EP2643204A2

EP2643204A2 - Apparatus to launch and recover a boat

Info

Publication number: EP2643204A2
Application number: EP11805140.8A
Authority: EP
Inventors: Derek William Frank Clarke
Original assignee: Ensco 392 Ltd
Current assignee: Ensco 392 Ltd
Priority date: 2010-11-26
Filing date: 2011-11-25
Publication date: 2013-10-02
Also published as: WO2012069853A3; CN103339027A; WO2012069853A2; US20130291779A1

Abstract

Launch and recovery apparatus for launching a boat into water from a supporting structure such as a ship comprises a cradle shaped to receive and support a boat and having a cradle axis, the cradle being moveable relative to the supporting structure between a first stowed position to a second ramp position at which the boat is typically in the water, and wherein the attitude of the axis of the cradle with respect to the water is steeper that when the boat is in the stowed positions. A movement mechanism is configured to move the cradle between the first stowed position and the second ramp position, typically having a linkage mechanism guiding the movement of the cradle into the water, which can be provided in a collapsing parallelogram arrangement which controls the change in attitude of the axis of the cradle as the cradle moves between the stowed and ramp positions.

Description

APPARATUS TO LAUNCH AND RECOVER A BOAT

This invention relates to an apparatus to launch and recover a boat, especially a vessel mounted apparatus.

In order to launch a daughter boat from a mother vessel, a variety of techniques are presently used. Commonly used to launch lifeboats, davits may be provided which connect to a line at each end of the lifeboat and hoist the lifeboat into the water. Such a manoeuvre however is time consuming and can be dangerous as it allows the lifeboat to swing in its central plane.

Rigid inflatable boats (RIBs) and other designs of boat are often deployed from larger vessels and are often used by the military, or as maritime rescue or offshore work boats. Normally these are deployed and recovered by a line from a crane on the mother vessel which is attached to a central pivot point on the smaller daughter boat. Similar disadvantages occur and in particular when boats are being recovered - this may be in more difficult conditions, with people on board, and perhaps onboard water causing unsteadiness in the lift back onto the mother vessel.

Moreover it is noted that both traditional methods require the boat to loiter alongside the mother vessel in order that the lift lines can be deployed, grasped by the boat crew and manually attached. This process is particularly hazardous. The consequences of failure during the lifting would be potentially very dangerous as the boat could fall back into the sea in an uncontrolled manner. It is for these reasons that ramp deployment is considered to be safer. Ramps are usually associated with mono-hull vessels and require the mother vessel to be making way in order to provide a more stable sea condition for launch and recovery. The boat may be placed on the ramp and then moved into the water. However because the mother vessel moves in the water, the boat being launched or recovered may move suddenly when it is lifted out of the water by a water swell, and may then collide with the ramp as the swell dissipates.

According to a first aspect of the invention there is provided an apparatus to launch a boat, the apparatus comprising:

a cradle shaped to receive a boat,

the cradle being moveable between a first stowed position to a second ramp position; and,

a movement mechanism configured to move the cradle between the first stowed position and the second ramp position.

Normally the apparatus is provided on a vessel, or other mount. Thus the invention also provides a vessel comprising the apparatus as described herein. Other mounts include offshore fixture structures, pontoons, or an onshore harbour wall for example. In one typical aspect the invention provides apparatus for connection to a supporting structure, for launching a boat into water from the supporting structure, and/or for recovering a boat from water to the supporting structure, the apparatus comprising: a cradle shaped to receive and support a boat and having a cradle axis, the cradle being moveable relative to the supporting structure between a first stowed position to a second ramp position, wherein the attitude of the axis of the cradle with respect to the water changes as the cradle moves between the stowed and ramp positions; and, a movement mechanism configured to move the cradle between the first stowed position and the second ramp position. Typically the angle of the axis of the cradle with respect to the water is larger when the cradle is in the ramp position than when the cradle is in the stowed position.

For the purposes of clarity, the daughter boat/vessel which may be received in or on the cradle is hereinafter referred to as a "boat", whilst the mother ship/vessel which may provide a mount for said cradle is referred to as a "vessel".

Thus the invention provides an apparatus which may be used to launch a boat into water, wherein the apparatus can be moved from a stowed position in which the water does not normally support the boat in use and where it is easier to board the boat and alight from it, to a ramp/angled position where the boat may be in use in contact with water and is typically floating in the water, whereby in the ramp position, the cradle can function as a ramp to launch or recover the boat.

The cradle typically has a central axis. The angle is typically the one between the central axis of the cradle and the water.

The stowed position can be an angled position although more typically the main plane of the cradle is normally parallel to the sea. Typically there is more than one ramp position. Indeed there may be a continuum or progression of ramp positions. Nevertheless, typically in use a launch position is at a greater angle with respect to the surface of the water than a recovery position. For example the launch position may be 10 - 15 ⁰ and the recover position 5 - 10 ⁰ with respect to the surface of the water. The cradle may be connected to the mount, typically the vessel. The cradle can optionally pivot around a pivot connection with the mount. Typically however, the cradle is connected to the mount by two link members. Each link member is optionally pivotally connected to the cradle at one end and optionally pivotally connected to the mount at its other end. Typically the two pivot connections between the link members and the cradle are spaced apart from each other, optionally vertically spaced apart from one another, above and below the axis of the cradle. Typically the two pivot connections between the link members and the mount are spaced apart from each other, optionally in the same spaced arrangement as the pivot connections on the link members. Optionally a parallelogram linkage is thereby provided by the link members, the cradle and mount.

