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(CNN) -- After less than a week at sea, the Vendee Globe single-handed round the world yacht race has lived up to its moniker as "the world's toughest race" -- with nearly a quarter of the field crashing out in the first few days.
Earlier this week, 20 sailors set off from Las Sables d'Olonne in France to begin the 38,700 kilometer circumnavigation -- in which they are expected to battle everything from fierce storms in the Southern Ocean to the dreaded doldrums of the equator, with just themselves and an 18 meter yacht for company.
In the six editions of the race, first held in 1989, only half of the competitors have ever completed it. So it is yet another testament, if one were needed, to the Vendee Globe's notorious difficulty that after five days, four competitors have already pulled out.
French skipper Marc Guillemot retired on the first day after his boat Safran broke her keel, just 95 kilometers off the coast of France.
Guillemont, 53, had been one of the favorites to win this year's Globe after finishing third in the last race, held in 2008-2009.
Day two was similarly dramatic with compatriot Kito de Pavant, 51, also pulling out after his yacht Groupe Bel was struck by a fishing boat off the coast of Portugal.
"I went to sleep at the wrong time," De Pavant told organizers. "I am not angry at the fisherman but at me because it should not have happened. You can't anticipate this," he said.
Skippers are pushed to the limit, sleeping in snatches as they first sail the Atlantic, then the Southern Ocean, round Cape Horn and head back through the Atlantic to France -- all in the hope of winning $190,600 in prize money.
When Sir Robin Knox-Johnston made history as the first person to sail non-stop around the world in 1969, the epic voyage took him more than 10 months. Fast forward 20 years and the Globe's competitors are expected to complete the course in just 90 days.
French sailors have won all previous races, held every four years, with Michel Desjoyeaux taking the last one.
But the third casualty was another Frenchman, Vende Globe first timer Louis Burton who, like his compatriot De Pavant, endured a dramatic collision with a shipping trawler on Wednesday.
Finally, hoping to have made history as the only woman to ever win the race was Briton Samantha Davies, the only female sailor in this year's competition.
But the mother-of-one, who finished fourth in 2009-2009, announced Thursday that the mast of her Open 60 Saveol yacht had come crashing down in rough seas north of Madeira in the Atlantic.
Both Davies and Burton are prevented by race rules from stopping at the nearest port to make repairs with a return to Les Sables d'Olonnes the only option under the rules for a repair and continuation. In both cases, however, their boats are too badly damaged to make the six-day journey back to France.
For the remaining 16 contestants -- currently led by 35 year-old Frenchmen Armel Le Cleac'h -- it's just the beginning of what is shaping up to be another drama-packed Vendee Globe.