniques (= evacuate from their cabins when a passenger ship interior of a cruising ships cabin. The cabin was experience). This has some influence on the has a given list. The evacuation event was equipped with a wooden travelling platform measured times at higher list angles, because the recorded on a video tape and the evacuation time which was also the floor of the cabin. The tests started from small angles of list. was measured. The situation where the cabin wooden travelling platform was strengthened and The requirement for handrails were also tested. door is opening inwards and the passenger has places for lifting brackets were added. The door A clear delay for evacuation proved to be a ° to drag the door upwards is of special interest. of the WC was used only for entering the cabin threshold value of 40 of the downwards list Special attention is paid to the 20° listing angle and it was closed during the tests. without handrails. Any noticeable advantage of since that is the limit described in SOLAS III/ The test was performed in the research hall of handrails was not found when the door was ° 48.1 for the usability of life saving appliances. VTT in Espoo. The cabin was inclined with two upwards in the list conditions under 25 . shed cranes. Stanchions were used The test results which contain only evacuation on both sides of the cabin in order times for a certain list condition did not describe to make sure that the cabin stayed the whole situation. The video taped material of in place during the tests and to the tests gives a clearer picture of the test minimise the risk of falling down. conditions. The cabin was inclined at intervals On the basis of the tests one can assume that of 5° up to 40° in both directions. some people will have problems with evacuation ° Inside the cabin two video cameras when the list is more than 25 without handrails. were installed. The videotape The major elements are the lack of hand support recorder and monitor were outside and the mass of the door itself. the cabin. The inclination The door can slam closed so hard that people arrangement is shown in Figure 1. can be hurt badly. The door also tends to close The selected test persons were behind each departing person. This can cause five normal persons of average problem when there are several people leaving weight who were aged between 38 the cabin especially people who need help and 70 years. (children, old people, and the handicapped). The evacuation of the different Arrangements, that hold the door open during test persons was recorded on the evacuation, will give people a better chance to survive. Figure 1. The inclination arrangement of the listing cabin. Note that the open door at the side of the The friction, between the floor and feet, is of great cabin, is the door of the WC and it was closed during the tests. importance at high list angles (more than 35°).

6 • In the case of “thin” ice (ice that was free to flake in the vertical direction) a A PROPELLER-ICE horizontal contact line was formed roughly at the mid-thickness of the ice and triangular shaped flakes were found. The CONTACT MODEL flakes did not fly loose, but were partially crushed. • In the case of impact into massive ice, no Harri Soininen, D.Tech. vertical cracks were found. A thin (about VTT Manufacturing Technology one grain wide) crushed layer was left contact load model non-contact load model between the blade and solid ice. • Based on the global loads and their INTRODUCTION directions, it was concluded that the pressure distribution in the massive ice case was fairly even in the vertical Propeller-ice interaction is a very complicated simulation model direction at some distance from the upper process. The loads consist of both actual contact edge of the ice. loads due to propeller penetration into an ice full-scale • o o verification The temperature drop from -2 C to -4.5 C block and non-contact loads, i.e. hydrodynamic at the path of the sensors roughly doubled disturbance loads generated by the presence of the uniaxial compressive strength, an ice block in the vicinity of a propeller. A increased the observed peak pressures model for the actual contact loads is developed. about 70%, the global transversal force The contact loads are studied experimentally about 20% and average pressure about during a milling type open propeller-ice contact. 20%. Thus the effective load was A model of the ice failure process is developed parameter runs governed by factors other than just the based on the experiments. strength of solid ice. • The leading edge pressure was directly The Canadian Coast Guard and Finnish Board proportional to the cut width at theface of Navigation established a project “JRPA #6 side, within the range of cut widths tested. (Joint Research Project Arrangement # 6), Propeller Ice Interaction” in 1991, which had as its aim the development of a new propeller ice dimensioning model tool tool interaction model. The final goal was to use the Load = f ( D, P/D, n, Vship, hice, σice ) model in formulating new machinery regulations water level for Arctic and Baltic ice conditions. The new z ice sheet z model was to be based on the theoretical analysis Figure 1. The structure of the project. y and experimental modelling of the physical X phenomena involved, and of existing full scale ice extension in massive ice tests measurements. The aim was to create a model X that is applicable to the practical dimensioning ice sheet of propellers and shafts for ice loads. The contact y model described in Soininen (1998), and were located at the leading edge of the profile tool and along the profile both at the face and back presented briefly here, was developed within α w side. Besides the pressure distribution, the global Α the context of the JRPA #6 project. The structure UP of the overall project, taking into account both transverse and longitudinal loads of the blade the contact and non-contact loads, and simulating profile were measured. Visual observations were the dynamics between the ice block and propeller made by high speed filming during four tests. Figure 2. The test arrangement i is shown in Figure1. Thin sections were prepared of ice samples at the location of contact.