Advantages of such a configuration allow the cradle to be pivoted by a more compact mechanism. Moreover the exact angle of the ramp position can be more accurately controlled by positioning the pivot connections appropriately during manufacture. Moveable connections to the mount or cradle are optional but not normally preferred.

Typically the parallelogram formed is an asymmetrical one. Typically, the two link members are of unequal length and typically they have non- symmetrical pivot points, such that the pivot connections with the mount on each link member are spaced apart by a different distance from the water in use. Thus for such embodiments the link members conveniently achieve the desired cradle attitude or angular orientation when fully raised up to the stowed position, when it is horizontal but automatically attains an optimum angle to assist launch and recovery in the ramp position. Typically the cradle comprises a buoyancy element such that it is at least partially buoyant when placed in water. For an embodiment including buoyancy, there is typically more than 1000 litres of air provided in the cradle, and frequently much more, although it depends on the size of the cradle and the boat with which it is intended to be used.

The ramp may be allowed in use to move passively between the first and second positions by action of sea swell. Since the boat being launched will typically also react to the sea swell, such a feature helps to mitigate or eliminate premature separation of the boat from the cradle during launch or recovery.

There may be any number of buoyancy elements provided in the cradle, such as 5 - 10. Typically there are an equal number on each side of the cradle. Buoyancy elements can optionally be sealed. The buoyancy elements can optionally comprise sealed compartments on each side.

Optionally the buoyancy in the buoyancy elements may be adjustable.

Optionally buoyancy elements can be individually adjusted (e.g. by partial flooding during or after commissioning) to attain the optimum neutral position in still water to match the specific boat hull profile and

displacement.

Optionally a portion of the cradle has a chamber which may be selectively filled with water or gas, in order to selectively vary the buoyancy of the cradle. Typically the chamber is an open bottom chamber which may be selectively filled with ambient air. A valve mechanism may be provided, optionally in the upper part of the chamber, to control the entry or exit of gas/water. For certain embodiments the chamber may gave a variation in buoyancy in the range, 1000 - 2500kg, typically 1500 to 2000kg. The valve mechanism may typically be a louvre valve mechanism, typically comprising slots normally in the upper part of the chamber covered by a plate which can be opened and closed by e.g. a lever mechanism.

Optionally the valve mechanism may be remotely actuated, optionally by a mechanical, electrical or hydraulically actuated system controlled from a control console linked from the vessel to the cradle via, for example, a drag link chain commonly used for such purposes. The chamber may be integrated within a link hinge plate and may be remotely opened at its upper surface.

In typical embodiments the buoyancy of the cradle is manipulated typically through adjustment of the buoyancy in the chamber, in order to restrict or eliminate up-thrust to the boat on launching - allowing the cradle to fall away and for the boat to float. During recovery however, it is useful to provide some up-thrust in order to recover the boat on the ramp.

In alternative embodiments, the variable buoyancy may be provided by a larger amount of fixed buoyancy and the provision to add ballast to the cradle. This avoids sea water entering inner portions of the structure, such as a chamber, where it may rust the structure.

In use the chamber may be filled with ballast e.g. water to encourage a lower ramp position in the water, typically a launch position. The chamber may be filled with gas, typically ambient air, in order to facilitate a relatively higher ramp position, such as a recovery position. Thus in this relatively lower ramp position buoyancy is normally provided by only the buoyancy elements, rather than the chamber. The chamber may be flooded during launch so the cradle falls away from the boat, which remains buoyant in the water. Typically the chamber would be at least partially buoyant during recovery to make the cradle ride higher in the water requiring the boat to drive "up the ramp" to engage a latch.

Optionally the movement mechanism comprises a winch mechanism, although other options are also possible such as a hydraulic ram, a rack and pinion mechanism and/or a lead screw drive.

The winch mechanism is typically attached to the cradle, normally via a line. Typically the winch mechanism comprises a constant tension winch mechanism. Typically the mechanism is actuated by a fast response winch with constant tension control. Typically when the cradle contacts the water causing a change in load on the winch mechanism, the change in load is detected by an optional control system for the winch mechanism and it pays out the line while maintaining a minimum tension to avoid slack rope. Thus the constant tension winch mechanism also helps the cradle to track the water motion once it has partly submerged.

Rolling elements are normally provided on the cradle to reduce friction between the boat and the cradle, typically on the sides and/or on the top of the cradle. In use, the boat is able to assist the gravity launch by use of the propulsion system (for example stern drives, inboards or jets). Rolling elements are optionally spaced apart from one another in a manner that supports substantially the whole of the boat. Optionally the cradle can comprise a convex design having a recess defined by the cradle to receive the boat. Optionally the cradle can comprise a concave design adapted to be received in a recess of the hull of the boat. Either design is suitable, and each can optionally comprise beams or struts to support the mass of the boat out of water in a manner that distributes the load of the boat across the outer surface of the hull so that a single point engagement of the hull on the cradle does not apply excessive pressure to the boat at that location when the boat is not supported by the water. Optionally the load bearing areas of the cradle can be faced with roller elements or other friction reducing elements.

