The present invention relates to mooring platforms, in particular to mooring platforms for offshore structures, for example wind turbines and oil installations.

Present government plans, internationally, propose thousands of offshore wind farm installations. However, access to offshore wind farm turbines is presently difficult, especially in areas such as around the UK coast, where there is a significant tidal rise and fall and potentially rough sea conditions.

This means that for a workboat to have a constantly available soft landing onto a well fendered facility, a specific device needs to be provided.

At present, most turbine columns are fitted with vertical fenders, spaced at intervals around the circumference of the turbine column. They are fitted as appropriate to the change of water level height as incurred by the rise and fall of tide. These are a basic but not entirely user friendly answer and they do not provide a platform to transfer spares, tools and equipment and nowhere for personnel to use safely as an access or department point from the turbine.

Thus, there is a need for improved mooring platforms.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a mooring platform for an offshore structure, the mooring platform comprising a buoyant member adapted, in use, to encircle a substantially vertical member of an offshore structure such that the buoyant member is able to rise and fall with the tide to provide a platform against which tending vessels are able to dock.

Preferably, the buoyant member comprises a ring member.

Preferably, the buoyant member comprises a plurality of rollers for engagement with a substantially vertical member of an offshore structure. Preferably, the plurality of rollers are for maintaining the buoyant member in a concentric position relative to a substantially vertical member of an offshore structure. Preferably, the rollers are resiliently moveable toward the buoyant member. Put another way, the rollers are secured to the buoyant member in a sprung fashion. As such, in use, the rollers are able to maintain engagement with the surface of a substantially vertical member of an offshore structure even when external forces are applied to the buoyant member resulting in movement of the buoyant member relative to the substantially vertical member of the offshore structure. Such forces could, for example, be caused by wave movement or the docking of a boat with the mooring platform. In addition, the resiliently moveable nature of the rollers means that even if the buoyant member is positioned around a tapered column of a wind turbine, the rollers will maintain engagement with the column as the buoyant member rises and falls up and down the column in response to changes in sea level.

Preferably, the rollers are substantially spherical and rotatably held by a holding member. Preferably, the rollers are substantially spherical and are moveable within a cup arrangement. Alternatively, the rollers are substantially cylindrical and are rotatable about an axle. In some embodiments, the buoyant member comprises (i) one or more rollers which are substantially spherical and are moveable within a cup arrangement; and (ii) one or more rollers which are substantially cylindrical and are rotatable about an axle.

In some embodiments, the rollers may be substantially spherical and held by a holding member. The holding member permits movement of the roller. Preferably, as above, the holding member is a cup arrangement. Alternatively, the holding member comprises a spigot device with a substantially spherical member on the end of the spigot for placement inside a substantially spherical roller.

Preferably, the mooring platform comprises a sleeve for encircling a substantially vertical member of an offshore structure.

Preferably, the sleeve is securable to a substantially vertical member of an offshore structure. Preferably, the buoyant member encircles the sleeve and is moveable relative thereto. Preferably, the buoyant member is rotatable about the sleeve. Preferably, the buoyant member is moveable along the length of the sleeve. For example, in some embodiments, it is preferred that, in use, the buoyant member is moveable relative to the sleeve in response to the rise and fall of the sea.

Preferably, the sleeve comprises a stop for controlling movement of the buoyant member relative to the sleeve. Preferably the stop is provided at one end of the sleeve whereby, in use, the stop prevents upward movement of the buoyant member above the height of the sleeve. Preferably, the stop is a stop ring.

In some embodiments, the sleeve is moveable relative to a vertical member of an offshore structure. Preferably, the buoyant member encircles the sleeve and is secured thereto. In such an embodiment, the buoyant member is not moveable relative to the sleeve.

Preferably, the sleeve is provided with a bearing on its inner surface for engagement with a substantially vertical member of an offshore structure.

