EP2370311A1

EP2370311A1 - Arrangement and method for dismantling a vessel

Info

Publication number: EP2370311A1
Application number: EP08876232A
Authority: EP
Inventors: Jan Marius Van Der Stoel; Doekle Siebren Mulder
Original assignee: Greendock BV
Current assignee: Greendock BV
Priority date: 2008-12-08
Filing date: 2008-12-08
Publication date: 2011-10-05
Also published as: CN102307779A; KR20110104518A; WO2010068085A1

Abstract

An arrangement (1) for dismantling a vessel (5), comprising a quay (2) and a pontoon (3) for carrying a vessel (5) to be dismantled in water bordering the quay (2). The arrangement further comprises a stabilizer (16) connected to the fixed world and arranged to prevent upward movement of the pontoon (3) relative to the quay (2) by exerting downward reaction force in response to upward buoyancy force of the pontoon (3), and means for controlling the buoyancy of the pontoon (3) such that, during dismantling of the vessel (5), a continuous downward stabilizing force is exerted by the stabilizer (16) onto the pontoon (3).

Description

Title: Arrangement and method for dismantling a vessel

The invention generally relates to an arrangement for dismantling a vessel, and in particular to an arrangement for dismantling a vessel, comprising a quay and a pontoon for carrying a vessel to be dismantled in water bordering the quay. Such an arrangement is known to the person skilled in the art and is e.g. described in WO 2007/081198. In an initial position the pontoon is below water level. The vessel to be dismantled is positioned above the pontoon. The pontoon is then moved upwards, e.g. by removing water out of compartments of the pontoon and filling the compartments with air, until the pontoon reaches the bottom of the vessel and starts lifting the vessel. Then the pontoon is moved further upwards until the pontoon is at the water level and the deck of the pontoon is above the water level. Preferably, a dock is used in which the water level may be raised until the deck of the pontoon has approximately the same height as a quay bordering the pontoon. In this position the vessel is above the water level and dismantling work on the vessel can be started. The vessel can e.g. be sectioned on the pontoon and sections of the vessel can be brought onto the quay. Also, when dismantling the vessel, the vessel may be moved fully or partially onto the quay, and may then be sectioned on the quay. Sections of the vessel on the quay can be moved on to cutting stations for further cutting and/or dismantling and/or recycling of the section.

Although the known arrangement is very advantageous, it may be difficult to stabilize the pontoon relative to the quay, in particular while moving a section from the pontoon onto the quay, where the section further can be processed. The invention contemplates an arrangement and method for dismantling a vessel, in which the above disadvantage is mitigated. According to the invention, there is provided an arrangement for dismantling a vessel, comprising a quay and a pontoon for carrying a vessel to be dismantled in water bordering the quay, further comprising a stabilizer connected to the fixed world and arranged to limit upward movement of the pontoon relative to the quay by exerting downward reaction force in response to upward buoyancy force of the pontoon, and means for controlling the buoyancy of the pontoon such that, during dismantling of the vessel, a continuous downward stabilizing force is exerted by the stabilizer onto the pontoon. By providing a stabilizer that limits upward movement of the pontoon with respect to the quay and means for controlling the buoyancy of the pontoon in reaction to a force exerted on the stabilizer, the pontoon may remain more easily relatively stable with respect to the quay during dismantling of the vessel. The arrangement for dismantling a vessel can thus be provided with a reactive ballasting system for stabilizing the pontoon when dismantling the vessel and/or when moving sections of the vessel onto the quay.

The reactive ballasting system reacts on the resulting upward force exerted on the stabilizer. If the resulting upward force exceeds a certain limit, the means for controlling the buoyancy force of the pontoon may decrease the buoyancy of the pontoon. The resulting upward force exerted on the stabilizer is the result of the net buoyancy force of the pontoon minus the weight of the pontoon. The net buoyancy force of the pontoon is equal to the magnitude of the weight of the fluid that is displaced by the pontoon. The resulting upward force is also noted as upward buoyancy force and/or buoyancy force.

