GB1571112A - Ssacv straddle cargo transporter - Google Patents

Description

(54) SSACV STRADDLE CARGO TRANSPORTER (71) I, THIRUVALAM KUMARAS WAMY SRINIVASA MURTHY 12 Westwood Road Southampton S02 1DN Nationality: Indian do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a semi-submerged Air Cushion Vehicle, hereinafter denoted by SSACV and of the type recently disclosed in U.K. Patent Specification No. 1,475,084 together with the incorporation of additional conoructional features enabling the vehicle to carry marine cargo in the underslung mode in addition to the carriage of such cargo on the large open deck in the conventional manner.

As disclosed in the abovementioned patent specification, the SSACV is a composite marine vehicle with a gas cushion hounded by flexible seals at the bow and at the stern and by thin, deep struts along the sides, which extend well below the surface of water and carry at their lower ends a pair of long, slender, streamlined hulls, providing a substantial hydrostatic buoyancy contribution, in addition to the aerostatic lift of the cushion, enabling the sustention of the hard structure and deck of the vehicle above the water.

When the cushion is not filled with pressurised gas, that is to say, in the "cushion off" mode of operation, the SSACV simply resembles a serni-sub'nerged ship.

There appears to be a requirement for the rapid movement of marine cargo and military stores and equipment over the surface of water. An example of the former is the cargo carried by LASH (Lighter Aboard Ship) vessels in loaded barges, which are taken aboard and moved on the deck and down into the hold by gantry cranes. The LASH vessels are deep water vessels and on arriving at the destination after a long ocean crossing, they are usually moored in off shore waters and the loaded barges are deposited back on the water. The barges are sometimes self-propelled, but are usually towed by tugs to. and from the LASH vessel, the speed of movement thus being very low indeed. Some type of fast feeder service for the loaded barges will therefore be of commercial advantage in increasing productivity.Similarly, there may he a case for the rapid deployment of submarines, deep submergence research and rescue vehicles and the like in their area of operation, or for their speedy return to base in the case of an emergency. There may also be a similar requirement in the space programme for the recovery of the rocket casings used in launching the space shuttle. Some of these missions are usually carried out by a helicopter, which can pick up the floating object from the water surface and then load it on the deck of a conventional displacement vessel.

Also, in the case of the offshore oil industry, there may be a requirement for the rapid transport of large and unwieldy types of equipment, pipes, machinery and other stores between the mainland and the off shore drilling rigs.

An embedment of the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic perspective view ob the SSACV Straddle Cargo Transporter.

Figure 2 is a diagrammatic front elevation of the vehicle approaching and straddling the floating cargo in the "cushion off" mode, that is to say, with the front and rear seals of the cushion raised well above the water surface.

Figure 3 is a view similar to that of Figure 2 showing the vehicle operating in its role as a cargo transporter with the flexible seals lowered to the normal position, the cushion pressurised. and the load raised out of the water and attached to the underside of the hard structure.

Figure 4 is a view from the rear of the vehicle straddling a finger pier extending from the docks.

Referring to Figure 1, the superstructure or body portion 1 with the navigation/crew accommodation 11 is supported well above the water surface by means of the side struts 2, which carry at their lower ends the submerged hulls 3. Flexbile sealing skirts 5 and 6 depend from the hard structure down to the water surface enclosing the air cushion 4.

Access to the catwalk 7 below the superstructure is gained through the manholes 8.

LASH barges or other loads 9 are underslung from the hard structure. The machinery for prnpuliin 10 may be housed in the rear portion of the submerged hulls. Air is mgested into the cushion from the atmosphere through the intake gills 12.

Referring now to Figure 2, the vehicle will approach the floating cargo 13 in the "cushion off" mode, that is to say, in its semi-submerged ship configuration with the lift fans stopped and with the hemline of the flexible seals raised to a height sufficient to clear the upper surface of the floating object to be carried.

Alternatively, the floating cargo can be towed to a position within the side struts of the stationary vehicle.

A catwalk 7 is provided on the underside of the hard structure, that is to say, against the ceiling of the air cushion, so that the crew can descad from the deck 1 through the manholes 8, or through air-tight doors (not shown) in the upper part of the side struts 2, and connect the load to the hard structure by the use of suitable fittings.

