'Nothing prepares you for a body in the water'

A day in the life (and deaths) of The English Channel

"You reach out to grab them," says Andy McMurray from the helm of the patrol boat, "but your hand goes right through."

He is talking about waterlogged dead bodies. Fishing them out of the Channel can be a challenge, especially after weeks in the water. "Sometimes they're only being kept together by the clothes."

My stomach lurches, and not because the Dover Harbour Patrol boat rolls as it hits the open sea. Nobody knows how many bodies are lost under these waves every year.

There is usually someone to mourn or miss the suicide who leaps from the White Cliffs, the drunk who falls off his yacht, or the child who gets swept out to sea. But what about the refugee stowaway who leaps off, unseen, as his overnight ferry approaches land? Tougher checks in French ports have driven many asylum seekers to try hitching a ride through the tunnel instead – but others are still desperate enough to take on the Channel itself.

The Strait of Dover is the busiest shipping route in the world, and often compared to a motorway. When six Russians tried to row across in a stolen speedboat with no engine and no navigational aids last June, an immigration officer described it as "like skateboarding in the middle lane of the M25".

They were lucky enough to get caught. So were the two Lithuanians who tried to paddle across the Channel on plastic airbeds last Sunday. They were rescued by a ferry.

How many others try equally unrealistic schemes and vanish without record? Sometimes Andy and his coxswain Derek Goodban help the lifeboat search for missing people. Sometimes they find unidentifiable bodies.

"First of all they sink to the bottom," says Derek, a lean and tanned man whose customary smile fades as he thinks of it. "Then the gases bring 'em back up to the top. Nothing prepares you for a body that's been in the water a while."

The engines roar and the talk ceases. We race alongside an enormous container ship, the Hornwind, as it heads for one of two shipping lanes that divide the Channel. It is misty out here and the only other vessel in sight is a Dutch yacht, but the apparent quiet is an illusion. Up to 400 large ships pass between England and France each day. This is high season, so ferries also cut across the lanes every few minutes.

A Dover pilot has steered the Hornwind through waters where sandbanks lurk. Now he has to climb down a 20ft rope ladder on the outside of the moving ship so we can take him back to port. Andy, a genial 42-year-old, brings our boat so close that it scrapes the side of the Hornwind. We're still moving fast. Derek, 56, more of a whippet than a sea dog, skips out on to the narrow deck to help the pilot aboard. "If he fell in," he warned earlier, "the screws would make mincemeat of him."

The pilot steps aboard elegantly, despite a sudden explosion of spray against the bow. He'll have to change his trousers before boarding the next job, a cruise liner.

Most of Derek and Andy's 12-hour shift is spent escorting foreign vessels in and out of harbour. Thousands of pleasure craft swarm the strait during the summer, and some of their skippers have no idea of navigation or the rules. "We're there to make sure they don't get run down."

Then there are the swimmers. This is the season for cross-channel attempts. The relatively sane swimmers use a support boat and give the coastguard warning. Last Sunday seven of them left from Dover; if the weather is good there will be more today.

The truly mad go it alone. One local legend set out with nothing but a rubber ring to which was tied a flashing red bicycle lamp, a bottle of squash, and his sandwiches.

The ones who leave from France in secret are not doing it for sport, but for the hope of a better future on this side. The Lithuanians who made their attempt last Sunday night had walked out of the Red Cross refugee centre at Sangatte near Calais.

After stripping down to underpants and vests the two men in their 20s lay on the airbeds and began to paddle with their arms, blindly hoping to reach England. They got seven miles out before being rescued at 5.25am. "They hadn't a hope of getting across," says Eric Musson, operations manager at coastguard headquarters on the cliffs above Dover. "The tide would have sucked them one way for six hours, then the other, out in the middle of the shipping lanes."

The control centre's mix of futuristic technology and crumbling, wartime architecture looks like a vintage Dr Who set. When those programmes were first broadcast in the 1960s there were about 30 collisions a year in the strait. Since the shipping lanes were established in 1972 there have been an average of four, few of them serious.

Each ship weighing more than 300 tons has to declare its identity and cargo as it enters the area, and its movements are tracked on screens that look as busy as air traffic control. The coastguards do not tell ships what to do, however, only watch to ensure the rules are being obeyed. Going the wrong way up a shipping lane can mean a fine of £50,000.

"We're like the police car on the motorway," says Eric. "Everybody's driving improves, the speed limit is observed, because they know we're watching them."

But airbeds don't show up on the radar. Neither do the rubber launches used by drug smugglers. "Lots of people try to cross secretly," says Captain Peter White, former harbourmaster now honorary secretary of the lifeboat based back down in Dover Marina. "We don't know how many."

The influx of asylum seekers into Dover has upset many people – "immigration is a burning issue here" – but that does not stop Capt White's crew powering up their gleaming £1.8m lifeboat when the alarm sounds. They would sooner save a life than pick up a body, given the choice. "The channel is very well managed," he says, "but you can't manage the illegal immigrant who is desperate. And we can't rescue them if we don't know they're in trouble."