LABORATORY TESTS The main parameters that were varied in the PROCESS MODEL tests were the angle of attack and the width of The existing full-scale blade and shaft the cut ice. Additional parameters were: the measurements are far away from the actual source speed of the blade, amount of confinement, freely In general, the contact process modeled in the of the load, the interaction process. The strain floating ice as against dry ice, temperature, and following is based on the test results above. The gauges in the blades measure the response of the grain direction. basic assumption is a two dimensional behavior blade against some load, not the load itself. within each section. The total contact load is Therefore a test series was performed at VTT The following main observations and achieved by integrating along the blade radius where pressure distribution was measured conclusions were made from the test results: the load of each individual section. The leading around a propeller blade profile. • edge opens a tensile crack towards the free ice The face side hardly experienced any load. edge formed by the path of the previous blade. The profile geometry was a 1:1 scale piece of Flaking from the leading edge towards the The next crack originates close to the leading the propeller of m/s Gudingen. From which there groove formed by the previous blade took edge at the back side and runs towards the open exists full-scale propeller ice load measurement place before any real contact at the face ice edge that the leading edge tensile crack has data (Koskinen and Jussila 1991). The impact side. The transverse resultant force bent opened. The ice is crushed within this small speed and kinetic energy for the blade was the blade towards the face side. • flake between the crack and the leading edge of obtained by means of a pendulum, Figure 2. The At the back side there was a cyclic the blade. A curved crack running towards the available space allowed an impact speed of up variation between high and low pressure. free ice edge formed by the previous crack is to 8 m/s. The thickness of the saline ice sheet When the cut width was zero, i.e. the ice formed at the next local peak pressure location was 20 cm. The pressure distribution was edge was located at the path of the leading along the profile. The crack geometry follows measured by means of a set of piezoelectric edge, there was a cyclic extrusion of grain boundaries. pressure-sensitive sensors. The small sensors crushed ice. 7 Crushed ice Crushed ice Crack EFFECTIVE LOAD

Blade Blade Combining instantaneous pressure pp distributions will give the effective pressure distribution along the profile. This includes phases of peak pressures and phases of extrusion between the peaks. The whole effective contact Phase 1 Phase 2 load of the blade is reached by integrating the loads of individual sections along the radius of Crushed ice Crushed ice the propeller. A simplified method to calculate Crushed ice Crushed ice Crack the effective pressure distribution of the process

Blade Blade along the section was developed. Assumptions were made of the regular size of individual spalls and geometry of the profile. This allowed a ppcalculation of the instantaneous pressure distributions at the moment of formation of each spall and the avarage during the whole process. Phase 4 A parameter study was performed to reach Phase 3 simple formulas for the shape of the effective pressure distribution, Figure 4. Assumptions Crushed ice Crushed ice Crack based on the test results had to be made of the Crushed ice Crushed ice numerical values of the pressures at the outlet of Blade Blade the crushed ice channel, at the leading edge and

the maximum value of the average pressure (pE ,

p A and pMA in the Figure 4). p p

Phase 5 Phase 6 Blade Force to the weakest direction 100 Figure 3. The Process model 50 0 -0,01 0 0,01 0,02 0,03 0,04 0,05 0,06 0,07 0,08 0,09 0,1 -50

