A MARINE VESSEL

The invention relates to a marine vessel operated with gaseous fuel having at least one gas powered engine, which vessel is provided with a fuel tank in which the fuel is stored at liquid phase, and in which vessel the engine is positioned in an engine room which is provided with an engine room casing extending from the engine room to exterior of the vessel according to preamble of claim 1.

Usage of gaseous fuel in various types of marine vessel is increasing due to its clean combustion and availability compared to e.g. heavy fuel oil or marine diesel oil.

Gas is typically stored in liquefied phase at low temperature tank, which is also a pressure vessel. Positioning of such a tank (or tanks) is problematic since conventional gas tanks are large pressure vessels and space utilization in a vessel is critical when considering economy and convenience of e.g. using the vessel. Uq- uefied gas tanks are larger in size and heavier than diesel oil tanks. And for example width of lanes in car decks is an important factor for e.g. roro-vessels, in which trucks are run in the ship along a ramp. Insulation of the gas tanks is also a feature which reserves room in the vessel, gas is typically stored at a temperature of about minus 162 ⁰ C (Natural Gas).

An object of the invention is to provide a marine vessel having an engine operated with gaseous fuel, which solves the above mentioned and other problems of prior art.

Object of the invention are met substantially as is disclosed in claim 1. The other claims present more details of different embodiments of the invention.

The basic idea of the invention is to integrate the fuel tank(s) in vicinity of the engine room casing and arranging the tank arrangement to have elongated shape.

According to a preferred embodiment of the invention a marine vessel operated with gaseous fuel having at least one gas powered engine is provided with a fuel tank arrangement in which the fuel is stored in liquid phase. In the vessel the en- gine is positioned in an engine room which is provided with an engine room cas-

ing extending from the engine room to exterior of the vessel. It is characteristic to the invention that the fuel tank arrangement is arranged in vicinity of the engine room casing. This way the tank arrangement may be located in a space which is easily ventilated upwards in the vessel.

The fuel tank arrangement is preferably of elongated shape in a direction substantially deviating from longitudinal axis of the vessel so that it has a vertical dimension and a horizontal dimension and that the vertical dimension is greater than the horizontal dimension. This way the usage of space in a vessel is advantageous.

The fuel tank arrangement preferably comprises a number of interconnected separate tanks. A separate tank is substantially easier to lift out of the vessel than a single large tank in case e.g. reparation is needed. Circular cross section of the tank is particularly beneficial due to tubes are commercially available and their pressure resistance is good.

According to another embodiment of the invention the fuel tank arrangement is positioned in front or aft from an engine room casing in relation to longitudinal axis of the vessel. This provides the maximum usage of space in the vessel.

Hence, the invention provides several benefits: • Space in which the tank is positioned may be easily ventilated upwards

• Meets the rules for gas tank location of Classification Society

• Located close to midship, which causes only small effect on trim of the vessel

• Long height gives small diameter for tank which results in small reserved area of decks and enables the use of standard pipes for building material

• The number of free lanes on car deck can remain unchanged, since the tanks are aligned with casing

• Small free surface area in tank minimises the formation of boil-off gas

• Tank can be lifted upwards out of the ship for replacement

In the following the invention will be described with the reference to the accompanying schematic drawing, in which figure 1 illustrates an embodiment of the invention, figure 2 illustrates another embodiment of the invention, and figure 3 illustrates cross sectional upper view of figure 1.

A marine vessel 1 as is shown in the figure 1 is provided with a main engine 2 providing power to the propulsion system 3 of the vessel. It is evident that depending on the type and size of the vessel the number and layout of installed engines may vary. The engine 2 is operated with gaseous fuel which is stored in a fuel tank arrangement 4 in liquid phase which in practise means that the temperature of the gas is typically at about minus 162 ⁰ C. The engine 2 is installed in an engine room 5. The engine room is provided with engine room casing 6 extending from the engine room to exterior of the vessel 1 through which e.g. the exhaust pipe of the engine may be led. The fuel tank arrangement 4 is arranged in vicinity of the engine room casing longitudinally aligned, in the embodiment of figure 1 above the bulkhead deck 8. Fuel tank arrangement 4 is connected with the engine 2 by mean of a gas supply system 7, which comprises the required piping 7.1 and evaporator device 7.2 for evaporating the liquid to gas and warming it up. The evaporator device is positioned at location separate to the tank arrangement below the bulkhead deck 8 and thus the gravity may be used in fuel conveying.

The fuel tank arrangement is of substantially vertically elongated shape in a direction substantially deviating from longitudinal axis of the vessel. In other words the fuel tank arrangement has a vertical dimension and a horizontal dimension and the vertical dimension is greater than the horizontal dimension. This way cross sectional area required by the tank arrangement is minimized, and deck space is saved. Also the free surface area of the liquid gas is small which minimizes the formation of boil-off gas. Preferably the tank arrangement comprises a tubular tank or, as can be seen from the figures, the fuel tank arrangement 4 comprises a number of tubular tanks 4.1 , which are interconnected with each other. This makes it possible to replace smaller individual tank rather than a large single tank. The vessel is preferably provided with a structure being openable at its top deck for hauling the fuel tank out of the vessel (not shown in the figures).

The space 9 for the tanks 4.1 has a vent 10 which connects the space to the atmosphere for keeping the space ventilated.

In figure 3 one can see an upper cross sectional view of figure 1. As can be seen the tank arrangement of the present invention makes it possible maximise the usable deck area in the vessel, As an example in figure 3 the lanes 8 on car deck have the maximised number and width since the tank arrangement 4 is positioned in front of the engine room casing in relation to longitudinal axis of the vessel. As depicted with dotted lines the tank arrangement 4' may be arranged also aft from the engine room casing and still providing the same benefits. It can also be seen from figure 3 that the tubular tanks 4.1 have circular cross section.

In figure 2 there is shown a vessel and arrangement corresponding to that of figure 1 and thus also corresponding reference numbering is used. Basically only difference is that the fuel tank arrangement is provided to extend below the bulkhead deck 8. This lowers the centre of gravity and makes the vessel to be more stable.

It is clear that the invention is not limited to the examples mentioned above but can be implemented in many other different embodiments within the scope of the inventive idea.