A known form of survival craft is a lifeboat for use on a marine structure such as an offshore oil rig or a ship comprises a conventional rigid hull carrying a protective shelter and is mounted on the structure by davits from which, after loading with people, it can be lowered into the water. The lifeboat may be provided with an engine to allow it to propel itself away from the structu re after entering the water.

The provision of rigid lifeboats and the associated davits occupy significant space on marine structures. This is a particular problem on passenger ships such as cruise ships where the space taken by the lifeboats and davits reduces the number cabins available with side views.

According to a first aspect of the invention, there is provided a survival craft comprising a hull formed from inflatable members and mounting a propulsion system for the survival craft, and a superstructure carried by the hull and formed from inflatable members, the superstructure providing the hull with additional longitudinal rigidity.

In this way, the craft can be stored on the structure in deflated form in a compact manner and, when deployed and inflated provide both the a bility to carry people and the ability to move clear of the structure under its own propulsion. In the abse nce of the superstructure, the provision of the propulsion system would tend to bow the craft in a longitudinal direction. In addition, the superstructure can provide shelter. Preferably, the propulsion system comprises at least one electrical motor and associated propeller mounted beneath the hull and receiving electrical power from a power source. The power source may be within the hull or outside the hull. Where the power source is outside the craft, the power source may be carried by a pod including also the propulsion system and mounted beneath the hull.

According to a second aspect of the invention, there is provided a marine escape system comprising a deployment system for mounting on a marine structure and carrying a deflated survival craft according to the first aspect of the invention, the deployment system transferring the container from the structure to the water where the inflation system inflates the survival craft.

The following is a more detailed description of an embodiment of the invention, by way of example, reference being made to the accompanying drawings in which:- Figure 1 is a schematic view from the rear, to one side and beneath of a first form of survival craft,

Figure 2 is a schematic view of the survival craft of Figure 1 from the rear, to one side and above showing the internal structure of a super structure of the survival craft,

Figure 3 is a schematic view from the front, to one side and beneath of the survival craft of Figures 1 and 2 showing propulsion units and a skeg,

Figure 4 is a similar view to Figure 2 showing an alternative form of the superstructure providing a self-righting capacity to the survival craft,

Figure 5 is a perspective view from the rear, beneath and to one side of a further form of survival craft with a hull and superstructure and with an outer cover of the superstructure removed and showing a propulsion pod beneath the hull,

Figure 6 is a view of the survival craft of Figure 5 from the front and to one side,

Figure 7 is a first perspective view of the propulsion pod of Figures 5 and 6, Figure 8 is a second perspective view of the propulsion pod of Figure 7,

Figure 9 is a view of part of a side of a ship showing a marine escape system carrying two uninflated survival craft of the kind shown in Figures 5 to 8,

Figure 10 is a similar view to Figure 9 showing a first stage of deployment of the two survival craft with the craft extended outwardly of the ship,

Figure 11 is a similar view to Figure 10 showing a second stage of deployment with the two survival craft starting to be lowered towards the water and two chutes commencing deployment,

Figure 12 is a similar view to Figure 11 showing a third stage of deployment with the two survival craft in the water and the chutes fully extended,

Figure 13 is a similar view to Figure 12 showing the chutes separated,

Figure 14 is a similar view to Figure 13 and showing the hulls and the superstructures of the survival craft inflated,

Figure 15 is a similar view to Figure 14 and showing the undersides of the hull of the survival craft of Figure 14,

Figure 16 Is a schematic view of a first bowsing arrangement for bowsing a survival craft, such as the craft of Figures 1 to 15, against a marine structure, and

Figure 17 is a schematic view of a second bowsing arrangement for bowsing a survival craft, such as the craft of Figures 1 to 15, against a marine structure Referring first to Figures 1 and 2, the survival craft comprises a hull 10 and a superstructure 11 carried on the hull 10.

The hull 10 is formed by port and starboard inflatable tubes 12, 13 that extend along the gunwales of the hull 10 and extend upwardly while converging to meet at a shaped bow 14. At the stern 15, the tubes 12, 13 are spaced by a stern member 16. A floor 17 extends between the gunwale tubes 12, 13 and the stern member 16 and is formed by spaced sheets of air-impervious fabric forming an inflatable chamber. The spaced sheets may be formed by a drop thread materia l. In addition, as seen in Figure 2 two longitudinal inflatable floor tubes 42, 43 may extend from the stern 15 to the bow 14. These tubes 42, 43 may also be formed of a drop thread material to give these tubes 42, 43 increased rigidity.

