GB2489679A

GB2489679A - Transfer vessel with a bow shaped for berthing

Info

Publication number: GB2489679A
Application number: GB1105356.8A
Authority: GB
Inventors: Andrew Francis White
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-03-30
Filing date: 2011-03-30
Publication date: 2012-10-10
Anticipated expiration: 2031-03-30
Also published as: GB2489679B; GB201105356D0

Abstract

The invention provides a vessel with a particular bow configuration. The vessel comprises a hull 10 with a bow 13 characterised by at least two distinct berthing projections 15, 16 and 17 located at and forwardly extending from the bow. Each berthing projection is adapted to allow engagement of the vessel with a landing structure 27, 28 and 29 having two spaced generally vertical members 27. The projections are spaced laterally across the width of the bow and each distinct berthing projection, or a part thereof, is adapted to locate between and contact the two vertical members of the landing structure. The hull may be shaped such that the bow is broad across the beam, and a berthing projection may be located at each lateral extremity across the beam. A third berthing projection may be located between the others.

Description

TRANSFER VESSEL

This invention relates to a vessel which is adapted to secure to a landing structure at a range of orientations relative to the structure to allow stable loading and unloading.

The structures for which the apparatus of the present invention has been primarily developed are offshore wind turbines having a boat landing platform.

As a consequence the present invention will be primarily described in relation to use with offshore platforms, particularly the bases of wind turbines, but it will be appreciated that the invention is not limited to such use.

In an attempt to reduce fossil fuel use and eliminate pollution caused by the burning of such fuels, there is an increasing need for renewable energy sources. Offshore wind turbines are an important source of renewable energy, generating power from both the wind and tide.

Wind turbines require regular servicing and maintenance in order to ensure efficient and effective operation. With offshore wind turbines (in contrast to onshore turbines), there is the added difficultly when carrying out such upkeep, in ensuring safe personnel transfer between a service vessel and the turbine structure. Most offshore wind turbines have a boat landing platform comprising two vertical bars which are attached to and are offset from the tower of the turbine, against which a vessel can moor. A ladder is also provided and is attached to the tower to provide access to the turbine. The landing platform bars need to extend along the length of the tower for a distance greater than the largest tidal variation in the water level to be accessible at all times and to allow for wave motion. Existing methods of connection of a service vessel to the boat landing platform of an offshore wind turbine generally involve mooring the vessel by pushing the vessel against the vertical bars using thrust from the vessel's engine. With existing vessel types this method of connection does not provide a stable path for transfer of personnel to and from the boat landing platform due to wind and sea movement. Consequently, the potential for injury to personnel is high. Moreover, in existing methods, when docking to the boat landing platform, the vessel is usually limited to an orientation where the centre of the bow is in direct alignment with the centre of the landing platform, between the vertical bars. To provide a safe stable transfer of personnel from the vessel, this is not always the most appropriate position for the vessel relative to the landing structure. To prevent undesired rotational movement of the vessel relative to the landing platform and to maintain the vessel against the structure, the vessel must be secured to the structure. There of course exists a delay and risk of injury to personnel undertaking such securing of the vessel.

Furthermore, in this environment there is quite often more than one vessel working in the same area carrying out servicing and maintenance of the turbines. Vessels docked in this head-on orientation can cause obstructions to these other vessels.

As the technology has developed the types of offshore installations (such as wind farms) has evolved and their locations have moved further offshore.

For example current wind farms generally have 30 to 200 turbines and are located up to 20km off-shore in water depths of up to about 15m. In these the wave heights are usually up to about 1.5 m. In contrast There thus exists a need for a vessel which can perform the function of a supply or support vessel, and which allows a range of docking orientations to enable maximum positional flexibility, for example to give clearance either side of the landing platform, as well as ensuring the safe transfer of personnel to and from a vessel to the boat landing platform of a structure, such as an offshore wind turbine. It is therefore a principal aim of the present invention to provide a vessel which is capable of securing to a landing platform at a range of orientations relative thereto and which also allows the safe transfer of personnel between a vessel and a boat landing platform.

