We are sitting on the mould of one half of the biggest composite structure ever built in Europe. A boat, to you and me, though hardly recognisable as yet. At the far end of a shed the size of a British Airways hangar, a yellow template lies against the doors, the one sign of the monster's birth. It is a life-size cross-section of the catamaran which will, Goss believes, reclaim the Jules Verne Trophy for the fastest circumnavigation of the globe - 71 days, 14 hours - and win The Race, a French-inspired no-holds-barred global joyride, due to start from Gibraltar at the stroke of midnight on 31 December, 2000. (The French regard 2001 as the true turn of the Millennium.)
In the absence of any composite structural evidence, Goss's party piece is to disappear into the furthest corner of the shed and wave his arms to signify the furthest extension of the boat. The distance from the stern of the starboard hull to the bow of the port hull, on the opposing diagonal, is 140 feet, the size of Wimbledon's Centre Court or the square metreage of 70 parked BMWs. A single-decker bus could drive comfortably beneath the bridge of the deck straddling the twin hulls.
The catamaran measures 70 feet across by 120 feet long and will be powered by twin rotating sails. It is the Godzilla of ocean racing. When the boat is launched in the middle of next year, the shed will have to be knocked down first to allow it out.
"I can't wait," says Goss. "As soon as it's on the water, I'm going to get the crew and run away. We'll head out into the Atlantic, even cross the Atlantic and just see what happens. That will let us breathe a bit, get all of us working as a team and identify what we need to do."
At night, when the builders have gone home and the telephone has been silenced, Goss will slip into the shed to air the two halves of his brain, the romantic one imagining the smell, feeling the adrenalin rush, sensing the power, the other more practical side calculating the position of handholds and wondering about medical kits. The sea demands a balance of conflicting characters, a blending of pointilism, of attention to detail, with the broad brush strokes of romanticism. "To do this properly, " he says, "we have had to expand from a one-man band in the back of a garage to a structured business, but in doing that I don't want to lose the magic of the whole thing." If the magic starts to fade, Goss replenishes it with a visit to his shed and his sub-conscious.
The Goss Challenge, as the project is rather self-consciously titled at present, is a perfect and logical conclusion to the forces at work in his hyperactive existence: from racing dinghies at Torpoint, from nine years' service with the Royal Marines, from his skippering of Hofbrau Lager in the inaugural British Steel Challenge and his reluctant celebrity after the dramatic Christmas Day rescue of Raphael Dinelli in the Vendee Globe single-handed round the world race.
The team is already wise and weather-beaten. Adrian Thomson, the project designer, designed Aqua Quorum, Goss's indestructible Vendee boat; Gary Venning built it and Mark Orr, the project's commercial manager, has long been a source of finance and comfort in more penny-pinching days. Mike Calvin, chief sports feature writer on the Mail on Sunday and a designated member of the five-man crew, sailed in Hofbrau Lager. The boat will be built in the West Country, fly the Red Ensign and carry the names of 10,000 pounds 25 sponsors on its side, an emotional, financial fillip.
"When I was young I wandered down to a boat near my home and felt very intimidated by people strutting about in designer sunglasses," Goss says. "It could be a really anal, selfish, project. We could have security guards jump on you if you come too close. I don't want that. Anyone can come and have a look and if I can persuade one kid to go that extra mile in his life, then it's been worth it." A visitor centre was opened last week on the banks of the Dart in Totnes and educational projects have already been established in local schools.
What is extraordinary about Goss is his inability to see his own extraordinariness. His self-effacement extends beyond humility into incomprehension. Discomfort to Goss is not bailing out a cabin full of leaking diesel in a force 10 or waking from fitful slumber to find the Southern Ocean washing over him, it is playing the role of hero which the media fitted out for him during Christmas 1996.
In his book, Close to the Wind, which reached No 4 in the bestsellers' list, Goss writes that his decision to turn back into the teeth of a full gale to rescue a fellow competitor was one demanded "by the tradition of the sea". Most of us would have feigned a groin strain or cocked a deaf 'un. But then most of us wouldn't have been surfing down 50-foot waves and loving every minute of it. Even now, he fails to see the problem. "I just happened to be in the right place at the right time," he says. Goss's idea of fear is not knowing what to do next.
On his return, faxes and letters poured in, 40 or 50 a day from all over the world, and France accorded him the Legion d'honneur, the highest civilian tribute. "This hero business makes me uncomfortable. For me the real achievement of that race was crossing the finishing line; the rescue was all part of it. I wasn't aware of all the fuss until I got home. It was lovely stuff and it really touched me - I got messages from Tibet and China - but it wasn't my choice.
"If you'd written the novel, you wouldn't have believed the story. But I think what really touched people was when it comes to the crunch, you either stand by your principles or you don't. Firemen, policemen, they do it all the time. It just happened I was in focus." And the focus has brought fame and celebrity, offers of lucrative lectures and guarantees of a warmer reception when he puts out the begging bowl. (Only half of the pounds 4m has been raised so far.) "I always say I should be buying Raphael a beer because there's no way this project would have happened without that. I'd had this in my mind before the Vendee, but he helped to bring it together."
Goss refuses to acknowledge his place in the lineage of maritime history. He is an adventurer and sailing is still a hobby, he says, which puts him firmly in the tradition of Sir Francis Drake and Sir Francis Chichester. "I wouldn't dream of standing in the same boots as people like that. I'm a sailor and I know I'm very lucky. But I'm not trying to prove anything to anyone." He has, though, just read Drake's diaries.
What those old sea dogs would have made of this latest machine, a cross between a drag racer and a windsurfer, is debatable. Both, I suspect, would have admired the concept and the man while questioning the point of it. Goss has a more fundamental concern. "Parking. Can you imagine trying to park this thing if the wind's blowing 30 knots?"