ROWING/Atlantic challenge: Seán Kennytalks to Dubliner Peter Donaldson, who is hoping to spend Christmas in the middle of the Atlantic Ocean

You know the small talk this time of year. "Any plans for Christmas?" Peter Donaldson has "a GPS-navigated plan for Christmas". He tells people with a kind of wry understatement. While others joke or bicker or snore boozily in tinselled, television-filled rooms, he will be somewhere in the vast grey sweep of the Atlantic Ocean: some empty place defined numerically - latitude this, longitude that; somewhere beyond the seasonal ubiquities.

He will be rowing the ocean with 13 other men in a 50ft boat. He gets the usual dull, stock responses: "Are you mad?" "What do you want to do that for?"

He sloughs them off. Mad; yes, yes. And passing up the opportunity would have been madder.

One day last January he was in the truck he drives for Dublin City Council. A voice on the radio came through the static and the bland, busy-afternoon chatter. Talk of rowing. He cocked a sharpened ear. He hit the volume. A man was talking about recruiting a crew to row the Atlantic in an attempt to beat the record for a crossing. The moment was crystalline.

"I came home that day and had my dinner. I was talking to Anne, my wife, and I just broached the subject. 'Oh, I heard that today as well. It was good,' she said. And I said, 'Yeah, it was great - do you fancy going for a pint?'"

He did some cajoling and Anne said okay, yes. He had "the blessing". She had long known of the powerful, rhythmic pull rowing exerted on her husband. Every year, Peter's summer evenings were defined by the sport.

"I always say to Anne, 'Rowing's after saving our marriage.' If I'd been home all them years we probably wouldn't have lasted. Never in the house, every night through the summer."

It started with a simple accident of geography. He grew up by the sea, in Ringsend. Around his neighbourhood, you played football or you rowed the coast.

"Some youngfellas had paper rounds; I had three or four rowboats belonging to friends of my father that I'd look after in the summer holidays. You were always messing around in boats. If you were from Ringsend it was more or less expected of you to go down and row."

Four of them from Ringsend became a crew. They rowed the Irish Sea from Arklow to Aberystwyth, 75 miles, much of it in darkness. They did the Great River Race, 22 miles down the Thames, three times. They were stolid timber among a polychromatic armada of Hawaiian canoes and Chinese dragon boats. They rowed Cobh and Cornwall. There was Dublin Bay, of course. Good times, but challenges rendered modest by the monumental task ahead.

This journey started with a phone call to Leven Brown, the boat's skipper, a Scottish stockbroker with idiosyncratic taste in leisure-time pursuits. So says the expedition website: He survived three hurricanes, a shark attack and lightning storms rowing the Atlantic solo two winters ago.

Many called, but few were chosen. Peter among them. Last July they travelled to Loch Tay in Scotland for training. An ex-SAS man was behind it. This could only mean pain. It was a weekend of undiluted sadism. A machine-gun barrage of physical and mental adversity, a rat-tat-tat of challenge after brutal challenge. They hiked and ran and swam and canoed and rowed, sleep-deprived and rain-pelted.

He knew what was happening - weeding out. People crumpled under the relentless, bullying force of it. They quit the expedition. Sheer bloody-mindedness kept him going.

A psychiatrist interviewed them. Peter thought his presence superfluous. He had reckoned madness was a prerequisite for involvement in the project. No madmen - no rowing the Atlantic. Sober, rational types tend not to embark on such reckless flights. Nonetheless, there were questions.

"He wanted to know why you wanted to do this. He asked what you were like under pressure, how you were at taking orders. We keep asking Leven for the psychiatrist's reports. 'When we get to the end,' he says."

The end is Barbados. They depart from the Canaries on December 15th. The record they aim to beat is 35 days, eight hours and 30 minutes. It was set in 1992 by a French crew in a boat called La Mondiale. Numerous attempts to beat their time have failed. This attempt, though, will have a symmetry no other effort has had. The crew will row in a renovated La Mondiale.

On the boat's sea trial in October they beat the record for longest non-stop row in the North Sea, Edinburgh to Scarborough, 180 miles in 56 hours. It was a forewarning in miniature, a harbinger of what lies ahead.

"We rowed two hours on, two hours off, like we will in the Atlantic. You realise that after this two hours, there's another two hours. And then there's tomorrow.

