Wading

On 6 June 1944, some 37,000 vehicles were landed on the Normandy beaches and, although landing craft carried the vehicles close to the beaches, all had to be waterproofed to allow them to be driven off a ramp and up the beach. An enormous amount of work was required to make this possible, and it is testament to both the methodology, and the care with which the work was carried out, that only around 1% of vehicles were lost.

Wading is fraught with difficulties. If water enters the intake system, the resulting hydraulic lock will destroy the engine. A small amount of water in the ignition system will short-circuit the plugs, whilst water in the fuel system will block the carburettor jets. If the engine stalls with the tail pipe under water, the exhaust system will fill, and the engine cannot be restarted. Water entering junction boxes, lights and instruments will cause short circuits and corrosion leading to unreliability. And water in the axles, transmission and engine lubrication system will cause damage to bearing surfaces which may result in seizure.

During the 1950s, the Amphibious Trials and Training Unit (ATTU) at Instow, North Devon, worked in conjunction with the Fighting Vehicles Research & Development Establishment (FVRDE) at Chertsey, to develop a waterproofing system for all military vehicles which employed various methods of sealing joints and surfaces against water ingress. Bostik adhesive was used to stick waterproofing fabric to metal surfaces. A self-adhesive plastic sealing tape called Prestikon was used to close small openings and joints. Canvas covers were provided to enclose larger components such as the starter motor, coil, distributor and fuel pump. A silicone compound was used to seal junction boxes and fuses. Purpose-made adapters raised the air-intake inlet above the water line. Finally, surfaces which were vulnerable, rather than vital, were liberally smeared with waterproof grease to prevent corrosion.

A 120-page, War Office document described the 25 man-hours’ work required to waterproof a Series I ready for wading to a depth of 60in (1.5m). And, never afraid to state the obvious, the document explained that the last stage of the work was to ‘memorise the tasks... which must be done (immediately) after landing... and place this instruction in the PVC bag provided and seal with adhesive tape’. There was an equally long list of work to be completed once the wading was over, and before the vehicle was considered fit for further service.

Waterproofed vehicles were trialled by immersion. At Chertsey, a vehicle was required to make a series of runs through a deep-water tank followed by 15-minutes static immersion at a depth of 48in (1.22m) with the engine running at full revs before driving out. The final trial was carried out in sea at Instow: the vehicle was disembarked from a landing craft, spending 15 minutes in the sea under its own power, followed by a 10 mile (16km) road run. The engine, axles and transmission were then stripped and examined for water contamination.

Until the appearance of the Royal Marines’ Defender XD, no Land Rovers were supplied from the factory prepared for wading. Nevertheless, the ability to disembark from landing craft remains a standard military requirement and a variation of these complex procedures was equally applicable to Series II and III and to the core military Defender.

Above: Partially-stripped ‘lightweight’, equipped with a makeshift snorkel for deep-water wading. (PW)

Above: Not much Is known about this amphibious ‘lightweight’ which was trialled in the late 1960s. Glassfibre floats have been attached to the body sides and at the front. Propulsion in the water was provided by a Dowty Hydrojet unit. (PW)

Right: Deep-water wading requires that the vehicle be fitted with a snorkel, and often an exhaust pipe extension.

It is also necessary that the electrical equipment is waterproofed. (PW)

Above and left: Just one prototype of the FV18061 amphibian was constructed. Whilst the artist's impression showed a sleek, futuristic machine, the reality was rather closer in appearance to a milk float. The vehicle used an exoskeleton foam-reinforced plastic body with load-bearing steel inserts.