Preferably, the sleeve comprises a plurality of rollers for engagement with a substantially vertical member of an offshore structure. Preferably, ^' the plurality of rollers are for maintaining the sleeve in a concentric position relative to a substantially vertical member of an offshore structure. Preferably, the rollers are resiliently moveable toward the sleeve. Put another way, the rollers are secured to the sleeve in a sprung fashion. As such, in use, the rollers are able to maintain engagement with the surface of a substantially vertical member of an offshore structure even when external forces are applied to the sleeve resulting in movement of the sleeve relative to the substantially vertical member of the offshore structure. Such forces could, for example, be caused by wave movement or the docking of a boat with the mooring platform. In addition, the resiliently moveable nature of the rollers means that even if the sleeve is positioned around a tapered column of a wind turbine, the rollers will maintain engagement with the column as the sleeve rises and falls up and down the column in response to changes in sea level.

Preferably, the rollers are substantially spherical and rotatably held by a holding member. Preferably, the rollers are substantially spherical and are moveable within a cup arrangement. Alternatively, the rollers are substantially cylindrical and are rotatable about an axle. In some embodiments, the sleeve comprises (i) one or more rollers which are substantially spherical and are moveable within a cup arrangement; and (ii) one or more rollers which are substantially cylindrical and are rotatable about an axle.

In some embodiments, the rollers may be substantially spherical and held by a holding member. The holding member permits movement of the roller. Preferably, as above, the holding member is a cup arrangement. Alternatively, the holding member comprises a spigot device with a substantially spherical member on the end of the spigot for placement inside a substantially spherical roller.

Preferably, the mooring platform comprises a counterweight system for preventing, in use, a sudden change in position of the mooring platform, for example the sleeve and/or buoyant member, relative to a substantially vertical member of an offshore structure.

Preferably, the counterweight system comprises one or more pairs of counterweights which balance the weight of the buoyant member and/or sleeve. Preferably, the one or more pairs of counterweights are secured to the buoyant member and/or sleeve by a system of ropes and pulleys.

Preferably, the sleeve comprises a plurality of slots or holes for allowing a person to climb the sleeve.

Preferably, the buoyant member comprises a protective surface, for example a foot plate, for protecting the buoyant member and/or for providing a surface upon which a person may stand.

Preferably, the foot plate extends beyond the upper surface of the buoyant member towards the column or sleeve. Preferably, the buoyant member comprises a flexible member to bridge the gap between the buoyant member and the column or sleeve. Preferably, the flexible member functions as a friction means to slow rotational movement of the buoyant member about the column or sleeve.

Preferably, the buoyant member comprises a friction means for slowing rotational movement of the buoyant member about the column or sleeve. Preferably, the buoyant member comprises a plurality of buoyant compartments.

Preferably the mooring platform is provided with a fender. Preferably, the fender is provided along the outer circumference of the buoyant member.

Preferably, the buoyant member comprises at least one elongate member extending therefrom for providing a docking area for a boat.

Preferably, the buoyant member comprises two or more elongate members extending therefrom which define a docking area for a boat. Preferably, the two or more elongate members are substantially parallel to each other and extend in a direction which is generally away from a centre line of the buoyant member.

Preferably, the docking area is substantially rectangular in shape.

Preferably, the buoyant member is rotatable about a substantially vertical member of an offshore structure. Alternatively, the buoyant member is secured to a sleeve and the sleeve is rotatable about a substantially vertical member of an offshore structure.

Preferably, one or more elongate members are provided with one or more extension arms for extending the docking area.

Preferably, the one or more elongate members are provided with one or more baffle plates for urging the elongate members in a downwind orientation.

Preferably, the buoyant member comprises a generally circular main body section from which at least one elongate member extends.

Preferably, the mooring platform comprises an elongate member encircled by the buoyant member and an attachment means for attachment of said elongate member to an offshore structure. Preferably, said elongate member is a column. An exemplary embodiment is shown in figures 5A and 5B. Accordingly, the mooring platform of the present invention can be used in relation to any offshore structure irrespective of whether the offshore structure has a suitable substantially vertical member.

Preferably, the attachment means comprises an arm for engagement with an offshore structure. Preferably, the arm comprises an engagement surface capable of withstanding a shock. For example, the engagement surface may comprise a rubber surface.

Preferably, the elongate member encircled by the buoyant member comprises one or more stops for controlling movement of the buoyant member relative to the elongate member.

