THOUGH Dame Ellen MacArthur still sails, she does so “under the radar”. “It’s always going to be part of my life,” she says. “Just not in front of a camera.” The woman who transfixed us by notching up a series of astonishing sailing achievements while still in her 20s, now does only one race a year, and she does it with a crew of young people recovering from cancer and leukaemia. That race is the Isle Of Wight Round The Island, and for her, “it’s all about the young people having fun”.

MacArthur created shockwaves in 2010 when she announced her decision to retire from competitive sailing. She was one of the most famous sailors on the planet, having come second in the round-the-world Vendee Globe race aged just 24 and, four years later, in 2005, set an astonishing world record for solo, non-stop circumnavigation of the globe. But then, seven years ago, at 34, an age at which sailors are still in their prime, she announced she had stopped racing.

That’s not to say that she swapped competitive sailing for the quiet life. Far from it. Nowadays MacArthur’s energies are focused on two key issues. One is the trust she set up to bring sailing courses to young people recovering from cancer. The other is the cause for which she left her sailing career: an ambitious attempt to “change the global economy”, by putting a halt to the way we are relentlessly using up finite resources. In short, she wants to save the planet.

MacArthur is talking to me by phone from her car while en route to an airport, the start of a giddy series of engagements which will take her to Denmark, Italy and Scotland. She lives with her partner on the Isle of Wight farm they bought after they sold the eco-house they had built. “I grew up on a small-holding in the Derbyshire countryside,” says MacArthur, “and in some ways you return to your roots and where you feel comfortable. I run the farm with my other half. Life’s always a balance. I’m probably busier now than I’ve ever been.”

This is not the first time we’ve spoken. I met Ellen MacArthur 15 years ago, not long after she’d come second in the Vendee Globe and become a sensation, having mesmerised millions, not just with her achievement, but through the video footage which recorded her along the way, crying, laughing and dangling, puppet-like from a 50ft mast over a churning sea.

When she took me on board her yacht, the Kingfisher, I made the mistake of calling the boat an “it”. “Careful,” she corrected. “Big mistake. She’s a she.” I was struck by the fact that, whenever she spoke of the sailing challenges she had faced, MacArthur used the word “we”, saying “we did it”, as if she and the boat were a team. “Without a boat you’re dead,” she said. “You’re out there in the middle of the ocean and the only thing between you and the bottom of the ocean is the boat. You trust the boat and you feel you have a relationship and your life depends upon her and you have to look after her as best you can.”

Long after that interview I would cite MacArthur as one of the most inspiring people I’d interviewed. It wasn’t just the achievements of this young woman, who had grown up in landlocked Derbyshire, far from the elite sailing set, and saved her school money to buy a dinghy. It was also her manner. She was so matter-of-fact about the challenges she had faced. It was hard to imagine how a woman who appeared so disarmingly free of ego, could have done what she had.

MacArthur visits Scotland this Saturday to launch Round Britain 2017, a sailing project which will see the Ellen MacArthur Cancer Trust’s nationwide “family” of young cancer survivors sail round the British coast. The charity, which provides trips and courses for young people, was inspired by an experience she had aged 23, when she was invited by a friend’s brother, who had leukaemia, to join him as a volunteer with Chacun Son Cap, a charity which organised sailing trips and courses for children recovering from cancer.

At the time, in spite of her confidence about the sailing, MacArthur was “completely nervous” of working with these young people: “What do you say? These were children who were recovering from cancer and leukaemia. And these were French kids – it wasn’t even as straightforward as speaking your own language.” Within five minutes of getting into the boat, however, she was having “more fun than I’d had in years”.

“They were the most cheerful, amazing young people,” she recalls. “Clearly they had gone through something harder than most of us can imagine, yet there they are on this boat really going for it. It made a massive impression on me.”

In the years that followed, when interviewers asked about her bravery, she would say that what she had done wasn’t brave, that those youngsters recovering from cancer she had worked with were brave. “I don’t think you know true bravery unless you face something you didn’t choose. Because however hard it was sailing round the world – and I’ll be the last person to say it wasn’t hard – I chose it.”

Among the young people who will be crewing sections of Round Britain 2017 is 14-year-old Scot Noah Duncan, who has done trips with the trust since he was 11 years old and coming out of rehabilitation following the removal of his eye. His mother, Brenda, recalls how when he went for the surgery he said to his father: “Today’s the worst day of my life because I’m going to lose my eye. But today’s the best day of my life because I’m going to lose my cancer.”

Also on board for part of the trip is Victoria Sanches, 20, who eight years ago was diagnosed with a benign brain tumour for which she received radiotherapy. Sanches describes how the trust has given her confidence. “I know I can talk to other people and share stuff and for once in my life I’m not the only person having to watch my medication. I feel normal when I’m there. We can all share our feelings. At the end of the day we can laugh about it.”