-100

There are two basic methods to model the -150

The ice is crushed within the spall, either extrusion process of crushed ice, either by using (kN) F -200 Measured partially or fully. The process goes on forming a viscous model or a granular Mohr-Coulomb -250 1000 kg 2000 kg a channel of crushed ice between the blade and model. Combinations of both of these have also -300 3000 kg the intact ice. The crushed ice is extruded through been used. In both models the pressure is very -350 this channel to the open space either profilewise sensitive to the channel width / length ratio. -400 to the leading edge or tangential point of the Observations of the test results at the blade -450 t (sec) contact, or radially to the free ice edge. The profile back side support a model where the pressure distribution follows the laws of extrusion towards the leading edge takes place in extrusion mechanisms. An instantaneous a granular form. On the other hand, the crushed “watershed” for the extrusion process is formed ice is sintered in the high-pressure “watershed Figure 5. Simulated time histories of MS in the vicinity of each location where the channel areas”, and remains in compacted form as it Gudingen blade ice forces together with the starts to narrow before a new crack is formed. moves from this area towards the trailing edge measured time history. The process is illustrated in Figure 3. along the surface of the moving blade. The correct model in this range is viscous, rather than SOLID ICE SPALLING granular. A combination of the models is accordingly applied in the propeller-ice rear face The validity of the model vas checked against AND EXTRUSION OF contact model. blade bending moments as functions of the angle CRUSHED ICE of attack as observed from full-scale measurements performed with M/S Gudingen, Koskinen and Jussila (1991). The trends against PMA angle of attack and order of magnitude of the A macroscopic slip line approach is used based P Aloads both in measured and calculated cases were on the Mohr-Coulomb criterion. It is developed P D similar. A full-scale event that is known to have for brittle materials and used, for example, for PE EDC Aoccured for a massive ice block was also studied. rocks. Lately, it has been applied to ice as well. The contact load model was used as an input in The failure described above leads to a sequence angle of attack line an overall simulation model described in Figure of spalling within the solid ice. The geometry of E D C 1, and presented briefly by Koskinen et. al. the solid ice can be simplified as a wedge that A (1996). The simulated blade force, with an will spall away. The Mohr-Coulomb criterion B assumption of a 2000 kg ice block corresponds defines the angle between the path of the failure well with the measured result, Figure 5. and the trajectories of principal stresses. The load distribution along the wedge depends on Figure 4. The schematic effective pressure the geometry of the channel of crushed ice distribution along the blade. Point D is defined between the blade and solid ice. An estimation to be the location where the local tangent of the of the required load level can be calculated using blade profile and the angle of attack line are ice strength values as parameters. close to parallel.

8 • CONCLUSIONS The solid ice at the back side fails by REFERENCES formation of spalls - in case of confinement the spall formation may be A deeper understanding of the propeller-ice Koskinen, P. and Jussila, M. 1991. Potkurin hindered and local crushing occurs contact has been reached. The contact process lavan jääkuormien pitkäaikaismittaus M/S • The ice within the spalls is crushed model that was developed for the case of milling Gudingenilla (Long term measurements of ice • The crushed ice is extruded from the slot contact is the core result of the work. Conclusions loads on propeller blade of M/S between the blade and the solid ice of the contact process are: Gudingen),Espoo: Technical Research Centre • The developed solid ice spalling models and The ice failure and removal is a process of of Finland, VTT Tiedotteita - Meddelanden - crushed ice extrusion models are simplified repeatable phases Research Notes 1260. 46 p. + app. 118 p. (In • descriptions of the physics of the phenomena in Contact loads at the face side are minor Finnish.) • Ice material has to be removed from the the process model. The effective load model is able to give the correct shape of pressure back side for the blade to be able to Koskinen, P., Jussila, M. and Soininen, H. distribution and guidelines for the correct load proceed 1996. Propeller ice load models. Espoo: level. Technical research Centre of Finland, VTT Tiedotteita - Meddelanden - Research Notes MARITIME 1739. 82 p. + app. 1 p. Soininen, H. , 1998. A propeller-ice contact OPERATIONS AND THE model. Thesis for the degree of Doctor in Technology. Espoo: Technical Research Centre ENVIRONMENT of Finland. VTT Publications 343, 116 p. Jorma Rytkönen VTT Manufacturing Technology