In convex designs of cradle adapted for use with boats with multiple concave hulls, e.g. catamaran or trimaran designs, the cradle can optionally have upstanding beams that extend upwards from the outside of the cradle to form a ridge extending into the recess in the hull thereby supporting the recessed hull when the boat is on the cradle.

In concave designs of cradle adapted for use with boats with convex hulls, e.g. RIB designs, the cradle can optionally have recessed beams that extend downwards from the outside of the cradle to support the apex of the hull when the boat is on the cradle.

To recover the boat, the buoyant elements of the cradle maintain it in general synchronisation with the water swell to enable the boat to readily drive up the cradle under its own power. However increasing the buoyancy during recovery by e.g. the air-filled chamber will mean the cradle rides higher during recovery whereby a latch will readily self-latch.

Thus the cradle is constrained predominantly by its buoyancy between a fixed raised horizontal position and a lowered position and so is able to react to the water swell. The cradle is normally moved between these two positions by lifting/lowering by winch with minimum tension control.

Typically the winch only holds a short length of wire rope in a single layer on a grooved drum sufficient to meet the full range of movement and may be rigged in a multi-fall arrangement to best match the load and winch size.

The winch mechanism may be driven by a hydraulic or an electric system. One suitable electric drive system may have the following components: efficient all electric drive, inverter vector control, and a tension/torque controller to automatically adjust in order to maintain a minimum value with the speed controlled by operator joystick. Any suitable vessel may be used, but typical embodiments use a twin hull vessel such as a catamaran or a SWATH type vessel. For example a 60m SWATH supplied by Abeking & Rasmussen (Lemwerder, Germany) may be used. According to a second aspect of the present invention there is provided an apparatus to launch a boat, the apparatus comprising:

a cradle shaped to receive a boat thereon,

the cradle comprising a connecting mechanism to connect with the boat with the cradle, and which may be released to release the boat from the cradle.

Typically the cradle according to the second aspect of the invention include some or all features of the cradle according to the first aspect of the invention and other optional features of the first aspect of the invention should be considered as optional features according to the second aspect of the invention, and vice versa.

The connecting mechanism may be a latch, provided on the boat or, more normally on the cradle. The latch typically connects with a suitable member on the cradle/boat respectively. The bow latch allows the boat to naturally attain an angle relative to the cradle as it becomes buoyant at the stern. Typically the connecting mechanism is provided at the front end of the boat/corresponding end of the cradle (relative to a motor of the boat which is at the back end).

Optionally the connecting mechanism is an automatic connecting mechanism.

Optionally the connecting mechanism connects the cradle with the bow of the boat and thus in use connects the boat to the cradle when it is driven into the cradle.

The connecting mechanism may be automatically disconnected depending on the angle of the boat. Thus the connecting mechanism can be arranged so that when the boat is being launched the connecting mechanism disengages in response to the angle of the boat without an operator manually disconnecting the connecting mechanism.

According to certain embodiments, the winch line is attached to the inboard end of the cradle, and the pivotal connection on the inboard end of the cradle guides the pivoting movement of the cradle as the winch supplies the power to lift the boat. In certain other embodiments, the winch line can be attached to the cradle at a location that is spaced apart from the inboard end of the cradle, for example at a mid point on the cradle or at or near the outer end of the cradle. In some embodiments, it is advantageous is the boat and cradle assembly are balanced around the centre of gravity. This can be achieved by attaching the line from a winch at or near that centre, or by other ways, for example, by attaching more than one line spaced apart on opposite sides of the centre of gravity. Optionally the winch can comprise a primary winch device and a secondary winch device. The secondary winch device is typically attached at or near an outboard end of the cradle, spaced away from the inboard end. The line(s) from the secondary winch can optionally be connected to the cradle at or near to the centre of gravity of the boat when located on the cradle, spaced on either side of the centre of gravity. The line from one of the winch devices (e.g. the secondary winch) can optionally be supported from above the cradle, and can optionally extend to the cradle from a support beam located above the cradle. The support beam can optionally extend from supports on either side of the launch bay, and can optionally cross the launch bay.

An embodiment of the present invention will now be described, by way of example only, and with reference to the accompanying figures in which:

Fig. 1 is a side elevation of a vessel comprising an apparatus to launch a boat in accordance with the present invention, the apparatus being in a stowed position;

Fig. 2 is a side elevation of a vessel comprising an apparatus to launch a boat in accordance with the present invention, the apparatus being in a ramp position;

Figs. 3 - 7 are a series of perspective views showing a boat in various positions being launched from a vessel comprising a second embodiment of an apparatus in accordance with the present invention;

Figs. 8a - 8d are a series of views of a latch and buoyancy tank which form part of the apparatus for certain embodiments of the present invention;

Fig. 9 is a schematic representation of an electric drive system for a winch used in certain embodiments the present invention;

Fig. 10 - Fig. 12 are various views of a vessel in accordance with the present invention;

Figs 13-15 are plan, side and perspective views of a cradle used in a third embodiment of the invention;

Fig 16 is a perspective view of the Fig 13 cradle launching a boat; Figs 17-18 show perspective views of a fourth embodiment in a stowed and ramp configuration respectively; and

Fig 19 shows a side view of a fifth embodiment in a stowed configuration.

