GB2522216A

GB2522216A - Marine escape systems

Info

Publication number: GB2522216A
Application number: GB1400733.0A
Authority: GB
Inventors: Damian Keown; Cyril Stocker; Richard Mccormick; Iain Mclean
Original assignee: Survitec Group Ltd
Current assignee: Survitec Group Ltd
Priority date: 2014-01-16
Filing date: 2014-01-16
Publication date: 2015-07-22
Also published as: GB201400733D0

Abstract

A survival craft 10 for a marine structure comprises a rigid hull 11 containing a propulsion unit (16, Fig 3), and carrying at least one inflatable life raft 27 and 28. When the survival craft is launched from the structure onto the water, the at least one life raft is deployed. Passages 51 and 52) are provided between the survival craft and the at least one life raft so that the at least one life raft is integrated with the survival craft and people can transfer from the structure to the at least one life raft and pass easily between the survival craft and the at least one life raft. The propulsion unit may then be used to move the at least one life raft clear of the structure. A marine escape system for mounting on a marine structure and comprising a housing (65, Fig 11) containing a survival craft in which the survival craft can be moved outwardly of the housing on deployment into water is also disclosed.

Description

MARINE ESCAPE SYSTEMS

The invention relates to marine escape systems and to survival craft for such systems.

Marine escape systems are used for evacuating personnel from either fixed marine structures, such as oil rigs, or mobile marine structures such as ships, particularly large passenger ships. The two most common forms of marine escape systems are firstly survival craft in the form of lifeboats and secondly life rafts in combination with means, such as a chute or a slide, for transferring people from the structure to the life rafts.

Lifeboats are rigid boats held on davits mounted on the structure. There is a requirement for sufficient life boats to accommodate all people on the structure and, particularly in the case of a large passenger ship, this can require a significant number of lifeboats that occupy significant space on the structure.

Life raft arrangements are shown in, for example, U55,765,500 and GB2,080,844. They comprise a chute and a life raft that are deployed from the structure to allow people to slide down the chute to an inflated life raft. The have the advantage that the undeployed system is compact and easily stored on a structure. In some such arrangements, the chute is replaced by a slide. Life rafts also do not have the problem of early hook release and users are not slammed against the side of the structure when moving from the structure to the water, A disadvantage is that the inflated life raft containing escapees must be towed clear of the structure.

In relation to fixed marine structures such as oil rigs, two forms emergency departure are widely recognised. "Evacuation" is the leaving of a structure and its vicinity, in an emergency in a systematic manner and without directly entering the sea. Successful evacuation will result in persons being transferred to a place of safety, which may be onshore or offshore, "Escape" is the leaving of a structure in an emergency when "evacuation" is not possible. It may involve entering the sea directly and is a "last resort" method of getting persons off the structure. Liferafts, along with helicopters and bridge links are used for "evacuation" but chute/life raft combinations are used only for escape" due to the absence of motive power and thus their inability to leave the vicinity of the structure under their own power.

Large passenger ships have, in general, both lifeboats and also separate life raft assemblies with chutes or slides. Lifeboats are seen as the preferred option for transferring passengers from a ship because of the ability of lifeboats to leave the vicinity of the ship under their own power.

Nevertheless, the disadvantage of the number of lifeboats required.

According to a first aspect of the invention, there is provided a survival craft for marine structures comprising a rigid hull containing a propulsion unit, the hull carrying at least one inflatable life raft, the inflatable life raft being deployable on the water from the hull and a passage being provided between the survival craft and the life raft.

In this way, a survival craft is provided for marine structures that is self-propelled so that it can clear the area of a marine structure and so be used for "evacuation" of fixed marine structures, The associated life raft with communication between the survival craft and the life raft provides an integrated structure with high capacity.

According to a second aspect of the invention, there is provided a marine escape system comprising a survival craft according to the first aspect of the invention and a mounting for supporting the boat on a marine structure and for deploying the survival craft from the structure to the water.

According to a third aspect of the invention, there is provided a method of deploying a survival craft according to the first aspect of the invention from a side of marine structure comprising lowering the boat into the water and then orientating the survival craft so that the length of the hull is normal to the side of the marine structure.

In this way, the hull can be stabilised against the side of the structure and this may mitigate the need for control arrangements at the waterline to keep the hull correctly orientated relative to the structure.