The seminar on the environment impact assessment was held in 15.9.1998 at VTT, Espoo. The seminar was arranged for the experts and professionals working in the harbours and maritime sector. The seminar was one part of the ADAPT-Maritrain sub-project Environmental Technology and EIA in Maritime Industry run by the Kymenlaakso Polytechnic, HUT and VTT. WHAT IS ADAPT/ MARITRAIN ? The western Harbour of the Port of Helsinki wider, global maritime community. The project The ADAPT project Maritrain, run by consortium hopes, that through the IMO the institutes in Gothenburg, Sweden, the South and CONTENTS OF THE courses will be disseminated outside Europe. West of Finland and Bremen, Germany, is a building brick in an accompanying measure to SEMINAR support the restructuring of the marine sector. SELECTED The thematic areas covered by Maritrain, as well The seminar, chaired by Mr. Juha Komsi of as the functioning network itself, prove that an the Port of Helsinki, focused on the LITERATURE interregional approach, involving both industry environmental issues in Ports and onshore and public partners, can find funding support in operations. The main goal was to increase the Carlberg, A. (Editor), 1998. New Perspectives regions and the structural funds of the EU. participants' own interest to improve on Training in Europe's Maritime Industries. environmental awareness and responsibility. The European Network of Regional Maritime The tools and courses developed and their special lessons covered the subjects such as Research and Development Training Transfer- broad acceptance, demonstrate the need for combating oil, ship emissions, port and fairway Centres & ESF. ISBN 91-972151-3-9. 77 p. training and qualification in maritime industries. construction, dredging works, monitoring, environmental management and Helcom Huhtinen, M., et al., 1997. Need for The Maritrain project of Finland continues until recommendations. Environmental Education within maritime the end of 1998. Some tasks, however, will be industry in Finland (in Finnish). Ecomaritrain completed early in 1999. The Finnish tasks FUTURE ACTIVITIES Project, project report 1. Kymenlaakso include: Polytechnic, Publication series B, No.3. ISBN - VTS operator training by the Rauma 951-97699-8-3. 71 p + app. 11. The project consortium aims to design parts of Vocational College, pilot courses to be model courses of the IMO - Ice Pilot Training by the Maritime Safety Vainio, J. (Editor, 1998). Conference on (International Maritime Organization) and to Training Center, HUT and VTT, Innovative Maritime Education in the Baltic Sea acquire an authorization from the IMO. In the - New Materials in Shipbuilding by Turku Region. Espoo, 5 - 6 March 1998. Conference pilot course Operation in Ice Covered Waters Polytechnic, Report. Publications from the Centre for the activity towards a model course of the IMO - A Training for Safe Pilotage by University of Maritime Studies, University of Turku. Report has already gained good momentum. In a later Turku and A27. 39 p. stage the pilot courses developed in the sub- - Environment Technology and Environment project Environmental Technology and Impact assessment (EIA) in Maritime Industry VTT, 1998. Proceedings of the EIA seminar in Environmental Impact Assessment (EIA) in by Kymenlaakso Polytechnic, HUT and VTT. 15.9.1998 (in Finnish). VTT Manufacturing Maritime Industry may also be interesting for a Technology. Espoo. 9 MODERNIZATION OF THE TOWING CARRIAGE

