Patent Description:
An escape system, such as an evacuation system is used for evacuating people from a structure at sea in the event of an emergency. Such a structure may be an oil rig or a ship.

One form of evacuation system includes an inflatable craft into which the people are evacuated. Since, when inflatable crafts are deployed on water, there is usually a significant difference in height (freeboard) between the point on the structure from which the people are evacuated and the inflatable crafts, it is necessary to provide some form of passage between the two.

It is known to provide an angled or vertical passage, which may be formed from inflatable members, extending between the evacuation point and the inflatable crafts. The angled or vertical passage can extend either direct to the inflatable crafts or to an inflatable floating structure or platform to which the inflatable crafts are attached. In some vessels, the freeboard may be <NUM>-<NUM> metres and so the angled or vertical passage is of significant length.

Evacuation systems should preferably be able to operate in force six weather which will include a <NUM> metre swell.

An angled or vertical passage is not readily able to meet such a requirement as the angled or vertical passage projects from the side of a vessel and is subjected to significant lateral movements in heavy weather which may make evacuation hazardous.

It would be desirable to provide an improved evacuation system able to operated safely in heavy weather.

<CIT> discloses an escape chute assembly intended for use as a mass evacuation unit through which a succession of personnel can escape in an emergency from a multiple-occupancy work station (for example an offshore oil-drilling rig) comprising an elongate open-ended tunnel (e. g a succession of open-ended pipes linked together in use by harnesses, or a net tube) and a restraining means fitted inside or defined by the said open-ended tunnel and extending for some or all of the tunnel's length. A secondary elastic connection between the work station and a pontoon guides the tunnel into a central point on the pontoon when off-vertical.

<CIT> discloses a marine escape system for use by evacuees disembarking from a vessel comprises an inflatable liferaft and an inflatable slide arranged for deployment with the inflated liferaft floating on the water and the inflated slide connected at a boarding end thereof to an exit position on the vessel and at the other end to the liferaft.

A first aspect of the present invention provides an escape system as defined in claim <NUM>.

A second aspect of the present invention provides an escape system as defined in claim <NUM>. One of the platform and the passage includes at least one engagement member or slidably engaging a corresponding structure of the other of the platform and the passage such that the movement of the passage relative to the platform is restricted in the at least one direction. The engagement member comprises a rail and the corresponding structure for slidably engaging the rail comprises a recess member defining a recess for accommodating the rail. This may allow longitudinal relative movement but restrict transverse relative movement. The recess is substantially rectangular or semi-circular in cross-section and may be configured for fitting onto the rail.

A third aspect of the present invention provides an escape system as defined in claim <NUM>. The rail includes a coupling portion that is connected to the associated one of the platform and the passage by a relatively narrow connector, and wherein the recess incudes a chamber having a relatively narrow mouth, the chamber being configured to accommodate the coupling portion of the rail, with the connector extending through the mouth. This may prevent the passage lifting off the platform. The coupling portion and/or the chamber may be substantially circular in cross-section.

The platform may be coupled to the passage so as to restrict lifting of the passage from an upper surface of the platform (e.g. caused by wind acting on the passage). A cable or the like may be used to perform the coupling. The coupling may be such that movement along the longitudinal axis of the passage is possible.

In any of these aspects, the passage and/or the platform may be inflatable.

In any of these aspects, the passage may be inclined to the platform and/or the structure in use. The passage may be a passage.

In any of these aspects, the escape system may further include the at least one craft, which may be a liferaft and/or which is preferably inflatable.

For a better understanding of the present invention embodiments will now be described by way of example, with reference to the accompanying drawings, in which:.

In the drawings, like elements are generally designated with the same reference sign.

<FIG> shows an inclined inflatable evacuation passage <NUM>, in deployed and inflated configuration between a ship <NUM> and platform <NUM> from which inflatable survival crafts <NUM> are launched. Although the inflatable evacuation passage <NUM> is deployed from a ship <NUM> in the embodiment, it should be understood that that the passage <NUM> can extend from between from any structure, such as an oil rig. The passage <NUM> may be a slide.

The upper or entry end of the passage <NUM> is connected to a stowage unit <NUM>, mounted on the ship <NUM>. The stowage unit <NUM> may be fitted in a recess <NUM> is the ship's structure or on an open deck.

