A DRIVE-OFF TROLLEY, SELF-POWERED OR PROPELLED BY SEPARATE TRACTOR, FOR LAUNCHING AND RECOVERY ON EXPOSED BEACHES by Ray Kipling Deputy Public Relations Officer, RNLI A DRIVE-OFF TROLLEY, SELF-POWERED OR PROPELLED BY SEPARATE TRACTOR, FOR LAUNCHING AND RECOVERY ON EXPOSED BEACHES by Ray Kipling Deputy Public Relations Officer, RNLI Duvivier and RNLI staff from Cowes Base. The bearers forming the base of the trolley are in the shape of a tuning fork and support on her outer chines the boat's bottom with her bows pointing out of the open end of theTork, so that she can be driven straight out with no obstruction to the engines. The bearers hold the boat in position but rollers can be raised to allow her to be moved when, for example, returning to the trolley after beaching.

Planked sides give the trolley the appearance of a haywain and act as guides in launching and recovery.

Water tanks are fitted to the sides of the trolley and these are connected to the ILB's outboard engines by plastic pipes. This means that the engines can be started and warmed up going down the beach before the boat enters the water, being cooled all the time with water from the tanks. The risk of stalling at the launch is therefore minimised and the pipes pull free as the boat drives off.

The ILB is held in the trolley with rope springs. The after springs prevent the boat being lifted backwards by a sea and the forward springs are held by the two crew members who release them on the helmsman's command.

Regardless of rough seas the boat can ride safely in her 'dock' with her engines running until the helmsman judges the right moment has come to launch.

Recovery into the trolley can be made using an arrester net which is rigged between the vertical posts. The boat is driven into the net which retards her forward movement and halts the boat in her correct position in the trolley.

The rope springs are then hooked on and the boat is safely back without having touched the beach. The upright posts also carry lights to facilitate night recovery. In very bad conditions or when landing off station, for example to transfer a casualty to an ambulance, the Atlantic 21 can be driven straight up the beach and well clear of the water.

When the boat has been recovered she must be turned round to be ready for service again. This is accomplished with a small turntable which is jacked up under the boat. The trolley is then withdrawn, the boat swung round and then replaced on the trolley right way round.

Manoeuvring carriages with lifeboats on them is a field in which the RNLI has considerable experience but with the new trolley came a new problem.

Conventional launching tractors, built to shift the weight of an offshore lifeboat, were too slow and if they had been used the ILB's advantage of speed on service would have been reduced.

Parallel development brought two solutions; a self-powered trolley, with the motive unit as an integral part of the trolley and a separate tractor connected to the trolley to produce an articulated unit. The former was named SPIDOT (self-powered immersible drive-off trolley) and after twelve months of evaluation it became fully operational in March 1977 at Littlestone. The engine, air intake and exhaust outlet are far enough above the water to allow the vehicle to be used on shallow sloping beaches without the engine being swamped. The drive-out end of the trolley is steered through the wheels supporting it so that direction of launch can be adjusted rapidly as necessary. In the event of the trolley bogging down in soft ground hydraulic feet raise it up to allow solid material to be put under the wheels.

The latter vehicle, originally a conventional four-wheel drive tractor, has (continued on page 103).