Ilkka Saisto MSc HUT, Ship Laboratory The carriage can be controlled manually using a THE ELECTRICAL joystick, or automatically by the control progam. When the automatic driving control is used the DRIVING SYSTEM desired speed, stopping place, acceleration and deceleration are given as parameters to the One of the main laboratory facilities in the The modernization involved the replacement control system. The program computes a target Maritime Institute of Finland, the towing tank, of the whole electical system except for the DC path which the carriage should follow. The was built in the early 70's. The first commercial motors, which were found to be in good condition system observes the position of the carriage and resistance and propulsion test was performed in during services and inspection. All the cables changes the reference as necessary. So called early 1975. The towing carriage of the tank was and wires of the towing carriage were also multispeed driving is also possible: The carriage equipped at that time with modern DC-motors replaced. is automatically driven at one speed to a certain controlled with thyristor rectifiers. However, The carriage is equipped with eight 20kW DC position and, without stopping, at the other during the 90's it was realized that the driving motors for speeds higher than 1.0 m/s, and two speed to a second position etc. The maximum systems of the carriage were out-of-date and 5 kW DC motors for lower speeds to give enough number of different speeds is eight. ageing so rapidly that there was risk of propulsion power to move the 40 ton carriage. The uninterrupted operation of the control endangering their safety and reliability. Following the modernization the higher speed system and measuring system is assured with In the autumn 1997 the planning of the renewal motors are driven by two digital Control two unbreakable power suppliers. was began together with Systecon Oy. The Techniques Mentor II M825R DC drives, which contract with Control Techniques SKS Oy was can control a maximum 825A output current. SAFETY AND signed on 12.2.1998. It included the renewal of The lower speed motors are driven by one the DC drives and control system of the towing Mentor II M45R DC drive, which has a maximum RELIABILITY carriage. The installation work was started at 45A output current. Maritime Institute of Finland on 18.5. and was The control system is based on the Arlacon The first reason for the modernization was to completed on 31.8. MC 400 control unit. It uses an McDOS increase the safety and reliability of the towing The total cost of the renovation was 1.470 000 operating system and the application program carriage. The old driving system was one of the FIM. is written with McBasic programming language. first thyristor controlled DC drives in Finland. The control unit relays the reference to the DC During more than 20 years of operation and a drives which produce a suitable electric current total of 4100 driving hours, the maintenance costs to the motors. increased because of the age of the electronic components. The ageing power electronics were also a possible safety risk for the workers and visitors. With the new drive and control system the high electrical current equipments were moved to the upper deck of the carriage, while the logical system and the lower current equipments remained on the lower deck. This arragement gives an uncreased safety area for the scientists to observe the phenomenas around the models. With old thyristor rectifiers the decelerating power was only half of the accelerating power. The new DC-drives allow that the accelerating and the braking powers are equal. In addition to safety this gives more time to the measurements with constant speed. If the braking is not started because of a possible error, the emergency sensors enforce the braking to start in both ends of the basin. As before, the emergency braking system consists of two separate pneumatic braking systems and a steel wire. The new driving system also complies the new standards and regulations for electrical safety.

10 MODEL TESTS IN system the towing carriage is moving at 3.6 m/s Table 2. Particulars of the Towing Carriage from the wave maker towards the beach and now FOLLOWING WAVES AT for example Fn=0.70 is achieved with a 2.7m Weight abt 40 tons model in following waves also. This increases Design max speed 11.5 m/s HIGH SPEEDS the capability of the Maritime Institute of Present max speed forward 8.2 m/s Technology to respond to the growing interest Present max speed backward 3.5 m/s The second reason for the modernization was in the research of high speed ships. Max. acceleration 1.1 m/s2 that the reverse speed was limited to 1.0 m/s Electrical deceleration 1.1 m/s2 with the old driving system. This restrictive Emergency deceleration2.6 m/s2 character limited model testing in following waves Table 1 Particulars of the Towing Basin Accuracy of the speed control 0.05% to only slow speeds. Driving system for low speed range ( < 1.0 m/s) Following sea can cause different critical Length 130.0 m 2 x DC motors 5kW, max 38 A, 220V, 2000 rpm capsizing situations. If the wave profile is Width 11.0 m Control Techniques MENTOR M45R DC Drive stationary relative to the ship, the ship may be Depth 5.5 m Driving system for high speed range ( > 1.0 m/s) statically unstable in a roll relative to the Wave maker plunger-type, for regular and 8 x DC motors 20kW, max 580 A, 110V, 2000 rpm waterline defined by the wave profile. It is also irregular seas 2 x Control Techniques MENTOR M825R DC possible that the ship may lose its directional Drives stability in following waves. With the current

The Annual Symposium of the Maritime Institute of Finland March 17, 1999

The Annual Symposium will be held on March 17, 1999 at the Hanasaari Cultural Centre in Espoo. This time the Symposium will have no specific theme but the papers will present recent work on various areas of the Institute’s work. Subjects of the papers will cover ship hydrodynamics, ship structures, sea transportation, safety of sea tranportation and ice navigation.

VTT SUPPLIED SIMULATOR TO EXPO'98 LISBON

VTT supplied a ship handling simulator to the Pavillion of Finland in the EXPO'98 Lisbon. The audience were able to navigate a vessel to the port of Helsinki in the virtual environment during the Expo from 22 May to 30 Sep.

