'Amphibious Demons' - Ford GPA Amphibious Vehicles II
More silent footage of testing the Ford GPA 'Seep'.
Part I - • 'Amphibious Demons' - ...
The Ford GPA 'Seep' (from Seagoing Jeep), was an amphibious version of the WWII Ford GPW Jeep.
After having commissioned Willys, Ford and Bantam to build the first 4,500 jeeps (1500 each) in March 1941, the US Motor Transport Board set up a project under the direction of the National Defense Research Committee (NDRC) to be designated "QMC-4 1/4 Ton Truck Light Amphibian".
As the war in Europe progressed bridges were frequently destroyed in front of the advancing Allies and the requirement for an amphibious version of the jeep arose. Roderick Stephens Jr. of Sparkman & Stephens Inc. yacht designers was asked to design a shape for a 2700 lb (1,200 kg) amphibious jeep, in the same vein as his design for the DUKW six-wheel-drive amphibious truck. Not surprisingly Stephens' hull design looked like a miniature version of that of the DUKW, and just like it, the 'Seep' was going to have a screw propellor, driven by a power take-off, operating in a dedicated tunnel faired into the rear end bodywork, as well as a proper rudder.
The construction of the vehicle was developed in competition by Marmon-Herrington and Ford Motor Company. Marmon-Herrington specialised in all-wheel drive vehicles. The Marmon-Herrington prototype's hull formed an integral unibody structure, created by cutting shapes out of steel plate and welding those together, much like the hull or chassis of an armoured vehicle. The Ford entry however used a sturdy chassis and internal frame, to which more or less regular automobile type sheet-steel was welded. This construction made the GPA some 400 lb (180 kg) lighter than its competitor. Also The GPA's design was based on the Willys MB and Ford GPW standard Jeeps as much as possible. When designing and building the GPA, Ford utilized many of exactly the same parts that the Ford GPW did. The GPA had an interior similar to that of the MB/GPW jeeps, although the driver's compartment had almost twice as many control levers: 2WD/4WD, hi-range/lo-range, capstan winch (on the bows), propeller deployment and rudder control. After a direct comparison of the two company's prototypes, Ford received a contract for production starting in 1942.
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An excellent graphic document. I like it so much.
Hope they have been efficient in action. During the tests, they seemed to perform well.
@Narrowgaugefilms
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They didn't live up to what the Army hoped they would be. They came in 900 Lbs. overweight and sat too low in the water, so they weren't very seaworthy. What's interesting is when it came down to crossing a shallow river, a conventional Jeep actually did much better too: a regular Jeep's wheels dug into the riverbed and it resisted the push of the current. The amphibians tended to lose contact because of the buoyancy of the hull and then got swept downstream. Only when the the water got deep enough to swamp a regular Jeep did the amphibian start to come into it's own. On land, they were basically a Jeep forced to wear a boat hull: a little awkward for getting in and out. They were a compromise: neither a good boat or a good Jeep! I think there were something like 250,000 conventional Jeeps and 13,000 of these: that in of itself says a lot! The amphibious truck (DKW), which inspired these, did much better.
Gpa has a screw.