Preferably a stop is provided at or toward one end of the elongate member whereby, in use, the stop prevents upward movement of the buoyant member above the height of the elongate member. Preferably, the stop is a stop ring.

Preferably a stop is provided at or toward one end of the elongate member whereby, in use, the stop prevents downward movement of the buoyant member below the base of the elongate member.

Preferably, two stops are provided at or toward each end of the elongate member. Preferably, the one or more stops are stop rings.

Preferably, the mooring platform is substantially round or circular. In other embodiments, the mooring platform may be a different shape, such as triangular, rectangular, for example substantially square, pentagonal, hexagonal, and so on.

Preferably, the mooring platform is provided with a second platform. Preferably, the second platform is connected to the mooring platform. The second platform could be fitted appropriately, as regulations and practice require, as a helicopter landing platform. Preferably, the second platform is connected to the mooring platform via one or more articulated joints. In some embodiments, the second platform may be referred to as a second buoyant member. Preferably, the articulated joints are operable in a plurality of axes, for example all axes.

Preferably, the mooring platform is provided with one or more positioning means for controlling the position of the second platform. Preferably, the one or more positioning means comprise one or more thrusters.

Preferably, the mooring platform comprises a walkway, for example a gangway, between the second platform and the buoyant member.

In another aspect of the present invention, there is provided a docking station for an offshore structure, the docking station comprising a mooring platform according to the present invention. For example, in particularly preferred embodiments, a docking station of the present invention comprises a mooring platform comprising an elongate member encircled by the buoyant member and an attachment means for attachment of said elongate member to an offshore structure.

Whilst the present invention has been described in relation to an offshore wind turbine, it will be appreciated that the present invention is applicable to any offshore structure, for example an oil installation. The present invention may also find utility in relation to inshore and harbour situations.

In relation to offshore structures, it will be appreciated that the mooring platform of the present invention could be adapted to fit around a whole oil installation rather than just a single leg.

Example embodiments of the present invention will now be described with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1A and IB show a first embodiment of the present invention;

Figures 2A, 2B and 2C show a second embodiment of the present invention; Figures 3A and 3B show a third embodiment of the present invention;

Figure 4 shows an embodiment of the present invention in a simplified form; Figures 5A and 5B show a further embodiment of the present invention; and Figure 6 shows an alternative roller and optional friction means for use in the embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to floating mooring platforms for offshore structures, such as offshore wind turbines and oil installations.

Within this specification embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention.

Present government plans, internationally, propose thousands of offshore wind farm installations. Maintenance access will be vital and repetitive; and there could be a useful application of the device outlined herein on the maintenance of these installations.

As described herein the basic concept of the Floating Mooring Platform (FMP) of the present invention can be simply explained by imagining a rubber tyre fitted around a vertical column in tidal water. That tyre could float up and down the column with the tide. The "tyre" can be considered as the shape of a floating mooring platform (FMP) that encircles the column.

Most turbine columns have a shape that tapers toward the top, so that, in order for the "tyre," or FMP to maintain a constant fit, a vertical sleeve section could be fitted around the column, in the area that the FMP moves up and down as a result of tidal rise and fall and sea and swell wave activity.

If the device is not of sufficient mass it is desirable to dampen the excessive motion of the FMP as a result of sea conditions so that it is not moving violently. This motion can be countered with appropriate weights. A sample arrangement of this basic concept is shown in the attached figures which show a vertical sleeve around the column and the counterweights on the inside of the column. The sheaves, ropes and weights could be as shown in opposing pairs, but there could be any number of such pairings (for example in figure 3B two opposing pairs of 4 sheaves, ropes and weights are shown).

Instead of an extremely large "tyre," the present invention could be constructed with a number of individual buoyancy compartments or tanks, such that if one part is damaged the other buoyancy tanks would maintain the buoyancy of the FMP until the damaged tank is repaired. Alternatively, the FMP could be of timber construction, so that it would float naturally, but its size would give it mass necessary for dampened movement from the sea conditions.

The outer circumference could be heavily protected with rubber, or other fender device, forming an effective circular fender around the FMP.

