Development of Multipurpose Icebreaker and Offshore Construction Vessel

Development of multipurpose icebreaker and offshore construction vessel

T.P. Tellefsen

(%%/tore ,4,9, P.O. Boz

ABSTRACT The MSV Fennica which was delivered early 1993 and her sister- vessel, MSV Nordica to be delivered early 1994, are the worlds first multipurpose icebreakers and offshore construction vessels. The concept was developed in cooperation between the Finnish National Board of Navigation and Ugland Offshore AS, where Ugland Offshore in particular has brough in the offshore requirements to the multipurpose design.

The vessels will during the winter-half year operate as tradi- tional icebreakers in Finnish waters, and during the summer season be operated by Ugland Offshore for offshore construction work, particularly with interest to the Northern and Arctic areas.

BACKGROUND

The Finnish National Board of Navigation

Since 1971, Finland has had 22 ports that are classified as winter ports and are kept open for traffic the year round. During the winter 1991 to 1992 about 19.000 ships visited Finnish ports counting arrivals and departures. The total volume of cargo carried by these vessels was 24.3 mill tonnes representing around 41 % of the total annual sea born transport.

The Finnish National Board of Navigation operates an icebreaker fleet totalling 9 vessels. These vessels are special purpose icebreakers and are only used during the winter season in Finland.

In connection with the oldest icebreakers in the fleet were reaching the end of their economic lifetime, The Finnish National Board of Navigation started a project to find a multipurpose application of a new generation icebreakers, thus giving an allround utilization and improved economics.

The Ugland companies have been involved in the design and operation of offshore dynamically positioned vessels since 1976. This includes specialized offshore installation vessels, as well as shuttle tankers. Considerable experience has been gained in the intervening years, all of which have been put to good effect in the development of the multipurpose icebreaker. Typical tasks that the multipurpose icebreaker will be employed in are laying of flexible pipe and cable, trenching and ploughing of cables and pipelines beneath the sea bottom, support vessel for off-shore operations in general.

OFFSHORE REQUIREMENTS TO THE MULTIPURPOSE ICEBREAKER

The main features in being able to utilize an icebreaker for offshore construction operations would be to re-design the vessel to give a large open deck area, have the vessel equipped with a full dynamic positioning system, living quarters for minimum 80 people and a helicopter deck. The largest challange was to improve the vessel's stability and make a design giving accept- able acceleration forces when subject to North Sea conditions.

A typical icebreaker is due to its broad beam and relatively shallow hull with typically no imparts for dampening vessel role effect, subject to suffer from a very short period that makes working on board the vessel extremely difficult due to its violent motion.

TECHNICAL CHALLENGES.

To the design of the vessel and which naval architecht consultancy company ILS played a major role, a number of alternative hull designs were evaluated. From an initial idea of removeable side sections to be taken off during summer period, the design has ended up with a vessel being narrow at mid-ships and stern compared to the above.

The narrow bredth of the vessel has reduced the stability and created a long overall period. Comparison tests have been run in laboratories with a model of a conventional large supply ship and the result show that the new icebreaker hull design will function better than a typical large supply vessel under normal operating conditions. Additional improvements have been made by inclusion of a U-shaped semi active anti rolling tank, across the widest point of the bow section.

From tank tests performed by the technical research centre of Finland, the result show that the vessel will be operatable in the summer and autumn seasons of the north sea more than 90 % of the time. The role stabilization system not considered.

The vessel is able to keep the speed of 15 knots in head seas in the North Sea, also more than 90 % of the time in the summer and autumn seasons.

Initially the parties were willing to accept a compromise in so far as due to its dual function, one would accept a vessel with less favorable motion characteristics for offshore work, as well as one for the icebreaking season would accept a vessel with less favourable icebreaking capacity than a conventional icebreaker. The results of the model test showed that the motion characteristics of the vessel with the chosen hull form, was better then a conventional comparable offshore vessel, and likewise, ice performance is also superior to existing comparable conventional icebreakers.