Referring to Fig. 1 , a mother vessel or vessel 10 comprises an apparatus 20 for launching a boat 30.

The apparatus 20 comprises a cradle 1 1 , a winch 22 and asymmetric link members 23a, 23b. The vessel 10 mounts the winch 22 which is connected to a double fall sheave 24 of the cradle 1 1 via a line 21 . The forward end of the cradle 1 1 has a substantial structure that forms pivot points for the two asymmetric links 23a, 23b which also connect the vessel 10 to the cradle 1 1 . In use the cradle may be moved from the stowed position shown in Fig. 1 to the launch/recovery position shown in Fig. 2, as described in more detail below. The cradle 1 1 comprises a base made from two parallel beams 12 and optionally transverse beams (not shown). The base of the cradle 1 1 is shaped to receive a boat 30, especially rigid inflatable boats (RIBs). In order to guide the boat 30 on and off the cradle 1 1 , upstanding roller elements 14 are provided around the perimeter of the cradle 1 1 , extending from the beams 12. The transverse beams may also have angled rollers; and these rollers together with the upstanding rollers 14 serve to guide the boat into the cradle 1 1 and reduce friction during recovery launching. The inside of the beams 12 comprise buoyancy elements 13. The beams 12 are circular hollow section members with two internal bulkheads, thus creating three separate compartments along the length of each beam 12. During installation, the whole beam can be adjusted in both the amount and distribution of buoyancy.

A chamber or tank 15 is provided at the front end of the cradle 1 1 which may be selectively filled with air or water in order to vary the buoyancy of the cradle 1 1 when lowered in the water. A bow fender 26 is also normally provided on the cradle 1 1 . The fender 26 is static and provided at the same relative angle as the bow angle of the boat 30. It is normally provided formed with "D" section fendering into which the boat can be driven under power. A latch 25 is provided on the cradle 1 1 in order to engage with a hook 27 (shown only in Figs. 8a - 8b) not shown) on the bow of the boat 30. The latch can therefore hold the boat 30 in place on the cradle as required, and also be disengaged when launch of the boat 30 is desired. Typically the hook is integrated into the stem of the hull of the boat and within its profile so as not to create a collision hazard. The hook 27 is a static element formed as a galvanised steel boat hook structurally tied to the hull with heavy duty mounting plates (not shown) matched to similar plates inside the hull. This distributes the latch loads into the strongest part of the hull, namely the prow extension of the keel.

As shown in more detail in Figs. 8a - 8d the boat hook 27 mates with the latch 25 which is formed from a solid round steel bar 28 of typically 100mm diameter which is supported between two substantial plates 18 which act as a trailing arm from a pivot point further forward. The swinging latch arm 28 is held in its raised position at all time by environmentally sealed hydro- pneumatic struts 29. As shown in Figs. 8a - 8e during the act of latching the weight of the boat 30 depresses the swinging latch arm 28 until the boat hook 27 passes the latch bar 28 whereupon it automatically recovers behind the boat hook 27. Release is simply achieved by the buoyancy control provided by the tank 15 which allows the cradle 1 1 to fall lower in the water only on launching so the boat floats out of the trailing latch arm 28.

In addition to the automatic bow latch certain embodiments may include a manually applied safety latch applied when the boat in the raised stowage position along with other sea fastenings.

For certain embodiments, a stand-by crane (not shown) may be provided. In use, passengers and equipment (not shown) are loaded onto the boat 30 from the vessel 10 in a convenient manner, via a corridor 34 with steps on the vessel 10. The winch is then instructed to pay out line 21 from a control station (not shown) which allows the cradle 1 1 , under gravity to move from the horizontal position towards the ramp position in a controlled manner. The links 23a, 23b control the angle through which the cradle travels. As the cradle is lowered towards a ramped, launch position, the cradle will contact the water, Fig. 2. The buoyancy elements 13 on the cradle allow it to move in response to any water swell, whilst the winch mechanism automatically moves with the swell in the water, retrieving and paying out line 21 as required to maintain a tension in the line 21 at all times. When launching, the tank 15 is allowed to fill with water, reducing the overall buoyancy of the ramp. The boat 30 will contact the water and start to float. Water swell causing the boat 30 to be raised during a launching procedure will also cause the cradle 1 1 to be raised and so will result in less, or no separation of the boat and cradle thus reducing the potential for damage when these would otherwise be separated and then brought back together with force when the swell dissipates.

The cradle 1 1 is lowered until it is in a position around 12° to the horizontal, and the boat 30 will then be floating in the water. At this angle the latch 25 will have automatically disengaged from the boat. The propulsion of the boat may be engaged to drive it out of the cradle 1 1 .

For certain embodiments, the cradle 1 1 may "fall away" from beneath the boat 30 so that it is comfortably clear of it.

