EP2733058B1

EP2733058B1 - Oil collecting vessel and method for collecting oil from water

Info

Publication number: EP2733058B1
Application number: EP12192585.3A
Authority: EP
Inventors: Pauli Immonen
Original assignee: Mobimar Oy
Current assignee: Mobimar Oy
Priority date: 2012-11-14
Filing date: 2012-11-14
Publication date: 2015-07-29
Anticipated expiration: 2032-11-14
Also published as: EP2733058A1

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an oil collecting vessel and to a method for collecting oil from water according to the preambles of the appended independent claims. The invention also relates to an arrangement for collecting oil from water.

BACKGROUND OF THE INVENTION

Oil spills occur almost daily in ocean and coastal waters. In most cases immediate actions are needed to limit the impact of an oil spill to the environment.
Various chemical, biological and mechanical methods are known for cleaning up oil spills. Oil can be dissipated for example with micro-organisms, dispersants and biological agents, or simply by burning oil in a controlled manner. The spreading of oil can be prevented by using oil booms, and oil can be collected from water with oil skimmers. The best method for each case depends upon many factors, including the size of the oil spill, the type of oil spilled, the weather conditions, the temperature of the water, and the types of shorelines involved.
A known oil collecting vessel comprises two sweeping arms attached to the bow of the vessel. When collecting oil, the sweeping arms are arranged in the water, so that the distance between the sweeping arms increases in the moving direction of the oil collecting vessel, whereby when the vessel moves, oil is collected in the area between the sweeping arms. Oil is collected from this area with an oil skimmer. Because the sweeping arms cannot be made long, the maximum collecting width of the vessel is small, typically about three times the width of the hull of the vessel. Due to this, oil collecting is inefficient. Additionally the movement of the oil collecting vessel in the area to be cleaned mixes the oil in with the water, which in turn makes the oil collecting more difficult.
A known arrangement for collecting oil from a large water area comprises an oil collecting vessel and two oil booms attached to its opposite sides by their first ends. The second ends of the oil booms are attached to towing vessels. When collecting oil, the oil booms towed by the towing vessels are arranged to delimit an oil-polluted water area. By towing the oil booms, oil is collected in the area near the oil collecting vessel, from where oil is collected to the vessel with an oil skimmer. A problem of the arrangement is that it can be used only in small waves. Another problem is that its movement between places to be cleaned up in an oil spill area is time-consuming.
Document WO 2009/056687 constitutes the closest prior art.

OBJECTIVES OF THE INVENTION

It is the main objective of the present invention to reduce or even eliminate prior art problems presented above.
It is an objective of the present invention to provide a vessel and a method enabling to efficiently collect oil from water. It is also an objective of the invention to provide an oil collecting vessel having a large oil collecting width. It is a further objective of the invention to provide an oil collecting vessel, which is suitable for both active and passive oil collecting.
It is also an objective of the invention to provide an arrangement and a method enabling to collect oil from a large water area.
In order to realise the above-mentioned objectives, the oil collecting vessel and the method according to the invention are characterised by what is presented in the characterising portions of the appended independent claims. Advantageous embodiments of the invention are described in the dependent claims.