Due to its buoyancy the pontoon exerts an upward buoyancy force on the stabilizer. The pontoon is thus pre-tensioned against a lock. The stabilizer acts as the lock against vertical movement of the pontoon. The motion of the pontoon is limited in upward and downward direction. Also the pontoon may be less susceptible to environmental influences such as waves and/or wind. By using the reactive ballasting system the height of the deck of the pontoon can be kept relatively level with respect to the surface of the quay. Damaging of the pontoon and/or of the quay due to upward movements of the pontoon while moving the section of the vessel from the pontoon onto the quay may be minimized. The section of the vessel may be moved relatively smoothly and easily from the pontoon onto the quay. Handling of the section of the vessel may become easier.

The stabilizer may be a structure that is anchored to the bottom of the water in which the pontoon floats e.g. a dock or a bay, or may be a structure that is fixedly mounted to the quay. More than one stabilizer may be provided.

In an embodiment, the stabilizer may comprise stop means to limit upward movement of the pontoon and may further comprise a force measuring unit to measure the upward force exerted by the pontoon and to provide the measured force as input to the means for controlling the buoyancy of the pontoon. When the measured resulting upward force exceeds a certain limit, the means for controlling the buoyancy of the pontoon will decrease the buoyancy of the pontoon such that the upward force on the stabilizer is decreased below the limit. Thus continuous contact may be obtained between the pontoon and the stabilizer, wherein the stabilizer and the means for controlling are arranged to keep the contact force below a certain predetermined force limit. Further, the stop means of the stabilizer may limit upward movement of the pontoon such that the deck level of the pontoon remains approximately level with the surface of the quay. The force measuring unit may be integrated in the stop means, thereby limiting the upward force of the stop of the stabilizer. By limiting the force exerted on the stop of the stabilizer, the design conditions of the stop means may be known and the stop may be designed and built more cost effective, e.g. less heavy and/or with less material. The reactive ballasting system may comprise a stabilizer and means for controlling the buoyancy of the pontoon. The stabilizer may comprise stop means for limiting upward movement of the pontoon and may further comprise a force measuring unit for limiting upwards force exerted by the pontoon. Advantageously the arrangement for dismantling a vessel may be situated in a dock that may be closed to minimize environmental influences such as tide and/or waves and/or blown up or blown off water. Also, in a closed dock, the water level in the dock may be changed independently of the water level in open water outside the dock. The dock may have one quay, but may also be provided with two or more quays. The water bordering the dock may also be connected to open water, such as a river, canal, a lake or the sea. The quay may be an artificial construction, but may also be a bank or a shore which can be reinforced. This may minimize the structural measures to be taken before the arrangement according to the invention can become operational. Dismantling a vessel may thus be done relatively safe and cost effective.

A pontoon usually has two opposite short sides and two opposite long sides. A short quay may be provided at a short side of the pontoon and/or a long quay may be provided at a long side of the pontoon. One or more stabilizers may be fixedly connected to the short quay. Also one or more stabilizers may be connected to the long quay. If there are long quays on opposite sides of the pontoon, one or more stabilizers may be connected to each of the long quays.

By arranging the stabilizer to cooperate with the pontoon to also limit lateral movement of the pontoon relative to the quay, the pontoon may be more stable during dismantling of the vessel. Advantageously two or more stabilizers may be for example fixedly connected to the quay or to the bottom of the water spaced at a distance from each other and may cooperate with the pontoon. By providing two or more stabilizers spaced at a distance from each other a tilting movement of the pontoon may be limited. In response to an upward buoyancy force on at least one of the stabilizers, the buoyancy of the pontoon may be controlled and tilting may be limited. The pontoon may thus be kept relatively level.

By providing the stabilizer with a locking arm or a beam to cooperate with the pontoon at a set height, the stabilizer may be arranged relatively robustly. In an embodiment, the stop means of the stabilizer may be a locking arm or a locking beam. Further, a force measuring unit may be integrated in and/or provided on the locking arm or beam, allowing continuous contact between the pontoon and the stabilizer, while limiting the upward force on the stabilizer.

The height of the stabilizer may be adapted to e.g. a rising or falling water level and/or a different height of the pontoon. The deck of the pontoon may be kept approximately as high as the surface of the quay. The locking arm or beam may be a structure that provides a pressing force onto the pontoon, such as a lid connected to the quay or an arm mounted on the quay that may cooperate with a cooperating element on the pontoon. The locking arm or beam may also be a structure that provides a pulling force onto the pontoon, such as a chain or rope anchored to the bottom of the dock. Also the locking arm or beam may be folded upwards or may be pivoted e.g. onto the quay when the locking arm or beam may be not in use.

