May 1987. The day after the Naruda had finished offloading its rice cargo in Haiti, armed guards boarded the freighter. Moments later the captain, Max Hardberger, had a grubby, badly photocopied piece of paper placed in his hands. "Pour les dettes," the guard said.

"What debts?" Hardberger asked.

The guard shrugged and said: "It's a matter for the courts. In the meantime my men will remain on board."

There were no debts, but that was beside the point. Haiti was a law unto itself; a place where court officials could be bought. And one clearly had been. The Naruda was about to be stolen from under Hardberger's nose.

He played for time. He pumped the guards with booze and waited for dark before ordering his engineer to lock them into their cabin. It was a toss-up whether they would try to shoot their way out, but they were either too drunk or not being paid enough to bother. Hardberger started the engines, switched off all the lights and sneaked out of harbour. If they were spotted, the Naruda would be seized, and he'd be slung in jail. Only when he was in international waters could he relax. Hardberger called down to the guards. He offered to set them loose in a lifeboat or take them to Venezuela; the choice was theirs. They chose the lifeboat.

This event was the making of the man who looks a bit like a salty Hulk Hogan, whose life could be a Hollywood film and whose name is a scriptwriter's dream. And the man with one of the world's wildest jobs. As far as he knows, Hardberger is the only man who makes a living by stealing back stolen cargo boats. When you think of modern-day piracy you probably imagine Somali gunmen holding men and boats for ransom. Yet there are many easier ways to steal a ship than making a mid-ocean boarding raid and hijacking a tanker. Throughout the more lawless ports of the world, piracy is a great deal more frequent than you might imagine. In fact, it's almost an institution in some places.

"The shipping business can be worse than the Wild West," says Hardberger in his southern drawl. "The normal rule of law just doesn't apply in some places; if you can bribe an official to say you have a claim against the boat or its owners, then you can have the boat impounded in that port indefinitely. Possession really is nine-tenths of the law."

Here's how semi-legalised piracy works: you wait until the cargo has been offloaded – the cargo's owner and the boat's owner are rarely one and the same, and you don't want to confuse the issue legally – and then bribe a local court official to validate your claim. And there's nothing the owner can do about it because the boat is subject to the court's jurisdiction.

"One of two things usually then happen," says Hardberger. "The owner either pays out on the bogus claim just to get his ship back, or the claimant uses his court order to sell it." It sounds absurd, but it's true. A chancer can't take the ship out of port, as once it is in international waters it would no longer be under local law and the claim would instantly be recognised as invalid elsewhere; but he can sell it at auction. Under International Maritime Law, all auction sales are deemed to be final; even if the claim against you is subsequently proven to be invalid, there is no means of redress, either against the new owner or the one who stole it off you. Once it's sold and renamed, it's out of reach . . . And it's financially rewarding; a 20-year old, 4,000-tonne freighter can fetch $500,000.

There is actually a third thing that can happen. You can get Hardberger to get your boat back. Word got round after he saved the Naruda, and since then Hardberger has retrieved "about 15" – he's not saying precisely how many – from ports in the Caribbean, South America and Russia. Though not Somalia. "That really is dangerous." It will cost you, mind; simple extraction starts at about $100,000, and the price rises sharpish the more complicated it gets. Even so, he reckons he's worth every cent.

"I've never actually failed to get a boat back," he says. This is less a boast; more a statement of the obvious. If he had failed, he'd probably be still stuck in a hellhole of a jail. "And I've got some basic rules. I never use violence and I don't accept jobs where there's a chance of someone getting killed."

Apart from that, pretty much anything goes. Over the years, he's distracted crews with prostitutes and witch doctors, bribed officials to look the other way, conned Russian mobsters and hidden from naval radar by riding out thunderstorms at sea; he's even taken a 10,000-tonne freighter out of Haiti while the 2004 revolution was going on around him. "It's basically a matter of planning," he says. "To get a boat out of port, you need a chief engineer and a one or two crewmen in your team, so everyone has to know exactly what they are doing.

"I make sure we all arrive in port separately. The aim is to draw as little attention to ourselves as possible, so none of us fly in; rather we come in by ferry or cargo ship. I always stay in lowlife hotels in the seediest part of town, as it fits with my usual cover story of a sea captain looking for work. During the daytime I will scope out the port, working out the easiest way to get the boat out of port; it's always best to have a plan where you can board it brazenly, rather than creep on surreptitiously. In the evenings I act the stereotypical drunk captain, tipping my whiskey down the sink while no one is looking. And when it's time, we move in."

Is it really that simple? "I guess not," he concedes. "I get scared each time I go in. Who wouldn't? You're in places where the normal rule of law doesn't apply. The secret is to be able to keep thinking straight under pressure and not panic. There have been times when I haven't been sure that everyone was on my side, and times when I've been fairly sure the local guys knew something was up. You just have to stay on your guard and try and stay ahead of the game."

And you can't help feeling it is the challenge of the game that is the main attraction for Hardberger. The job has already cost him his marriage – his wife couldn't stand the strain of not knowing if he was going to end up in jail each time he went away – but he keeps going back for more. He even lives for part of the year – "I'm not saying exactly where" – in one of the most lawless parts of Haiti.

"There's no real legal structure there," he laughs, "but it's surprisingly peaceful. Sure, you can have someone killed for $50, but the murder rate is very low. Apart from the passion killings. There's a lot of pilfering, but people leave me alone. I guess it's because I drive a white SUV with blacked-out windows and people aren't sure I'm not the local police chief . . . "

With most people, the longer you spend talking to them, the more normal they appear. With Hardberger, the reverse applies. Just when you think you've heard it all, he comes up with something wilder. He could just as easily have made a career in academia. He's got an English degree from the University of New Orleans, an MA in poetry and fiction from the Writers' Workshop at the University of Iowa (one of the best creative-writing programmes in the US), has a law degree from the University of Northern California, and has taught English and history at high school.

It's just that his seemingly hotwired need for an adrenaline rush kept tempting him away. First, to light aircraft, where he made a living flying dead bodies round the country, towing banners and cropdusting. "It wasn't the danger that stopped me," he says. "I had no worries flying so close to the ground; I just thought I was getting exposed to too many toxic chemicals." His piece de resistance was organising a squadron of young pilots to help him spirit 47 light aircraft out of East Germany shortly after the fall of the Berlin Wall, by flying them under radar to Rostock on the Baltic.

He eventually settled on a career at sea in his late 30s. "Like most kids from New Orleans, I'd been messing about in boats since I was 15, getting work on the oil-rig supply boats to pay my way through college," he says. "And while I was at a loose end, I kept noticing cargo freighters being sold at super-cheap prices; so I thought I might get one. Within a couple of days I was a captain . . . "

For a long while he made a living by plying a junk route between Miami and Haiti, transporting buckets, bicycles and cooking oil, until one day someone tried to steal his boat. It was a defining moment. Hardberger made his choice, and has gone on to carve out one of the more unusual careers on offer, and is still going strong at 62. But for how long? "Who knows?" he says, though he's in no mood to quit any time soon. And what next? "There's talk of a Hollywood movie and a videogame of my life." Silly me. I should have guessed.

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