DESCRIPTION OF THE INVENTION

A typical oil collecting vessel according to the invention comprises a first and a second side hull, a central hull between said side hulls, and an oil collecting means for collecting oil from water, the oil collecting means being arranged in connection with the central hull. A typical oil collecting vessel according to the invention further comprises a first and a second guiding arm for guiding oil towards the central hull, the first guiding arm being arranged between the central hull and the first side hull, and the second guiding arm being arranged between the central hull and the second side hull. In a typical oil collecting vessel according to the invention a first end of the guiding arm is pivotally attached to the central hull so that the guiding arm can be turned relative to the central hull.
The oil collecting vessel according to the invention is a three-hulled vessel, i.e. a trimaran. The hulls of the vessel are located longitudinally in parallel and laterally spaced apart, whereby water may flow between the hulls. The central hull is a main hull, which typically is longer and wider, and has a larger draught than the side hulls. The length of the central hull can be for example 12-35 m, and the length of the side hull can be for example 6-20 m.
The vessel may comprise a deck to which the central hull and the side hulls are attached. The side hulls may alternatively be attached to the central hull with supporting structures, such as lateral struts. The oil collecting vessel according to the invention is preferably a motor-driven vessel having one or more propulsion devices arranged to one or more of the hulls. The oil collecting vessel may comprise for example two water jet propulsion devices arranged to the aft of the central hull.
The oil collecting means is arranged in connection with the central hull in such a manner that oil can be collected from an area between the central hull and at least one of the side hulls. The oil collecting means is arranged so that oil is collected in front of the guiding arms. The oil collecting means can be located on the deck of the central hull, or at one or both of the sides of the central hull. The oil collecting means can also be arranged at least partly inside the central hull.
The purpose of the guiding arms is to guide oil-polluted water towards the central hull, and thus towards the oil collecting means arranged in connection with the central hull. The guiding arms can be attached at their first ends to the central hull and/or at their second ends to the side hull. Preferably, the first guiding arm is attached to the first side of the central hull, and the second guiding arm is attached to the second side of the central hull. Preferably, the guiding arm has a rigid structure. The length of the guiding arm can be for example 1-4 m or 4-10 m.
The oil collecting vessel according to the invention is suitable for active oil collecting, wherein the vessel is kept in motion when collecting oil. The oil collecting vessel is driven on an oil-polluted water area and oil between the hulls is guided towards the central hull with the guiding arms to be collected. The oil collecting vessel according to the invention is also suitable for passive oil collecting, wherein the vessel is kept substantially in place and the natural flows of the water system are utilised in collecting oil. The longitudinal direction of the vessel is kept against the direction of the surface flow, whereby oil-polluted water flows to an area between the hulls from where oil can then be collected.
An advantage of the guiding arms arranged between the central hull and the side hulls is an improved efficiency of oil collecting. Because a three-hulled structure allows making a wide vessel, a large oil collecting width can be achieved. Because the oil collecting vessel according to the invention is stable, it can be used also in strong waves.
The first end of the guiding arm is pivotally attached to the central hull so that the guiding arm can be turned relative to the central hull. The first end of the first guiding arm is attached to the first side of the central hull, and the first end of the second guiding arm is attached to the second side of the central hull. When collecting oil, the first and the second guiding arm are turned into such a position that they are directed obliquely forward relative to the central hull. In other words, the first guiding arm is turned towards the first side hull, and the second guiding arm is turned towards the second side hull.
According to an embodiment of the invention the guiding arm is provided with an actuator for turning the guiding arm. The first actuator is arranged in connection with the first end of the first guiding arm, and the second actuator is arranged in connection with the first end of the second guiding arm. The actuator may comprise a hydraulic cylinder, a first end of which is attached to the guiding arm, and a second end of which is attached to the central hull.
