She sailed the world – now Ellen MacArthur is doing her bit to save it

Ellen MacArthur learned about self-sufficiency at sea. Now she’s applying the same principles on dry land by building her own eco-friendly house

Dame Ellen MacArthur is licking her mobile phone. Once, twice, three times her tongue darts out of her mouth and onto the bottom of the keypad.

"I've had a sweet in my pocket for ages and it's melted all over my phone," she says, flashing a quick grin and carrying on. She takes a £20 note out of her pocket, wraps the mobile in it to protect it from further stickiness and puts it back in her pocket.

Then the offending sweet, a squashed Drumstick lolly, is fished out, unwrapped, and disappears in one go into the mouth of this British institution and bastion of sailing, white teeth pulling the pink goo off the stick it is so stubbornly clinging to. The lollipop is gone in seconds, leaving a faint trail of emulsified sugar on her lower lip.

This is Ellen on an off-duty day. She's on board a yacht, BT IMOCA 60, taking part in the Artemis Challenge at Cowes Week, which is meant to be a fast and furious 55-mile race around the Isle of Wight. Except there's not much wind around and the race is still going ahead, painfully slowly, along a much shorter course.

She's not at the helm – that role falls to Frenchman Sebastien Josse, one of three top class sailors who make up BT Team Ellen, alongside MacArthur and Australian Nick Moloney, who take part in races under the BT banner.

Instead Ellen's job is to babysit journalists and corporate guests on board, which generally means asking us to shift from one side of the foredeck of the boat to the other, to use our weight to even out the boat and make it move faster through the water.

And babysit us she does, and does well. Having read that some commentators find her personality challenging, and knowing of her tearful video diaries and that Viz magazine's Roger's Profanisaurus had coined the "Dame Ellen MacNomates " to mean the female equivalent of a "Billy no mates", I had expected someone much more aloof, not this very warm, chatty bundle of energy who is much more attractive, feminine and elfin in real life than in photographs, with dark blue eyes, pale skin (unusual for a sailor) and the odd white hair now she's 33. Sailing solo round the world and even having the guts to make it round Britain aged 19 would surely risk making someone so self-sufficient that they might find it hard to engage fully with others. Certainly in her first autobiography, Taking On The World, which chartered her solo round the world attempt in the Vendee Globe in 2001, MacArthur threw in many mentions of friends and colleagues but managed to portray herself as a bit of an outsider in spite of that. Ellen in 2009 is very much like George from the Famous Five adventures.

Today she is constantly surrounded by people, her PA, corporate guests, crew, another skipper. And she had to share the BT boats that bear her name with Seb and Nick. But she seems very happy to be in the company of so many people.

The race start is so quiet that I don't even realise it has begun. We're cut up by Team Pindar but are soon at level pegging and steal their wind and sneak ahead. Forty minutes in and we catch up with rock star Bryan Adams on Artemis the Profit Hunter, which is dead on the water. We inch past them amid some heckling from their crew. Adams is relaxing in the cockpit. The other BT guests and I are working similarly hard on our bums, sitting on the foredeck and shifting port, aft, starboard on command. Ellen translates for us in case we don't speak sailing – "Move forwards a couple of feet, that's it, mind your head on the ropes." We've got a little nest for ourselves next to the sails.

Things have moved on for her since she made her name as the plucky English girl from landlocked Derbyshire who became the fastest woman to sail solo non-stop around the world, twice. She became the darling of the French, who adopted her as a kind of honorary countrywoman following her success – solo sailing is a big deal across the Channel – and a Dame of the British Empire over here, aged 29.

But now she is mainly focussed on the Ellen MacArthur Trust, a charity she established which is taking 85 young people aged between eight and 18 sailing around the perimeter of the country to help them regain their confidence on their way to recovery from cancer, leukaemia and other serious illness. The challenge started in May and will end back in Cowes on September 13. If BT IMOCA 60 wins the Artemis Challenge, the £10,000 prize money will go to the Trust to fund places for more sick children. It costs £500 per child for four days on board. That's one of the reasons she's out on the water today.

"They are so fantastic," she says. "They are just like any other kids, they just want to have fun. We laugh and laugh. They've been through so much, much more than I ever had, but they do it with a smile on their faces. They're just amazing."

