James May on how to float

Posted by James May at 9:00PM on Sunday 14 October, 2007 12 Comments

James May The premise of the original Top Gear amphibious car challenge, which went out a year or so ago, was that there has never been a truly successful boat/car hybrid, and that it was about time there was.

The two most notable examples to date have been the original Amphicar - whose lower door seals were below the water line, so when forgetful motorist-mariners opened the door to get out at the quayside the thing sank immediately - and the Gibbs Aquada, which was far too expensive and still sank.

There still hasn't been a truly successful amphibious car.

But for Amphibious Car Cock-Up part II I stuck with my original Triumph Herald of Free Enterprise sailing boat. The Herald seemed intrinsically right to me - it looks a bit like a sailing boat, has flat sides to give a sort of keel effect to aid directional stability, and is a convertible, allowing easy escape.

Bigger sails and a collapsible mast for clearing low bridges and telegraph wires were all that was required for a trouble-free drive to Dover and a successful attempt at the channel crossing. It sank in the harbour.

I now realise that the ideal car for conversion to maritime duties is in fact the MGB roadster; not only that but, ideally, the one with the rubber bumpers, because they would float. The MGB looks a bit like a small motor launch, so we're halfway there already.

The underside will be entirely covered with a smooth aluminium plate, to allow the car to 'ride the step' under power. Buoyancy will be achieved with the passenger and luggage areas of the bodyshell, which are the most voluminous and the easiest to seal. The engine bay will merely be waterproofed and provided with a snorkel, like a Land Rover.

Drive to the shrouded rear-mounted propeller will be effected automatically with a simple dog-clutch arrangement whenever the transmission is in second or reverse. This means that, on the road, the shrouded propeller at the back will be seen to spin briefly during acceleration, hill-climbing and when reverse parking, but most of the time it will be stationary and hence completely safe.

The rudder, which drops down below the boot, will be permanently linked to the steering rack by cables. Sailing the B will be a simply matter of pressing the right hand pedal and turning the wheel, like driving, which is what we want.

It will be manoeuvred using second and reverse, with all other gears effectively being neutrals. Including Neutral. There is absolutely no reason that I can think of why this wouldn't work brilliantly and be capable of around 20 knots.

Amphibious cars work very well in my head.