According to an embodiment of the invention the second end of the guiding arm is arranged to be releasably attachable to the side hull. The second end of the first guiding arm is arranged to be releasably attachable to the first side hull, and the second end of the second guiding arm is arranged to be releasably attachable to the second side hull. When collecting oil, the second end of the first guiding arm is kept attached to the first side hull, and the second end of the second guiding arm is kept attached to the second side hull. Because both ends of the guiding arms are attached to the hulls, long guiding arms can be used. This means that the distance between the hulls can be large, whereby a large oil collecting width can be achieved.
According to an embodiment of the invention the height of the guiding arm in relation to the water level is arranged to be adjustable. The height level of the guiding arm can be adjusted, for example, based on the thickness of an oil layer on water.
According to an embodiment of the invention the guiding arm can be turned between a first and a second position. In the first position the guiding arm is arranged against the side of the central hull, whereby the water may flow freely between the central hull and the side hull. Preferably, in the first position the second end of the guiding arm is closer to the bow of the central hull than the first end of the guiding arm. In the second position the guiding arm is turned towards the side hull, whereby at least part of the passage between the central hull and the side hull is closed, and thus oil can be guided towards the central hull to be collected. Preferably, in the second position the second end of the guiding arm is arranged against the side of the side hull.
According to an embodiment of the invention the guiding arm comprises a first plate arranged vertically between the central hull and the side hull. The first plate is arranged in such a manner that the lateral direction of the first plate is in the vertical direction, and the longitudinal direction of the first plate extends between the first end and the second end of the guiding arm.
According to an embodiment of the invention the guiding arm comprises a second plate, a first longitudinal edge of the second plate being attached to a first longitudinal edge of the first plate in such a manner that the second plate is angled towards the moving direction of the oil collecting vessel. The second plate can be arranged either above or below the first plate. The angle between the first plate and the second plate can be adjustable. The angle between the first plate and the second plate can be for example 90-135 or 135-170 degrees.
According to an embodiment of the invention the guiding arm further comprises a third plate, a first longitudinal edge of the third plate being attached to a second longitudinal edge of the first plate in such a manner that the third plate is angled towards the moving direction of the oil collecting vessel. In this case the first, the second and the third plate form a channel along which oil-polluted water flows to-wards the central hull. The angle between the first plate and the third plate can be adjustable. The angle between the first plate and the third plate can be for example 90-135 or 135-170 degrees.
When collecting oil the plate assembly consisting of one, two or three of the above described plates is arranged in water in such a manner that at least 0.3 m or at least 0.5 m of its width is under the water level.
According to an embodiment of the invention the central hull comprises a flow passage for the water, the flow passage having a first inlet on the first side of the central hull, a second inlet on the second side of the central hull, and an outlet on the aft of the central hull. The inlets of the flow passage are arranged in front of the guiding arms, i.e. the inlets are located closer to the bow of the central hull than the first ends of the guiding arms. The inlets are preferably arranged at the water level. The inlets and the outlet can be provided with hatches.
According to an embodiment of the invention the outlet is positioned at a lower level than the first and the second inlet, and the flow passage is provided with a pump for pumping water through the outlet. The pumping of water through the outlet produces a suction in the inlets, which suction enhances the water flow and thus allows the vessel to be used for oil collecting when the vessel is kept substantially in place. Because the outlet is positioned at a lower level than the inlets, the spreading and mixing of oil in the water is greatly reduced.