The following is a more detailed description of some embodiments of the invention, by way of example, reference being made to the accompanying drawings, in which:-Figure 1 is a schematic perspective view from above and to one side of a boat formed by a rigid hull and an inflatable superstructure, Figure 2 is a schematic perspective view of the boat of Figure 1 from beneath and to one side showing the underside of the hull and a stern mounted container holding two life rafts, Figure 3 is schematic perspective view of the life boat of Figures 1 and 2 from the other side and above with the inflatable superstructure in section to show the interior of the boat, Figure 4 shows the boat of Figures ito 3 with the life rafts deployed and inflated, FigureS shows a detail ofa connection between the boat of Figures ito 4 and a life raft, Figure 6 is a schematic perspective view from above and to one side of a second form of boat formed by a rigid hull, a cuddy and an inflatable superstructure, Figure 7 is a schematic perspective view from above and to the other side of the boat of Figure 6 with the inflatable superstructure in section to show the interior of the life boat including two packed inflatable life rafts) Figures is a similar view to Figure 6 showing the two life rafts deployed and inflated, Figure 9 is a similar view to Figure 8 but showing the boat and the life rafts orientated normal to the side of a ship, Figure lOis a view of a side of a ship showing the boat of Figures ito 9 stowed between two decks.

Figure ii is a schematic view of a further embodiment of the invention showing a marine escape system including a rigid survival craft and two life rafts integrated with the survival craft and shown undeployed stored on a marine structure such as a ship, Figure 12 is a similar view to Figure ii but showing a first stage of deployment of the survival craft by the system, Figure 13 is a similar view to Figure 12 but showing a second stage of deployment of the survival craft by the system with the survival craft adjacent the water, Figure 14 is a similar view for Figure 13 but showing a third stage of deployment of the survival craft by the system with the survival craft rotated relative to the structure, Figure iSis a view from above of the survival craft in the third stage, Figure 16 is a similar view to Figure i'l but showing a fourth stage of deployment of the survival craft is by the system with cables of the system detached from the survival craft, Figure 17 is a similar view to Figure 16 showing a fifth stage of deployment of the survival craft by the system with a first life raft inflated, and Figure 18 shows the fully deployed survival craft with both life rafts inflated.

Referring first to Figures 1 to 5, the boat 10 is formed by a rigid hull 11 and an inflatable superstructure 12.

The hull 11 is formed from a suitable material such as a fibre reinforced plastics material or a metal such as aluminium. It is provided with a shaped bow 13 and a stern 14 and designed to minimise drag. Referring to Figure 3, the interior of the hull is provided with a floor is beneath which are two power units 16. The power units 16 may be diesel engines each having a power, for example, of 110 kW. Each engine drives a respective propeller 17 via an associated shaft 18. Rudders 19 are provided for steering the hull 11. Alternatively, as described below, the boat could be powered, and steered, by electrical motors.

The superstructure 12 is formed by arches 20 and a cover 21. Each arch 20 is an inflatable tube 22 formed into an inverted tJshape and having its free ends fixed to opposite sides of the hull 11. The arches 20 are spaced at intervals along the hull 11 and the end arches 20 are lower than the intermediate arches 20. The arches 20 support the cover 21, which may be formed from a waterproof fabric of any suitable type As seen in Figures 1, 2 and 3, the cover includes an observation window 23 and opposed side entrances 24. The arches 20, when deflated, and the cover 21 are packed flat over the floor 15 and the arches 20 are inflated by an inflation system 25 (see Figure 3) as described in more detail below. Of course, there could be more or less arches 20 than shown in the drawings and the cover 21 may be supported by a different arrangement of inflatable members. The hull 11 may also include transverse inflatable members that provide seating for occupants as well as transverse rigidity to the hull 11.

The hull 11 carries, at the stern 14, a container 26, which may be formed in two parts from a plastics material. The container 26 houses two inflatable life rafts 27, 28 and associated inflation equipment of known type. The container 26 could be replaced by a fabric valise as this can allow alternative shapes to be created when packing the life rafts 27, 28.

In use, the life raft is deployed from a marine structure such as an oil rig or a ship with the superstructure deflated, collapsed and stored on the floor 15 of the hull 11. On entering the water, the inflation system 25 for the superstructure 12 inflates the arches 20 and this erects the cover 21 to form an enclosure. At the same time, the life rafts 27, 28 in the container 26 are inflated and this causes the parts of the container 26 to separate and the life rafts 27, 28 to deploy behind the boat 10, as seen in Figure 4.