To recover, a similar procedure is used in the opposite order and with some small modifications. The tank 15 is filled with air to provide additional buoyancy and the cradle 1 1 therefore sits at an angle of around 7° to the horizontal with the upstanding roller elements 24 providing a visual guide for directing the boat 30. In this embodiment at this point about 10% of the structure may be visible above the waterline. The boat 30 is driven into the cradle 1 1 and the arm automatically engages with the latch 25 on contact. When this occurs the winch 21 then pulls in the line 21 to return the cradle to the stowed position as show in Fig. 1 . Embodiments of the present invention benefit in that the electric drive even avoids any hydraulic fluid spills. Fig. 9 shows one suitable electric drive system comprising a gear box 51 , motor 52, inverter drive 53 and control panel 54. The gear box is connected to the winch 22 which drives the sheave 24.

The cradle 1 1 may be formed from enclosed tubular sections

predominantly manufactured from marine grade aluminium. The two shaped beams are compartmented to provide separate buoyancy compartments 13 as described above.

The cradle can be sized to suit the most appropriate boat depending on the particular embodiment. However a typical boat for use with

embodiments of the present invention would be a Rigid Inflatable Boat (RIB) of 2.8m beam and 8m OAL fitted with two 150HP outboards. The approximate weight of such a RIB is 2 tonnes dry. Typical embodiments of the cradle 1 1 are designed to support a fully flooded boat as may happen in a following sea.

It is proposed that the SWATH Vessel will carry four boats and have two boat apparatus of the present invention along with a heli-deck as shown in Figs. 10 - 12. Two boats are stowed in the cradle of the boat apparatus of the present invention while two more are stowed on deck but able to be loaded into the cradles by port and starboard work cranes with the boat unmanned thus avoiding man riding certification. This strategy will enable maintenance crews to be deployed to a typically a large number of turbines. Referring now to Figs. 13-15, a third embodiment will now be described, which comprises similar features to the embodiments described earlier, and in which similar reference numbers will be used to designate similar features, but increased by 100. In the third embodiment, the apparatus 120 to launch a boat can typically be deployed from the same mother vessel or vessel using e.g. a winch and similar asymmetric link members operated by various different lowering and raising mechanisms as previously described in earlier embodiments. However, the third embodiment 120 has a modified design of cradle 1 1 1 typically adapted to launch and typically recover a different kind of boat 130, namely a concave multi- hulled boat such as a catamaran.

The cradle 1 1 1 is a convex design having a recess on either side of a ridge to receive the boat. The recess is defined by two parallel lower beams 1 12I, two parallel upper beams 1 12u and transverse beams 1 12t connecting the upper and lower beams. Typically the lower beams 1 121 are spaced apart at the base of the cradle 1 1 1 , and the upper beams 1 12u are arranged closer together to form a general ridge arrangement at the apex of the cradle 1 1 1 , so that the cradle generally assumes the shape of an inverted V which supports the mass of the boat out of water in a manner that distributes the load of the boat across the outer surface of the hull so that a single point engagement of the hull on the cradle does not apply excessive pressure to the boat at that location when the boat is not supported by the water.

The cradle 1 1 1 is thereby generally shaped to receive a boat 130, especially a catamaran design. The load bearing areas of the cradle are typically faced with friction reducing elements, which in this case are roller elements. In order to guide the boat 130 on and off the cradle 1 1 1 , upstanding roller elements 1 14 are provided on the sides and optionally on the upper surface of the cradle 1 1 . Typically the side roller elements 1 14 can be disposed around the transverse beams 1 12t. Typically the top roller elements 1 14 can be disposed on struts interconnecting the upper beams 1 12u. The roller elements can optionally be angled at the same angle as the transverse beams 1 12t, which are typically set in the cradle at the same angle and separation as the inner faces of the hulls of the catamaran boat 130. The roller elements 1 14 on the sides and top of the cradle 1 1 1 serve to guide the boat 130 into the cradle 1 1 1 and reduce friction between the boat 130 and the cradle 1 1 during recovery and launching operations.

The beams extend upwards from the outside of the cradle to extend into the recess in the hull of the boat 130 thereby supporting the recessed hull when the boat 130 is on the cradle 1 1 1 .

The beams 1 12 can optionally comprise buoyancy elements and as previously described can comprise three separate compartments along the length of each beam 1 12, or can incorporate them in other ways.

During installation, the whole beam can be adjusted in both the amount and distribution of buoyancy.

A chamber or tank 1 15 can be provided at the front end of the cradle 1 1 1 which may be selectively filled with air or water in order to vary the buoyancy of the cradle 1 1 when lowered in the water. Alternatively or additionally tanks buoyancy tanks that are adjustable in use of the apparatus can be incorporated into the beams 1 12 if desired.

A bow fender 126 is also normally provided on the cradle 1 1 1 , which can function as previously described. A latch 125 is typically provided on the cradle 1 1 1 in order to engage with a hook on the bow of the boat 130 as previously described. The latch 125 can optionally be automatic as described for earlier embodiments. In addition to the automatic bow latch certain embodiments may include a manually applied safety latch applied when the boat in the raised stowage position along with other sea fastenings.

In use, passengers and equipment (not shown) are loaded onto the boat 130 from the vessel and the cradle 1 1 1 is lowered under gravity to move from the horizontal position towards the ramp position in a controlled manner, as described for previous embodiments. The buoyancy elements on the cradle allow it to move in response to any water swell, whilst the winch mechanism automatically moves with the swell in the water, retrieving and paying out line as required to maintain a tension in the line at all times. When launching, the tank 1 15 is allowed to fill with water, reducing the overall buoyancy of the ramp. The boat 130 will contact the water and start to float. Water swell causing the boat 130 to be raised during a launching procedure will also cause the cradle 1 1 1 to be raised and so will result in less, or no separation of the boat and cradle thus reducing the potential for damage when these would otherwise be separated and then brought back together with force when the swell dissipates.

