Spacecraft's air-bag hull system is totally cool

by Mark Rothfield on 21 Jul 2011 As your average clean-cut, Kluger-driving conservative, I’ve never quite grasped the American ‘gang’ thing – the baggy pants, the hoods, the tats and the rap (which is surely missing the letter ‘c’).

What I particularly don’t get is those hoon cars with air suspension that bounce up and down like Maasai tribesmen. They remind me of the nodding dogs our parents liked to rest on the rear parcel tray.

What possible benefit does this serve to automotive handling and performance? None …

The new Spacecraft 5.4 metre runabout can bounce up and down too. Place it on the ground, activate an air compressor, and the hull will raise and lower itself up to 200 millimetres.

This, however, is much more than a party trick. This is change for the better, not worse … possibly the biggest breakthrough in monohull design since Raymond Hunt was a lad.

Unlike hoon-mobiles, boats spend their life running on chop the size of a country pothole, and the purpose of using airbag suspension is to soften the ride.

The idea came to Larry Wilthshire, builder of Spacecraft plate-alloy boats at Toronto NSW, around five years ago and first he had to convince himself of the merits.

Though it’s a remarkably simple concept, it took some guts to slice the bottom out of a perfectly well designed boat then suspend the resulting pod on shock-absorbing airbags forward and hinges at the transom.

The central section rides independently of the main hull. By adjusting the air pressure the ride can go from firm – as with a conventional plate boat – to soft. You can tailor it to suit hull load and sea conditions.

It’s all done with the press of buttons at the helm, with the compressor and tank being secreted inside the cabin. A clear Lexan polycarbonate sheet in the cabin floor allows the driver to see the suspension system at work.

Passengers can apparently feel the difference in their spines too, and there’s less movement and vibration for the outboard which is suspended on the main hull.

A further advantage comes at rest, when the chines can sit lower in the water for superior static stability. This was an unintentional benefit, Larry admits, but it will be appreciated by fishos who stack the cockpit sides.

Fuel is stored in the central hull, nice and low. There’s 17-degrees deadrise at the transom but ample more vee amidships and at the forefoot, where it really counts.

Larry’s had the 5.4 wave-jumping offshore without any problems.

The airbag system adds about $10,000 to the 5.4-metre hull, bringing the package price with 150hp, four-stroke Yamaha and custom-made alloy trailer to $65,000.

Money well spent, I reckon, because conventional plate alloy boats are notorious for banging around in chop.

A hull that rides on a cushion … now that I understand. A patent has been applied for.

Contact Spacecraft on 4950 4083, email Spacecraft website