By providing an upwardly disposed guide for guiding the pontoon relatively to the quay, the upward and downward movement of the pontoon may be facilitated and/or guided and/or the lateral position of the pontoon may be kept relatively constant. Also the guides may improve the stability of the pontoon and/or of the pontoon with vessel by limiting and/or avoiding a tilting movement of the pontoon. The upwardly disposed guide may for example be a rail track mounted at the side of a quay or may be one or more guiding piles placed at one or more sides of the pontoon. Also, the upwardly disposed guide may for example be two upwardly extending guides each at a long side of the pontoon. More than two upwardly extending guides along the long and/or short sides of the pontoon may be provided. Two upwardly extending guides each at a long side of the pontoon may be connected to a short side of the quay and may thus form a recess for receiving a short side of the pontoon. Also, the upwardly extending guides may be provided on the pontoon itself as upwardly extending side walls. A pontoon with upwardly extending side walls is also known as a floating dock. The upwardly extending side walls may also provide stability to the pontoon and/or may facilitate upward and downward movement of the pontoon.

By including a control system for controlling the buoyancy of the pontoon in response to the force exerted on the stabilizer, a substantially continuous downward stabilizing force may be exerted relatively easily by the stabilizer onto the pontoon, thus keeping the pontoon relatively level during dismantling of the vessel. There may be provided for automated means for controlling, such as a mechanical and/or hydraulic and/or electronic control system. For example, when the upward buoyancy force onto the stabilizer exceeds a certain predefined value, the stabilizer might activate via a hydraulic system a water inlet valve to open as to let water into a compartment of the pontoon. Also, the stabilizer may be provided with a spring that may activate a system of rods connected to e.g. a water inlet valve. The spring may activate the water inlet valve via the rods when the exerted upward force exceeds a pretension force of the spring. Also the stabilizer may be provided with electronic load sensors to measure the exerted upward force on it. The load sensors might via wires or wireless transmit the data to a central control unit. The central control unit may analyze the data and may via wires or wireless send a signal to e.g. a water inlet valve to open. The control system may also control a pump and/or a compressed air system. By using a control system the reactive ballasting system may operate fully automatically.

By arranging the means for controlling the buoyancy of the pontoon such that they keep a continuous downward stabilizing force at a substantially constant level, the stabilizer and/or the pontoon and/or the quay may be constructed lighter. A lighter structure may be more cost effective and may be more advantageously used when no or not sufficiently heavy and/or reinforced infrastructure is present. By arranging the means for controlling the buoyancy of the pontoon such that they may adapt the water level in one or more compartments of the pontoon, the buoyancy of the pontoon may be relatively easily changed in reaction to the upward buoyancy force of the pontoon onto the stabilizer. The water level may e.g. be adapted by using a pump and/or water inlet valves and/or a compressed air system. The means for controlling the buoyancy may be automated or manual.

By arranging the means for controlling the buoyancy such that the pontoon may be trimmed to an even keel position, the pontoon may be kept relatively stable and level during dismantling of the vessel. The invention also relates to a method for dismantling a vessel carried on a pontoon in water, comprising stabilizing the pontoon by exerting downward force in response to upward buoyancy force of the pontoon, and controlling the buoyancy of the pontoon such that, during dismantling of the vessel, a continuous downward stabilizing force is exerted on the pontoon. The invention will be elucidated further with reference to an exemplary embodiment represented in a drawing. In the drawing:

Fig. 1 shows a schematic top view of an embodiment of an arrangement according to the invention;

Fig. 2 shows a schematic side view along the line A-A of the arrangement of Fig. 1;

Fig. 3 shows a schematic side view along the line B-B of the arrangement of Fig. 1;

Fig. 4 shows a schematic presentation of a method for dismantling a vessel; Fig. 5 shows a schematic side view of an embodiment of an arrangement according to the invention;

Fig. 6 shows a schematic top view of the arrangement of Fig. 5;

Fig. 7 shows a schematic side view of a detail of the arrangement of Fig 5 and Fig. 6;

Fig. 8 shows a schematic side view of a stabilizer according to the invention; and

Fig. 9 shows a schematic top view of a dock arrangement according to the invention. It is noted that the drawings are only diagrammatic and schematic representations of exemplary embodiments of the invention. The embodiments are given by way of non-limiting examples. In the figures, the same or corresponding parts are represented with the same reference numerals.