The lower or exit end of the passage <NUM> is connected to the platform <NUM> in a manner to be described below.

The passage <NUM> may be of the type disclosed in our co-pending patent application number <CIT> and publication <CIT> (our ref: <NUM>).

Briefly, as shown on a larger scale in <FIG>, the structure of the passage <NUM> comprises a framework comprising three longitudinal triple beams, one of which is an upper beam <NUM>, in a substantially central position above the other two, which are lateral lower beams <NUM>, between which is fixed and stretched over the whole length of the passage <NUM>, a flexible track or trackways <NUM> (preferably four parallel chutes for rapid evacuation).

Each of the three longitudinal triple beams <NUM> and <NUM> comprises three longitudinal tubes, each in the form of an elongated cylinder having a substantially circular cross-section, individually inflatable (i.e. each inflatable independently of the others), stacked one above the other two so that they are tangential two by two over their length, and thus connected together adjacent and side by side. The tubes may be connected intermittently or continuously over their length, for example by an adhesive or by high-frequency welding, so that the cross-section of each beam <NUM> or <NUM> has substantially the shape of an equilateral triangle in the inflated state.

The framework of the passage <NUM> also comprises a plurality of stiffening modules <NUM>, which are inflatable, but pneumatically and mechanically independent of each other, and arranged side by side at their base, from the entry end to the exit end of the passage <NUM>, and each mechanically connected to the longitudinal tubes of the longitudinal beams <NUM> and <NUM> by connection means, and inflated from the longitudinal tubes of the longitudinal beams <NUM> and <NUM> by inflation means, so that, in the inflated state of the passage <NUM>, they can brace and stay the beams <NUM> and <NUM>, keeping them spaced apart transversally to their length, and so that they extend substantially parallel to each other, in order to give the inflated passage <NUM> a cross-section (perpendicular to the beams <NUM> and <NUM>) having substantially the shape of an isosceles or equilateral triangle.

Each stiffening module <NUM> includes two symmetrical halves 19A and 19B, each being composed of two inflatable side panels 21A, B connected together at the top, before assembly of the two halves.

The side panels 21A and 21B of each half 19A and 19B of the stiffening module <NUM> are joined to each other.

The side panels 21A/B are formed from drop stitch (or drop thread) material, which has the general form shown in <FIG>. In such a material, thousands of (e.g. nylon) threads connect the two opposite faces to keep side panels 21A and 21B in the desired shape when inflated and to provide rigidity.

Each stiffening module <NUM> has, in the inflated state, the general outer shape of a hollow truncated pyramid with a square or rectangular base, the inclined edges of which are formed by two pairs of side panels 21A, 21B thus comprising four independent inflatable structures.

The base of the passage <NUM> comprises a plurality of abutting but independent floor panels. The floor advantageously provides a smooth flat surface. The floor panels are formed from drop stitch (or drop thread) material, which has the general form shown in <FIG>. In such a material, thousands of (e.g. nylon) threads connect the two opposite faces to keep the floor panel in the desired shape when inflated and to provide rigidity. The air gap between the opposite faces also provides thermal insulation.

The crafts <NUM> may be of the type disclosed in our co-pending patent application number <CIT> (our ref: <NUM>) and <CIT>. <CIT> claims priority from <CIT>.

Briefly, as shown in <FIG> each craft <NUM> comprises a hull <NUM> formed from inflatable members, a canopy support structure carried by the hull and formed from inflatable members, an inflatable wall structure, and a rigid pod <NUM> configured to carry a survival craft in a deflated state and be coupled to the hull <NUM> when the craft is in an inflated state. The inflatable parts may be formed from drop thread material of the type shown in <FIG>.

The crafts <NUM> may or may not have propulsion, such as an electric motor or internal combustion engine.

The platform <NUM> is a generally T-shaped inflatable structure with a generally flat upper surface that engages the passage <NUM>. The platform <NUM> comprises a bar <NUM> that extends generally parallel to the side of the ship <NUM> in use, with a leg <NUM> extending perpendicularly from midway along the bar <NUM> in a direction away from the side of the ship <NUM> in use. The passage <NUM> engages the leg <NUM>. A first one of the crafts <NUM> is accommodated in a first recess of the platform that is formed between the bar <NUM> and one side of the leg <NUM>. A second one of the crafts <NUM> is accommodated in a second recess of the platform that is formed between the bar <NUM> and the opposite side of the leg <NUM>.

