It was years since I had taught beginners to sail. The ones that I taught then, are the organisers of the sailing courses now. Thinking that I would return to my roots I signed up to help out with 'Beginners', on a reservoir, in a fat dinghy, with training sails hardly bigger than my shirt lap. Would I die of boredom before the week ended?

"Joy ride them first, then let them have a steer later." said the Chief Instructor whom I recall once had difficulty tying his bowline. We went out and did some circuits and bumps; quite pleasant really.

The safety boat passed and waved us towards the shore. It was time to return. We were the last ones on the water. A couple more turns I indicated to the helm and then we'll go in, but the boat was heeling to a sudden gust

The last thing I was saying was "Okay. We're Okay", in my reassuring voice of calm certainty, when the water reached my middle. Oh ignominy! With two absolute beginners, on a reservoir, in a fat dinghy, this experienced sailor was about to disappear beneath the water with a surprised look on his drained, pale face.

In that instant of descent I suddenly knew that I could no longer swim. All the skills of my youth when I have won races in record time; swum 50 metres under-water and surfed in big seas all afternoon, had gone. For the first time in a long time I was going unprepared into Easter cold water and I realized that my unquestioned ability to always be able to look after myself in and around the water was lost. Years stack up slowly like grains of sand in a jar, but inevitably there comes a time when the jar sinks. I was humbled.

As I went down, the buoyancy jacket took up and I lifted comfortably like a cork. Thankful, thankful, relief. I didn't even get my chin wet. I was saved by the rigid rules of authority.

I was there to teach, and I did, but what I taught in the whole week was meagre against the lesson I learned in that brief moment, that youthful ability ebbs and the fittest man will find his limits when cold water grips his body. It had no name to me then, but now it is called Cold Shock and its powerful paralysis is utterly real whatever its name, as you gasp for air and flounder ineffectively.

For years I had neglected my lifejacket when rowing backwards and forwards to my mooring alone in my tender; just about everybody else did the same. I notice it now because I am sometimes the only one wearing buoyancy on my patch of river. I have heeded my warning. It was lucky for me that I realized the truth on a reservoir, in a fat dinghy. Where will you be?