"After sitting on them seats, your arse is sore. You think: 'Jaysus, here we go again, another two hours.' You try not to think about it. You have to sit on that seat and it's going to be sore, whether it's in an hour, a day or a week.

"On the sea trial, a couple of lads were sitting on a piece of foam. Then they had two pieces of foam on their second shift. And then three pieces on their third shift. I'm thinking, 'your arse is going to hurt, your hands are going to hurt - let them toughen up and get used to it'."

At 48, he is the second-oldest member of the crew. He has an evidently powerful upper body, but might his age be an issue?

"I wouldn't think so. The age range is 25 to 54. You're not looking for a lad to row 2,000 metres; it's 3,000 miles. It's about stamina."

Multifarious discomforts await. Finding sleep in a cramped cabin on a woozily undulating sea is no trivial matter.

"You can sleep eventually, because what happens is that when you get tired you'll sleep standing up. What else can you do? You can't stay awake for 35 days. If you're not getting some sort of sleep, it's going to affect your stamina and you won't be able to do your two hours' rowing. You can imagine what conditions will be like, with five or six men in an enclosed space."

Malodorous, perhaps?

"Yes, and then there's condensation. You get extremely warm days and very cold nights. With the body heat and the cold nights, you'll have dripping water in the cabin. It's the little things like that."

The drip-drip-dripping of water is the kind of banality that could become torturous in the specific circumstances of the row. Big projects are composed of a multitude of fine details like this. The sun will be hot, so they will wear French Foreign Legion-style hats. There is slow starvation, as physically taxing as it sounds, whereby the body burns more calories than it can replace. They will burn around 10,000 calories per day but can hope to replace only 5-6,000.

He has an idea: The Row the Atlantic Diet. Guaranteed results! More far-fetched titles have been bestsellers.

The crew's relationships, collective and individual, are crucial. Fourteen tired men on a small boat in nowhere - it is the kind of environment where tiny sparks of conflict can catch and burn fiercely.

"I have no doubt there'll be some sort of blow-up between people along the way, myself included. But we've agreed that, if there is, it's purely out of frustration and tiredness and we can just stop for 10 seconds and let it go.

"When you're stuck on a boat with someone for so long, you get to know them pretty well. Fellas will tell you stuff about themselves, in that situation, that they wouldn't tell you anywhere else. We've done a lot of bonding."

He pauses for comic effect. The lineaments crease puckishly: "And where we've done most of that bonding is in the pub, and that's another place fellas will tell you things they won't anywhere else."

Small indulgences help people through. On his solo Atlantic row, when he was not facing down storms or feeling the toothy clamp of shark on boat, Leven Brown would sometimes stop for a cigar under the black, starry canvas of the sky. It sounds like one of Hamlet's more surreal ads. Another Transatlantic rower, a man by the name of Tiny Little, brought bottles of wine as his ever-diminishing ballast.

Through psychological necessity, rather than asceticism, Peter will allow himself no luxury. He is entering a tunnel, so he will adopt tunnel vision: "It'll come to the stage that I'm going to miss my wife and kids. But I told Anne, 'I don't want any phonecalls off anyone and I won't be making any'.

"I watched a DVD of (Olympic rowing gold medallist) James Cracknell and (TV presenter) Ben Fogle crossing the Atlantic a couple of years ago. They were in a bad way on Christmas Day, three weeks in. They'd promised they wouldn't phone home, but did. When the person at the other end said hello they just went to bits altogether.

"If I'm that low, the worst thing I could do is pick up the phone and be brought down lower. If I'm that low, I want to turn it round to my advantage and do an extra 20 minutes on the oars, just to get it that little bit out of your system."

There may be moments of mental comfort. He likes rowing at night. There is a kind of sweet, mellow rhythm to the lap-lapping of oars in quiet dark water.

And all going well, they will arrive in Barbados in mid-January, bearded, buffeted and bedraggled in their French Foreign Legion hats.

All may not go well, but you throw the dice in any case.

Incidentally, Leven Brown plans another challenge next year, across the Indian Ocean. But that will have a different crew, right?

"Yeah, different," he nods, smile askew, as Anne stands behind him in their kitchen, wisely dubious.

"Ah, I might get the blessing again. Or it could be a case of 'never again'. But I don't know how many times I've said that."