RiverTrailer Alligator

A multi-purpose aluminium craft built for rough handling — floods above all, where nobody knows what lies under the surface. It floats in as little as 60 cm (24 in) of water. Wheels and a drawbar are built in, so it travels the road on its own as a trailer rated to 3.5 t.

What it does

Sets up a ferry between banks, carries firefighting equipment to a boat fire, evacuates people from excursion vessels, tows damaged craft.

Lands equipment where the only access is from the water — a forest fire by a lake, a flooded area. It will also tow smaller vehicles out of flooded ground.

Structure

The hull is made of displacement bodies filled with closed-cell foam; puncturing them does not affect the craft afloat. Inside are two connected tanks holding 1,700 l (450 gal).

The rear cargo deck carries 2 t (4,400 lb) on the water — a car up to one tonne, or twelve people. Under the front canopy there is seating for four including the helmsman, with eight more along the sides at the back.

Steering

We were the first to put the outboard — a Honda 90 HP — in the middle of the bow. That lets the craft move in among swimmers without the propeller being a hazard, and the helmsman, also at the bow, can see exactly where he is heading.

Landing and rescue work

Aluminium ramps 3.5 m long fit at the stern on plug-in pins; hand winches on the rear rail posts adjust their height, so people and a buggy can land even on a raised bank up to three metres away.

The bow winch pulls 3.1 t and the stern winch 2.2 t — worked against each other they turn the craft into an emergency ferry across up to 33 m of water. Two towing eyes at the stern take craft up to 6.5 t.

Getting into the water

An extension bar adds 4 m between the towing vehicle and the craft, so it can be launched where there is no proper slipway. Coming back, you moor four metres out and hitch up.

The overrun brake sits 105 cm off the ground, matching Tatra, Scania or Mercedes-Benz Actros trucks. Plug in the electrics, drop the coupling on and it is ready to roll.

What the trials showed

We tested the craft in bad weather — which is the weather equipment like this should be tested in. The trials covered loading a car and a quad without a towing vehicle attached, entering the water loaded, cruising, and landing on an unprepared bank.

Afloat with a car and ten people aboard: around 9 km/h (5 knots) with minimal roll. The car drove off onto the bank without jack-knifing the trailer; the stern winch was enough to hold the craft against the shore.

Landing the quad on a forest bank needed no mooring at all — reverse gear engaged and one crew member holding the stern line did the job.