The life raft 28 immediately behind the survival craft 10 is connected to the survival craft 10 by a sliding connection seen in Figure 5. As seen in that Figure, a shoe 29 is mounted on the stern 14 of the survival craft 10 and engages an arcuate track 30 on the bow of the life raft 27. This allows the connection between the survival craft 10 and the life raft 27 to move to either side of the longitudinal axis of the life raft 27. This allows the survival craft 10 to turn through 90° relative to the life rafts 27, 28 in order to permit good manoeuvrability and, in particular, to facilitate departure from the side of a ship in a direction perpendicular to the ship's side.

In addition, a first pathway 51 is provided between the survival craft 10 and the life raft 28 immediately behind the survival craft 10 and a second pathway 52 is provided between the that life raft 28 and the next life raft 29. The pathways 51, 52 could be enclosed.

When the superstructure 12 has been deployed and the life rafts 27, 28 inflated, an integrated structure is formed. People can enter the survival craft 10 and the life rafts 27, 28, passing between the survival craft 10 and the life rafts 27, 28 via the pathways 51, 52. Each may, for example, have a capacity of 150 persons.

The persons may access the survival craft 10 and the life rafts 27, 28 by any known transfer system.

They may access the system through sea-level access points in the marine structure or down deployable slides. As shown in Figure 4, the transfer system may be formed by two chutes 31 that lead from the marine structure to the first life raft 27. The chutes may be of known type as shown, for example, in US5,765,500 and GB2,080,844. Once in the first life raft 27, persons will access the survival craft 10 and the second life raft 28. When full, the engines 16 are used to tow the life rafts 27, 28 a safe distance away from the marine structure. The engines 16 and the associated fuel may be sufficient to allow towing for a significant time e.g. up to 12 or 24 hours. Alternatively, the life rafts 27, 28 could be detachable from the survival craft 10 to allow the survival craft 10 to operate independently.

The survival craft 10 and the life rafts 27, 28 will contain supplies of both food and medicines. In addition, the power units 16 may include generators to supply power to the life rafts 27, 28.

The survival craft 10 may be designed to be self-righting once fully deployed. This may be achieved by the upper body shape of the superstructure 12 or by a self-righting extension above the roof arches 20 at the aft end of the survival craft 10, Of course, access to the survival craft 10 and the life rafts 27, 28 need not be through the first life raft 27. It could be though the survival craft 10 or the second life raft 28 or through two or more of them simultaneously. There need not be two life rafts 27, 28: there could be just one or three or more.

The survival craft 10 and life rafts 27, 28 described above with reference to Figures 1 to 5 have a number of advantages, some of which are as follows. The survival craft 10 and the life rafts 27, 28 occupy on the marine structure, a similar space to a conventional survival craft of similar size but provide greatly increased capacity in comparison to such a conventional survival craft. It gives the same capacity as three conventional life survival crafts but has the length of only one conventional life boat, so reducing the space occupied by life boats on a marine structure. The integration of the life rafts 27, 28 with the survival craft 10 provides a substantially single structure that allows easy passage for people between the structures so making it easily usable by less able people.

When the life rafts 27, 28 are packed and the superstructure 12 of this embodiment deflated and packed, the survival craft 10 is compact. It has the advantage over escape systems that include only life rafts that it is a powered system so allowing persons using the system to move away from the structure. This makes it suitable for the use in the "evacuation" mode in fixed marine structures. As seen in Figure 10, the undeployed survival craft 10 is of sufficiently low height that it can be stowed between two decks of a ship, either internally or externally, so not obstructing the view from any deck. This may allow the distance between the escape point in the structure and the water to be sufficiently low to allow the use of a slide for the passage of people from the structure to the survival craft 10. This height may be such that the freeboard of the hull is at the waterline when the survival craft 10 is fully loaded. The reduced height of the survival craft 10 allows a cruise ship, for example, to have more high revenue outside cabins.

The system is easy to maintain. The life rafts 27, 28 can be detached from the survival craft 10 and serviced separately -or replaced at service intervals with new or pre-serviced life rafts 27, 28. The hull 11 and the power units 16 are also easily accessed for servicing.

In the embodiment described above with reference to Figures 1 to 5, the whole of the hull 11 along the waterline of the survival craft is rigid. This need not the case, The hull 11 may be formed by a rigid portion that contains and supports the power units 16 and an inflatable portion that only inflates and deploys when the survival craft is lowered into the water. In general, in such an arrangement, the aft portion of the hull will be rigid and the fore part inflatable. The relative lengths of the rigid and inflatable parts will be determined at least in part by the size of the power units 16.

Such an arrangement has the advantage of further reducing the length of the survival craft 10 when stored on a marine structure.

