Platypus amphibious 4x4 to land at under US$40,000

"The first step was to select a donor vehicle for the mechanicals. We went through a detailed examination of more than thirty 4x4's, scrutinising each one against a check list of the requirements we'd developed using the prototype vehicle. The only vehicle that had ticks against all the requirements was the Suzuki Jimny. In summary, though there's a lot more to it than this, it's very light, very reasonably priced and very capable off road.

"It has simple mechanicals with a modern engine meeting all emission requirements. Once we'd chosen the base vehicle, we went about translating the year of testing in real world conditions with the old prototype into a new design based on the Jimny chassis.

"The twin tunnel hull / deck and internal sections are all composite materials and since we started with the first military-based prototype, we've halved the weight for the same displacement potential and achieved a very stable watercraft.

"The composite construction means there's no corrosion, it's ultra strong and it's far easier to form the complicated shapes we wanted. The build process actually makes the chassis and hull combination far stronger and more rigid than the original vehicle due to our new encapsulation technique.

"One of the targets was to ensure most the original Jimny geometry and systems were not changed. We figured there was no point redoing what the Suzuki engineers had already spent thousands of hours getting right.

"The vehicle retains all of the original Jimny road characteristics and is still very capable as a 4x4, and there's a host of aftermarket gear available for the Jimny.

"We chose a jet drive for the water over a propeller for ground clearance, safety and neatness in the off-road environment plus plenty of thrust without cavitation problems.

"The jet is a 7.5" purpose-built unit with a Power Take Off (PTO) from the transfer case means the car's engine drives the jet and there's no need for a second power unit, as many amphibians use. The aim was for simplicity, no needless complexity and cost-efficiency of manufacture and the result is a water-going craft that is comfortably capable of seven knots with speed improving all the time.

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