GB2208372A - Moveable/flexible bulkheads - Google Patents

Abstract

A system of moveable, flexible partitions 1, made of polymeric materials, for example, is installed, rolled or folded, in the deck, bulkhead or sides of a marine vessel or ship. When manually or mechanically deployed, the flexible bulkhead compartmentalises or partly compartmentalises the vessel, preventing or inhibiting the 'free surface effect' of water across the deck. The flexible bulkhead is sealed against the deck and walls of the vessel with flexible gasket 9 or self-sealing flap. Bracing struts 10 and/or cables transmit the loading forces in a self-contained manner within the bulkhead housing. <IMAGE>

Description

MOVEABLE/FLEXIBLE BULKHEADS The present invention relates to shipping design and the provision of safety measures to prevent capsize or sinking of ships at sea by means of deployable flexible membranes to compartmentalise the ship.

The recent design of ships has included large free deck areas in the hold to facilitate the easy loading and movement of vehicles on and off the ship, so called "roll-on roll-off" or "ro-ro" ships. Such ships have been shown to have an increased risk of capsize if water for any reason accumulates on an open deck e.g. from within the vessel or through a breach in the ship's side caused by collision, explosion, grounding or through otherwise water/oil tight doors which have been left open.

The main cause of instability is the "free surface effect" which arises when water/oil or other fluid is free to flow across an unrestricted area.

The invention has in mind a means of preventing unrestricted flow of liquid and so prevent the "free surface effect".

In order to retain the advantages of an open and clear deck for vehicle loading, movement and discharge it is proposed that a system of moveable flexible partitions be installed in the deck, deckheads, bulkheads or sides of the vessel. The vessel would thus be capable of division or compartmentalisation after the vehicular cargo is in place and the vessel would thus be compartmentalised while at sea. The flexible bulkheads may or may not include doors.

The way the vessel is divided may be in lateral and/or longitudinal sections to fprm compartments such that in the event of water/fluid accumulating on one of the decks for any reason, the quantity of water able to enter the compartment would be insufficient to so destabilise the vessel as to cause capsize or sinking.

The provision of flexible bulkheads improves damage stability.

The restriction of water flow giving additional time for passenger movement through the ship and escape from the ship.

The additional time gained by the damage stability increasing the chance to save or salvage cargo or the ship.

Moveable flexible partitions may also be deployed as emergency only devices, sealing smaller passages or channels such as air pipes, corridors, stair wells or ventilation shafts.

Compartmentalisation is known to be the most effective means of preventing water, fire or gas spreading through a ship.

However, permanent transverse bulkheads with doors could constitute a grave penalty against the commercial operation of a ferry for its primary purpose. Many proposals have been put forward for temporarily dividing a ship with for example portable transverse bulkheads, top or side hinged. Such bulkheads are fitted to deep sea ro-ro freight vessels.

However, with such vessels the need for a minimum turnaround time is not as pressing as with short sea ferries. Other proposals have been made for retractable metal cills rising from housing in the deck, or portable bulkheads, vertically sliding with housing below the bulkhead deck, or sideways rolling shutter bulkheads. What has not heretofore been proposed is the use of moveable bulkheads made of thin flexible membranes easily folded or rolled. The advantages of such flexible membranes being less bulk, lighter weight, more easily stored in less space, more easily deployed manually or mechanically, more easily replaced or repaired and to have a greater range of design options to suit changing safety, operational or cost requirements of large or small ships. Some of these design options will presently be described.

In addition there are many secondary operational or design advantages to such flexible membranes; they may be retro-fitted to existing ships; enabling older ships to be upgraded and safety standards conform to new regulations. Flexible bulkheads may also prevent the spread of fire and limit the movement of water applied to a fire from a drencher system or firefighters not knowledgeable in the effect of fire water movement on the stability of the ship.

Flexible bulkheads also serve to restrict the movement of cargo and may be additionally reinforced or designed for special cargoes. flexible bulkheads are equally suitable for longitudinal division to suit cargo such as trains or indivisibly large loads. Additional operational requirements are minimised by the use of easily and quickly deployed flexible bulkheads which require a minimum of storage space and occupy a minimum of space when deployed.

The design and material technology of flexible membranes has advanced greatly in recent years for other applications in building and civil engineering. These advances may also be employed to advantage in the provision of additional watertight integrity and collision safety for marine vessels.

Suitable materials include for example P.V.C. coated woven polyester or nylon, neoprene coated fabrics, high tensile polyester fibre reinforced webbing, P.V.C. coated 'Kevlar' or flourocarbon polymers.

The moveable partitions may be of a wide range of designs and materials for example folding or sliding doors or screens, inflatable bulkheads, top hung or side hung membranes. In the preferred embodiment the partitions are made of a flexible material, allowing the partitions to be folded and stored/housed in positions which offer no hindrance to the loading and unloading of cargo. Once the cargo is in place the flexible screen may be deployed manually or mechanically by for example attached cables operated on pulleys by electric, pneumatic or hydraulic means. The deployment may be triggered by the presence of water, oil, toxic gas or fire.

