LAUNCHING AND RECOVERY OF TETHERED CONTROLLED SUBMARINE VEHICLES

Abstract: For launching and recovering tethered remote controlled submarine vehicles a reinforced flexible free-flooding tube 3 adapted to be deployed from a ship is provided with one end of the tube remaining attached to the ship, the tube having passed therethrough an umbilical cable 1 for a remote controlled submarine vehicle. The cable and tube are deployed from a winch drum 2. The upper end of the tube has a conical termination 4 which locates in a support 6 mounted outboard of the ship. The lower end of the tube may have a docking latch to assist in recovery of the vehicle.

Description: LAUNCHING AND RECOVERY OF TETHERED REMOTE CONTROLLED SUBMARINE VEHICLES This invention relates to launching and recovery of tethered remote controlled submarine vehicles. The major difficulty in launching and recovery of remote controlled submarine vehicles is at the interface between the ship and the sea surface, particularly under adverse weather conditions. Existing solutions employ cable tethered subsea docking cages complete with cable drums and underwater slip rings, etc., for deployment of the vehicle umbilical. According to the invention there is provided an arrangement for launching and recovering a tethered remote controlled submarine vehicle characterised in that a reinforced flexible free-floodine tube is adapted to be deployed from a ship with one end of the tube remaining attached tc the ship, the tube having passed slidably therethrough an umbilical cable for a remote controlled submarine vehicle. In a preferred embodiment of the invention the other end of the tube is fitted with a docking attachment whereby a vehicle during recovery is automatically docked and locked to the tube preparatory to drawing in of the tube with the attached vehicle. Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figs. la and lb illustrate two methods of deploying a flexible tube carrying an umbilical cable, Figs. 2a and 2b illustrate winding of a flexible tube carrying an umbilical cable onto a drum, and Fig. 3 illustrates a docking and latching arrangement for a flexible tube. As shown in Fig. la an umbilical cable 1 for a remote controlled submarine vehicle (not shown) is deployed from a ship-mounted winch drum 2. The cable 1 passes slidably through a heavy reinforced flexible tube 3 which hangs over the side of the ship and extends some depth into the sea, e.g. 40 metres. The upper end of the tube is fitted with a conical termination 4 which locates in a complementary support ring 6 mounted outboard of the ship, thus allowing the tube to hand straight down. The tube is constructed so that it is free-flooding when immersed in the sea. Because of its weight and its low flexibility it will resist hydrodynamic drag forces when deployed. One form of construction for the tube is a close helical spring armoured with an open mesh steel wire braid. The sea end of the hose may require extra weights to ensure stability. Alternatively the tube may be wrapped in lead tape to provide the required weight. It may be armoured with several torque balanced layers of preformed steel wires instead of or in addition to the breid to achieve a breaking load an order of magnitude greater than the umbilical control cable itself. Assuming an umbilical cable having a diameter of 12 mm (0.5") and a breaking load of the order of approximately 1Kg (1 ton) the reinforced flexible tube will have an internal diameter of 15mm (0.6") and a breaking load of 35,000 Kg (30 tons). The reinforced tube can be manufactured with a faired external cross section to further minimise drag whilst the tube is deployed when the ship is stationary in a tidal flow. As an alternative to the outboard deployment of the tube the support ring 6 can be mounted inboard, as shown in Fig. lb, the tube then being deployed over a sheave 7. In both cases the umbilical cable 1 and the tube 6 are wound up on to the winch drum 2. Figs. 2a and 2b show how the cable and tube are wound onto a triple flanged drum. The cable 1 is initially wound onto a major portion 2a o' the drur, between flanges 8a and 8b. The centre flange 8b has a slot 9 through which the cable 1 will pass in order that continued rotation of the drum will wind up the tube 3 onto a minor portion 2b of the drum. This occurs only when the entire length of cable except for the last 40m has been wound onto the major portion 2a. To assist in the winding of the flexible tube onto the drum a short length, say lOm, of wire rope is attached to the conical termination 4. The cable is wound onto the drum initially until the sea end of the cable engages the free end of the tube. The initial winding strain for the tube is then taken via the wire rope instead of by the umbilical cable, the wire rope having been attached to the drum for this purpose. At the sea end of the tube a docking and latching arrangement 15 for the submarine vehicle is preferably provided as shown in Fig. 3. The end of the tube 3 carries a bellmouth guide 10 attached to the tube by a termination 3a. The bellmouth carries spring loaded latches or clamps 11. The submarine vehicle 12 has on its upper surface a probe 13 through which the sea end of the umbilical cable 1 is threaded and secured at termination la, the electrical conductors ending in a gland or connector 14 within the vehicle. When the vehicle is drawn up towards the tube end during a recovery operation, by winding in of the umbilical cable, the probe 13 is guided into the guide 10 and locked in place by the latches 11. Further recovery of the vehicle is then effected by winding in of the tube until the vehicle is at the sea surface when it can be secured to a davit or the like for lifting on board the ship. The docking arrangement 15 is in this case provided with additional lead weights 16. The use of the flexible tube 3 for deploying the umbilical cable 1 during operation of the submarine vehicle obviates the need for underwater slip rings etc, since the ship board end can be connected at deck level to the vehicle control system. For deployment there are alternative methods. The vehicle can be readied on deck with a coiled length of cable on the vehicle upper surface, the ship-board end of the cable leading into and through the tube which is deployed first. The vehicle is then dropped into the sea and the cable uncoils automatically as the vehicle sinks. Or the vehicle can be lowered into the sea from a davit with the tube only partially paid out, the remainder of the tube being paid out once the vehicle is submerged. Thereafter the umbilical cable is paid out through the tube. Whatever method is used the vehicle is not docked and locked to the tube end during deployment, only when recovery is nearly completed. In the event that it is required to ensure that the vehicle is docked and locked to the tube end during deployment, remote detachment from the locking device may be achieved by pneumatic or hydraulic actuators, or by means of passing electrical currents through memory metal springs or alternatively by the use of pressure sensitive bellows.

