If you're looking for a safety device that's small enough to stow away easily in a BC pocket, yet makes a splash of colour big enough for air and sea rescue services

I remember when they first went on the market. I saw them advertised in an American diving magazine. I cut out the advert and we all had a good laugh about it. What a ridiculous idea! And then, one day, it just didn't seem so funny after all. It was a late afternoon dive, dusk was falling quickly, and the weather had changed while we had been carrying out our final dive, a drift dive. A swell had come up from nowhere and a fresh wind was chopping up the surface of the ocean. We could see little beyond a few feet from us - no land, and certainly no dive boat. I realised that we could be in serious trouble and that in this sea, and with the failing light conditions, the chance of potential rescuers spotting a couple of distant, bobbing heads was exceedingly remote.

It was then that, almost sheepishly, my buddy unzipped a pocket in his BC and for the first time I saw one outside the pages of a magazine. Unfurling it one-handed, he held his regulator slightly underwater - and on the choppy surface, a floppy tube of plastic filled, and majestically raised itself upright. And, seemingly from nowhere, the dive boat materialised within moments. I had never been happier to see that peeling, barnacle-encrusted wooden hull.

Of course, once on board, the puerile jokes started. 'My, you've got a big one!' But I was willing to be the butt of anyone's humour provided I could have one of my own. And since that day, I have never dived without my inflatable safety sausage.

Nothing underwater frightens me. Sharks, eels, caves, confined spaces, darkness, current, big schools of big fish, sea monsters ... They thrill me, yes; but frighten me not. I have only one fear when I dive, and that is about what will happen when I return to the surface.

On every dive you are placing your life largely in someone else's hands; in particular, those of the driver of the boat on the surface. Often, on your vacational dive trip, this may be a total stranger. In a foreign country I have dived on boats where the boatman has rolled up a smoke of his finest, home-grown marijuana the moment the divers have hit the water. I have been on dive boats where the man on the surface has gone fishing or gone to sleep. And so the nagging doubt is always there: when you surface, will the boat spot you? Have you and the boat drifted far apart, so that you may be out of sight of the boat? Has the boat engine broken down? Has the boat sunk?!

We have all heard the horror stories from fellow divers, and about how long they have been adrift before being found: half an hour, two hours, several hours, even overnight. And we also know that the unlucky ones have never been found.

My biggest nightmare is that I am surfacing and no one is there. Or if they are there, they are powerless to help and, as if in a bad dream, I am carried off in a cold, offshore current, out into the shipping lanes where huge supertankers on auto-pilot pass close by me, totally unaware of my presence. And then I am floated out beyond the shipping lanes to the barren, open ocean wastes, hungry, parched with thirst, yet drifting in a living hell just waiting to die, the occasional jumbo jet passing high above with its cargo of merry holidaymakers en route to Disney World, drinking their first gin and tonic totally oblivious to my presence ... As you can see, I take this very seriously!

A friend of mine, with whom I often work, is a professional contract underwater photographer for National Geographic magazine. When he dives during an assignment, he has a support team of divers who shuttle back and forth to the surface reloading his cameras, renewing batteries, and bringing him down fresh tanks and BCs when he has exhausted his air supply. The longest I have known him to be underwater on one dive was three hours and 35 minutes, and his massive decompression time is usually spent on top of a shallow reef continuing to photograph. In one dive he puts in a bottom time of four or five normal dives.

I wish I could dive like that - all my diving is usually made in just one block, so that I only have to surface once. Indeed, I really wish I didn't have to surface at all! But we do have to surface, and on the surface the inflatable

There are two golden rules when selecting your safety sausage:

1 The bigger the better. I eagerly scan all diving magazines for the latest developments in 'sausage technology'. I have recently sent off to the US for a fluorescent sausage which is reputed to stand six feet tall out of the water! One incredibly refined sausage that I saw on a recent trip could be inflated direct from the BC connector hose and would also double as a surface flotation device!

2 It must stay up. (Smutty joke time again). A limp or wilting sausage is of no earthly use to anyone. One of my less successful imports from the United States wilted limply within moments of inflation. Remember, too, that sausages can get punctured so check them before dives - it's too late once you're out there.

Now, when I dive, I have every aid imaginable to ensure surface recovery. My power whistle, my flares: in fact, I would carry a whole arsenal of surface-to-air missiles if it would ensure my collection by cover boat.

But most of all, I carry my trusty sausage - that is, until someone brings out a bigger and better one and then, fickle as I am, it will become my new best friend underwater.