Figures 6 to 9 show an alternative form of the survival craft 10 and the life rafts 27, 28. Parts common to Figures 1 to 5, on the one hand) and to Figures 6 to 9, on the other hand, are given the same reference numerals and will not be described in detail.

In the embodiment of Figures 6 to 9, the surviva' craft 10 has a hull 11 that is provided with a rigid forward cuddy 41 that may be formed from the same material as the hull 10. The deployable superstructure 12 is provided aft of the cuddy 31 and includes three spaced arches 20 and a cover 21. The observation window 23 is omitted but the entrances 24 are retained.

The stern container 26 is omitted. In its place, two life raft containers 43,44 are carried on the floor of the hull 11 adjacent respective entrances 24. The life raft containers 43, 44 and associated inflation equipment are of known type such as the Survitec The survival craft 10 of Figures 6 to 9 is stowed on a marine structure with the arches 20 collapsed onto the floor 15 of the hull 11 and the cover 21 folded over the collapsed arches 20 and the life raft containers 43, 44, When deployed on the water, the arches 20 are inflated as described above with reference to Figures 1 to 5 and the cover 21 erected. This allows a person or persons to access the interior of the survival craft 40. The life raft containers 43, 44 are then deployed from the entrances by the person or persons and the life rafts 45, 46 are then inflated, as seen in Figure 8. Covered walkways 51 are provided between each entrance 24 and the adjacent life raft 45, 46.

The life rafts 45, 46 and the survival craft 40 can be accessed in any of the ways described above with reference to Figures ito 5. This may include chutes 47 leading to one of the life rafts 45 that is adjacent the side of a marine structure, as seen in Figure 8, with the chutes 47 being of any of the kinds described above with reference to Figures ito 5. It could be by means of one or more slides.

The provision of a cuddy 41 provides better shelter when under way. The location of the life rafts 45, 46 laterally of the survival craft 40 provides more even weight distribution than the arrangement of Figures 1 to 5 and possibly a more reliable inflation sequence. The survival craft of Figures 6 to 9 also has the advantages of the embodiment of Figures 1 to 5 of providing a high capacity for a small footprint of the structure and of providing an integrated structure that operates effectively as a single unit.

Referring next to Figure 9, the configuration of Figures 6 to 8 gives the possibility that of orientating the survival craft 40 so that it extends normal to the side 48 of a ship. The life rafts 45, 46 are then deployed as described above and the whole assembly held against the side 48 of the ship. This may be achieved using magnetic anchor points (shown in broken line at 49 in Figure 9) on the side 48 of the ship or it may be by reversing the engines 16. This may eliminate or reduce the need for bowsing lines.

The survival craft 40 may be lowered to the water with the length of the hull 10 parallel to the side of the structure (the side of a ship, where the structure is a ship) and then rotated by 90° to project normal to the side. Alternatively, the survival craft 40 may be lowered at an angle to the side of the structure -for example an angle between 3Q0 and 900 to the side. In this case, the movement of the survival craft 40 required to achieve the disposition shown in Figure 9 is reduced or eliminated. This may allow the life rafts 45, 46 to be deployed from the survival craft 40 immediately the survival craft 40 reaches the water. The survival craft 40 may be deployed at such an angle by suitably adapted davits.

In this embodiment, a single chute 47 is provided leading from a housing 50 on the side 48 of the ship to the survival craft 40. The chute 47 is accessed from the housing 50.

Referring next to Figures 11 to 18, parts common to this Figure and to Figures 6 to 9 are given the same reference numerals and will not be described in detail. In the embodiment of Figures 11. to 18, the survival craft 60 is formed from a rigid hull 61a and a rigid superstructure divided into a forward superstructure Sib and an aft superstructure Sic separated by a platform 62, The aft superstructure Sic includes a roof 63 with an access point 64 for a purpose to be described below.

The platform 62 carries) prior to deployment and as seen in Figure ii, the two packed life rafts 45, 46, as described above.

The survival craft 60 forms part of a marine escape system seen in Figures 11 to 17. The system includes a rectangular cross-section housing 65 formed in the marine structure, for example, in the side of a ship. The housing 65 has a floor 66, a roof 67, end walls 68 a front wall 69 and a rear wall 70. The floor 66, roof 67 and end walls 68 are fixed. The front wall 68 can be detached from the housing 65 prior to deployment of the survival craft 60 and allowed to fall into the water. The rear wall 70 is movable from the position shown in Figure 11 to the position shown in Figure 12, as will be described in more detail below. The rear wall 70 includes a central section 71 that carries three escape chutes 72a, 72b, 72c (seen in Figures 13 to 17). The roof 67 carries a pair of davits 73a, 73b powered by respective motors 74a, 74b.