An arrangement 1 for dismantling a vessel as shown in Fig. 1 comprises a quay 2 and a pontoon 3 for carrying a vessel to be dismantled. The pontoon 3 floats in water 20 bordering the quay. The water 20 can be a dock 4 that can be closed for environmental influences e.g. via doors, or can be surrounded by more natural sides 21 such as a bank or shore, also the water 20 can be enclosed e.g. by a natural or artificial bay. In the embodiment of Figs. 1, 2, 3, 4 and 9 the arrangement 1 for dismantling a vessel comprises a dock 4 with water 20 surrounded by at least one quay 2 and further side walls 21. The dock 4 can preferably be closed by doors 6 and is broad enough for two vessels 5 adjacent to each other, as for example is shown in Fig. 9.

In the dock 4 of Fig. 4a, the pontoon 3 is floating at the water level. The pontoon 3 is provided with a rail track 22. At the opposite side of the dock 4, piles 23 with rail track 24 are provided. Adjacent to the pontoon 3 a vessel 5 can be brought into the dock 4 between the rail track 22 and the rail track 24. The vessel 5 can be connected to guides 25 that on their turn are connected to winches (not shown) mounted on the quay 2. The vessel 5 can then be pulled into the dock 4 using the winches and the guides 25 that guide the vessel 5 between the rail track 22 and the rail track 24 adjacent the pontoon 3. The vessel 5 is then in a position adjacent the pontoon 3 as shown in Fig. 4a.

As a next step, shown in Fig. 4b, the pontoon 3 is lowered towards the bottom of the dock 4 and the vessel 5 can be brought above the submerged pontoon 3. To this end, winches (not shown) may be used to pull the vessel 5 sideways on the pontoon 3. Then the pontoon 3 can be brought higher until it carries the vessel 5, as shown in Fig. 4c. Lifting the pontoon 3 may be done by draining water from compartments of the pontoon 3 and supplying air in compartments of the pontoon 3, thereby increasing the buoyancy of the pontoon 3. When the pontoon 3 floats at the water level, the vessel 5 carried on the pontoon 3 is above the water level. When the water 20 is a closed dock 4, the water level in the dock 4 can be raised independently from the water level in open water outside the dock 4. The water level in the dock 4 can e.g. be raised until the deck of the pontoon 3 is approximately at the same height as the surface of the quay 2.

When the pontoon 3 is at the water level and the vessel 5 is above the water level, the vessel 5 can be dismantled and/or sectioned. Sections of the vessel 5 can be brought onto the quay 2. When the pontoon is at the water level, the rail track 22 is above the water level, a second vessel can be pulled into the dock 4 by using the guides 25 on the rail tracks 22 and 24.

While dismantling the vessel 5 the pontoon 3 is floating at the water level. During the work of dismantling the vessel 5, in particular when moving a section of the vessel 5 from the pontoon 3 onto the quay 2, the position of the pontoon 3 may tend to vary due to the variation of the weight distribution of the pontoon 3. In order to keep the pontoon 3 more stable and level, the arrangement 1 for dismantling a vessel is in accordance with the disclosure provided with a stabilizer 16. The stabilizer 16 is connected to the fixed world, in the embodiment of Figs. 1, 2 and 3 the stabilizer 16 is connected to the quay 2. As shown in Figs. 1, 3 and 8, the stabilizer 16 comprises a beam 26 extending from the quay 2. Further, the stabilizer 16 can comprise guiding piles 27 along which the pontoon 3 can be guided in upward/downward direction. The guiding piles 27 thus limit lateral movement of the pontoon 3 and/or may limit a tilting movement of the pontoon 3 thus providing more stability to the pontoon 3 A second embodiment of an arrangement 1 for dismantling a vessel

5 according to the invention is schematically shown in Fig. 5. The water 20 in which the pontoon 3 floats borders a quay 2. The water 20 is surrounded by a dock 4 that can be closed with doors 6.