The floor 17 carries a powered propulsion system for the survival craft. This may be an electrical system with a generator (not shown), which may be a diesel power unit, mou nted within the survival craft and electrical connections to fore and aft thrusters 18, 19 located beneath the floor 17. Each thruster 18, 19 includes an electrical motor 20 driving a shielded propeller 21 with the thrusters 18, 19 being steerable from within the hull 10. Of course, there could be more or less thrusters 18, 19 and they could be differently located on the hull 10.

The under surface of the hull 10 also carries a skeg 34 (see Figure 3) located towards the bow 14 to give the hull 10 lateral stability. There may be more than one skeg 34.

The superstructure 11 is formed by a roof 22 and port and starboa rd sidewalls 23, 24. Each sidewall 23, 24 is formed by an upper elongate inflatable tube 25, 26 extending a long the length of the hull 10 genera lly parallel to the associated gunwale tubes 12, 13 with the upper tubes converging and meeting above the bow 14. At the stern, the upper tubes 25, 26 are separated by an upper stern spacer 27. The upper tubes 25, 26 are spaced by lateral inflatable spacer tubes 44 at spaced intervals along the upper tubes 25, 26. A sheet 28 of flexible water-impervious material extends between the upper tubes 25, 26 and forms a roof. Again, any or all of the tubes may be made from a drop thread material. The side wa lls 23 24 are formed by inflatable side spacer tubes 29a - 29i that extend between the gunwale tubes 12, 13 and the associated upper tubes 25, 26. The side spacer tubes 29a - 29i are arranged in a zigzag configuration along the gunwale tubes 12, 13 with successive side spacer tubes 29a - 29i being inclined in respective opposite directions relative to the gunwale tubes 12, 13. In addition, two inflatable stern tubes 30a, 30b extend in a V-configuration between the stern member 16 and the upper stern spacer 27. The inflatable side spacer tubes 29a - 29i may be formed by consecutive sections of a single tube or by separate tubes. The tubes 29a - 29i may be formed of a drop thread material. Sheets 31a 31b, 31c of flexible water-impervious material cover the sides of the superstructure 11 and the end of the superstructure 11 and are provided with door and window openings 32, 33. In this way, the superstructure 11 forms a truss structure carried by the hull 10 that provides the hull 10 with increased longitudinal rigidity, resisting any tendency of the hull 10 to bow. In addition, it forms a protective shelter for occupants of the survival craft.

In use, the survival craft is deflated and packed in a container (not shown) that may be rigid or flexible. The container includes an inflation system (not shown) of any suitable known type. The container is carried by a deployment system that is for mounting on a marine structure such as a rig or a ship. The system may carry more than one such container.

When required for use, the system releases the container into the water. On reaching the water, the inflation system commences inflation of the survival craft and the container opens, so allowing the survival craft to complete inflation and deploy. People 21 from the marine structure can then enter the survival craft. The central floor tubes 42, 43 provide a pathway for persons entering the survival craft through the stern door 32 or for people entering the survival craft through the roof 28. The propulsion system is used to move the survival craft clear of the structure and to steer it. The survival craft may be accessed from the structure through a transfer system such as a chute or a slide. The chute or slide may lead directly into the survival craft, for example to an entrance through the roof 28 or to a point adjacent the stern door 32, or may lead to a platform adjacent the survival craft from which the survival craft may be accessed.

The provision of a rigid floor 17 reduces the tendency of the floor 17 to crease as the hull 10 travels through water so reducing the drag on the hull 10. The electrical thrusters 19 are compact and obviate the need for a drive shaft to pass through the hull 10 - flexible electrical connections can run in any required path to the thrusters 18, 19, Since the thrusters 18, 19 are steerable, there is no requirement for separate steering such as a rudder. Of course, as an alternative, non-steerable thrusters could be used with a separate rudder.

The survival craft described above with reference to the drawings is more compact than rigid survival crafts and so occupies less space on a marine structure, This can be important on passenger ships where outside space to the sides of the ship is at a premium. At the same time, the survival craft has the advantage over unpowered inflatable life rafts that it is powered and steerable and so can be used to move persons clear of the marine structure.