According to an embodiment of the invention the oil collecting means comprises two oil collecting units, the first oil collecting unit being arranged in connection with the first side of the central hull, and the second oil collecting unit being arranged in connection with the second side of the central hull. The first oil collecting unit is arranged to collect oil in front of the first guiding arm, and the second oil collecting unit is arranged to collect oil in front of the second guiding arm.
According to an embodiment of the invention the oil collecting unit is a brush skimmer. The brush skimmer is arranged in connection with the inlet so that the ingoing water flows through the brush skimmer, whereby oil can be collected with the brush skimmer from the water. Preferably, the brush skimmer is arranged transversely in relation to the longitudinal direction of the central hull.
According to an embodiment of the invention the oil collecting means comprises an oil container for receiving collected oil. The capacity of the oil container can vary, depending for example on the size of the central hull and the designed operating environment of the vessel. The capacity of the oil container can be for example 0.5-3 m³ or 3-10 m³.
The present invention also relates to an arrangement for collecting oil from water. A typical arrangement according to the invention comprises a first and a second oil boom, and a first and a second towing vessel for towing said oil booms, a first end of the first oil boom being attached to the first towing vessel, and a first end of the second oil boom being attached to the second towing vessel. A typical arrangement according to the invention further comprises an oil collecting vessel according to an embodiment of the invention, a second end of the first oil boom being attached to the first side hull, and a second end of the second oil boom being attached to the second side hull. Preferably, the first end of the oil boom is attached to the aft of the towing vessel, and the second end of the oil boom is attached to the bow of the side hull.
The arrangement according to the invention can be used in the following manner for collecting oil, which has ended up in a water system, such as a sea or a lake. Most of the oil is typically in the surface layers of the water. First the oil collecting vessel and the towing vessels are driven to the oil spill site and the oil booms are spread out with the towing vessels over the oil-polluted water area. In passive oil collecting the idea is to utilise the surface flows of the water system. Therefore, the oil booms are arranged in the water so that the area they delimit remains open in the direction of the surface flow. The first ends of the oil booms are held at a suitable distance from each other and moved only when the direction of the surface flow changes. In active oil collecting the oil booms and the oil collecting vessel are actively towed with the towing vessels along the oil spill site. In passive and active oil collecting, oil-polluted water flows through the opening between the first ends of the oil booms into the area delimited by the oil booms. Oil accumulated in the area delimited by the oil booms flows towards the oil collecting vessel and with the help of the guiding arms towards the central hull. The oil may then be collected with the oil collecting means. The passive method generates very little flows, which mix and spread the oil. Because the passive method utilises the water system's own flows, the oil booms can with very small movements collect oil from a significantly larger area than the one they delimit. The active method enables oil to be collected efficiently.
The lengths of the oil booms are mostly selected case by case, for example based on the size of the oil spill or the conditions prevailing at the oil spill site. The lengths of the oil booms can for example be under 50, 50-100, 100-200, 200-400 or 400-1000 m. The oil booms can for example be so-called sea booms, the height of which is 1-2 m and which are equipped with air-filled floats in their upper edge and with a chain in their lower edge. The upper edge of the oil booms can have signal lights for night-time use.
According to an embodiment of the invention the arrangement comprises a floating container for receiving collected oil, the floating container being attached to the central hull. The collected oil is transferred from the oil container of the central hull to the floating container by pumping. The capacity of the floating container can be for example 10-50 m³ or 50-100 m³. The arrangement can comprise more than one floating container. An advantage with having more than one container is that oil can thus be collected without interruptions. The filled containers can be towed to a harbour to be emptied.