According to this invention, there is provided a vessel comprising a hull with a bow, characterised in that at least two distinct berthing projections are located at and forwardly extending from the bow, each berthing projection being adapted to allow engagement of the vessel to a landing structure having two spaced generally vertical members, wherein the at least two projections are spaced laterally across the width of the bow and each distinct berthing projection, or a part thereof, is adapted to locate between and contact the two vertical members of the landing structure.

The present invention has been principally developed for the adaptable and safe transfer of personnel between the vessel and a boat landing platform.

It has been developed with offshore wind turbines in mind and therefore will be described herein with particular emphasis on this application. It is envisaged however, that the vessel of the present invention may be used to safely transfer personnel to any structure in, or adjacent the water and having two suitably spaced vertical members. The two vertical members may be the vertical bars of a boat landing platform, the sides of a ladder, or even support struts of a docking platform.

Each projection is adapted independently to locate between the vertical members in order to maintain the vessel against the landing platform. By providing more than one projection, a range of orientations of the vessel relative to the landing platform are possible. The most appropriate projection is simply selected depending on the desired orientation.

Preferably, the projections are spaced well apart laterally to provide clearance either side for flexible positioning of the vessel to a landing platform.

Desirably, the hull is shaped such that the bow is relatively broad across the beam and a berthing projection is located at each side of the bow across the beam. This arrangement allows the vessel to dock to the landing platform at either side dependent on conditions.

The vessel may have more than two berthing projections to provide a greater range of positioning orientations. In a preferred arrangement, the vessel has three berthing projections. For greater versatility, the third projection may be a central projection extending from the bow along the centre line of the hull. This provides the vessel with the ability to secure to the landing structure in a straight orientation, where the centre of the landing structure is in alignment with the centre of the bow. The presence of three projections laterally positioned across the bow may serve to give additional support to maintain the vessel in engagement with the landing structure. The spacing of the projections may be such that when one projection is located between the vertical members of the landing structure, one or all of the other projections bear upon the structure and thus enhance the stability of the vessel.

As each berthing projection can in use engage with the landing structure, it follows that each will have a region of contact where the projection contacts the structure. It is essential that each projection is capable of being positioned at least partially between the vertical members. As such, it is preferable that each projection narrows inwardly at the region of contact, thereby to ease location of the projection at least partially between the vertical members. The distance that each projection extends from the bow should be sufficient to ensure appropriate engagement. The distance need not be the same for each berthing projection. For example, the centre projection may not project quite as far from the bow as the other projections. This arrangement is particularly advantageous when the vessel is to be moored in a straight orientation relative to the landing structure. If suitably configured, when a centre projection is engaged with the vertical members, the side projections can provide additional support by engaging other parts of the structure. In this way, a prevention or restriction on the range of rotational movement of the vessel relative to the structure can be achieved.

The projections may adopt a variety of shapes, to suite the shape of landing structures. Often it is advantageous that the berthing projections are capable of engaging the landing structures at a variety of angular positions, so that the vessel may be positioned at various angles relative to the structure whilst still being capable of secure engagement. Further, it is preferable that the angular position of the vessel may change whilst the projection is engaged between the vertical members. Therefore each projection may have a curved profile and preferably is substantially semicircular in plan view to facilitate location thereof between the vertical members of the landing structure.

Projections of this shape allow the vessel to dock at a range of angles with respect to a landing structure and to alter the angle when engaged.

Alternatively, one or more of the projections can be a component separate from the hull but mounted thereon to permit a degree of rotation. A structure such as that described in our co-pending UK Patent Application No. 09 13832.2 would be suitable and the details of that are incorporated herein by reference.

In a preferred embodiment, each projection is substantially the same width. This helps to ensure that each is capable of locating in a snug-fitting arrangement between the vertical members of a particular landing structure.

The spacing between the vertical members of a landing platform may be of a standard separation, or may not usually vary considerably. Nevertheless, the vessel may need to locate between two vertical members of some other structure. Therefore, in an alternative arrangement, the vessel may comprise projections configured to fit in a wide range of sizes, or may comprise projections with different widths (or profiles) to accommodate a wider variety of differently spaced vertical members.