In this embodiment a dock 4 is provided, as shown in Fig. 5. The vessel 5 to be dismantled can be brought into the dock 4 and the dock 4 can then be closed e.g. with doors 6. In the dock 4 an environment can thus be created that is less subject to external environmental forces, such as wind and/or tides and/or waves and/or blown off or blown up water. In an initial position, the pontoon 3 is below the water level and the vessel 5 is brought above the pontoon 3. The pontoon 3 is then raised until it reaches the bottom of the vessel 5 by filling compartments 15 of the pontoon 3 with air. The pontoon 3 is then raised further until the deck 7 of the pontoon 3 is above the water level and the vessel 5 is brought above the water level. In case the pontoon 3 is provided in a closable dock 4, the water level in the dock 4 can be changed so the deck 7 of the pontoon 3 can become approximately level with the surface 8 of the quay 2.

The pontoon 3 usually has an elongated shape with two short sides and two long sides, as shown in Fig. 6. A short side 11 of the pontoon 3 borders the quay 2. Preferably the size of the pontoon 3 is approximately the size of the vessel 5 to be dismantled. The most common size vessel type to be dismantled may be a vessel of the Panamax-type.

If the vessel 5 falls dry on the pontoon 3, dismantling and/or sectioning of the vessel 5 can be started. The vessel 5 can be cut into sections 10 on the pontoon 3. As shown in Fig. 6, floating work units 9 can be provided near the pontoon 3 for assisting the work on the pontoon 3 and/or for reaching the pontoon 3. The floating work units 9 can be anchored e.g. via piles in the water near the pontoon 3. Preferably floating work units 9 are used when no or no usable quay or bank or shore is available in the longitudinal direction of the pontoon, e.g. when only a quay is provided at the short side of the pontoon 3, or when at the long side of the pontoon only a sloped shore or bank is present.

A Panamax type vessel can e.g. be sectioned in 20 sections of approximately 12 m per section. Each section may weight approximately 400 to 500 tonnes. Sectioning the vessel 5 on the pontoon 3 is relatively efficient. In a relatively short time (e.g. two weeks), the vessel 5 can be sectioned and/or dismantled. Due to sectioning of the vessel on the pontoon and further dismantling of the sections onto the quay, the vessel occupies the pontoon a relatively short time. Thus, a relatively high efficiency can be obtained in dismantling vessels.

As shown in Fig. 7, the pontoon 3 can be provided with supports 12 and the quay 2 can be provided with supports 13. The supports 12 and 13 can be arranged in rows corresponding to a section 10 of the vessel 5. The section 10 can then be supported relatively optimal. The supports 12, 13 may be arranged such that they support the underside of the vessel 5. The supports 12 for example may be adjustable in height so a negative print may be provided of the underside of the vessel by the supports 12 to optimally support the vessel. Also, the supports 13 may be adjustable in height to provide an optimal support for sections of the vessel. The supports 12, 13 may be adjustable in height, for example hydraulically.

Further a roller base 14 can be provided for transporting the section 10 of the vessel 5. The roller base 14 can be adapted for driving between the rows of supports 12, 13. Preferably, the roller base 14 can be provided with one or more jacks for lifting the section 10 from the supports 12, and for lowering the section 10 onto supports 13 on the quay 2. Once the section 10 is transported onto the quay 2 it can be moved on the quay 2 to cutting stations where the section 10 further can be dismantled. When transporting the section 10 of the vessel 5 from the pontoon 3 onto the quay 2, as shown in Fig. 7, the load distribution on the pontoon 3 varies. In particular, the load distribution varies on an outwardly situated compartment 15 of the pontoon 3 near the short side of the pontoon 3 bordering the quay 2. The section 10 is moved over the deck 7 of the compartment 15 in a direction towards the quay 2. First the side of the compartment 15 opposite the quay 2 intends to lift due to the moving load of section 10. When moving the section 10 onto the quay 2, the side of the compartment 15 bordering the quay 2 intends to lift. To minimize damage and to facilitate a smooth transport of the section 10 from the pontoon 3 onto the quay 2, a stabilizer 16 is provided for stabilising the pontoon 3 with respect to the quay 2. The stabilizer 16 is connected to the fixed world, in this embodiment to the quay 2.

