Although you are at an altitude of just a few feet, you are strapped into an aircraft seat. You cannot see anything besides a salvo of surf smashing against age-streaked windows, while all you can hear is the roar of engines burning up fuel at a frightful rate. And in anything approaching a storm you will be going nowhere fast. No wonder the world hasn't taken to car-carrying hovercraft.

Yet this morning, weather willing, the Princess Margaret will make a dozen or more crossings between Dover and Calais. All but one of her five siblings has been scrapped, stripped down for spare parts or destroyed by fire (the fate of the Prince of Wales), but she will continue the Channel tradition she began exactly 30 years ago. Concepts such as fast ferries, the Channel Tunnel and cheap air travel were unknown three decades ago. Yet the hovercraft can be seen as an heroic attempt to combine the main virtues of all three: speed and economy.

When the Princess Margaret departed from Dover Hoverport on 1 August on her maiden commercial flight, (hoverphiles insist on the use of that term, on the grounds that the craft is airborne by definition), she revolutionised cross-Channel travel, covering the 25 nautical miles to Boulogne in 35 minutes. She now flies to Calais in the same time.

Even Le Shuttle, the train that carries cars through the Channel Tunnel, cannot beat that speed. And though the view from both modes of transport is dismal, on the hovercraft at least you enjoy one of the great British mechanical engineering endeavours of the 20th century.

The idea of using a reverse-vacuum-cleaner approach to transportation was first realised at a factory on the Isle of Wight in 1959. Christopher Cockerel, the inventor of air-cushion technology, crossed the Channel aboard the SRN1 (Saunders Roe Nautical) 39 years ago this week. Though today's kit looks a little less comical than the cup-and-saucer prototype, the technology remains the same: a lift fan creates a cushion of air that enables the craft to hover over land or sea, while propellors provide forward motion.

Within three years the first commercial hovercraft service had begun, between Wallasey on the Wirral and Rhyl in North Wales. The operator was British United Airways (now part of BA). Three weeks later, the Southdown bus company opened a link between Portsmouth and Ryde, on the Isle of Wight. International services began in 1965, with a passenger-only hovercraft between Ramsgate and Calais run by the Swedish company Hoverlloyd. But until vehicles could be carried too, there was little hope of making money on cross-Channel routes.

Kent has played host to some pretty silly ways to cross the Channel. Not just the bathtub brigade of brave individuals but also the old Bristol freighters that formed a kind of roll-on/take-off/roll-off service from an airfield in the county to Le Touquet on the French coast.

The Princess Margaret, prototype for the Mountbatten class of giant hovercraft, was supposed to change all that, and revolutionise transport not just across the Channel but worldwide. A year before her first run, the QE2 had been launched and Concorde had taken its first test flight. Britain seemed, in the words of Tony Benn, to be fuelling the "white heat of technology". But ultimately the hovercraft has proved even less successful than supersonic passenger aircraft.

The original owner was Seaspeed, part of British Rail, whose slogan was "Fast & Fun". The first flight is recorded in Air-Cushion Vehicles: The International Hovercraft Journal (not a publication that has stood the test of time): "She outpaces her maritime peers without a trace of the skittishness shown by her smaller sisters... The passengers are tended by what Seaspeed calls `purserettes', an ungainly description for such attractive girls."

You could buy a day return to Boulogne for pounds 3, or take the rail-hovercraft link to Paris for pounds 14 return - just over six hours each way, and real competition against the Air France Caravelle or BEA Trident.

Yet in the great tradition of British transport innovation, three days after her launch the Princess Margaret was temporarily taken out of service because of mechanical problems.

When describing the subsequent history of hovercraft, the words "catalogue" and "disasters" appear singularly apt. Within five years, the price of oil had rocketed, adding greatly to the cost of what is inevitably an energy-inefficient form of transport. Nevertheless, French Railways wanted to join the revolution, and slowly and painfully developed the N500 Naviplane. Weeks before the first two French craft were due to enter service in 1977, one was destroyed by fire, leaving the Ingenieur Jean Bertin as the only child. Anyone who was unfortunate enough to travel on this brick-like beast will recall that it was even noisier and less comfortable than the British original.

In 1978, the Princess Anne (today's other survivor) famously lost much of her air-cushion skirt in heavy seas off the French coast. The following year, the French craft drifted for eight hours when the engine failed in mid-Channel.

Initially Seaspeed had been in competition with Hoverlloyd, but by 1981 it became painfully clear that the only possible hope for making a profit was to merge the operations as Hoverspeed. In the same year, the British Hovercraft Corporation came up with a long-range, fuel-efficient replacement called the BH88. No one ordered it. With touching understatement, The Hoverspeed Story (Ferry Publications, 01834 891460, price pounds 3.45) describes this as "a fact which spelled some difficult times for the British Hovercraft Corporation".

The nadir of the cross-Channel hovercraft was in 1985. On 30 March, the Princess Margaret struck a breakwater at Dover on her approach from Calais, and four passengers died. In October, French interest in air-cushion technology finally disappeared when the Ingenieur Jean Bertin was broken up on the hoverpad at Boulogne by a mechanical digger.

What future for the Princesses? Bizarrely, these days you can cross the Channel for even less than 30 years ago. Hoverspeed (0990 595522) is selling day returns from Dover to Calais for pounds 2.50 for foot passengers travelling in pairs, while a full car costs pounds 35. The reason the company can keep fares low is because itmakes a profit on duty-free sales. The hovercraft is being kept afloat - sorry, aloft - thanks to the hidden subsidy afforded by cheap booze and smokes. When the European Union brings these to an end 11 months from today, the Princess Margaret could finally hover to a halt.