In a preferred arrangement, one or more resiliently deformable member is located on at least part of at least one projection, and preferably on all the projections. This may be mounted on the projection in the region of contact with the vertical members so that the resiliently deformable member engages the vertical members when the projection is held therebetween. Compression of the resiliently deformable member ensures a snug fit of the projection between the vertical struts as well as minimising and cushioning relative movement. It also provides an element of friction to help ensure that the projection does not easily become disengaged from the landing structure when it should be secured. The resiliently deformable member may be located only in some common regions of contact, however, it may also be provided around much, or all, of the periphery of the, or each projection. The resiliently deformable member is preferably one or more separate component that may be removeably secured to the projections, to facilitate replacement thereof. This ensures that the parts of the vessel that wear more than others can be easily maintained. A single resilient member may extend round more than one projection, or several separate resilient pads may together provide the resilient member.

The resiliently deformable member may be a fender adapted to secure around the periphery of the vessel and in particular around the projections. This provides a buffer for the vessel to reduce shock and damage to the operating apparatus, should impact with the structure occur when engaging the projection between the vertical members.

In an alternative arrangement, one or more of the projections may actually be formed predominantly or substantially of a material that has suitable resilient deformability.

The vessel of the present invention is usually a work boat that takes personnel, equipment and supplies to the structure. Such boats are often broad across the beam and have multi-hull designs that provide a large load area and stable sea handling. In a preferred embodiment of the invention, the hull is a catamaran design with a deck that is generally rectangular in plan view.

Berthing projections may be integrally formed as part of the deck or bow, or instead may be secured thereto. They may be located over the bow of each hull of the multi-hull design. This will conveniently place them generally at the front corners of the vessel.

The vessel of the present invention provides a stable platform for gaining access to a landing structure. By providing a selection of projections, the vessel can be secured to a landing structure at a range of orientations thus providing maximum clearance at either side of the structure for other vessels working in the area, whilst also allowing the vessel to dock directly in alignment with the centre of the structure if necessary. By engaging one of the berthing projections with the landing structure and rotating the vessel until another of the projections (or a different part of the vessel) engages a fixed structure (such as another part of the landing platform), the vessel may be securely held in place.

These two points of contact and appropriate vectoring of the thrust from the vessels propulsion system can hold the vessel in place without the need of other fixing means. Use of more than two berthing projections, and particularly three, provides a greater degree of flexibility in the secure positioning of a vessel relative to the landing structure.

By way of example only, one specific embodiment of vessel of this invention will now be described in detail, reference being made to the accompanying drawings in which:-Figure 1 is a perspective view of the bow of the vessel according to the present invention; Figure 2 is a plan view of the vessel engaged with a structure in a first orientation; Figure 3 is a plan view of the vessel engaged with a structure in a second orientation; and Figure 4 is a plan view of the vessel engaged with a structure in a third orientation.

All of the Figures show the same embodiment of vessel according to the present invention but in different orientations with respect to a landing platform and the associated structure. In each case the vessel has a catamaran type hull 10 with twin hulls. This particular embodiment of vessel is designed specifically for offshore wind farm maintenance work and will be described in respect of that use. The vessel is a work boat that is broad across the beam to provide a large load space and enhanced stability, and it has a deck that is generally rectangular in plan view. Other features such a wheelhouse or control console have been omitted for clarity, but could be present on the deck. Two water jet propulsion units 11 are located at the stern 12 one in each of the twin hulls 10 and are linked to engines (not shown) to provide propulsion and directional control. The bow 13 is provided with a raised platform 14 for providing crew access to and from structures such as the landing platform of wind turbines.

As can best be seen in Figure 1, three projections 15, 16, 17 extend from the otherwise broad flattened bow-end of the platform 14. Projections 15, 17 -10-extend forwardly from each lateral extremity 18, 19. Resiliently deformable fenders 20 locate around both of the side projections 15, 17 and extend along at least a part of the periphery of the hull 10. The or each fender 20 may be removed so that it can easily be detached for cleaning, storage, maintenance, or replacement.

A central projection 16 extends forward between the side projections 15, 17. The central projection 16 in this embodiment comprises a large resiliently deformable member 25.