It is possible that something could be swept against the underside of the FMP and potentially jam the bearing between FMP and column; so a rubber gasket could be fitted around the circumference of the underside of the FMP covering the gap between the FMP and the sleeve.

If a smaller version of the FMP did jam against the column, not by fouling as prevented above but by distortion or wear, it should be capable of release by pulling on a freeing rope, perhaps with a boathook. When freed, the FMP would only drop back slowly because of the counterweights. The freeing rope would be attached at both ends so that it would not foul workboat propellers and be kept under tension to prevent it lying slack in the water at low tide.

For access to the ladder for the maintenance door of the turbine column, the vertical sleeve could also have slots cut into it to act as steps up to the ladder to the usual access to the turbine column. This would stop ladder rungs fouling the FMP as it rises and falls with the tide.

In addition to a circular shape, the FMP could be constructed in a horseshoe shape. This shape would naturally tend to turn the round, or closed part, of the horseshoe shape toward the most environmentally strong effect and allow a workboat to approach the inner part of the horseshoe from the lee side (as shown in the figures). In addition to the shape, which should itself turn toward sea, side drogues could be added to assist the weathervane effect, as could the wind vanes shown.

This horseshoe type, if acting with counterweights as described above, would need the vertical sleeve and the counterweight system to rotate with the FMP. Thus, it would also require a space between the outer sleeve and the turbine column for the counterweight system to work inside the sleeve. It would therefore be necessary to support the sleeve on upper and lower bearings, wide enough to allow space for the sheaves and counterweights, with the counterweight system fitting in the space between them. In addition, an access platform would need to be added as the sleeve would not always be in line with the main ladder access to the turbine door.

If, however, it was fitted with a pressured roller system, it might not need the complication of counterweights, but the rollers would need to work both in the vertical and horizontal planes to cope with movement in those directions. It will, therefore, be envisaged that in such an embodiment the rollers could be substantially spherical and each rotatable within a cup arrangement.

As a further modification, a "surfer boat" mooring device could be fitted as used by Total Oil Company off West Africa. This uses a "V" shaped docking facility shaped to fit the bow of the workboat and a purpose built ladder access from the foredeck to the FMP.

Further variants on the FMP would be possible for larger turbine columns. Instead of using a vertical sleeve to compensate for the taper of the column, rubber rollers are held against the column by hydraulic pressure or springs. Counterweights are not likely to be needed as the mass of the larger FMP should be sufficient to dampen the vertical motion caused by sea and swell; and its own mass should prevent it from jamming on the column. In a worst case analogy, a jam should be capable of being freed when the tide refloats the FMP.

As described herein, the mooring platform may be provided with a second platform to provide a helideck. For example, the horseshoe version could be extended with articulated joints fitting to a separate platform. This platform could be fitted appropriately, as regulations and practice require, as a helicopter landing platform (helideck). This would give the added facility of using helicopters which would always have a landing area approachable from the lee side.

The articulated joints could operate in all axes, so that the mass of the helideck (and the weight of anything on the helideck, such as the aircraft) working in relation to the sea and environment's motion, would not impose a leverage on the central tower.

Further, this structure could also be fitted with thrusters which could be used to aid positioning of the helideck should it be lying in a direction that would not be favourable to the aircraft approach, on-deck or departure requirements.

An articulated gangway could be provided between the helideck and the central FMP.

Further, the FMP could be fitted with one or more stores cranes (as well as emergency equipment).

Given the huge amount of wind turbines about to be constructed around the globe and the thousands anticipated for the UK coast alone, the market potential for the FMP is significantly high.

It would be of relatively simple construction, using materials that would be familiar to, and easily workable for, wind turbine component manufacturers. It would not be a high unit cost in relation to the rest of the turbine installation.

It would provide a simple, virtually maintenance free mooring platform that will ease access, loading and unloading; and aid safer personnel transfer, especially if injured or sick personnel are being dealt with; when at present it is difficult, even in only slightly demanding environmental conditions.

