Terrapin (amphibious vehicle)

Terrapin
A Terrapin Mark 1 under test (October 1944)
Type	Armoured personnel carrier
Place of origin	United Kingdom
Production history
Designer	Thornycroft
Manufacturer	Morris Commercial
Produced	1943–1944 (Mark I)
No. built	200
Specifications
Weight	7 tonnes (6.9 long tons)
Length	7.01 m (23 ft 0 in)
Width	2.67 m (8 ft 9 in)
Height	2.92 m (9 ft 7 in)
Crew	2
Main armament	none
Secondary armament	none
Engine	2 x Ford V8 190 horsepower (140 kW) in total
Power/weight	hp/tonne
Suspension	none
Operational range	240 km
Speed	24 km/h 5 mph (8.0 km/h) in water
Steering system	wheel braking

The Terrapin (officially 4-ton amphibian) was a British-manufactured amphibious armoured transport vehicle of the Second World War. It was first used in 1944 at Antwerp during the Battle of the Scheldt.

Terrapins served with the Royal Engineer assault teams of the 79th Armoured Division and were used to carry infantry units (Canadian and British) over rivers.

Due to a shortage of US-manufactured DUKWs, the British Ministry of Supply commissioned Thornycroft to design an amphibious vehicle capable of ferrying supplies and troops from ship to shore for the D-Day landings.

Some 500 Terrapin Mark 1 were built by Morris Commercial, the commercial vehicle side of Morris Motors Limited.

A Mark 2 Terrapin with a number of improvements reached the prototype stage, but the war ended before it entered production.

The Terrapin was powered by two Ford V8 engines mounted side-by-side, with each motor driving the wheels on one side. Wheel braking was used to steer, the brakes being operated by levers.

On a level surface, the vehicle was supported on the four middle wheels, the front and rear wheels remaining clear of the surface (the front pair being raised significantly, the rear pair only slightly). The front and rear wheels provided support and traction on soft surfaces and when climbing slopes, such as riverbanks. When driven in the water, it was propelled by two rear-mounted propellers.

Despite success in its first military action, the Terrapin was not overall a successful design and had many significant defects, which were never overcome in service.

Due to the large diameter tyres, the Terrapin was a relatively high vehicle and, although open-topped, it was difficult to enter and exit. Any soldier attempting to exit over the side faced both prolonged exposure to enemy fire and possible injury from the fall.

Like the Medium Mark A Whippet tank of the First World War, the Terrapin had separate engines driving each side of the vehicle with skid steering. This arrangement was awkward on the Whippet, and on the Terrapin as well. If one engine broke down, the Terrapin tended to swing around violently.