The cradle 1 1 1 is lowered until it is in a position around 12° to the horizontal, and the boat 130 will then be floating in the water. At this angle the latch 125 will have automatically disengaged from the boat. The propulsion of the boat may be engaged to drive it out of the cradle 1 1 1 .

To recover the boat 130, a similar procedure is used in the opposite order and with some small modifications. The tank 1 15 is filled with air to provide additional buoyancy and the cradle 1 1 1 therefore sits at an angle of around 7° to the horizontal with the upstanding roller elements 1 14 on the struts on the top of the cradle 1 1 1 providing a visual guide for directing the boat 130. In this embodiment at this point about 10% of the structure may be visible above the waterline. The boat 130 is driven into the cradle 1 1 1 and the arm automatically engages with the latch 125 on contact.

When this occurs the winch then pulls in the line to return the cradle 1 1 1 to the stowed position.

Referring now to Figs. 17-18, a fourth embodiment will now be described, which comprises similar features to the embodiments described earlier, and in which similar reference numbers will be used to designate similar features, but increased by 100. In the fourth embodiment, the apparatus 220 to launch a boat can typically be deployed from the same mother vessel or vessel optionally using e.g. a bow winch and similar asymmetric link members operated by various different lowering and raising

mechanisms as previously described in earlier embodiments; however, in the embodiment shown the apparatus 220 uses a single winch set in the deck of the mother vessel and raising the cradle at or near the centre of gravity of the boat. The fourth embodiment 220 has a similar design of cradle 21 1 to the third embodiment, typically adapted to launch and/or typically recover a catamaran.

The cradle 21 1 is a convex design with lower and upper beams with a ridge arrangement at the apex of the cradle 21 1 in the shape of an inverted V. The cradle 21 1 can have roller elements, buoyancy elements and separate compartments to adjust buoyancy as previously described. A latch can be provided as previously described.

The cradle 21 1 differs from the previous embodiment in the winch arrangements. In the fourth embodiment, the cradle 21 1 is typically lifted by a winch device 222 from above the cradle 21 1 . The winch device 222 is located in side pillars of a support frame supported above the launch bay receiving the boats. The support frame is typically arranged across the launch bay from side to side, and is located approximately at the mid point of the cradle, approximately equidistant between the free outboard end of the cradle 21 1 and the inboard end connected to the link

mechanisms, which is typically similar to those described earlier, and which optionally incorporates a bow-winch mechanism for applying a lifting force to the cradle at the inboard end, in addition to the overhead winch arrangement 222. The line 223 from the overhead winch 222 extends over sheaves 224 located on the overhead beam of the frame and the cradle to a fixture such as a ring or other fixing typically located on the beam of the frame. Recovery of the line 223 onto the winch drum of the winch 222 pulls the line 223 around the sheaves 224, thereby raising the cradle 21 1 from the ramp position shown in Fig 18 to the generally (not necessarily perfectly) horizontal position as shown in Fig 17.

In use, passengers and equipment (not shown) are loaded onto the boat 230 from the vessel 210 and the cradle 21 1 is lowered under gravity to move from the horizontal position towards the ramp position in a controlled manner, as described for previous embodiments, with the line 223 from the overhead winch arrangement being paid out from the drum 222 to lower the cradle 21 1 into the water. The buoyancy elements on the cradle allow it to move in response to any water swell, whilst the winch

mechanism automatically moves with the swell in the water, retrieving and paying out line as required to maintain a tension in the line at all times. When launching, the tank is allowed to fill with water, reducing the overall buoyancy of the ramp. The boat 230 will contact the water and start to float. Water swell causing the boat 230 to be raised during a launching procedure will also cause the cradle 21 1 to be raised and so will result in less, or no separation of the boat and cradle thus reducing the potential for damage when these would otherwise be separated and then brought back together with force when the swell dissipates. The winch line 223 can be arranged to be automatically in tension to take up slack in the line 223 during swells. A line guide 225 fastened to the upright of the frame has a bore through which the line 223 passes, and this stabilises the cradle 21 1 against side to side movements within the launch bay.

The cradle 21 1 is lowered until it is in a position around 12° to the horizontal, and the boat 230 will then be floating in the water. At this angle the latch will have automatically disengaged from the boat. The

propulsion of the boat may be engaged to drive it out of the cradle 21 1 .

To recover the boat 230, a similar procedure is used in the opposite order and with some small modifications. A tank can be filled with air to provide additional buoyancy and the cradle 21 1 therefore sits at a slightly shallower angle of around 7° to the horizontal. The boat 230 is driven onto the cradle 21 1 and the arm automatically engages with the latch on contact. When this occurs the winch 222 then pulls in the line 223 around the sheaves 224 to return the cradle 21 1 to the stowed position. The position of the frame at approximately the mid point of the cradle (or the centre of gravity of the boat 230 when loaded on the cradle 21 1 if that is different from the midpoint of the cradle 21 1 ) means that the cradle 21 1 can recover larger boats. The overhead winch 222 can be used alone or in conjunction with the bow winch as described in relation to earlier embodiments.