Mr. Pertti Broas, VTT Manufacturing Technology, assists Mr. Martti Ahtisaari, President of Finland, in steering the vessel with the VTT EXPO simulator. 11 Riska, K., Talven merkitys kuljetuslogistiikassa. Satama RECENT PUBLICATION Hildebrand, Martin. Predicting the strength of sandwich 98 Port, Naantali 14. - 15.10.1998, 18 p. panels under penetrating impact 4th International Conference on Sadwich Construction. Stockholm, 9 - Rytkönen, Jorma; Liukkonen, Sauli; Riipi, Timo. LABORATORY 11June 1998, (1998)s. 11. Laboratory tests of oil spreading under the ice cover 1st International Conference on Oil and Hydrocarbon Spills. REPORTS Hildebrand, Martin; Riihentaus, Jyrki. Benefits and Southampton, July 1998. Garcia-Martinez, R. & Brebbia, consequences of non-linear effects in sandwich panel- C. (eds), (1998)s. 155 - 164. fields 4th International Conference on Sadwich Holttinen, Hannele; Liukkonen, Seppo; Furustam, Karl- Construction. Stockholm, 9 - 11 June 1998, (1998)s. 12. Rytkönen, Jorma. The improvement of oil bioremediation - Johan; Määttänen, Mauri; Haapanen, Erkki; Holttinen, testing and analysing in laboratory and field conditions. Esa. Offshore-tuulivoima Perämeren jääolosuhteissa. European Workshop on Oil Bioremediation. Brest, FR, 15 Espoo, VTT, 1998. 118 s. + liitt. 13 s. VTT Julkaisuja - Hildebrand, Martin; Hentinen, Markku. Efficient Oct. 1998, European Commission, DG XI/Civil Publikationer; 828, ISBN 951-38-5001-3 solutions for joints between large FRP-sandwich and Protection, 1998. 2 p. + 25 overheads metal structures. 19th International SAMPE Europe Lensu, M., Arctic’96: RV Polarstern trafficability report. Conference. Paris, 22 - 24 Apr. 1998. Paris, Royal Rytkönen, Jorma. Ympäristövaikutusten arviointi osana Report M-235, Helsinki University of Technology, Ship Institute of Technology, 1998. 12 p. merenkulun ympäristö- ja onshore-rakentamista. Laboratory, Otaniemi 1998, 163 p. Ympäristövaikutusten arviointi. Satama- ja merenkulkualan ympäristöseminaari. Espoo, 15.9.1998. Tuhkuri, J., Lensu, M., Ice tank tests on ridging of non- Holm, Olli; Nyman, Tapio; Piironen, Seppo; Riipi, Timo; Espoo, VTT, 1998. 17 s. + 4 s. uniform ice sheets. Report M-236, Helsinki University of Rytkönen, Jorma. Winter navigation in inland waterways Technology, Ship Laboratory, Otaniemi 1998, 130 p. Finnish experiences and improvement plans Tuhkuri, J., Lensu, M., Hopkins, M. 1998. Laboratory and Conference Proceedings, Section I / Subject 3. PIANC field studies on ridging of an ice sheet. Proc. of the 14th International Navigation Association; 29th Navigation International Ice Symposium, IAHR ’98, Vol 1, Balkema, SCIENTIFIC JOURNALS Congress. The Hague, NL, 6 - 11 Sept. 1998, (1998)s. 17 - Rotterdam. pp. 397-404. 32. Daley, C., Tuhkuri, J., Riska, K. The role of discrete failures in local ice loads. Cold Regions Science and Hopkins, M., Tuhkuri, J. 1998. Simulation of ridging and Technology,1998, 27: 197-211. rafting in first-year ice. Proc. of the 14th International Ice OTHER PUBLICATIONS Symposium, IAHR ’98, Vol 1, Balkema, Rotterdam. pp. 623-630. Kotisalo, K., Teräksisten kerroslevyrakenteiden Laasonen, Juha; Rytkönen, Jorma. pitkittäisliitosten väsymislujuus. Journal of Structural Vanhankaupunginkosken kunnostushanke 1996 Häkkinen, P., Konehuoneen paloturvallisuus. Alusten Mechanics, 1998, Vol. 31, No. 1-2, pp. 15-31. - 2000. Vantaanjoki tapahtuma / The Vantaa River Event. tekninen turvallisuus, Turku Helsinki, 14 - 15 Nov. 1998, Finnish Fly Fishing 23. - 24.10.1998, 19 p. Kujala, P., Ultimate strength analysis of all steel Association, 1998. 