The same concept can also be applied to oil and gas installations, whether they are in tidal areas or not. A simple structure could be fabricated around one leg of an installation; or a larger structure could be built that totally surrounds an installation, providing protection from damage by supply and maintenance vessels. Another example could be to have a separate leg attached to an offshore installation, such that it need not extend vertically down to the sea bed, but sufficiently sub surface so that a floating mooring platform could encircle it and rise up and down with the tide and sea movement. This would act as a protection to the main offshore structure and provide a platform for spares and equipment to be landed by a vessel, which could on most sea states actually berth alongside the floating mooring platform. It need not be circular at its outer perimeter and could be shaped to suit the installation or expected operational requirements.

The benefit of this, and indeed the presence of a FMP at any installation, would be that on a number of occasions a vessel could simply berth alongside the FMP and not have to maintain position with dynamic positioning (DP). DP operations require expensive DP Class vessels and trained operators and not needing them will reduce operational costs. It also will save fuel, being berthed as opposed to holding position by DP or by manual ship handling. It will also save emissions to the environment.

One of the more difficult manoeuvres for offshore supply vessels is when holding a vessel in such a position that it does not drive in and damage the installation's legs or other structures. The FMP would provide protection to the main structure and an alternative area to transfer stores and equipment to and from.

The Floating Mooring Platform (FMP) is a method of providing a working access platform to offshore wind farm turbines or similar structures at all states of tide. It comprises a floating platform, constructed of floatable material or a structure made buoyant by buoyancy tanks. The structure fits around the turbine column and floats up and down the column as a result of tidal and/or wind and wave swell effects. It compensates for violent sea movement as result of wave action by a damping system. It can be in simple form for smaller turbine columns and more complex for larger ones. It can be modified in design to accommodate a rotating structure that will provide a leeward approach and a protected mooring zone for workboats. The present provisions on offshore wind turbines are simple vertical fenders on the turbine sides. Such existing arrangements do not give a working platform to unload stores and equipment or personnel and do not have any provision for medical evacuation cases. The FMP of the present invention could also be useful if a workboat was lost and the crew were in the sea, because the crew would have something to climb onto. This is especially the case in embodiments in which grab lines 25 are provided. In addition, the FMP may be provided with an emergency station which could include, for example, a communications link with a coastguard, flares, emergency rations, water, life jackets, and so on.

EXAMPLES

Example embodiments of the present invention are shown in the attached figures.

A first embodiment of the present invention is shown in figures 1A and IB.

As shown in figure 1A, a floating mooring platform comprises a buoyant member 1 which encircles the column 2 of an offshore wind turbine. The sea level is shown by a dashed line 3. As will be seen, the shape of the column 2 tapers towards the top of the column 2. In order to accommodate this change of shape and allow movement of the buoyant member 1 relative to the column 2, a sleeve 4 is provided around the column 2. The sleeve 4 is secured to the column 2 to prevent movement relative thereto. The buoyant member 1 encircles the sleeve 4 and is capable of moving up and down the sleeve 4 in response to changes in the sea level caused by wave, swell and tidal movements. The buoyant member 1 is also capable of rotational movement around the sleeve 4.

The sleeve 4 is provided with a stop ring 5 for preventing the buoyant member 1 from extending beyond the height of the sleeve 4. The stop ring 5 is provided with a rubber gasket 6 positioned to engage with the buoyant member 1 and thus minimise damage to the buoyant member 1.

Also provided is a pair of counterweights 7. The counterweights 7 are secured to the buoyant member 1 by ropes 8 which each pass through a sheave or pulley 9. The counterweights 7 allow movement of the buoyant member 1 to be dampened in the event of a sudden drop in sea level. This can happen, for example, during rough sea conditions when the buoyant member 1 may otherwise drop violently. A further counterweight system (not shown) may be provided to work in the opposite direction, by a separate arrangement of counterweights, ropes and sheaves or pulleys, to allow upward movement of the buoyant member to be dampened as well as downward movement.

It will be appreciated that the amount of counterweights can be adjusted to give control over the speed of vertical movement of the floating mooring platform.

The sleeve 4 comprises a plurality of slots 10 which allow a person to climb the sleeve 4. The provision of slots 10 rather than a traditional ladder arrangement means that movement of the buoyant member 1 up and down the column 2 is not impeded.

