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Propulsion characteristics of multi-mode ships in aspect of ship's dynamic positioning application

Herdzik J.

Journal of KONES

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2010

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Vol. 17, No. 3

127-134

EN

The dynamic positioning systems require multi-element ship propulsion application. The chosen solutions have decisive effect on propulsion system possibilities, in ship dynamic positioning accuracy also. The automation system has an essential influence on it, because it is an integral part with propulsion system mponsible for this process. The most often ship propulsion solution based on unconventional thrusters driven by electric motor s also. A few independent propulsion systems is essential but it complicates this system, it is limited the number (most often to 4, seldom more up to eight). There are no solutions with traditional rudder and steering gear. These functions take over azimuthing thrusters because they can generale directional thrust force. It must be settle the question of the number of thruster choose and the span angle of azimuthing (most often by thruster turning). In that case it gets the possibilities of ship positioning, they may display as propulsion system characteristics, giving a view on ąuality of positioning process. The last veriflcation is made in real sea conditions when it may test if chosen solution of ship propulsion system fulfils the requirements of positioning accuracy. It was presented the examples of multi-mode ship propulsions and parameters of theirs propulsion plants.

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Problems of propulsion arrangement choice of multi-mode ship

Herdzik J.

Journal of KONES

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2010

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Vol. 17, No. 2

129-135

EN

The propulsion system of multi-mode ships cause many problems of proper the choise of propulsion system elements and theirs arrangement in the design process. This system has to fulfil at least two inverse demands. It ought to make possible efficient ship shift (transit mode) from the port to the off shore work place and return to base, to ensure a ship survive at sea in the worst sea condition possible on that sea area and to fulfil conditions of dynamic positioning accuracy (stationkeeping mode) at specified bad state of the sea - not to stop the ship work for long time. The dynamic positioning systems require multi-element ship propulsion application. The fulfilment, all required possibilities and accuracy of ship positioning by chosen propulsion system specified in the project data, is the most important project problem to obtain the minimum investment costs. The redimensioning of propulsion system, increasing the number of thrusters and theirs possibilities gives the benefits in dynamic positioning accuracy, but increases the investment costs. An expensive project may not be realized because of price. The aim of designer is the choice optimum solution of propulsion system, which is fulfils all expectations of ship owner and crew, and performs all project assumptions.

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Application possibilities of electric driven propulsion of multi-mode ships

Herdzik J.

Journal of KONES

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2010

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Vol. 17, No. 1

163-168

EN

The ship propulsion solution based on unconventional thrusters driven by electric motors is most often applied for the multi-mode ships. These ships ought to have dynamic positioning system. It forces an application of a few thrusters (most often four, seldom more up to eight). Records from a number of multi-mode ships show amean load of less than 40% of maximum load on the propulsion system. In other side the demand for electric energy of ship industrial part is large, more often than for the propulsion part. In that case the diesel-electric propulsion system application may be economical, because the electric energy generation for all ship's purposes makes possible the main engines work on the optimum loads on lowest specific fuel consumption and allows them a long-term work on heavy fuels. For multi-mode ships like cable ships, suppliers, drilling vessels are convenient an application of unconventional thrusters with direct electric propulsion as well, especially for dynamic positioning systems. The efficiency of the thrusters is a predominant factor for the successful and economical operation. Forecasted development and rise of quantity of diesel-electric propulsion (it means with electrical transmission) would cause increased interest of unconventional thrusters. Ultimately they may revolutionize ship propulsion systems.

4

Application possibilities of electric driven propulsion of multi-mode ships

Herdzik J.

Journal of KONES

|

2010

|

Vol. 17, No. 4

177-183

EN

The ship propulsion solution based on unconventional thrusters driven by electric motor s is most often applied for the multi-mode ships. These ships ought to have dynamic positioning system. It forces an application of a few thrusters (most often four, seldom more up to eight). Records from a number of multi-mode ships show a mean load of less than 40% of maximum load on the propulsion system. In other side the demand for electric energy of ship industrial part is large, more often than for the propulsion part. In that case the diesel-electric propulsion system application may be economical, because the electric energy generation for all ship 's purposes makes possible the main engines work on the optimum loads on lowest specific fuel consumption and allows them a long-term work on heavy fuels. For multi-mode ships like cable ships, suppliers, drilling vessels are convenient an application of unconventional thrusters with direct electric propulsion as well, especially for dynamic positioning systems. The efficiency of the thrusters is a predominant factor for the successful and economical operation. Forecasted development and rise of quantity of diesel-electric propulsion (it means with electrical transmission) would cause increased interest of unconventional thrusters. Ultimately they may revolutionize ship propulsion systems.