When MacArthur comes to Scotland next week for the launch, she returns to a place that’s close to her heart. It’s where part of her family came from. Her great-grandfather had a croft on Skye and although the last of her living relatives in Scotland died last year, she still visits regularly, since Largs is where the trust have one of their two bases, and also to see friends.

One of the big questions, of course, is why did she give up competitive sailing? Why would a woman who had found such success in her “dream job” want to draw a line under the activity she so loved? Sailing was what she’d wanted to do since she first stepped on a boat aged four years old.

The trigger for change came when she stepped off her boat after doing her record-making trip in February 2005. It was a revelation she summed up in a talk for the online ideas-promoting site, TED. Out at sea, far from land, she had always been conscious that her boat was her entire world. What she took with her would be meticulously planned right down “to the last drop of diesel and packet of food”. “No experience in my life,” she said in that talk, “could have given me a better definition of the word finite. What we have out there is all we have. There is no more …”

But it was only when she stepped onto land in 2005, having broken the round-the-world sailing record, that she connected the dots between her boat and the planet. It struck her then that “our global economy is entirely dependent on finite resources we only have once in the history of humanity”. When she first started to think like this, she changed everything in her life, reducing her consumption of many things. “Then I realised that’s not going to solve the problem, even if we all do it – and we all can’t actually.”

The problems, she began to perceive, lay in the systems. “We don’t design products in the right way. We don’t design plastics so that they can be recycled. We don’t design cars so that they can be completely re-manufactured or disassembled and all the materials fed back into the system.”

In 2010, she set up the Ellen MacArthur Foundation to inspire a generation to “build a positive future through the circular economy”. It has already had a huge impact. Scotland was the first country to join its CE100 global network of companies and administrations pushing for the shift. A report it commissioned into current plastics production and recycling was launched at the World Economic Forum (WEF) last year, and, MacArthur observes, became “one of the most picked-up reports ever to come out of the WEF in its history”.

She throws out some shocking figures. Only 2 per cent of plastic packaging can be recycled into the same quality material. “There has to be that systems element that changes in order to solve the bigger picture,” she says. “Clearing up the beaches is not going to solve the problem. Waste plastic is still going in the water.”

As activities, competitive sailing and trying to prompt global systemic change may seem entirely different, yet it still seems there is something of the pragmatic, determined sailor in the way MacArthur approaches her current cause. The biggest connection, she observes, is that both activities revolve around “establishing a goal and trying to get there”.

“That’s exactly what you do with a round-the-world record. You say the goal is to be the fastest person ever to sail solo non-stop round the world. What do I need to achieve that? You break that down into all the constituent parts. It’s the same with the circular economy. The goal is absolutely clear. It’s for the economy to be restorative and regenerative. The question is then, how do we do that?”

Of course, this shift in her life hasn’t happened without some agonising soul-searching. Even now when she talks of sailing MacArthur seems to still have a deep connection to it. She describes how much she now finds it hard to be around race boats. “A massive part of me wanted to continue racing boats around the world because I love it. I always have.”

Yet she felt uneasy with the fame. “I never sailed around the world to get a name or be in the papers. If I could have done it completely under the radar, I would have loved to.” Fame, she observes, was never what was she was pursuing. Rather, the sea and adventure were her goals. “It was about me sailing around the world, my childhood dream.”

When her epiphany about the global economy hit her, she thought she was in a position to open doors. She perceived that, being “an all or nothing” person, she would not be able to do both competitive sailing and this. She describes, in her TED talk how her revelation was like picking up a stone and looking under it and finding something unexpected. She could have just put the stone back down and got on with her life, but once she had seen what was under it, she couldn’t go on and pretend it wasn’t there.

The younger MacArthur I met back in 2002 would no doubt have found it hard to imagine ever giving up sailing for anything. Today’s MacArthur muses on this. “I really never would have thought I would have stopped sailing. And if you’d asked me the year of the round-the-world, what I’d be doing, I’d have been sailing. It was all I ever wanted to do. I loved everything about it.” But along the way, the “penny dropped”.

“I’m the same person I was when I was 18, and when I was sailing round the world,” she says. “But the understanding of finite resources led me to see things differently. Things happen in our lives that change our perspectives.”

Back in 2002 I remember thinking Ellen MacArthur was a dazzlingly impressive figure in a way that few people are: driven but strangely humble. She seems all the more impressive now that her boat is the world, or the economy, and her “we” is not just her and her boat, but all of us.

Round Britain 2017 starts in Largs this Saturday (May 20) www.ellenmacarthurcancertrust.org