According to an embodiment of the invention the arrangement comprises a third towing vessel, another oil collecting vessel according to an embodiment of the invention and a third and a fourth oil boom. A first end of the third oil boom is attached to the second towing vessel, and a second end of the third oil boom is attached to the first side hull of the second oil collecting vessel. A first end of the fourth oil boom is attached to the third towing vessel, and a second end of the fourth oil boom is attached to the second side hull of the second oil collecting vessel. By concatenating the oil collecting vessels in the above-described manner the oil collecting is made more efficient, because oil can be collected from a larger area. There can also be more concatenated oil collecting vessels, for example three, four or five oil collecting vessels. The directions, from which the concatenated oil collecting vessels are used to collect oil, may differ from each other. This makes possible efficient oil collecting in areas, where the directions of the surface flows vary greatly depending on the location.
According to an embodiment of the invention the bollard pull capacity of the towing vessel is less than 8 tons. The bollard pull capacity of the towing vessel can also be for example less than 6 tons or less than 4 tons, or for example 1-5 tons. The bollard pull capacity of the towing vessels is advantageously dimensioned to be so great that they can move also the oil collecting vessel to which the oil booms are attached.
According to an embodiment of the invention the displacement of the oil collecting vessel is less than 50 tons. The displacement of the oil collecting vessel can also be for example less than 30 tons or less than 20 tons. An advantage with a light vessel is that the oil booms and thereto attached oil collecting vessel can easily be moved just with the aid of the towing vessels. Thus there is also a smaller probability that oil can escape from the area delimited by the oil booms. If the oil collecting vessel is too heavy, the oil booms may when pulled sink at least partially beneath the water surface.
The present invention also relates to a method for collecting oil from water. A typical method according to the invention comprises using an oil collecting vessel according to an embodiment of the invention in an oil-polluted water area, collecting oil from water with the oil collecting means, and guiding oil towards the central hull with the first and the second guiding arm.
According to an embodiment of the invention the method comprises towing a first and a second oil boom with a first and a second towing vessel, the first oil boom being attached between the first towing vessel and the first side hull, and the second oil boom being attached between the second towing vessel and the second side hull.
According to an embodiment of the invention the oil booms and thereto attached oil collecting vessel are moved only with the aid of the towing vessels. An advantage is that the flows generated by the oil collecting arrangement can thus be kept as small as possible. When the oil booms and the oil collecting vessel are moved only with the aid of the towing vessels, the oil collecting vessel must be sufficiently light, so that the oil booms when pulled do not sink partially under the water, whereby there is a risk that the oil escapes from the area delimited by the oil booms.
According to an embodiment of the invention the first ends of the oil booms are held at a distance of at least 50 m from each other. In some situations the first ends of the oil booms are held at a distance of at least 200 m, at least 500 m or at least 800 m from each other. The suitable distance depends among others on the length of the used oil booms and the conditions prevailing at the oil spill site. The distance must in any case be so large that the oil can easily flow into the area delimited by the oil booms.
According to an embodiment of the invention the oil collecting vessel is attached in its place. The oil collecting vessel is typically attached in its place by anchoring. Attaching the oil collecting vessel in its place is advantageous in situations, where oil is collected close to the shore.
According to an embodiment of the invention a propulsion device of the oil collecting vessel is used for generating a flow in the water system. With the aid of the flow the collecting of oil from the area delimited by the oil booms can in some situations be made significantly more efficient. Use of the propulsion device is advantageous especially when the natural flows of the water system are minor.
The exemplary embodiments of the invention presented in this text are not interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used in this text as an open limitation that does not exclude the existence of also unrecited features. The features recited in the dependent claims are mutually freely combinable unless otherwise explicitly stated.
The exemplary embodiments presented in this text and their advantages relate by applicable parts to the oil collecting vessel, the arrangement as well as the method according to the invention, even though this is not always separately mentioned.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