The escape system deploys the survival craft 60 as follows.

From the position shown in Figure 11, the front wall 69 is released and falls into the water. The davits 73a, 73b are then extended (Figure 12) so that the survival craft 60 projects from the side of the structure above the water. The rear wall 70 moves forward with the survival craft 60 until it fills the open outboard end of the housing 65 as seen in Figure 12. The davits 73a, 73b then commence lowering the survival craft via cables 75a, 75b. As lowering commences from the position shown in Figure 12, the central section 71 of the rear wail 70 pivots forwardly about a horizontal axis and a canopy 76 deploys between the edge of the section 71 and the remainder of the wall 70 to provide an enclosed space above the section 71. The section 71 has three spaced access points and an escape chute 72a, 72b, 72c is attached at one end to a respective access point and the opposite end attached to the survival craft 60. Accordingly, as the survival craft 60 is lowered) the escape chutes 72a, 72b, 72c are extended as seen in Figure 13.

The survival craft 60 is lowered until it is close to the water, as seen in Figure 13. One davit 73a is then extended telescopically, as seen in Figures 14 and 15 to rotate the survival craft 60 about a vertical axis so that it is at an angle to the side of the marine structure. The cables 75a, 75b are then detached from the survival craft 60 and the survival craft 60 falls into the water, as seen in Figure 16.

One life raft 45 is then inflated, as seen in Figure 17, and deploys from the side of the survival craft closest to the structure. This inflation further rotates the survival craft 60 until, as seen in Figure 17, the survival craft 60 is at 900 to the side of the structure. As seen in Figure 17, the life raft 43 includes an inflatable structure that forms part-housing 77 and an enclosed passage 78 leading from the survival craft 60 to the life raft 45 to integrate the survival craft 60 and the first life raft. At the same time, a first chute 72a is connected to an access point 79 on the first life raft 45 and a second chute 72b is connected to the access point 64 on the survival craft 60.

Finally, as seen in Figure 18, the second life raft 46 is inflated and the third chute 72c is connected to an access point 80 on the second life raft 46. The second life raft 46 provides a part-housing 81 that co-operates with the part-housing 77 provides by the first life raft 45 to form an enclosed housing between the forward and aft superstructure sections 61a, 61b. The second life raft 46 also forms an enclosed passage 82 is also from the housing to the life raft 46. In this way, the second life raft 46 is integrated with the survival craft 60. The third chute 72c is connected to an access point on the second life raft 46.

After deployment, people leave the structure by entering the housing 65 and moving to the access points in the lowered section 71 shrouded by the canopy 76. People then descend any one of the chutes 72a, 72b 72c into the interiors of the first and second life rafts 45,46 or the survival craft 60.

S When loading is complete, the chutes 72a, 72b, 72c are disconnected and the survival craft 60 and the life rafts 45,46 move away from the marine structure under the power of the survival craft 60.

The embodiment of Figures 11 to 18 has the advantage of the other embodiments of reducing the number of survival crafts required on a marine structure and of providing a large capacity system with a small footprint on the structure. The survival craft 60 is powered and so has the ability to move itself and the associated life rafts 45, 46 clear of the marine structure.

It will be appreciated that, in the embodiment of Figures 11 to 18, the survival craft would be used as a tender without deploying the chutes 72a, 72b and 72c and the life rafts 45, 46. The life rafts 45, 46 could, in such an arrangement, be carried on a saddle that can be lifted from the survival craft prior to its use as a tender. In addition, the housing 65 need not be formed within the structure: it could be formed as a projection on the exterior of the structure. The housing 65 need not be of rectangular cross-section: it could be of any suitable shape.

Of course, the life rafts 45, 46 in the embodiment of Figure 10 could be in line astern of the survival craft as in the embodiment of Figures ito 5.

In the embodiments described above with reference to the drawings, the people evacuating the marine structure pass directly into either the survival craft 10 or the life rafts 27, 28, 45, 46. This is not essential. There could be a platform adjacent the survival craft 10 and the rafts 27, 28, 45, 46 with people passing from the marine structure to the platform and then to the survival craft 10 and the life rafts 27, 28, 45, 46, In the embodiments described above with reference to the drawings, persons leaving the marine structure are accommodated in the survival craft 10 as it moves away from the structure, This need not be the case. All evacuees could be located in the life rafts 27, 28, 45, 46 and the survival craft 10 simply contains crew for operating the survival craft. Alternatively, it is possible that the survival craft 10 is empty and controlled remotely either from the structure or from one of the survival crafts 27, 28, 45, 46.