Referring next to Figure 4, this shows a self-righting version of the survival craft of Figures 1 to 3. Parts common to Figures 1 to 3, on the one hand, and to Figure 4, on the other, a re given the same reference numerals and will not be described in detail.

In this embodiment, the side walls 23, 24 include respective port and starboard intermediate elongate inflatable tubes 35, 26 located between the upper tubes 25, 26 and the gunwale tubes 12, 13. The upper tubes 25, 26 are closer to a vertical plane extending through the centreline of the hull 10 than the intermediate tubes 35, 36. The side spacer tubes 29a - 29i are fixed to the intermediate tubes 35, 36 and so the spacer tubes 29a, 29i incline inwardly from the intermediate tubes 35, 36 to the upper tubes 25, 26. The effect of this is to provide the survival craft with a more circular cross- sectional shape in planes normal to the length of the hull 10 and this provides the survival craft with a self-righting facility.

Of course, this could be provided in other ways. For example, inflatable bags may be carried on the superstructure 11 to provide a self-righting force.

As described above, the propulsion is supplied by electrically powered thrusters 18, 19 supplied with power though electrical cables leading from a generator within the hull 10. It would be possible to provide propulsion through a self-contained propulsion unit slung beneath the floor 17 and including a power source as well as propulsion means such as a propeller. Such a n arrangement has the advantage that the unit contributes to the self-righting of the survival craft. The propellers 21 may be replaced by, for example, a water jet.

The truss configuration of the upper tubes 25, 26 and the side spacer tubes 29a - 29i may be varied while still providing additional longitudinal rigidity to the hull 10. For example, there could be a single upper tube or more than two upper tubes. The side spacer tubes 29a - 29i may be angled differently and there may be more or less tubes or tube sections extending between the hull 10 and the upper tube or tubes 25, 26.

Referring next to Figures 5 to 15, there is shown a further from of survival craft and a marine escape system incorporating two such craft. The hull 10 and the superstructure 11 of the survival craft of Figures 5 to 15 are as described above with reference to Figures 1 and 2 and so will not be described in detail. The difference is in the propulsion of the craft. As seen in Figures 5 to 7, in this embodiment, a propulsion pod 50 is carried beneath the floor 17 of the hull 10. The pod 50 is formed from a rigid moulded plastics material. Referring particularly to Figures 7 and 8, the pod 50 has a hull 51 with a shaped bow 52 and a stern 53. A deck 54 forms with the hull 51 an enclosed chamber that contains a battery pack (not shown) and electric motors (not shown) that d rive respective propellers 55. The stern 54 amounts two steerable rudders 56. The rudders 56 are optional. The steering may be achieved by varying the thrust of the propellers 55 or other thrust producing systems.

The deck 54 is formed with a central recta ngular depression 57. Prior to deployment, this depression 57 carries an inflation system of known kind (not shown) with the deflated a nd packed hull 10 and superstructure 11 (see Figure 10) above in a weather valise. A marine esca pe system for deploying two survival craft of the kind shown in Figures 5 to 8 is shown in Figures 9 to 15. Referring first to Figure 9, the system is mounted in a rectangular opening 58 formed in the side 59 of a ship (although it may be mounted on any suitable marine structure). The opening 58 contains a cradle 60. The cradle 60 is a rectangular framework of bars carrying side-by- side two propulsion pods 50 of the kind described above with reference to Figures 5 to 9 with respective packed hulls 10 and superstructures 11. The pods 50 are aligned in the cradle 60 with their longitudina l axes extending normal to the side of the ship. The cradle 60 is mounted in the opening for movement outwa rdly of the side 59 of the ship.

A pair of davits 62a, 62b is carried at the top of the opening 58 and a chute assembly 63 is carried on the propulsion pods 50. The chute assembly 63 will be described in more detail below. In normal operation, the opening is closed by a door (not shown). The davits 63a, 63b are connected by cables 64a, 64b to a bar 65 that is connected by cables 65a, 65b, 66a, 66b to the corners of the cradle 60 (see Figure 10) The deployment sequence is as follows, referring to Figures 10 to 15. _g 50399

First, the door (not shown) is removed and may be allowed to fall to the water. This is the position shown in Figure 9. Next, see Figure 10, the davits 62a, 62b are extended so, via the cables 64, 64b, 65a, 65b, 66a, 66a, moving the cradle 60 so that it projects from the side 59 of the ship. The davits 62a, 62b then commence lowering the cradle 60 towards the water, see Figure 11. The chute assembly 63 includes a floor 67 that lowers to form a contiguous surface with the floor 68 (see Figure 9) of the opening 58. At the same time a curtain 69 deploys around the floor 67 to form an enclosed space with the opening 58. The chute assembly 63 also includes two escape chutes 70a, 70b that may be of any known type such as shown in US5,765,500 or GB2,080,844. These chutes 70a, 70b start to extend as seen in Figure 11.