Fig. 1a: illustrates an oil collecting vessel according to an embodiment of the invention as seen from above,
fig. 1b: illustrates the oil collecting vessel of fig. 1 a as seen from the front, and
fig. 2: illustrates an oil collecting arrangement according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The same reference signs are used of the same or like components in different embodiments.
Figs. 1a and 1b illustrate an oil collecting vessel according to an embodiment of the invention as seen from above and from the front, respectively. The oil collecting vessel 100 is a trimaran, which comprises two side hulls 101, 102 and a central hull 103 between the side hulls 101, 102. The hulls 101, 102, 103 of the vessel 100 are located longitudinally in parallel and laterally spaced apart, whereby water may flow between the hulls 101, 102, 103. The side hulls 101, 102 are attached to the central hull 103 with supporting structures 104, 105. The oil collecting vessel 100 comprises two water jet propulsion devices 106, 107, which are attached to the aft of the central hull 103.
The oil collecting vessel 100 comprises two guiding arms 108, 109 arranged between the central hull 103 and the side hulls 101, 102 for guiding oil towards the central hull 103. The first end of the first guiding arm 108 is pivotally attached to the first side of the central hull 103, and the first end of the second guiding arm 109 is pivotally attached to the second side of the central hull 103. The second ends of the guiding arms 108, 109 are arranged to be releasably attachable to the side hull 101, 102. The purpose of the guiding arms 108, 109 is to guide oil-polluted water towards the central hull 103, so that oil can be collected from the water.
The guiding arm 108, 109 comprises two plates 110, 111, which are attached to each other along their longitudinal edges. The first plate 110 is arranged vertically between the central hull 103 and the side hull 101, 102, and the second plate 111 is angled towards the moving direction of the oil collecting vessel 100. The second plate 111 is arranged below the first plate 110, and to be at least partly under the water level.
The guiding arms 108, 109 are provided with actuators 112, 113 for turning the guiding arms 108, 109 relative to the central hull 103. The first actuator 112 is arranged in connection with the first end of the first guiding arm 108, and the second actuator 113 is arranged in connection with the first end of the second guiding arm 109.
When the oil collecting vessel 100 is not used for collecting oil, the guiding arms 108, 109 are turned against the sides of the central hull 103, whereby the water may flow freely between the hulls 101, 102, 103. When collecting oil, the guiding arms 108, 109 are turned towards the side hulls 101, 102, and the second ends of the guiding arms 108, 109 are kept attached to the side hulls 101, 102 (as seen in figs. 1 a and 1b). In this case the passage between the hulls 101, 102, 103 is closed, and thus oil can be guided towards the central hull 103 to be collected.
The central hull 103 comprises a flow passage 114 (shown as the dotted line) for the water. The flow passage 114 has a first inlet 115 on the first side of the central hull 103, a second inlet 116 on the second side of the central hull 103, and an outlet 117 on the aft of the central hull 103. The inlets 115, 116 of the flow passage 114 are arranged in front of the guiding arms 108, 109. The first and the second inlet 115, 116 are arranged at the water level, whereby the surface water, which typically comprises most of the oil, can be guided through the inlets 115, 116. The outlet 117, which is positioned at a lower level than the inlets 115, 116, is provided with a pump 118 for pumping water through the outlet 117.
The oil collecting vessel 100 comprises two brush skimmers 119, 120 arranged in connection with the central hull 103 for collecting oil from water. The brush skimmers 119, 120 are arranged transversely in relation to the longitudinal direction of the central hull 103. The first and the second brush skimmer 119, 120 are arranged in connection with the first and the second inlet 115, 116 respectively, so that the ingoing oil-polluted water flows through the brush skimmer 119, 120 that collects oil from the water. The collected oil is stored in an oil container 121 that is located at the central hull 103.
Fig. 2 illustrates an oil collecting arrangement according to an embodiment of the invention. The arrangement 200 comprises two towing vessels 201, 202, two oil booms 203, 204 and an oil collecting vessel 100 according to fig. 1 a. The first end of the first oil boom 203 is attached to the aft of the first towing vessel 201, and the second end of the first oil boom 203 is attached to the bow of the first side hull 101 of the vessel 100. The first end of the second oil boom 204 is attached to the aft of the second towing vessel 202, and the second end of the second oil boom 204 is attached to the bow of the second side hull 102 of the vessel 100.
The task of the towing vessels 201, 202 is to pull the oil booms 203, 204 into place in an oil-polluted water area and to move the oil booms 203, 204 during oil collecting, so that the oil 205 in the water can as efficiently as possible be collected into the area delimited by the oil booms 203, 204 and from there onward into the oil collecting vessel 100. The oil 205 is guided towards the central hull 103 with the guiding arms 108, 109 and collected into the vessel 100 with the brush skimmers 119, 120. The oil collected into the oil container 121 of the vessel 100 can be pumped into a floating container 206, which is attached to the aft of the vessel 100.
As is shown in fig. 2, the oil booms 203, 204 are arranged in the water so that the area delimited by them is open. Thus the oil 205 can flow via an opening between the first ends of the oil booms 203, 204 into the area delimited by the oil booms 203, 204. The oil booms 203, 204 are arranged in the water system so that a straight line drawn through the first ends of the oil booms 203, 204 is mainly perpendicular in relation to the direction of the surface flow prevailing in the area between the first ends of the oil booms 203, 204. The direction of the surface flow is in fig. 2 shown with an arrow A. When the direction of the surface flow changes, the first and the second oil boom 203, 204 are moved so that the angle α between the straight line drawn through the first ends of the oil booms 203, 204 and the direction of the surface flow remains between 75 and 105 degrees during oil collecting.
Only advantageous exemplary embodiments of the invention are described in the figures. It is clear to a person skilled in the art that the invention is not restricted only to the examples presented above, but the invention may vary within the limits of the claims presented hereafter. Some possible embodiments of the invention are described in the dependent claims, and they are not to be considered to restrict the scope of protection of the invention as such.