Referring now to Figs. 19, a fifth embodiment 320 will now be described, which comprises similar features to the fourth and other embodiments described earlier, and in which similar reference numbers will be used to designate similar features, but increased by 100. In the fifth embodiment, the apparatus 320 to launch a boat can typically be deployed from the same mother vessel or vessel optionally using e.g. a bow winch and similar asymmetric link members operated by various different lowering and raising mechanisms as previously described in earlier embodiments; however, in the embodiment shown the apparatus 320 uses a single winch 322 set in the deck of the mother vessel and raising the cradle 31 1 at or near the centre of gravity of the boat 330. The fifth embodiment 320 has a similar design of cradle 31 1 to the fourth embodiment, typically adapted to launch and/or typically recover a catamaran.

The cradle 31 1 differs from the previous embodiment in the winch arrangements. In the fifth embodiment, the cradle 31 1 is typically lifted by a single winch device 322 from sheaves set in the support frame above the cradle 31 1 . The winch device 322 is located on the deck of the mother vessel forward of the support frame and the sheaves guiding the line 323 are supported above the launch bay receiving the boats 330. The support frame is typically arranged across the launch bay from side to side, and is located approximately at the mid point of the cradle, approximately equidistant between the free outboard end of the cradle 31 1 and the inboard end connected to the link mechanisms, which is typically similar to those described earlier. The line 323 from the deck winch 322 extends over sheaves located on the overhead beam of the frame and the cradle to a fixture such as a ring or other fixing typically located on the beam of the frame. Recovery of the line onto the winch drum of the winch 322 pulls the line around the sheaves, thereby raising the cradle 31 1 from the ramp position to the generally (not necessarily perfectly) horizontal position. Deployment and recovery of the boat 330 is essentially as described for previous embodiments, with the line 323 supporting the cradle at or close to the centre of gravity of the boat 330. The boat apparatus of the present invention is designed to ordinarily launch craft in up to 1 .5m Hs. Recovery is designed to be accomplished in up to 2.5m Hs.

Another advantage of certain embodiments is the incorporation of a straightforward but automatic bow latch positively captures the boat on recovery and holds it until the optimum point of launch.

Embodiments of the present invention benefit in that the asymmetric parallelogram link automatically attains the optimum stowage, launch and recovery angles.

Embodiments of the present invention benefit in that they provide an ability to launch and recover in higher sea states with both a stationary and moving vessel.

Embodiments of the present invention benefit in that they avoid the need to loiter and connect lift lines associated with other established methods. Certain embodiments increase the safety and/or reduce the time of launching and recovering the boats.

Embodiments of the present invention benefit in that they provide a "Drive in" method to recover a boat, under the control of the boat coxswain into a cradle which is always synchronised with the water motion thus a relatively stationary target. Embodiments of the present invention benefit in that they speed the process of both launch and recovery, increase the safe sea state for launch and recovery, lift system failure simply result in the boat dropping back into the sea in a controlled manner, they automatically capture the boat during recovery and holding it until the optimum point of launch and they give the boat coxswain full control of the launch and recovery.

Indeed certain embodiments enable a boat to be safely recovered even if substantially swamped. Improvements and modifications may be made without departing from the scope of the invention.

Claims

1 Apparatus for connection to a supporting structure, for launching a boat into water from the supporting structure, and/or for recovering a boat from water to the supporting structure, the apparatus comprising:

a cradle shaped to receive and support a boat and having a cradle axis,

the cradle being moveable relative to the supporting structure between a first stowed position to a second ramp position, wherein the attitude of the axis of the cradle with respect to the water changes as the cradle moves between the stowed and ramp positions; and,

a movement mechanism configured to move the cradle between the first stowed position and the second ramp position. 2 Apparatus as claimed in claim 1 , mounted on a vessel.

3 Apparatus as claimed in claim 1 or claim 2, wherein when the cradle is in the stowed position, the axis of the cradle is substantially parallel to the surface of the water.

4 Apparatus as claimed in any one of claims 1 -3, wherein the cradle is movable between at least two ramp positions comprising a launch position and a recovery position, and wherein the angle of the cradle with respect to the surface of the water is greater when the cradle is in the launch position than when in the recovery position.

5 Apparatus as claimed in any one of claims 1 -4, wherein the cradle is pivotally connected to the supporting structure. 6 Apparatus as claimed in any one of claims 1 -5, wherein the cradle is pivotally connected to the supporting structure by a linkage mechanism comprising at least one link member pivotally connected to the cradle at one end and pivotally connected to the supporting structure at its other end.

7 Apparatus as claimed in any one of claims 1 -6, having at least two link members connected between the supporting structure and the cradle arranged in a collapsing parallelogram arrangement which controls the change in attitude of the axis of the cradle as the cradle moves between the stowed and ramp positions.

8 Apparatus as claimed in claim 7, wherein the parallelogram is asymmetrical and wherein the linkage mechanism raises the cradle into a substantially horizontal configuration relative to the water in the stowed position, and lowers it into a non-horizontal configuration relative to the water in the ramp position.

9 Apparatus as claimed in any preceding claim, wherein the angle of the axis of the cradle with respect to the water is larger when the cradle is in the ramp position than when the cradle is in the stowed position.