On reaching the water, as seen in Figure 12, the pods 50 enter the water with the cradle 60 and, as seen in Figure 13, eventually enter the water. The inflation systems are then actuated and the hulls 10 and the superstructures 11 inflated as seen in Figure 14 so that two inflated survival craft float on the water with a chute 70a, 70b leading to the interior of each craft . As seen in Figure 15, the cradle 60 is released from the pods 50 so that the survival craft float freely.

People on the ship then enter the opening 58 and move to the entrances of the chutes 70a, 70b in the floor 67 surrounded by the curtain 69. The people descend the chutes 70a, 70b and enter the craft. When loading is complete, the chutes 70a, 70b can be disconnected and the craft move away from the ship under the power and control of the propulsion pods 50, which may be connected to a control unit (not shown) within the craft.

As seen in Figures 9 to 15, the opening 58 takes up considerably less space on the side 59 of the ship than two conventional lifeboats 71. Each craft may have a capacity of 150 - 300 people. Although the system is shown as including two pods 50, there may be more or less pods. In addition, each survival craft nay have more than one pod beneath the hull 10.

In any of the embodiments described above with reference to the drawings, the survival craft may be bowsed to the marine structure after deployment to stabilise the position of the craft relative to the structure. This can be by a ny known bowsing arrangement or by either of the arrangements now to be described with reference to Figures 16 and 17.

Referring first to Figure 16, a survival craft 80, which may be a survival craft of any of the types described above with reference to the drawings, is eated adjacent a marine structure 81, such as ship. First and second lines 82a, 82b are attached to the structure 81 at respective first and second laterally spaced points 83a, 83b, with spacing being greater than the dimension of the craft 80 along the structure 81 (the craft may extend parallel to or normal to the structure 81). The lines 82a, 82b cross as they pass through a first guide 84 above the craft 80 before passing through respective second and third running guides 85a, 85b located at respective opposite edges of the dimension of the craft 80 before meeting at, a nd being fixed to, a weight 86 beneath the craft 80.

Figure 16 shows the craft 80 in an equilibrium position relative to the structure 81. If the craft 80 moves to the right, as seen in Figure 16, the distance between the first point 83a and the second guide 85a lengthens and the distance between the second point 83b and the third guide 85b shortens so that the weight 86 is raised towa rds the second guide 85a. This causes the weight 86 to apply a force to the craft 80 at the second guide 85a that tends to return the craft 80 to the equilibrium position. If the craft 80 moves to the left as seen in Figure 16, the weight applies a restoring force to the craft 80 at the third guide 85b. In this way the position of the craft 80 can be stabilised relative to the structure 81.

Referring next to Figure 17, parts common to Figure 16 and to Figure 17 are given the same reference numerals and will not be described in detail. In the bowsing arrangement of Figure 17, the lines 82a, 82b do not cross. The spacing of the first and second points 83a, 83b is wider than in Figure 2.

The arrangement of Figure 17 operates on the same principle as the arrangement of Figure 16. If the craft 80 to the right, as seen in Figure 17, the distance between the first point 83a and the second guide 85a lengthens and the distance between the second point 83b and the third guide 85b shortens so that the weight 86 is raised towards the second guide 85a. This causes the weight 86 to apply a force to the craft 80 at the second guide 85a that tends to return the craft 80 to the equilibrium position.

If the craft 80 moves to the left as seen in Figure 17, the weight applies a restoring force to the craft 80 at the third guide 85b.

In this way the position of the craft 80 can be stabilised relative to the structure 81.

Of course, the bowsing arrangements described above with reference to the drawings need not be used with the survival craft described above with reference to the drawings. They could be used to stabilise any floating body against a marine structure. In addition, other arrangements of the lines 82a, 82b could provide the same effect by holding a weight beneath floating body in an equilibrium position when the body is in a desired position relative to the marine structure and moving the weight away from the equilibrium position as the body moves from the desired position so that the weight applies a restoring force tending to return the body to the desired position.