Claims

An oil collecting vessel (100), comprising:
- a first and a second side hull (101, 102),

- a central hull (103) between said side hulls (101, 102),

- an oil collecting means (119, 120, 121) for collecting oil from water, the oil collecting means (119, 120, 121) being arranged in connection with the central hull (103), and

- a first and a second guiding arm (108, 109) for guiding oil towards the central hull (103), the first guiding arm (108) being arranged between the central hull (103) and the first side hull (101), and the second guiding arm (109) being arranged between the central hull (103) and the second side hull (102);
characterised in that a first end of the guiding arm (108, 109) is pivotally attached to the central hull (103) so that the guiding arm (108, 109) can be turned relative to the central hull (103).
The oil collecting vessel (100) according to claim 1, characterised in that the guiding arm (108, 109) is provided with an actuator (112, 113) for turning the guiding arm (108, 109).
The oil collecting vessel (100) according to claim 1 or 2, characterised in that a second end of the guiding arm (108, 109) is arranged to be releasably attachable to the side hull (101, 102).
The oil collecting vessel (100) according to any of the preceding claims, characterised in that the guiding arm (108, 109) comprises a first plate (110) arranged vertically between the central hull (103) and the side hull (101, 102).
The oil collecting vessel (100) according to claim 4, characterised in that the guiding arm (108, 109) comprises a second plate (111), a first longitudinal edge of the second plate (111) being attached to a first longitudinal edge of the first plate (110) in such a manner that the second plate (111) is angled towards the moving direction of the oil collecting vessel (100).
The oil collecting vessel (100) according to any of the preceding claims, characterised in that the central hull (103) comprises a flow passage (114) for the water, the flow passage (114) having a first inlet (115) on the first side of the central hull (103), a second inlet (116) on the second side of the central hull (103), and an outlet (117) on the aft of the central hull (103).
The oil collecting vessel (100) according to claim 6, characterised in that the outlet (117) is positioned at a lower level than the first and the second inlet (115, 116), and the flow passage (114) is provided with a pump (118) for pumping water through the outlet (117).
The oil collecting vessel (100) according to any of the preceding claims, characterised in that the oil collecting means comprises two oil collecting units (119, 120), the first oil collecting unit (119) being arranged in connection with the first side of the central hull (103), and the second oil collecting unit (120) being arranged in connection with the second side of the central hull (103).
The oil collecting vessel (100) according to claim 8, characterised in that the oil collecting unit is a brush skimmer (119, 120).
The oil collecting vessel (100) according to any of the preceding claims, characterised in that the oil collecting means comprises an oil container (121) for receiving collected oil.
An arrangement (200) for collecting oil from water, comprising:
- a first and a second oil boom (203, 204), and

- a first and a second towing vessel (201, 202) for towing said oil booms (203, 204), a first end of the first oil boom (203) being attached to the first towing vessel (201), and a first end of the second oil boom (204) being attached to the second towing vessel (202);
characterised in that the arrangement (200) comprises an oil collecting vessel (100) according to any of the preceding claims, a second end of the first oil boom (203) being attached to the first side hull (101), and a second end of the second oil boom (204) being attached to the second side hull (102).
The arrangement (200) according to claim 11, characterised in that the arrangement (200) comprises a floating container (206) for receiving collected oil, the floating container (206) being attached to the central hull (103).
A method for collecting oil from water, characterised in that the method comprises:
- using an oil collecting vessel (100) according to any of claims 1-10 in an oil-polluted water area,

- collecting oil from water with the oil collecting means (119, 120, 121), and

- guiding oil towards the central hull (103) with the first and the second guiding arm (108, 109).
The method according to claim 13, characterised in that the method comprises:
- towing a first and a second oil boom (203, 204) with a first and a second towing vessel (201, 202), the first oil boom (203) being attached between the first towing vessel (201) and the first side hull (101), and the second oil boom (204) being attached between the second towing vessel (202) and the second side hull (102).