With six hours to go before I embark on the final training phase for the Round Britain and Ireland Challenge, I have an appointment in Harley Street. The old salts at Yachting World, alarmed by my susceptibility to seasickness, have come up with the brilliant wheeze of sending me to see a hypnotherapist. Given the wretchedness of my previous ordeals by water, I am more than willing to suspend my scepticism and give it a go.

So I am heading for No. 1 Harley Street, where Kevin Laye, clinical hypnotherapy practitioner, master practitioner of neuro-linguistic programming and thought field therapy, has his clinic. Since the purpose of the exercise is to quell my anxieties, I am off to a good start. The address alone inspires confidence. Even more encouraging is the burly presence of Kevin himself. With a background in the special forces, plus a spell as a stunt double for Hollywood heavy Chuck Norris, and a taste for free climbing and scuba diving, he is clearly a man of action. But one adept at treating less robust souls who suffer from, say, a fear of flying or a dread of snakes.

He has never dealt, however, with someone prone to seasickness and is clearly relishing the challenge. He takes me through various techniques I can use to combat queasiness, teaching me how to raise my energy levels by gently tapping with my fingers on a number of acupressure points while uttering morale-boosting affirmations. (Will my crewmates think they have a lunatic on board if I start patting my head while muttering to myself?) Finally he tries programming my subconscious by guiding me, almost subliminally, though an imaginary sea voyage while a CD of nautical noises plays softly in the background.

Before I leave, Kevin warns me that vivid dreams often follow this kind of therapy, but that night on board one of the eight 72-foot, steel-hulled racing yachts in the Challenge fleet moored in Ocean Village Marina my sleep is untroubled – despite the fact that, along with the other 95 crew volunteers taking part in the race, I don’t yet know which vessel will be my home for the next three weeks.

The following morning gathered in the large dockside marquee with my fellow volunteers, I learn that I have been assigned to Besso, which has affable Aussie Matt Riddell as skipper and redoubtable Brit Jenny Dixon as professional mate. My 12 crewmates come from all walks of life and parts of the globe. We have an anaesthetist on board, and a chiropractor, a metallurgist and a management consultant, the MD of a Renault dealership and a former dancer turned bilingual PA. And we hail from all compass points too, from Suffolk to South Africa, Harbor Springs, Michigan to Arnhem in the Netherlands.

By contrast, the eight yachts in the race are identical, from the rigging right down to the cutlery in the galley. Whichever yacht wins will be down to which crew performs best as a team.

On board Besso, it’s remarkable how quickly we bond as a group. A few of us met on one or other of the earlier training sails; most of us, though, are perfect strangers to each other. But we are soon thinking and working as a crew. Our team clothing helps: blue polo and rugby shirts that we all agree are the best colour in the fleet. The matching fleeces supplied by Roddy Caxton-Spencer, a crew member who also happens to be the managing director of our sponsors, international insurance brokers Besso Ltd, mark us out as special too.

The camaraderie fires up everyone. The race itself may be days away, but we are soon discussing tactics among ourselves, unbidden by the skipper, working out techniques that might give us an edge on the other crews. I’m as charged as the rest. Yet I sleep far better than I have previously managed on a yacht – even though our boat has an Olympian of a snorer on board, who practically rattles the mast with his rasping breathing.

I’m not sure whether I have Kevin to thank, but the next four days are the best by far that I have spent at sea. It helps that the weather is glorious: light winds, calm seas and hours of sunshine. We could almost be in cruising in the Mediterranean. But this is far from being a cruise, even though many on shore find the idea hard to grasp. ‘Are the crew volunteers actually working or just along for the ride?’ is the query that’s been put to us again and again. The questioners can’t imagine how hard the work is. Hauling warps, hoisting sails, spiking cunninghams and grinding winches is more draining than any session in the gym. When you sweat the halyard at the mast to raise the mainsail, you really do sweat. Yet no matter how energy sapping the activity, you must stay focused until the task is done.

This time I pass the test. When the yacht completes a circumnavigation of the Isle of Wight and I am still on my feet, I feel a great sense of accomplishment. Staying on deck throughout the trip means that my skills improve too. The fearsome snakepit, with its array of sheets and winches, may seem, initially, like a piano whose keys you don’t know, as one crewmate suggests, but things gradually fall into place. And when I turn my hand to trimming the vast spinnaker, I even find something at which I’m good.

It’s immensely satisfying to stand on deck gazing up at the billowing spinnaker, slowly easing the sheet out as the wind fills the sail, watching for the point at which the luff of the sail is about to collapse, then calling ‘Trim’ and ‘Hold’ to the crewmate on the winch. As the sail gently swells and the sun beats down, I’ve found bliss at sea at last.

I’m all too aware, though, that there are bigger challenges ahead. I may have coped with the Isle of Wight, but the British Isles will be immensely more formidable: it has more miles of coastline than the eastern seaboard of the United States. And there’s evidently foul weather in prospect. A front is coming in from the Atlantic, followed by an ominous low. When the race starts on Sunday, notwithstanding Kevin’s assurances, I think I’ll persevere with the seasickness tablets.