It is obvious that the height of the hard structure of the vehicle in its "cushion off" mode should be designed to provide adequate cleamce over the top surface of the floating object to be carriei A small adjustment of the vertical position of the vehicle can be carried out by the use of water ballast carried in the side struts. For example, if the vehicle is to be slowly lowered over the load for the purpose of ensuring a secure connecon, valves can be opened in the side struts and the ingress of the appropriate amount of water will enable this to be done. Similarly, if the vehicle is to be slightly raised to clear rhe load, a suitable amount of water ballast can be released by, say, the use of compressed air.

When the load is securely connected in the underslung position from the hard structure of the vehicle straddling it, the flexible sealing skirts at the bow and the stern are lowered to the water surface and the cushion energised by starting the lift fans. The additional lift due to the air cushion will have the effect of raising the vehicle and its load out of the water. The hemline of the flexible sealing skirts is lowered to such a depth that the base of the load out of the water clears the water surface by an adequate margin, bearing in mind the prevailing sea state, in this moderate to high speed "cushion on" mode of operation. The load can be ttanspcyrted to its destination at an arbitrarily high speed governed entirely by the level of the chosen power installation (see Figure 3).

On reaching the destination, the process is exactly reversed. The lift fans are first stopped.

The loss of cushion lift will make the vehicle descend and the load sink back into the water.

The fastenings are then disconnected and the vehicle raised slightly by releasing some of the water ballast. The flexible sealing skirts are now raised to the level of the underside of the body portion and the floating cargo towed away by a tug, unless self-propulsion is avail able, to complete the final stage of slow move ment to the docks.

It is obvious that loads lying on floating barges can be picked up and transported in exactly the same way and deposited on barges at the destination.

A vehicle according to the present invention is also suitable for picking up loads, such as containerised cargo, from a narrow finger pier extending from the docks as illustrated in Figure 4. In this case, the pier 14 is itself straddled by the vehicle. After the load 9 is picked up, the flexible sealing skirts are lowered and the cushion pressurised. The vehicle then backs away with its load from the docks.

It is the unique capability of the SSACV Straddle Cargo Transporter that loads floating on the water surface can be straddled and carried in the underslung position, in addition to loads carried on the deck in the conven tional manner. The SSACV has also the unique capability of directly picking up and transporting at high speed large loads from the water surface, from floating barges or from narrow finger piers extending from the docks. Similarly, the loads can be deposited back on the water surface, on barges or on finger piers extending from the docks, without the use of cranes, helicopters, or other expensive equipment The SSACV Straddle Cargo Transporter acts, in fact, like a floating, mobile, gantry crane, capable of motion at a very high speed over water.

It will be appreciated that various modifications and changes can be made without departing from the scope of the accompanying

Claims (5)

claims. WHAT I CLAIM IS:

1. A gas cushion vehicle for operation over the surface of water, comprising a plenum chamber for the gas cushion, formed by the underside of the body portion of the vehicle; a pair of longitudinal side struts extending along and below the sides of the body portion; flexible sealing skirts extending between the side struts at the front and the rear ends of the body portion, each side strut carrying at its lower end a buoyant hull portion, wholly or partially immersed below the surface of the water, the arrangement being such that, in an unloaded condition, the body portion is sustained above the surface of the water entirely by the buoyancy of the submerged hull portions, thereby enabling a load floating on the water, or carried on the deck of a floating vessel, to be attached to the underside of the body portion within the plenum chamber and, in a loaded condition, the body portion and the load which is attached thereto are sustained above the surface of water by the additional lift provided by the pressurised gas in the plenum chamber; the body portion being further provided with airtight hatches or manholes and the side struts also being provided with airtight doors, so that access may be obtained to a catwalk located on the underside of the body portion for the purpose of securing the load thereto or releasing the load therefrom.

2. A gas cushion vehicle as claimed in claim 1, in which the flexible sealing skirts are of a type capable of being raised to the level of the underside of the body portion, when the gas cushion is not used.

3. A gas cushion vehicle as claimed in claims 1 or 2, in which the side struts and hull portions carry water ballast for lowering or raising the height of the body portion above the water surface.

4. A gas cushion vehicle as claimed in any preceding claim, in which the machinery for propulsion is housed in the rear of the hull portion.

5. A gas cushion vehicle substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.