The platform <NUM> may be formed from drop thread material of the type shown in <FIG>.

The passage <NUM>, the platform <NUM> and the crafts <NUM> are part of an evacuation system. As described above, each of the passage <NUM>, the platform <NUM> and the crafts <NUM> comprise inflatable structures. These structures, when not deployed, are folded and stored in an uninflated state in the stowage unit <NUM>.

The stowage unit <NUM> is weatherproof enclosure protecting the evacuation system from the external environment and providing a stable internal environment to safely store the marine escape system. The stowage unit may have a closable door to help provide the stable internal environment.

The storage unit <NUM> includes a launching appliance, which comprises a mechanism for moving the marine escape system form the stored position to the position where it is lowered in a controlled manner to the water, as shown for example in <FIG>. The mechanism may comprise two davits <NUM>.

A lowering plate <NUM> supports the two crafts <NUM>, platform <NUM> and passage <NUM> when stored and when being lowered to the water. As shown most clearly in <FIG>, the lowering plate <NUM> extends generally parallel to the bar <NUM> of the platform but spaced away therefrom towards the distal end of the leg <NUM> of the platform <NUM>. After the crafts float off the lowering plate <NUM>, the plate <NUM> is lowered to a safe distance below the surface of the water (as shown in <FIG>) where it now acts as a stabilising plate to control the position of the platform <NUM> and passage <NUM>.

Lowering lines <NUM> are stored on a winch that is attached to the stowage unit <NUM>. The lowering lines <NUM> extend from the davits <NUM> through the platform <NUM>, where they are attached to the lowering plate <NUM>, to control the descent of the evacuation system to the water.

Stabilising bowsing control lines <NUM> extend between the side of the ship <NUM> and the passage <NUM> to tend to maintain the position of the passage <NUM> with respect to the ship <NUM>.

As shown in <FIG>, the edge of the leg <NUM> of the platform <NUM> may be arranged so that the side <NUM> cannot fall off due to wave (or other) movement. For example, vertical walls <NUM> may extend above the flat upper surface of the platform <NUM> along all or part of the leg <NUM>.

Additionally, or alternatively, longitudinal stiffening beams <NUM> may be provided along the underside of the leg <NUM>. The walls <NUM> and the stiffening beams <NUM> are inflatable and may be formed from drop thread material of the general arrangement shown in <FIG>. Alternative inflatable structures may be used to form the side wall arrangements.

As shown in <FIG>, there may be also a retaining arrangement to secure the exit end of the passage <NUM> against wind (or other) force lifting it off the platform <NUM>. The retaining arrangement may comprise a pair of hoops <NUM> (only one of which can be seen in <FIG>) that are attached at or near the exit end of the passage <NUM> by respective passage cables <NUM>. A platform rail or cable <NUM> (only one of which can be seen in <FIG>) is attached to the interior side of each of the walls <NUM> and extends generally parallel to the leg <NUM> of the platform <NUM>. The platform rails or cables <NUM> pass through respective ones of the hoops <NUM>. Such an arrangement allows the passage <NUM> to move forward and backward along the surface of the leg <NUM> of the platform <NUM> in a direction generally parallel to the platform rail or cable <NUM>. However, relative movement between the passage <NUM> and the leg <NUM> of the platform <NUM> in other directions (e.g. due to wind), such as generally perpendicular to the surface of the leg <NUM> of the platform <NUM>, is restricted by the connection between the passage hoops <NUM> and cables <NUM> and the platform rails or cables <NUM>.

It is desirable for the platform <NUM> to be held against the side of the ship <NUM>. Without any other forces applied, the platform will rest against the side of the ship <NUM>. However, as the ship <NUM> and platform <NUM> move on the waves, the exit end of the passage <NUM> will move backwards and forwards across the top surface of the platform <NUM>.

A platform control arrangement is provided, which is a device/arrangement or mechanism which provides a restoring force to the outboard of the platform <NUM> to tend to hold it against the side shell of the ship <NUM> (or other host vessel).