In between work for the trust and speaking engagements around the country (a friend who has seen her says she talks for 90 minutes, non stop, barely pausing for breath, and despite that it's gripping stuff), she is building an ecologically-friendly house on the island that she's designed herself. At first she's reluctant to talk about it but the environment is one of her passions and she can't help herself. "It's got solar panels to heat 400 litres of water. It goes through a heat exchanger and heats up the fresh water to 53 degrees. There's underfloor heating in the ground floor and a Rayburn and two wood burners. It's mainly all about insulation. The walls are 2ft thick and there's 20cm of insulation. You don't even really need heating with that," she says. The Rayburn she got second hand for £100. "It's great. Solid and better than the modern ones. They just said if you take it away, you can have it for £100. So we did."

It sounds like a functional house, rather than one necessarily designed to provide all the creature comforts, but living on a boat teaches you to go completely back to basics. There is nothing inside the black carbon hull of BT IMOCA 60. Just a bean bag, a couple of computers and a single burner camping stove. Food on a long race is freeze-dried. Ellen has eaten so much of it that she can't digest bread any more.

"Food is just fuel," she says. "When you get back you go to the pub and people think you must be dying to eat something real. 'What do you want? Steak? Fish?' they ask you. And you just don't care. It's just food. There's so many choices on the menu and you just don't care.

"Being on a boat teaches you how little you actually need. We all use so much and we just don't need it."

That, it becomes apparent, includes toilets. I've been holding on as much as I can but by lunchtime it's time to visit the little girls' room. Ellen talks me through it. "Go down below, to the low side of the boat, and in the corner you'll find the bucket. Just stay down there. It's fine – no one can see you." It's not without a little trepidation that I make my way below. There it is, a black bucket stowed in the corner. I squat in pitch darkness, with no door or even curtain to protect my modesty.

"All OK? Comfy, isn't it?" she asks when I make it back on deck after slopping out over the side. "There are no loos on race boats. You get used to it, even for number twos." I can't believe I'm having this conversation with a dame. "On the Vendee I had a thin plastic bucket which cracked near the top. It could get a bit nippy sometimes."

I mention Hull, where the Clipper Round the World Yacht Race will start from in five weeks' time (with me on board). "I love Hull," she says. "When I was 18 I worked there for a year at a sailing school and as an instructor teaching guys from the tugs. They had changed the law and these guys had been using the VHF radios for years. They'd never gone to school, just started working on the tugs when they were kids and then they were being told they had to do an exam. They couldn't read or write. So I used to ask them what their answer was and write it in for them."

I ask how they reacted, these burly, rollie-smoking men, to being forced into a classroom and taught by a tiny 18-year-old girl. She's a little surprised by the question. "We just got on with it. It was fine. I used to go to the pub with them at lunchtime. It was great." Does nothing phase this woman?

Although she's off duty, she bounces up every now and again to help pull a sheet round a stay or guide a sail up. The mainly French crew work efficiently and quietly. Pretty much the only sound, now we've left the spectator boats and helicopters behind, is the whir of the hydraulic system moving the cantilvered keel. We're gaining on Aviva, skippered by Dee Caffari, as we hoist the spinnaker. As we get close to the mark, we gybe the kite. Aviva screws up her manouevre and and we immediately gybe again round the mark and overtake her. We're in the lead, cruising a good half a mile ahead of everyone else.

Then suddenly we're becalmed, bobbing ducks on the flat, mirror-like water. Ninety minutes later and we're still stuck level with the town of Ryde on the island. The time of the official race end, 4.30pm, comes and goes. Two boats closer to the island have managed to creep ahead of us, so we're lying in third place but there's still every chance we could win, if the committee go on timings round the marks instead. The crew sit slowly toasting in the heat, sweat starting to come through their T-shirts. A rib comes alongside, with a TV crew on board. Their presence means two things: first, the race is over, and second, we've won. Ellen goes straight over to do her duty. She's resigned to it in a good-humoured way. She knows that this is very much her job now – and that Seb and the team have just pocketed £10,000 for her trust. Throughout the day there's constant talk of sponsors and how important they are. Whenever a slightly difficult question comes up there is a reluctance to answer. When asked if she'd like to do the round Britain trip with the children again she says "We'll see". I'm sure what she means is "definitely" but she won't say that. There's no inkling of her feelings about it, more a sense of she doesn't want to say anything that might not be toeing the party line, either with a current sponsor or possible future partners.

At the award ceremony – Frank [Fletcher, who runs the trust] will be so chuffed" – she accompanies Seb but discreetly disappears when the winner is announced, leaving him to collect the trophy by himself. She reappears an hour or so later, inviting the crew members to her house the next day for a barbecue. As I leave she kisses me on the cheek, something she doesn't have to do but chooses to, and wishes me luck with my race.

"Write about the bucket", she says. "Definitely write about the bucket." Dame Ellen NoMates? Dame Ellen LoadsaMates, more like.