SIGN. WAVE HEIGHT

The vessel is able to maintain 8 knots in 80 cm of first year arctic ice, as well as to maintain continous speed ahead in ice- thicknesses of 1,8 metres. At the same conditions the vessel will maintain continuous speed astern at an ice thickness of 1,7 metres. The vessel is built to the Norske Veritas polar 10 ice class.

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DYNAMIC POSITIONING OF OFFSHORE VESSELS

The use of dynamically positioned vessels and their application has increased tremendeously during the last 10 years. The flexibility of this type of vessel is substantial and is the benefit to the user. The standard decomplexity of the system available has improved, and redundancy has been become a key issue. Systems today have a high level of safety, and from a technical point of view reliable operations are to be expected.

Consequential analysis performed on-line computer and based upon worst cased failure is now a standard requirement during operations. This provides a good operational guide line for the operator.

The basic design philosophy for a dynamically positioned vessel is to achieve reliable and accurate positioning and working.

When developing this project it was seen that the basic icebreaker with its high propulsion power, diesel electric propulsion system and proposed thrusters as main propulsion units provided an excellent basis for introducting a dynamic positioning system on board this vessel. The dynamic position control computer system is fully redundant. The power management system used in the DP system is part of a total vessel integrated management system which improves the speed of the response to a power demand from the DP system. The DP system provides, under loss of one computer an automatic transfer to the other, which does not effect the vessel's position or operation.

CONTROL SYSTEM

The vessel is equipped with a redundant power management system as part of the integrated vessel management system. The system lay-out for the integrated vessel management system is displayed in fig 4.

The internal communication system is a redundant internet system, with a redundant control system, thruster control system and vessel management system are interconnected.

Maritime Information Technology Program

The vessel has been agreed to be the "Pilot vessel" under the Maritime Information Technology program operated by the Royal Norwegian Council for Scientific Research and Development. The basis for this integrated system is the redundant data network on board, with the connection and integration of various part functions.

Integration of Electronic Charts, Thruster Control, Auto Pilot, and Dynamic Positioning.

Electronic charts are integrated with radar picture and navigation sensors, including digital GPS (DGPS in the same screen picture). Route planning is done on the electronic chart system and cause data transferred automatically through the net work to the auto pilot. Thruster outtake is transmitted from the auto pilot to each individual thruster via the network, and the auto pilot gives a continuous status back to the electronic chart displacement system that will set an alarm if fault shoud occur. During DP operations the DP system will report estimated and required position together with current and wind data to the electronic chart display system for graphical presentation together with navigation data and charts.

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Integration of Fire Alarm and Automated Vessel Management System

The fire alarm system is integrated in the vessel management system for graphical and display into the overall vessel management system.

HITS / TIMIS

The system installed in Fennica is called TIMIS - Total Inte- grated Maritime Information System. TIMID is a realisation of HITS - Maritime Information Technology Standard, which has been an ongoing program in an attempt to standardize communication protocols between various subsystems. The results of the development work undertaken as part of this Norwegian research program, has led for the first time to the installation of a total integrated network as done on board this vessel with communication between the various sub systems.

User Support

The system offers users support and suggestive action to the operator in charge. The user support is the defined through five different main modes.

Mode no. 1. - Harbour mode

Mode no. 2. - Mode for maneuvering in ports and congested areas.

Mode no. 3, - Transit mode.

Mode no. 4. - Dynamic positioning mode. Mode no. 5. - Icebreaker mode.

The mode is selected by the vessel operator, and the system will in term automatically initiate stand-by and start-up of necessary machinery etc. to support the selected mode. Utility system and main functions are controlled and necessary safety factors are included in the system. When faults occur in a sequence the operator can interim, and if necessary complete the sequence manually. Functional graphic giving status on the various modes, both principle diagram and detailed sequence is available on all AVM operator stations.