The buoyant member 1 is provided with a protective foot plate 11. The protective foot plate 11 provides a suitable surface upon which personnel may stand whilst at the same time protecting the buoyant member. The protective foot plate may be provided with a non-slip surface.

The buoyant member 1 may be formed from a single tyre-shaped compartment. Alternatively, as shown in figure IB, the buoyant member may comprise a plurality of individual buoyancy compartments 13 such that if one compartment is damaged the other compartments will maintain the buoyancy of the buoyant member until the damaged compartment is repaired.

The sleeve 4 may be provided with a bearing 14 positioned between the sleeve 4 and the column 2.

The buoyant member 1 may be constructed from a buoyant material such as timber. In such an embodiment, there is no need for a plurality of buoyant compartments.

The outer circumference of the buoyant member 1 is provided with a fender 15 to protect the buoyant member from being damaged as a boat docks therewith. The fender may be made from any suitable material, for example a rubber material. An alternative embodiment is shown in figures 2A, 2B and 2C in which the floating mooring platform is not provided with a sleeve. Rather, the floating mooring platform comprises a buoyant member 1 provided with a plurality of rollers 12 which maintain the buoyant member 1 in concentric position relative to the column 2. The rollers 12 may be termed pressure rollers.

As described elsewhere herein, the embodiment shown in figures 1A and IB may also be provided with a plurality of rollers 12 which maintain the buoyant member 1 in concentric position relative to the sleeve 4.

The interior diameter of the buoyant member 1 is dimensioned to suit the largest column diameter as required at low water. As the floating mooring platform rises with the tide, the rollers 12 keep the buoyant member 1 concentric to the column.

The rollers 12 may be formed from a rubber material and be provided with pistons, springs 16 or other sprung arrangement to allow the rollers 12 to maintain engagement with the column 2. The pistons or springs 16 take up slack as the floating mooring platform rises up the tapered column 2. In addition, the pistons or springs 16 are able to absorb shock loadings caused by the sea conditions and/or the docking of a boat with the mooring platform.

As shown in figure 2C, the rollers may be substantially cylindrical and rotatable about an axle. Alternatively, as shown in figure 6, the rollers 12 may be substantially spherical and moveable within a cup arrangement 37.

As shown in figure 2C, the foot plate 11 may extend beyond the upper surface of the buoyant member 1 towards the column 2. A flexible member 17 is provided to bridge the gap between the foot plate 11 and the column 2. The flexible nature of the flexible member 17 means that as the gap between the foot plate 11 and the column 2 alters, the flexible member 17 maintains the bridge between the foot plate 11 and the column 2. The flexible member 17 may be manufactured from a rubber material and may extend around the entire inner circumference of the foot plate 11 of the buoyant member 1. The flexible member 17 is capable of functioning as a friction means to slow rotational movement of the buoyant member 1 about the column 2 in the event of an impact which causes the floating mooring platform to spin around the column 2. Alternatively or in addition, as shown in figure 6, a friction means 35 may be provided. The friction means 35 may be secured directly to the foot plate 11 or via a mounting means 36. The mounting means 36 allows the friction means to be removed from the buoyant member when not needed.

The friction means 35 may be in the form of a heavy rubber friction seal, or in effect a large rubber washer, which would allow movement but not a rapid spin.

A further embodiment of the present invention is shown in figures 3A and 3B. The buoyant member 1 is provided with two elongate sections 19 which together define a docking area 20 formed between said elongate sections 19. As such, it will be seen that the buoyant member is formed into a generally horseshoe shape. In the embodiment shown, the main body of the buoyant member 1 is generally circular in shape such that it encircles the column 2, with the two elongate sections 19 being substantially parallel to each other and extending in a direction which is generally away from the column 2. The edge of the main body of the buoyant member 1 which is positioned between and joins the elongate sections 19 is provided in a substantially straight rather than curved form such that the docking area 20 is generally rectangular in shape.

The edge of the buoyant member 1 which defines the docking area 20 is provided with a protective fender 24.