When a further section 10 of the vessel 5 is transported over the pontoon 3 to the quay 2, first the compartment 15 bordering the quay will move downward due to the weight of the section 10. When the section 10 is moved further on the pontoon 3 towards the quay 2 and onto the quay 2, the compartment 15 bordering the quay 2 will move upwards again. Limiting the upward and downward movement of the compartment 15 of the pontoon 3, may be provided by supplying and/or draining water from the compartment 15. Thereto, when moving a further section 10 towards the quay 2, first water may be drained from the compartment 15 to limit downward movement of the compartment 15 and subsequently water may supplied to the compartment 15 to limit upward movement of the compartment 15. Alternatively, or additionally, the limit force of the stabilizer 16 may be chosen such that there remains sufficient upwards force on the stabilizer 16, also during movement of a further section 10 over the compartment 15. When moving a further section 10 over the compartment 15, the compartment 15 will first move downwards thereby reducing the upward force on the stabilizer 16. By choosing an appropriate value of the limit force an upward force on the stabilizer 16 remains during the initial downward movement of the side of the pontoon 3 bordering the quay. Thus, contact between the pontoon 3 and the stabilizer 16 is provided during movement of the sections 10, which may improve the stability of the pontoon 3. The stabilizer 16 is arranged to cooperate with the pontoon 3. As shown in Fig. 8, the stabilizer 16 comprises in this embodiment an arm 17 that cooperates with a cooperating element 18 of the pontoon 3. In this embodiment, the cooperating element 18 is arranged as a recess 18 for receiving the arm 17. The arm 17 and the recess 18 cooperate as a locking system for locking the pontoon 3 with respect to the quay 2. Due to the construction of the arm 17 and the recess 18, the pontoon 3 cannot rise higher than the level of the surface of the quay 2 and the pontoon 3 is locked with respect to the quay 2. The arm 17 of the stabilizer 16 acts as stop means to limit upward movement of the pontoon 3. The locking arm 17 can e.g. be set at different heights, depending on the water level and/or the height of the pontoon 3 and/or the height of the supports 12 on the pontoon 3. The locking arm 17 can be arranged to pivot to the quay 2 for example when the arrangement 1 for dismantling a vessel is not in use. On the stabilizer 16, an upward buoyancy force B is exerted by the pontoon 3. The stabilizer 16 may be provided with a force measuring unit 28 to measure the upward force exerted by the pontoon 3 onto the stabilizer 16. When the upward buoyancy force on the stabilizer 16 becomes too high, higher than a predetermined force limit, e.g. higher than approximately 1 x 10⁵ N (approximately 10 tonnes), the means for controlling the buoyancy induce that the water level in the compartment 15 of the pontoon 3 is adapted. The water level in the pontoon 3 will be increased in order to decrease the buoyancy of the compartment 15 of the pontoon. Thus a continuous downward stabilizing force can be exerted by the stabilizer 16 on the pontoon 3 and a continuous contact between the pontoon 3 and the stabilizer 16 may be obtained. In an other embodiment, the predetermined force limit for the upward buoyancy force on the stabilizer 16 may be set to approximately 600 tonnes (approximately 60 x 10⁵ N). When moving a section 10 of approximately 500 tonnes over the pontoon, the weight distribution of the pontoon 3 varies. However, the remaining resulting upward force of the pontoon 3 will be approximately 100 tonnes, so contact between the pontoon 3 and the stabilizer 16 may be maintained during transport of the section 10. This way, the buoyancy of the pontoon 3 may be controlled less precise. In this embodiment, when a section 10 is moved over the pontoon 3 onto the quay 2 only the more inwardly situated compartments 15 of the pontoon 3 have to be filled with water in order to keep the pontoon 3 approximately level. The water level in the outwardly situated compartments 15 bordering the quay 2 may remain unchanged, thus providing for a more robust arrangement 1.