The marine escape system described above with reference to Figures 11 to 18 need not be used with a survival craft 60 of the kind described above with reference to those Figures. It could be used with any form of survival craft with the lowered section of the rear wall providing access to the survival craft via chutes or slides or any other known form of transfer from a marine structure to a survival craft. For example, the survival craft carrying the life rafts could be a rib without any superstructure.

Claims

CLAIMS1. A survival craft for marine structures comprising a rigid hull containing a propulsion unit, the hull carrying at least one inflatable life raft, the inflatable life raft being deployable on the water from the hull and a passage being provided between the survival craft and the life raft to integrate the life raft and the survival craft.
2. A survival craft according to claim 1 wherein the hull carries a rigid superstructure.
3. A survival craft according to claim 1 wherein the hull carries an inflatable superstructure,
4. A survival craft according to claim 3 wherein the rigid hull forms all of the waterline length of the boat.
5. A survival craft according to claim 3 wherein the rigid hull forms part of the waterline length of the boat, the remainder of the waterline length being formed by an inflatable structure.
6. A survival craft according to any one of claims 1 to 5 wherein the hull carries two packed inflatable life rafts deployable from the hull.
7. A survival craft according to claim 6 wherein the two packed inflatable life rafts are deployed to respective sides of the hull.
8. A survival craft according to claim 6 wherein the two packed inflatable life rafts are deployed in succession to the stern of the hull.
9. A survival craft according to claim 8 wherein the life raft adjacent the hull is connected to the hull by a sliding joint that permits the connection to move in an arc to either side of the centre line of the life raft.
10. A survival craft according to any one of claims 1 to 9 wherein the hull includes a generator power from the generator being supplied to the at least one life raft,
ii. A survival craft according to claim 4 or to any one of claims S to 10 when dependant on claim 4 wherein the hull includes a rigid cuddy
12. A survival craft according to any one of claims 1 to 11 and including at least one transfer system having an upper end for access from a marine structure and a lower end leading to the hull and providing a passage for people from the structure to the hull.
13. A survival craft according to claim 12 wherein the transfer system comprises a chute
14. A survival craft according to claim 13 wherein the lower end of the chute terminates within the hull.
15. A survival craft according to claim 12 wherein the end of the chute terminates within the at least one life raft,
16. A survival craft according to any one of claims ito 15 wherein the hull is self-righting.
17. A survival craft according to any one of claims 1 to 16 wherein the hull has a minimum freeboard that is at the waterline of the hull when the boat is fully laden.18. survival craft substantially as hereinbefore described with reference to the drawings 19. A marine escape system comprising a survival craft according to any one of claims 1 to 18 and a mounting for supporting the survival craft on a marine structure and for deploying the boat from the structure to the water.20. A system according to claim 19 and including at least one chute having an upper end for access from a marine structure and a lower end leading to the hull, the mounting providing access to said upper end.21. A marine escape system substantially as hereinbefore described with reference to the accompanying drawings.22. A ship having a plurality of decks and a marine escape system according to any one of claims 19 to 21 located on the ship between two adjacent decks.23. A ship substantially as hereinbefore described with reference to the drawings.24. A marine escape system for mounting on a marine structure and comprising a housing including a wall and containing a survival craft, the survival craft being movable outwardly of the housing on deployment into water and the wall being movable on said deployment to provide access to the deployed survival craft 25. A method of deploying a survival craft according to any one of claims 1 to 18 from a side of marine structure comprising lowering the survival craft into the water, the survival craft in the water being orientated so that the length of the hull is normal to the side of the marine structure.26. A method according to claim 25 and comprising lowering the survival craft into the water at an angle to the side of less than 9Q° and the orientating the survival craft to a position normal to the side of the structure.27. A method according to claim 26 and comprising lowering the survival craft into the water normal to the side of the structure.28. A method according to any one of claims 25 to 27 and comprising maintaining a stern of the hull on or adjacent the side of the structure by use of the propulsion system.29. A method according to any one of claims 25 to 28 wherein the hull carries two inflatable life rafts deployable from respective sides of the hull, the method comprising deploying the boat, inflating the life rafts, orientating the hull and then maintaining respective ends of the life rafts against the side of the structure.30. A method of deploying a boat substantially as hereinbefore described with reference to the accompanying drawings.