In order to 'pull' the platform <NUM> back against the side of the ship <NUM>, a position restoring force is applied by the platform control arrangement that can be positioned between the end of the leg <NUM> of platform <NUM> and the exit end of the passage <NUM>.

This force can be generated by several methods. The force can be generated by fitting spring type devices <NUM>, as shown in <FIG>, between the exit end of the passage <NUM> and the distal end of the leg <NUM> of platform <NUM>. The spring type devices may be elastically deformable objects used to store mechanical energy, such as either mechanical metal springs (e.g. coil tension springs) or elastic shock cord types.

With a platform control arrangement installed between the exit end of the passage <NUM> and the distal end of the leg <NUM> of platform <NUM>, as the ship <NUM> rolls away from the platform <NUM>, moving the exit end of the passage <NUM> inboard along the surface of the leg <NUM> of platform <NUM>, the spring type device <NUM> is extended, and the force it exerts increases, thereby applying a restoring force to pull the platform <NUM> back against the side of the ship <NUM>.

Multiple spring devices <NUM> may be used to generate the restoring force. Two are shown in <FIG>.

Other platform control arrangements for generating the restoring force may alternatively or additionally be provided.

An arrangement that is not in accordance with the invention may include running a line or lines <NUM> over the outboard edge of the platform from the exit end of the passage <NUM>, with a weight <NUM> (as shown in <FIG>) or sea anchor <NUM> (as shown in <FIG>) attached to the lower end of the line or lines <NUM>. Guide members <NUM> may be provided at the distal end of the passage <NUM> to control the path of the line or lines <NUM>. As the ship <NUM> rolls away from the platform <NUM>, the exit end of the passage <NUM> is pulled inboard across the top of the platform <NUM>, lifting the weight <NUM> or sea anchor <NUM> up, creating drag. This drag is has a similar effect to the spring force, creating the restoring force. As the passage <NUM> moves outboard, the weight <NUM> then sinks and the sea anchor <NUM>, which is weighted, collapses and sinks, expanding again when the passage <NUM> moves inboard. Multiple sea anchors <NUM> and weights <NUM> may be used.

<FIG> show a distal end portion <NUM> at the exit end of the passage <NUM>. The distal end portion <NUM> is arranged to contact the leg <NUM> of the platform <NUM>, and may extend generally parallel to the upper surface of the leg <NUM> (in contrast to the main body of the passage <NUM> which is inclined with respect to the surface of the platform <NUM>).

The arrangement of the passage <NUM> and the platform <NUM> may be generally the same as that of <FIG>. Similar elements are designated with the same reference signs and will be not be described again, for the sake of brevity.

In one aspect, a plurality of rails <NUM> extend generally parallel to one another in a longitudinal direction along the length of the leg <NUM> of the platform <NUM>, as best shown in <FIG>, <FIG> and <FIG>. The underside of the distal end portion <NUM> (the side facing the upper side of the leg <NUM> of the platform <NUM>) includes a plurality of corresponding generally parallel recess members <NUM>. The recess members <NUM> are configured to receive the rails <NUM>. In <FIG>, the recess members <NUM> have a generally rectangular recess <NUM> formed therein, while the rails <NUM> are generally circular in cross section. The arrangement shown in <FIG> allows relative sliding movement in the longitudinal direction between the platform and the exit end of the slide <NUM> whilst restricting relative transverse movement between the exit end of the slide <NUM> and the platform <NUM>.

In an alternative arrangement, as shown in <FIG>, the rails <NUM> include a coupling portion <NUM> that is connected to the leg <NUM> of the platform <NUM> by a relatively narrow (in a transverse direction) connecter <NUM>. The recess member <NUM> has a recess <NUM> that includes a chamber having a relatively narrow mouth <NUM> (in the transverse direction). When the coupling portion <NUM> is a accommodated in the chamber the connector <NUM> passes through the mouth <NUM>. Longitudinal relative sliding between the distal end portion <NUM> and the platform <NUM> is possible. However, separation of the distal end portion <NUM> from the platform <NUM> in the vertical direction is not possible because the coupling portion <NUM> has a greater width than the mouth <NUM>.

The coupling portion <NUM> and the chamber may have a substantially circular cross-section, although other cross-sectional shapes are possible within the scope of the invention.

