I caught sea fever as a child. Growing up near the Dorset coast, I saw the sea in many guises. Boiling around the rocks on the Jurassic Coast; flat, calm and sparkling on a perfect summer¡¯s day; bleak, cold and dangerous in the late winter - once even, when Poole Harbour was frozen, with ice encrusting the shore and icebergs floating in the shallows. The sea was the background to my life and it helped make me a scientist. We went dredging on school trips and returned with a vast panoply of sea creatures, each of which told an interesting story. We crouched in the sand dunes watching terns, tramped miles along the cliffs hoping for the sight of a puffin, and stood at the harbour mouth, sheets of rain sliding off our oilskins and sou¡¯westers, watching the sailboats come in to shelter from the storm. And we went sailing. I was not fortunate enough to own my own boat, so I became a boat parasite - and have remained so for most of my life. Dinghies, yachts, cruising, racing: I¡¯ve tasted them all.

My introduction to large-boat sailing came from Martin Wells, a lecturer at the University of Cambridge, who invited several of us undergraduates to crew his boat. She was berthed at Dunstaffnage, near Oban in Scotland. A wooden boat, she had lovely lines but she leaked so everything soon got damp. I remember my first sail in her very well, as I was standing on the deck when we went about and I got smacked on the back by the boom as it swung across. I almost fell overboard. It was not a mistake I made again.

Sailing around the Inner Hebrides was breathtakingly beautiful, and our trips were always filled with adventure. There was the time we came sailing into Iona, showing off our newfound skills to the watching tourists - and promptly hit an isolated underwater rock that stuck up like a spike from the sea floor. On another occasion, we lost the engine as we motored into Tobermory harbour and had to navigate the rocks and anchored boats under sail, a task made trickier by the unfavourable wind direction. And then there was the night we were surrounded by phosphorescent sea creatures known as ctenophores, which flashed bright blue when we pumped out the loo (bizarrely, on a boat the loo is called the ¡°head¡±).

One of the great joys of sailing a yacht is that you can visit places that are otherwise inaccessible, and the Treshnish islands off the coast of Mull were a particular joy. The anchorage is difficult, being ringed by rocks. Landing is possible only on a calm day, but you are rewarded by the tameness of the birdlife. Shags peck at your legs as you walk along the path; puffins, their comical brightly coloured beaks filled with sand eels, whizz in, their orange feet acting like rudders. They are often attacked by herring gulls and forced to relinquish their catch. We also visited Fingal¡¯s Cave at Staffa, with its majestic basalt columns, similar to those of the Giant¡¯s Causeway, and Canna, a small paradise of white sand, turquoise sea and purple seaweed.

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But the weather was not always clement. I remember a storm suddenly engulfing us off the coast of Rum, and struggling on the bucking foredeck to put up the storm jib, my fingers all thumbs in the cold and rain (no roller reefing foresails in those days). On that occasion, we even used the trysail - a tiny mainsail - as the wind was scarily strong. Snug in our sheltered anchorage later that night, there was a certain exhilaration in having survived unscathed. Another time, the rain was so heavy we experienced a ¡°white-out¡±, the sea and sky a seemingly unbroken sheet of water. Running before the wind with a heavy following sea, concerned we might broach and capsize, the entrance to the harbour no longer visible, I confess to having felt anxious. But then the rain cleared slightly, the harbour appeared exactly where our navigation predicted and all was well. In fact, my anxieties were less about the sailing than the anchorage. That region of Scotland has notoriously bad holding ground and our boat had a tendency to snatch at the chain in any kind of wind, so we were always dragging the anchor. We often laid out two of them but even that did not always help. I spent many a night hopping up and down taking compass bearings to check we had not moved position; and, like a sleeping mother ever alert to her child¡¯s cry, I can hear the rattle of an anchor chain even in my deepest sleep.

I think of myself as a novice sailor but when I enumerate what I have done I am surprised. I¡¯ve sailed the East Coast from Ipswich to Inverness, spent several holidays exploring the waters around the Inner Hebrides, crossed the English Channel starting at West Mersea and ending up in Amsterdam, raced a small yacht off the coast of California, chartered a catamaran in New Zealand, joined a flotilla in the Sporades in Greece, and spent many happy (and occasionally terrifying) days cruising the coastal waters around the UK. But always as crew. I tell myself it¡¯s about time I skippered the boat myself. I¡¯ve made some headway towards that goal, as I¡¯ve passed the yachtmaster theory exams, and - in principle - know how to navigate, the meaning of the various lights boats carry, how to read the clouds and what three short hoots signify (namely that the boat is reversing). But somehow I have not yet found the time to take the practical exam, and this is what matters. Theory is no substitute for practical sailing skills, and there is much I need to learn before I am qualified to take a yacht out without support. Perhaps I can squeeze it in next year ¡­ or the year after that?

