The first time South African inventor Gary Gribben saw a hovercraft was when he crossed the English Channel on one during his honeymoon.

"I'm going to build one of those," he told his new wife and, more than 20 years later, he did.

A hovercraft is a remarkable thing. It’s neither boat nor plane, but a bit of both. Hovercrafts float on a cushion of air, so they do fly, albeit very low, and that's the secret. It's what gives them their smooth ride, and their ability to travel over any terrain or surface. Hovercrafts can traverse mud, deep water, sand, tar and even thin ice, moving from one surface to the other at top speed without a shadow of a bump.

How it works is simple. There are two types of hovercraft – single-engined and double-engined. The latter is by far the easiest to drive. One engine powers a fan that diverts air under the craft, where it is held in place by a flexible skirt. The second powers a rear-mounted fan, or propeller, that moves the craft forward. A single-engined hovercraft works in the same way, except one engine powers both fans.

While the engines aren't particularly noisy, the fans are – and that is the only environmental disadvantage of hovercrafts. They're not exactly quiet.

But other than noise, hovercraft are very environment-friendly. Unlike motor boats they don't create a wake, which erodes river banks. They don't have a propeller in the water that can injure and kill marine life, and they don't pump fuel or fumes into the water like an outboard engine. And, unlike four wheel drives, they travel lightly indeed over the ground. You can drive a fully laden hovercraft over a dozen eggs and they will not be damaged.

Less impact

In fact, the hovercraft has less impact on, for example a beach, than a barefoot stroller. If you look carefully, you can see a faint trail of swept sand where the hovercraft has travelled. And, of course, hovercrafts do not get stuck in mud or soft sand.

This makes them perfect for many South African rivers, which are often quite shallow and not considered navigable. They can also be safely used on wetlands, as they have no impact on the water, the vegetation, the animals and the birds.

They do have some disadvantages. They are tricky to drive, and it takes a while to learn to steer them. But once you've got the hang of it, you've got it. Making the dream a reality

As any good business consultant will tell you, it's all very well having a fabulous product, but if you don't have a market, you don't really have a business. So Gribben decided to build a little single-seater inflatable hovercraft that could be hired out on beaches for joy rides. It seemed like a fun idea.

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