20 slides sandwich panels. Journal of Structural Mechanics, 1998, Häkkinen, P., Kaasuturbiinin pakokaasupäästöt ja niiden Vol. 31, No. 1-2, pp. 32-45. Laasonen, Juha. Jokikunnostusten mallitus Vesitalous, rajoittaminen ja erikoiskoneistot. Maritrain pilot-kurssi: 39(1998) 3, s. 33 - 37. Mälkki, P., Riska, K., Tuhkuri, J. 1998. Finland: Ice, Meriympäristönsuojelu, Kotka 13. - 15.10.1998, 9 p. environment, cold seas - Themes for marine S&T. Sea Rytkönen, Jorma. Environmental impacts of maritime Jalonen, R., Tekniikka laivaonnettomuuksissa. Alusten Technology, Vol. 39, No 8 (August), pp. 18-21. activities in the Gulf of Finland. Our Common tekninen turvallisuus, Turku 23. - 24.10.1998, 22 p. Environment Forum - Yhteinen ympäristömme; kansalaisfoorumi. St. Petersburg, RU, 14 - 16 Sept. 1998, Kujala, P., Kotisalo, K., Kukkanen, T., Fatigue of all steel Finnish Ministry of Environment; Russian Ministry of sandwich panels. Applications on bulkheads and decks CONFERENCE PAPERS the Environment; City of St. Petersburg/Ecat Secretariat, on cruising ship. The 7th International Symposium on 1998. overheads Bäckström, Mika; Marquis, Gary. On the multiaxial Practical Design of Ships and Mobile Units (PRADS’98), The Hague, The Netherlands, 20-25 fatique of weldments: Experimental results, design code Rytkönen, Jorma. Näkökulmia merenkulun September 1998, pp. 879-887. and critical plane approaches VTT Symposium 181. ympäristötutkimustarpeesta ja kehityssuunnista. Fatigue Design, FD’98. Espoo, FI, 26 - 29 May 1998. Tieteiden yö. Saaristomeren tutkimusasema, Seili, 26 - Kujala, P., Strength testing under wheel loading for Vol. 1, (1998)s. 231 - 245. 27.8.1998. Tampere, Pirkanmaan ympäristökeskus, 1998. precurved all steel sandwich panels with composite 11 kalvoa. Happonen, Kai; Sukselainen, Juhani. Management of coatings. 4th International Sandwich Constructions Congress, Stockholm, 9-12 June 1998. navigational risk in Helsinki Harbour and in its Pylkkänen, Jaakko; Sanchez-Caja, Antonio. CFD tools approaches Conference Proceedings, Section II / Subject for predicting the flow around marine screw propellers 1. PIANC International Navigation Association; 29th Kujala, P., Development of laser welded all steel CSC News, 10(1998) 3, s. 28 - 31. Navigation Congress. The Hague, NL, 6 - 11 Sept. 1998, sandwich panels. Teräsrakenteiden tutkimus- ja (1998)s. P.15-20. kehityspäivät, 25.-26.8.1998, Lappeenranta.

Helle, Lauri. Wind tunnel tests of Helsinki harbour. 29th Laasonen, Juha; Rytkönen, Jorma. The rehabilitation of Navigation Congress. The Hague, NL, 10 Sept. 1998. The the Vanhankaupunginkoski rapids of River Vantaanjoki. Hague, NL, PIANC International Navigation Nordic Conference on Fish Passage / Nordisk Symposium Association, 1998 om Fiskepassasjer. Oslo, NO, 9 - 11 Sept. 1998. Oulu, University of Oulu; Direktoratet for Naturforvaltning, 1998. 4 p. MARITIME INSTITUTE OF FINLAND

VTT Manufacturing Technology / Maritime and Mechanical Engineering P.O.Box 1705, FIN-02044 VTT, Espoo, Finland Phone 358-9-4561 Telefax +358-9-455-0619

HUT Ship Laboratory / Arctic Offshore Research Centre Otakaari 4 , FIN- 02150, Espoo, Finland Phone 358-9-451-3501 Telefax +358-9-451-3419

Editors: Sakari Rintala & Pentti Tuononen, VTT Manufacturing Technology Maritime News home page: http://www.vtt.fi/manu/val3/institut/mrnnews.htm

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