10 Apparatus as claimed in any one of claims 1 -9, wherein the cradle comprises a buoyancy element such that it is at least partially buoyant when placed in water.

1 1 Apparatus as claimed in claim 10, having more than one buoyancy element in the cradle. 12 Apparatus as claimed in claim 10 or claim 1 1 , wherein the buoyancy is adjustable.

13 Apparatus as claimed in any one of claims 1 -12, in which the cradle is less buoyant in the water when in the launch position than in the recovery position.

14 Apparatus as claimed in any one of claims 1 -13, having a chamber adapted to be flooded during launch so that upon entering the water, the cradle falls away from the boat, which remains more buoyant in the water than the cradle.

15 Apparatus as claimed in any one of claims 1 -14, wherein the buoyancy in the cradle is increased during recovery of the boat.

16 Apparatus as claimed in any one of claims 1 -15, having a latch device to restrain the boat on the cradle.

17 Apparatus as claimed in any one of claims 1 -16, wherein the connection between the supporting structure and the cradle allows the cradle to move passively in the water relative to the supporting structure response to wave action in the water.

18 Apparatus as claimed in any one of claims 1 -17, wherein the movement mechanism comprises a winch mechanism having a winch line connected between the cradle and the supporting structure.

19 Apparatus according to claim 18, wherein the winch line is attached to the cradle, and wherein the movement mechanism on the inboard end of the cradle guides pivoting movement of the cradle as the winch supplies the power to lift the boat.

20 Apparatus as claimed in claim 18 or 19, wherein the winch line is attached to the cradle at a location between the ends of the cradle.

21 Apparatus as claimed in any one of claims 18-20, wherein the winch mechanism comprises a primary winch device and a secondary winch device, each with a respective winch line, and wherein the winch lines from the primary and secondary winch devices are attached at different spaced apart locations on the cradle, at least one of the winch lines being spaced away from the inboard end of the cradle, at or near to the centre of gravity of the boat when located on the cradle. 22 Apparatus as claimed in any one of claims 18-21 , wherein at least one winch line from the winch mechanism is supported from above the cradle, and extends to the cradle from a support beam located above the cradle. 23 Apparatus as claimed in any one of claims 1 -22, having at least one rolling element on the cradle to reduce friction between the boat and the cradle during relative movement of the two.

24 Apparatus as claimed in any one of claims 1 -23, wherein the cradle is convex and has a recess configured to receive the boat and to support the hull of the boat out of the water.

25 Apparatus as claimed in any one of claims 1 -23, wherein the cradle is concave and has a protrusion configured to be received within a recess of the hull of the boat, and configured to support the hull of the boat out of the water.

26 A vessel incorporating apparatus as claimed in any one of claims 1 -25.

27 A method of launching a boat into water from a supporting structure, or recovering the boat from the water to the supporting structure, the method comprising a supporting the boat on a cradle that is movably connected to the supporting structure via a movement mechanism, and moving the cradle and the boat supported thereon relative to the

supporting structure between a stowed position, in which the boat is out of the water, and a ramp position, in which the boat is in the water. 28 A method as claimed in claim 27, including the step of mounting the cradle on a vessel and launching and recovering the boat from and to the vessel.

29 A method as claimed in claim 27 or 28, including the step of moving the cradle between at least two ramp positions comprising a launch position and a recovery position, and wherein the angle of the cradle with respect to the surface of the water is greater when the cradle is in the launch position than when in the recovery position. 30 A method as claimed in any one of claims 27-29, including the step of pivotally moving the cradle relative to the supporting structure.

31 A method as claimed in any one of claims 27-30, wherein the cradle is pivotally connected to the supporting structure by a linkage mechanism comprising at least two link members pivotally connected to the cradle at one end and pivotally connected to the supporting structure at its other end, and wherein the link members control the change in orientation of the axis of the cradle as the cradle moves between the stowed and ramp positions.

32 A method as claimed in any one of claims 27-31 , including the step of raising the cradle into a substantially horizontal configuration relative to the water in the stowed position, and lowering the cradle into a non- horizontal configuration relative to the water in the ramp position.

33 A method as claimed in any one of claims 27-32, including the step of adjusting the buoyancy of the cradle in the water between the stowed and the ramp positions. 34 A method as claimed in claim 33, including the step of reducing the buoyancy of the cradle when the cradle is in the launch position as compared to the amount of buoyancy in the cradle when the cradle is in the recovery position. 35 A method as claimed in claim 33 or claim 34, including the step of flooding a chamber in the cradle during launch so that upon entering the water, the cradle falls away from the boat, which remains more buoyant in the water than the cradle. 36 A method as claimed in any one of claims 33-35, including the step of increasing the buoyancy in the cradle during recovery of the boat.

37 A method as claimed in any one of claims 27-36, including the step of latching the boat to the cradle in the stowed position. 38 A method as claimed in any one of claims 27-37, including the step of allowing the cradle to move passively in the water relative to the supporting structure in response to wave action in the water, when the cradle is in the ramp position.

39 Apparatus to launch a boat, the apparatus comprising:

a cradle shaped to receive a boat thereon,

the cradle comprising a connecting mechanism to connect the boat with the cradle, and which may be released to release the boat from the cradle.