The vessel of this invention is designed selectively to secure to a structure which in this case is the base of a wind turbine 26. The turbine base 26 includes a boat landing platform (not shown), access to which may be gained by a landing structure that comprises two vertical bars 27 spaced from the turbine base 26 and attached thereto by arms 28. A ladder 29 is attached to the turbine base 26, between the vertical bars 27 to enable access to the platform provided higher up the turbine pillar.

To secure the vessel to the turbine base 26, the projection 15, 16, 17 which is the most appropriate for docking the vessel in a desired orientation is selected. The vessel is then positioned relative to the turbine so that the chosen projection on the bow 13 is in alignment with the vertical bars 27. The vessel is then propelled towards the turbine base 26 so that the fender 20 or the resiliently deformable member 25 as the case may be, locates between the bars 27. The desired angle of the boat relative to the turbine base may be altered before or after inter-engagement of the berthing projection with the vertical bars 27. The fender 20 or member 25 is then securely held in position between the bars 27, whether by clamping means (not shown) that can then be used to secure the vessel to the turbine, or by using sufficient thrust from the propulsion units 11.

As shown in Figure 2 and Figure 3 the vessel can dock to the turbine at such an angle that the other of the side projections 15, 17 not positioned between the bars 27 may locate against, and bear upon the wind turbine base 26. This arrangement provides maximum clearance on one side of the ladder 29 and also enhances the stability of the vessel. The vessel can be docked to the wind turbine at various angles between the positions shown in Figures 2 and Figure 3. In order to dock the vessel head on so that the centre of the bow 13 is in alignment with the ladder 29, the central projection 16 is selected to locate between the vertical bars 27 in the same way as discussed above. In this arrangement the vertical bars 27 may locate between one of the side projections 15, 17 and the centre projection 16 which again enhances the stability of the vessel.

The selection of the most appropriate proiection 15, 16, 17 to dock the vessel to the base of the wind turbine 26 can be dependant upon the position which best suits the wind and / or tide, in order to minimise the instability experienced by the vessel and/or to provide a desired clearance on either side 18, 19 of the vessel so as to minimise obstruction to other vessels.

The engagement of the vessel to the turbine base 26 of the present invention provides a stable platform for the transfer between the vessel and the landing platform. Steps 30 are provided on the deck 35 of the vessel which lead up to the platform 14 to aid access. Guard rails 36 are located around the -12-platform 14. Personnel may access the boat landing platform by simply stepping from the projection 15, 16, 17 engaged with the vertical bars onto the ladder 29. -13-

Claims

CLAIMS1. A vessel comprising a hull with a bow, characterised in that at least two distinct berthing projections are located at and forwardly extending from the bow, each berthing projection being adapted to allow engagement of the vessel to a landing structure having two spaced generally vertical members, wherein the at least two projections are spaced laterally across the width of the bow and each distinct berthing projection, or a part thereof, is adapted to locate between and contact the two vertical members of the landing structure.
2. A vessel as claimed in claim 1, wherein the hull is shaped such that the bow is relatively broad across the beam and a berthing projection is located at each lateral extremity of the bow across the beam.
3. A vessel as claimed in claim 1 or claim 2, wherein a third berthing projection is provided.
4. A vessel as claimed in claim 3, wherein the third berthing projection extends from the bow along the centre line of the hull.
5. A vessel as claimed in any of the preceding claims, wherein each projection narrows inwardly at a region of contact with the vertical members, thereby to ease location thereof between said vertical members.
6. A vessel as claimed in any of the preceding claims, wherein a berthing projection is provided with a resiliently deformable member that is located in a region of contact with the vertical members.
7. A vessel as claimed in claim 6, wherein the resiliently deformable member locates around a periphery of the berthing projection. -14-
8. A vessel as claimed in any of the preceding claims, wherein at least one berthing projection is predominantly formed from a resiliently deformable material.
9. A vessel as claimed in any of the preceding claims, wherein the hull, has a multi-hull design.
10. A vessel as claimed in any of the preceding claims, wherein each projection is substantially curved or semicircular in plan view.
11. A vessel as claimed in claim 1 and substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.