The compartment 15 can be provided with a valve 19 that can be an inlet for water entering the compartment 15. The valve 19 can be controlled either manually, mechanically, hydraulically or electronically or via an other control system. Also, water may be drained from or supplied to the compartment 15 via a pump. Also, the water level of other compartments 15 than the compartment bordering the quay 2 may be adapted to react on upward or downward movement of the respective compartment.

The buoyancy of the compartment 15 is usually measured with a force measuring unit 28 at the locking arm 17. As an example, in the arm 17 a hydraulic piston with a hydraulic cylinder can be provided. When the buoyancy becomes too high, i.e. the force on the hydraulic cylinder becomes too high, above a predetermined limit, an input - either mechanically, hydraulically or electronically - can be given to the valve 19 to open so the water level in the compartment 15 can be increased.

Fig. 9 gives a schematic overview of a dock arrangement for dismantling vessels. The dock 4 is broad enough to receive two vessels 5 parallel to each other, similar to the arrangement shown in Fig. 4. The pontoon 3 borders in this embodiment at both short sides to a reinforced quay wall 2. Sections of the vessel 5 may moved from the pontoon 3 on both sides onto the quay 2, thus improving the efficiency of dismantling the vessel. From the quay 2, sections 10 may be moved further to cutting and/or scraping areas farther away from the dock for further treatment of the sections. At both short sides of the quay 2 bordering the pontoon 3 stabilizers 16 may be provided to stabilize the pontoon, e.g. when moving a section 10 of the vessel 5 onto the quay 2. By choosing an appropriate limit for the resulting upward force on the stabilizer, e.g. approximately 600 tonnes when a section weights approximately 500 tonnes, only the more inwardly situated compartments of the pontoon 3 have to be filled with water when a further section 10 is moved off the pontoon onto the quay. The buoyancy of the more outwardly situated compartments has already been adapted when moving earlier sections of the vessel onto the quay and the buoyancy of those compartments may remain unchanged. Thus a relatively simple controlling means for controlling the buoyancy may be provided.

Many variants will be clear to the person skilled in the art and are understood to fall within the scope of the invention as set forth in the appended claims.

Claims

1. An arrangement for dismantling a vessel, comprising a quay and a pontoon for carrying a vessel to be dismantled in water bordering the quay, further comprising a stabilizer connected to the fixed world and arranged to limit upward movement of the pontoon relative to the quay by exerting downward reaction force in response to upward buoyancy force of the pontoon, and means for controlling the buoyancy of the pontoon such that, during dismantling of the vessel, a continuous downward stabilizing force is exerted by the stabilizer onto the pontoon.

2. The arrangement of claim 1, wherein the stabiliser is arranged to cooperate with the pontoon to also prevent lateral movement of the pontoon relative to the quay.

3. The arrangement of claim 2 or 3, wherein the stabilizer comprises a locking arm or beam arranged to cooperate with the pontoon at a set height.

4. The arrangement of any one of the preceding claims, further including an upwardly disposed guide for guiding the pontoon relative to the quay.

5. The arrangement of any one of the preceding claims, further including a control system for controlling the buoyancy of the pontoon in response to the force exerted on the stabilizer.

6. The arrangement of any one of the preceding claims, wherein the means for controlling the buoyancy of the pontoon are arranged to keep the continuous downward stabilizing force at a substantially constant level.

7. The arrangement of any one of the preceding claims, wherein the means for controlling the buoyancy of the pontoon are arranged to adapt the water level in one or more compartments of the pontoon.

8. The arrangement of any one of the preceding claims, wherein the means for controlling the buoyancy of the pontoon are arranged to trim the pontoon to even an even keel position.

9. A method for dismantling a vessel carried on a pontoon in water, comprising stabilising the pontoon by exerting downward reaction force in response to upward buoyancy force of the pontoon, and controlling the buoyancy of the pontoon such that, during dismantling of the vessel, a continuous downward stabilizing force is exerted onto the pontoon.

10. The method of claim 9, wherein the continuous downward stabilizing force is kept at a substantially constant level.

11. The method of claim 9 or 10, wherein the buoyancy of the pontoon is controlled by adapting the water level in one or more compartments of the pontoon.

12. The method of any one of claims 9 - 11, wherein the pontoon is trimmed to even an even keel position.

13. The method of any one of claims 9 — 12, further including sectioning the vessel on the pontoon.