Watch and Engineer Call

A totally new generation watch call system is installed. The system is developed to simplify both response time and fault detection.

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WATCH CALL SYSTEM CONFIGURATION

LOCAL WATCH CALL PANELS V/ATCH CALL PANELS

ENGINEER CABIN 2 12C-BU$

ECR OPERATOR STATION AVM LAN (ETHERNET)

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MAIN VESSEL FEATURES

Particular intention was during the design given to enable a largest possible open deck area. The resulting deck area is 1050 m* with a deck load capacity of 10 tonnes pr. m*. Total dead weight capacity 4870.

The vessel has a 120 ton A-frame and smaller crane support.

A special innovation on this vessel is the use of two large azimuth thrusters, each of 7500 KW as main propulsion units together with three bow thrusters each of 1100 KW. This ensures that the icebreaker has excellent manouverability also during DP performance offshore. The propulsion system in term enables the vessel to turn around its own axes in Baltic ice conditions while today's conventional icebreakers need minimu five ship lengths to turn.

The drawing of the AQUAMASTER USARS 1 illustrates clearly the size of the unit. AQUAMASTER USARS 1 Input power 7500kW Weight abt. 2001 Propeller diameter 4,2 m Total height abt. 10m

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Total installed engine power 21.000 KW This plentiful propulsion system has resulted in the vessel obtaining bollard pull result of 234 tons continuous pull. This result has made the vessel the most powerful offshore construction vessel in the world. This power together with a 300 ton double towing anchor handling winch allows the ship to tow the largest seabed ploughs available single-handed for offshore pipe- line burying operations.

High Lights

Four independent main engines with diesel electric propulsion. Two independent main propulsion units and three independent bow thrusters gives the vessel a very high degree of redundancy and reliability. Despite its high horse power with 30.000 BMP totally installed, the diesel electric propulsion system ensures optimal power out-take for any operation, and as all engines use medium fuel 180 Cst, the vessel has a very economic performance.

World's most powerful offshore support vessel with 234 tonnes continueos bollard pull.

Even when operated on maximum bollard pull, the vessel still has surplus power available for 100 % out-take of side power to ensure position keeping during such pulling operation.

Four independent radars integrated with electronic charts, and differential DPS.

Fully integrated vessel management and control system.

300 tonnes towing winch interfaced to DP system for dynamic towing operation.

Full weather station and satellite receiver for producing own weather forecasts.

Fully redundant DP system

Accommodation for 82 persons, together with good recre- ational areas including gymnasium, two saunas and swimming pool.

For clients, the vessel offers offices, conference room and operation centre for their usage.

Helicopter landing facilities for Super Puma type helicopter. Helicopter scissor lift for indoor parking of smaller sized helicopter, typical Bell Jet Ranger.

120 tonnes A-frame for up to 350 metres of water.

Deck area 1050 m* with a strength of 10 tonnes per m*.

Total deadweight capacity 4870 tonnes.

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CONCLUSION

Through this development board the Finnish National Board of Navigation has received a vessel that as an icebreaking tool will be superiour to its conventional icebreakers, as well as through the summer occupations through Ugland Offshore has improved the overall economy of its icebreaking services tremendeously compared to a conventional icebreaker that has no alternative summer occupation.

REFERENCES

R. Lindqvist - Multipurpose icebreaker, Finnish shipbuild- ing know-how at its best. Navigator 1992. I. L0vdal, Simrad Albatross AS. Integrated system for operation of multi-purpose icebreaker / Offshore Special Vessel.Information technology in maritime businesses 7th October 1992. V. Reinertsen, C.P. Halvorsen, N. Alvheim - Ugland Offshore, Norway. Operation of a dynamic positioning offshore vessel - offshore technology conference, Houston - Texas, 4th - 7th May 1992. VTT Technical Research Centre of Finland. Ship Laboratory- Sea keeping performance assessment of the Finnyards multipurpose icebreaker by model tests and operatability predictions LAI-1210/92.