DUKW

In earlier modelling days

I was a member of the Greater Wellington Marine Model Club. One pond on which we sometimes sailed had quite a large ramp/beach at one end.

Another member of the club had made a model of an amphibious vehicle, which he successfully manoeuvred into and out of the water.

Some time later we moved as a family to Christchurch and I was introduced to the Christchurch Society of Model and Experimental Engineers. At that time they occupied land in Addington which included a 5” raised model train track which encircled a boating pond. And YES it had a well formed ramp going down into the water. This was normally used for the launching of large boats on trailers.

At the suggestion of our youngest son, I started to investigate the practicalities of building our own DUKW.

This was a six wheeled amphibious vehicle used in WW II.

The meaning of the acronym: D= Vehicle designed in 1942, U= Utility vehicle, K= Driven front wheels, W= Two powered rear axles. In total, 21,147 of them were built. Among other things, they were the first vehicles to allow the driver to vary the tire pressure from inside the cab.

To simplify construction, I decided to make it a shortened version, with only two axles and four wheels. The scale is approximately 1/12 full size.

The basic construction material was particle board with some balsa wood used. The wheels are turned out of MDF board using my electric drill held in a horizontal mount. Various wood chisels were used to achieve the shape. Rubber bands cut from suitably sized inner tube are stretched and glued on to give a wearing surface.

To help both front wheels remain on the ground when going over an uneven surface, individual vertical movement of the suspension is allowed by compression springs. The steering linkage to the two vertical shafts which support the wheels is above the wheel wells and inside the hull. Only one wheel (the left rear) is driven via an old clock spring gear attached to it. The shaft and pinion meshing with the gear is just above the water line. The rear axle passes through two lengths of tube mounted in the hull. Hence no water can enter here. No attempt was made to separate the motor drive to the propeller shaft and the wheel, so they both turn together. The large driven pulley and internal gears are Meccano.

A tourist version on Lake Wakatipu, Queenstown NZ.

Speed and direction control is achieved by a rotating switching drum. It has three speeds both ways, heater element wire providing the two resistors.

The four buffers are knitted by myself from string and stuffed with old panty hose.

Having only one wheel driving is at times a problem, especially when leaving the water, but generally its performance is adequate. It generates interesting reactions from young children when entering the water and floating away.

Underside view.

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DUKW in action

Video by A Farrow.