Claims: CLAIMS: 1. An arrangement for launching and recovering a tethered remote controlled submarine vehicle characterised in that a reinforced flexible free-flooding tube is adapted to be deployed from a ship with one end of the tube remaining attached to the slF, the tube having passed slidably therethrough an umbilical cable for a remote controlled submarine vehicle. 2. An arrangement according to claim 1 characterised in that the other end of the tube is fitted with a docking attachment whereby a vehicle during recovery is automatically docked and locked to the tube preparatory to drawing in of the tube with the attached vehicle. 3. An arrangement according to claim 1 or 2 characterised in that the tube is constructed of a close helical spring armoured with an open mesh steel wire braid. 4. An arrangement according to any preceding claim characterised in that the tube is provided with layers of preformed torque balanced steel wires. 5. An arrangement according to claim 3 or 4 characterised in that the tube has a faired cross section to minimise hydrodynamic drag forces. 6. An arrangement according to any preceding claim characterised in that the one end of the tube is provided with a bellmouth termination adapted when deployed to locate the end of the tube in a complementary support means affixed to the submarine vehicle. 7. An arrangement according to claim 2 characterised in that the docking attachment comprises a belimouth guide means through which the umbilical cable passes slidably, the guide means including spring loaded latches whereby the guide means will engage and lock to a probe attached to a submarine vehicle. 8. A method of launching and recovering a tethered remote controlled submarine vehicle wherein the vehicle is tethered by an umbilical control cable, characterised in that the cable is passed slidably through a reinforced flexible free flooding tube deployed from a ship, inciud ng the steps of unreeling and reeling in the cable and the tube together, the tube when deployed being anchored at its upper end to the ship and hanging from the ship into the water allowing the cable to pass freely through the tube as required.

Inventors: SPICER, LINDON REGINALD
Applicants: STC PLC
Application year: 1985
Main classification: B63B27
IPC codes: B63B27, B63C11