BBC SPORT | Special Events | 2001 | MacArthur in the Mondial

Imagine a giant string bag strung just a few metres above the water flying through the surf at speeds of up to 40 mph.

That is what Ellen MacArthur will experience when she tries her hand at her newest challenge - the high-risk, high-speed sport of trimaran racing.

The sight of a 60ft multihull carving through the water on a single outrigger is one of the most impressive sights in sailing.

These giant multihulls, known as multicoques in French, travel so quickly that crew need to wear goggles just to protect their eyes from the spray.

Foncia is 60ft long with a mast 100ft high
Trimarans are not a new invention. The Melanesians used them in their travels 5,000 years ago.

But it wasn't until the 19th century that they began their career as racing yachts.

Now, the modern-day multihull is a space-age breed of boat that has taken high-speed ocean-racing to new levels.

They are known as the Formula Ones of the ocean, their technological and powerful wonders making them possibly the most sophisticated machines on the high seas.

The lightness of the boat coupled with their huge sails - the masts can reach 100ft - means they can move at up to 35 knots.

History of mulithull racing

1876: The catamaran Amaryllis wins the centennial regatta in NY

1947: Rudy Choy designs the first ocean-going catamaran

1966: Trimaran Toria wins the Round Britain race

1978: Mike Birch sails his 30ft trimaran Olympus Photo to victory in the Route Du Rhum

1980: Elf Aquitaine becomes the first catamaran to win a major event

1985: Apricot, a 60ft trimaran, inspires the current generation of multihulls with victory in a stage of the Round Britain

1990: Serge Madec sets the record, which still stands, for an Atlantic crossing (6d 13h3mns)

1994: French sailing legend Eric Tabarly breaks 40-knot limit

2001: Club Med, a 112ft catamaran, sets a new distance record (655 miles in 24 hours)

Though those speeds are rarely sustained for long, average speeds of 25 knots are common in races.

On paper, that equates to nearly 30mph in a car.

But some sailors say the sensation is more like travelling at 250mph in the comfort of a metal cocoon.

So while it does not sound fast, on water it feels like the wind.

Consequently, life on board may be thrilling but tough.

A trimaran is made up of a main hull, which contains the living space for the crew, and two stabilising outriggers.

Depending on the rules of the race, the outriggers can be contain ballast tanks which can be emptied or filled with water to provide extra weight and extra speed.

The living quarters will be contained inside the main hull, though unlike a monohull, it is mostly above the water line.

Most of the work will be carried out in a cockpit at the back of the boat.

The pod is designed to give the helmsman and crew a degree of protection from the elements.

Working on the boat's extremities can be extremely risky
It is designed so that most work, such as trimmming of sails, can be carried out from within its protective walls.

That makes life pretty cramped, and although Ellen MacArthur knows her four fellow shipmates well, she will know them far more intimately by the end of this nine-day race.

Occasionally crew members will be called upon to make their way out to the extremities of the boat, which can be a dangerous and unpleasant operation.

The risk of being swept over the side or getting injured are high.

A crew of seven is said to be ideal to handle the boat and sustain the speeds necessary to win a long-distance race.

But Alain Gautier has chosen to limit his crew to just five.

That means fewer provisions and less gear, creating more work for the crew and leaving little room for error.

As with all racing, Gautier's task will be to balance the pursuit of speed with the welfare of the boat and its crew.

Thanks to Frazer Clark, editor of popular fortnightly sailing magazine, Yachts and Yachting, for the preparation of this article.