In this embodiment, the buoyant member 1 is capable of rotating around the column 2. In addition, by virtue of the elongate sections 19, the buoyant member 1 will naturally turn such that the curved side of the buoyant member 1 which does not have elongate members is faced toward the most environmentally strong effect, for example, into the wind or against the tide. This will mean that the docking area 20 provided between the elongate sections 19 will be protected from the environmental conditions. It will also be appreciated that the water surface within the docking area 20 will be substantially calmer than that outside the docking area 20.

Rotation of the buoyant member 1 towards the desired position discussed above can be aided by extension arms 21 provided on the elongate sections 19 which increase the length of the extension sections and the resultant docking area. The extension arms 21 may be provided in the form of drogues.

Baffle plates or wind vanes 22 may further be provided in order to aid rotation of the buoyant member 1 and to increase protection of a vessel within the docking area from the environmental conditions encountered at sea.

If the horseshoe-shaped embodiment is provided with counterweights the sleeve 4 and the counterweight system must also be capable of rotating at the same time as the buoyant member 1. In order for this to occur, a gap 18 is provided between the sleeve 4 and the column 2 for accommodating the counterweight system. The sleeve 4 is supported on upper and lower bearings (not shown) wide enough to allow space for the sheaves 9, counterweights 7 and ropes 8 to fit between the sleeve 4 and the column 2.

An access platform 23 is provided on the sleeve 4 and extends around the circumference of the sleeve 4. The access platform allows a person to access a ladder positioned on the column 2 whatever the orientation of the mooring platform relative to the column.

Instead of being provided with a counterweight system, the mooring platform shown in figures 3A and 3B could be provided with a plurality of pressure rollers between the sleeve 4 and the column 2.

It will be appreciated that in the horseshoe embodiment, the buoyant member 1 may be secured to the sleeve 4 with movement of the buoyant member 1 relative to the column 2 being facilitated by movement of the sleeve 4 relative to the column 2. As such, the rollers 12 would need to work in multiple planes (horizontal and vertical) in order to permit vertical and rotational movement of the sleeve 4 relative to the column 2. For example, as described elsewhere herein, the rollers could be substantially spherical and rotatably held by a holding member. For example, the rollers could be substantially spherical and moveable within cup arrangements, as shown in figure 6. A simplified version of a floating mooring platform according to the present invention is shown in figure 4. The buoyant member 1 is formed in a tyre shape which surrounds the column 2 of the wind turbine and which rises and falls with the tide. A further optional feature of ropes 25 acting as grab lines may be provided around the buoyant member 1. Large versions of the floating mooring platform, such as that shown in figure 4, are unlikely to require the counterweight systems described above.

A further embodiment of the present invention is shown in figure 5A (in elevation) and 5B (in plan view). The water level is indicated at 31. The buoyant member 30 is shown fitted concentric to a purpose built column 32, which is suspended from a supporting and locating arm 26 from the side of an offshore installation structure 27. It is separate from the supporting legs 28 such that any large impact on the floating mooring platform will not be directly transferred to the supporting legs 28, a susceptible factor on offshore constructions. This could also be helped by building in a shock absorbing barrier in the joints between the arm 26 and the structure 27. The buoyant member 30 will be able to rise and fall with tide, sea and swell action as with the other embodiments described herein. A stop ring 29 prevents the buoyant member rising too high and a base support 33 prevents it from dropping from the base of the column 32. The buoyant member is surrounded by a fender 34. The buoyant member can be specifically shaped on its outside perimeter to suit the size and type of vessels expected to berth alongside.

It will be appreciated that the purpose built column 32 and arm 26 can be retrofitted to any existing offshore structure.

The Floating Mooring Platform provides a method of greatly improving the safe access of personnel onto wind farm turbine structures or any similar structure, such as the leg of an oil rig installation; or indeed a large version could be built that totally surrounds an offshore oil or gas installation.

Personnel transfer is of enormous importance in offshore construction, and for access to installations of all kinds, both for renewable power sources (wind farms) and for oil and gas installations. It is presently being carried out on oil and gas installations by crane and personnel basket or by helicopter. In the case of the wind farm turbines it is by workboat mooring alongside a turbine base in such position that personnel have to climb onto a vertical ladder and up to a manhole access into the turbine itself.

It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications are covered by the appended claims.