The flexible bulkheads may have a combined deployment and self sealing action activated by the pressure of for example flood water, oil or toxic chemical.

The design of the screens are such that in the event of compartments being filled to some level with water the stresses are distributed equally throughout the membrane and do not transmit more load to the vessel's structure than it can withstand. This is achieved in the detailed design of the membrane partitions and attachment points and by, for example, designing the partition such that in loading the forces are distributed and transferred between the arrangement of membranes, cables, bracing struts and framing in a self contained manner and do not impose substantial extra loading on the main ship frame or substructure.

In the embodiment of the invention shown in the accompanying drawings, a vessel (fig.l and 2) is divided into compartments by flexible membranes (1) positioned across the vessel.

Fig.3 shows a flexible membrane (1) rolled into a metal housing (2) positioned in the deck of a vessel (3). The membrane is partially deployed by a cable (4) pulled by a motor (5) housed in the deckhead. The cable is attached to the membrane by a detachable hook (6) which in turn is attached to a cable running through the leading edge of the membrane (7).

The metal flap is shown in an open position (8) and a hollow rubber sealing gasket (9) seals against water-flow between the unrolled membrane and the deck. A bracing strut (10) attached to the end of the leading edge of the membrane (11) braces against the metal housing (12).

Fig.5 shows a system of rigid or semi rigid panels, hinged at their edge with flexible membranes. The folded and stored screen may be manually or mechanically pulled out to form a bulkhead.

Fig.6 shows a flexible membrane stored in the deckhead, which may be deployed releasing a containment flap or catch, to allow the membrane to deploy by the action of gravity, and may be deployed and held in a deployed position by for example a clamping system housed in the deck.

Fig.7 shows a double walled membrane joined by diaphragms which may for example have interconnecting holes. It may readily be seen for example that if the first compartment is inflated the action of the air passing from segment to segment will self deploy the membrane bulkhead into position from, for example, a side-housing along for example grooves, rails or cables.

Fig.8 shows a similar double walled membrane as fig.7 which may be housed in the ships deck and be self-deployed vertically to the deckhead.

Fig.9 shows a flexible membrane bulkhead (1) under loading from flood water (2). The membrane deforming under load for even distribution of forces. A secondary flexible membrane or flap (3) is shown pressed against the other housing (4), (5) self sealing against water flow.

Fig. 10 and 11 shows a self sealing flexible membrane in a housed position (fig.10) the membrane is self deployed by the pressure of flood water, and acting as a self sealing, non return valve or screen.

Claims (21)

Claims

1. A system of stored flexible membranes in the deck, deckhead, bulkhead frame or sides of a ship, boat, marine vessel or floating structure, which may be deployed to compartmentalise or partly compartmentalise the interior of such vessel.

2. A system of folded, rolled, packed or otherwise contracted flexible membranes housed or otherwise positioned on board a marine vessel, which may be deployed to compartmentalise or partly compartmentalise the vessel.

3. A system as in claim one where flexible membranes are used to prevent the flow of water through a vessel by, for example, the free surface effect.

4. A system as in claim one where flexible membranes are used to prevent the flow of oil, gas or dangerous chemicals through the vessel.

5. A system as in claim one where flexible membranes are used to prevent the spread of fire through a vessel.

6. A system as in claim one where the flexible membrane includes a rigid or flexible door.

7. A system as in claim one where the arrangement of forces under loading is self contained within the membrane, cables and bracing struts or frames.

8. A system as in claim one where the membrane consists of a single reinforced membrane bounded by cables.

9. A system as in claim one and six and is deployed by a system of cables, pulleys and electric motors.

10. A system as in claim one where the membrane consists of a single reinforced membrane deployed mechanically by pneumatic or hydraulic means.

11. A system as in claim one where the membrane is double walled and deployed pneumatically.

12. A system as in claim one where the membrane is double walled and deployed hydraulically.

13. A system as in claim one in which the membrane consists of rigid panels or struts joined by flexible membranes.

14. A system as in claim one which is additionally sealed by a tubular flexible gasket.

15. A system as in claim one which is additionally sealed by a flexible gasket inflated pneumatically or hydraulically.

16. A system as in claim one which is self sealing under gas or liquid pressure by means of an additional flexible membrane flap attached to the base of the membrane.

17. A system as in claim one which acts as a self sealing barrier or valve through the pressure of flood water.

18. A system as in claim one which in a stored position is moveable to allow variable positioning of the membrane when deployed.

19. A system as in claim on which consists in part of available flexible membrane designs or products.

20. A system as in claim one consisting of any combination of claims 1-19.

21. A system of stored flexible membranes, as described in any of claims 1 - 20, which may be deployed or self deployed to maintain or increase damage stability and/or watertight integrity of the vessel by means of compartmentalisation or partial compartmentalisation.