As shown in <FIG>, the distal end portion <NUM> may be configured to direct evacuees from the passage <NUM> in a particular direction after they exit the passage <NUM> so that they are in an appropriate position on the platform <NUM> to board the liferaft <NUM>. As described in relation to <FIG> flexible chutes or trackways <NUM> may be provided within the structure of the passage <NUM>, along which evacuees slide. In the second embodiment two chutes <NUM> are provided - 13A and 13B as best shown in the enlarged view in <FIG>.

The distal end portion <NUM> includes a first guiding wall 120A associated with the first chute 13A and a second guiding wall 120B associated with the second chute 13B. The guiding walls 120A and 120B are curved. The part of the walls 120A and 120B that are connected to the common dividing wall of the chutes 13A and 13B is generally parallel to that wall. The opposite end of the guiding wall is almost perpendicular to the dividing wall. The guiding walls 120A and 120B therefore gently guide the path of an evacuee from a longitudinal direction along the chutes 13A and 13B into a transverse direction, so that the evacuees are safely guided to a particular area of the leg <NUM> of the platform <NUM> for boarding the crafts <NUM>. The walls 120A and 120B may also slow the descent of the evacuees so that they arrive at the platform at a safe speed.

The walls 120A and 120B may be supported on the distal end portion <NUM> by a series of supporting pillars <NUM>.

The distal end portion <NUM> may include an inclined and curved floor that bridges the difference in height between the exit of the chutes 13A and 13B and upper surface of the leg <NUM> of the platform <NUM>.

The passage <NUM> may have a different orientation to that shown in <FIG>. The structure of the passage <NUM> may be generally the same as that of <FIG>. Similar elements are designated with the same reference signs and will be not be described again, for the sake of brevity.

In <FIG> the passage <NUM> extends in a vertical plane that is generally perpendicular to the side of the ship <NUM> - in the direction P shown in <FIG>. In <FIG>, the passage <NUM> is configured to extend aft from the evacuation point (corresponding to the position of the stowage unit <NUM>). The passages <NUM> extend at an acute angle α to a vertical plane L extending between the bow <NUM> and the stern <NUM> of the ship <NUM>. The angle α to the vertical plane L may be less than <NUM>°. The passages <NUM> may be generally parallel to the plane L.

A first control line <NUM> extends from the port side of the ship <NUM> and is attached to either the platform <NUM> or the passage <NUM> on the port side of the ship <NUM>. A second control line <NUM> extends from the starboard side of the ship <NUM> to either the platform <NUM> or the passage <NUM> on the starboard side of the ship <NUM>. The length of the control lines <NUM> may be adjusted by an associated control line winch <NUM>. The shorter the control lines <NUM>, the smaller the angle α between the passage <NUM> and the plane L.

Although the system has been described with two crafts, it should be appreciated that one or any number of crafts may be used with the system.

Claim 1:
An escape system comprising:
a passage (<NUM>) having an entry end and an exit end, and
a platform (<NUM>) for allowing access to at least one craft (<NUM>), the platform (<NUM>) being deployable from a structure (<NUM>) to water to facilitate evacuation of the structure (<NUM>) via the passage (<NUM>),
wherein the passage (<NUM>) is mounted to the platform (<NUM>) by connecting means, the connecting means comprising an elastically deformable member (<NUM>) that is deformed elastically in response to relative movement of the platform (<NUM>) away from the structure (<NUM>),
characterised in that:
the entry end of the passage (<NUM>) is configured to connect to a stowage unit (<NUM>), mounted on the structure (<NUM>);
the platform (<NUM>) has a generally flat upper surface configured to engage the passage (<NUM>); and
the passage (<NUM>) is mounted to the platform (<NUM>) by the connecting means, comprising the elastically deformable member (<NUM>), such that the platform (<NUM>) is urged towards the structure (<NUM>) when deployed, the elastically deformable member (<NUM>) being fitted between the exit end of the passage (<NUM>) and an outboard edge of the platform (<NUM>), and the arrangement being such that, as relative movement of the platform (<NUM>) away from the structure (<NUM>) occurs, this moves the exit end of the passage (<NUM>) inboard along the surface of the platform (<NUM>), the elastically deformable member (<NUM>) is extended, and the force it exerts increases, thereby applying a restoring force to pull the platform (<NUM>) against a side of the structure (<NUM>).