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For now, I am enjoying my small dinghy - a 14ft Topper. It¡¯s the sort of boat that children learn to sail in, but she is perfect for me as I can haul her out of the water by myself, and am able to right her when I capsize (which happens with unfortunate regularity). She is very old, having previously been owned by Mandy, my oldest friend, for many years, which means that I don¡¯t worry about a minor scrape. Like her owner, Topless is now slightly battered by the years, and she has an old-fashioned rig. But she sails well and any deficiencies in her performance are due to pilot error.

Having recently joined Parkstone Yacht Club, I sail regularly in Poole Harbour with a group of other women. Instruction and rescue boat cover are provided. Both are valuable: there is always something new to learn and knowing that help is at hand, if needed, encourages you to push the boat and yourself harder - to go ever faster, lean out further or venture out in a stronger wind.

I said I can right Topless after capsizing but this is not strictly true. A couple of weeks ago, there was quite a breeze. The wind gauge pronounced it 20 knots but as it is known to underestimate, the actual wind speed could have been even greater. Happily, I was oblivious to what 20 knots translates to on the Beaufort scale or I might not have had the courage to go out. But sail I did, albeit with a reef. And it was utter bliss. We screamed back and forth on a broad reach at breakneck speed and I quickly realised that speed thrills. But of course, the inevitable happened: I capsized. And got my comeuppance, for not only was I unable to right my dinghy, but after the rescue boat crew had helped me to do so, I could not even scramble aboard. I was hauled ignominiously into the rescue boat where I sat fretting about it. Surely I could not suddenly be so old and feeble? And then I realised that all I had eaten that day was two bananas. I had simply exhausted my energy reserves.

Taking up dinghy sailing after many years, there is one noticeable and welcome difference. As a child, I sailed in shorts, plimsolls and a windcheater. If I was lucky, I managed to borrow an oilskin. But I always got wet and usually cold. Today, it is very different, as the kit is so much better. With wetsuit, wind jacket, lifejacket and sailing boots you can stay warm. With a drysuit you can also remain dry even if you capsize. The yachting gear is equally good. I have sat in a boat for several hours in the pouring rain and felt snug and warm inside my foul-weather gear (proving it is not named that for nothing). Navigation, too, has been transformed: dead reckoning and triangulating compass bearings are little used now that GPS technology pinpoints your position in seconds. But as batteries have been known to fail I, for one, still double-check my coordinates the old-fashioned way.

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It is true that racing can bring out a fierce competitive spirit, transforming a mild-mannered friend into an aggressive firebrand of a skipper. But sailing is also a sport in which people help one another. If a yacht is in real trouble, everyone in the vicinity goes to its aid. People give up their time to drive the rescue boats and once when we towed in a dinghy and its exhausted crew, the whole class was at the dockside to help. There is a friendly camaraderie, in which sea stories and tall tales abound. Sailing is also a sport for all ages. It teaches children responsibility - fail to check the tide-tables and you may end up stranded on the mudflats - along with teamwork and independence, and gives them a taste of adventure. True, the safety boat may be standing by, but you are normally expected to right the boat by yourself and continue the race. It¡¯s not exactly ¡°better drowned than duffers¡±, as my mother used to say, quoting Arthur Ransome, but sailing certainly helps you learn how to take charge in a tricky or unexpected situation. In later life, when one is perhaps less agile, there is always the option of inviting a young crew to help sail the yacht as one sits in the cockpit, tiller in hand, shouting instruction. I am planning on doing so!

So what is it about sailing that captivates me? Perhaps the fact that you use only the power of the wind to move the boat, perhaps the lack of traffic noise that plagues life on land or the way it brings you close to nature.

One of my favourite memories is of sailing into the Moray Firth and being greeted by a pod of dolphins. They came to play and to show off, surfing the bow wave and leaping in high curves alongside the boat, the water dropping from their flanks sparkling in the sun. My brother, who has sailed across the Atlantic, tells of flying fish, curious whales, and the inky blackness of the night sky in which stars and comets glitter like diamonds. Then there is the physical challenge, your tired muscles bringing instant sleep at the day¡¯s end. And there is always that frisson of fear, which comes with pushing yourself slightly beyond what is comfortable. Wimp-like, I sometimes feel that the wind is too strong and my skill too small but should I confess as much to Mandy, she instantly dismisses the idea. I am always glad I listened to her, because the exhilaration at having risen to the challenge is life-enhancing.

Now, as I sit at my landlocked desk looking out across the fields and the billowing clouds, I long for the ¡°flung spray and the blown spume and the seagulls crying¡± of John Masefield¡¯s poem Sea-Fever. I listen to the Shipping Forecast and dream of the Sound of Mull; and I scan the weather reports to see if this weekend it will be worth the trek from Oxford to Dorset to sail Topless. Sailing is not as much of a passion for me as science is, but it has an important place in my life. Invariably, when I step into a boat I relax and the cares of the world drop away. With a fair wind, a sparkling sea, the long line of the blue Dorset hills in the background, it does not matter if I am crewing a yacht, sailing my Topper, manning the safety boat or paddling a kayak: anything on the water makes my heart sing. The sea has my soul.

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