Recreating the voyage of St Columba around the Scottish coast in 563

After 10 years living in Edinburgh, the author Nick Thorpe set off to navigate the watery fringes of his adopted country in an attempt to get to know it better. Undeterred by the lack of a boat, he talked his way on to other people's, through canals, lochs and coastal waters. Over five months he made his way from the Clyde to Shetland on everything from a narrowboat to a fishing trawler, from a sea kayak to a yellow submarine. Of all the nautical nomads who came to his aid, however, few were as strange as his companions from Crinan to the island of Iona ...

There was no doubt in Donald McCallum's mind: a spiritual battle was in progress. "We're under attack," he confided, as we heaved at neighbouring oars. "It's the obvious explanation for the problems we've had - we're being tested from another source."

I'd had a strange sort of month. Having hitched westwards from Edinburgh on canal boats and out beyond the Firth of Clyde on a vintage motor launch and a wartime steam puffer, I was now heading north from Crinan harbour in one of the simplest vessels ever invented: a flimsy wooden skeleton covered in a few layers of canvas and pitch. What I hadn't reckoned on was theology to match.

The brief article in the Argyllshire Advertiser had given hints. "The Irish-built curragh Colmcille will this week sail up the West Coast of Argyll on an epic voyage replicating that of St Columba in 563 AD," I had read. "The crew of 13 dedicated rowers will depart from Ballycastle, Northern Ireland and sail to Iona via the Mull of Kintyre. They will eat the same food as sixth-century monks, dress in robes and sing ancient hymns as they make their way to the island."

And, as it now emerged, pray like sixth-century monks. In Donald's world, nothing happened by accident. Even my own speculative boat-hitching request, I was disconcerted to learn, had been an "answer to prayer": a crew member had been taken sick and needed a replacement at the oars. It was similarly "a miracle" that the boat had managed the voyage from Ulster in the teeth of a relentless wind. Then, while the exhausted crew were ashore giving thanks for their safe crossing, a gale had dragged the Colmcille from her moorings and torn a hole on rocks. "But - praise God! - we found a carpenter and were able to patch her up. So the Lord's really been looking after us!"

I tried not to dwell on the divine DIY job currently keeping the sea out, and focused instead on the timing of our oars, which were unlike any I had ever seen. They pivoted on pegs protruding from the gunwales, their seaward ends tapering into sharpened wedges to minimise wind drag. It was like rowing with giant toothpicks. Yet the boat climbed the waves easily, stabilised by a jumbled ballast of luggage: waterproofs, sleeping mats, watertight barrels for personal belongings. Also visible were the brown bundles of discarded monastic robes - almost impossible to row in, but useful for cushioning the bare wooden benches.

Who exactly were these people? They had seemed friendly enough when I introduced myself at the pub the previous night - a multi-generational mix of Irishmen, Scots and ancestor-hunting Americans recruited to Donald's bizarre retirement project through internet and newspaper ads. Graciously overlooking my non-Celtic blood, they had enthused a lot about teamwork, but I sensed a little confusion about the precise aim of the voyage. A vocal minority seemed fond of the word "mission". A bearded American called Ernest even brandished a wad of tracts including a "prayer of commitment" for potential converts. And now Donald was talking about "spiritual warfare". Suddenly, more than a mile from land, I was anxious to know exactly what I had let myself in for.

"Well, on one level it's a re-creation of St Columba's journey," clarified the 65-year-old. "But I guess the real purpose of the voyage is to rekindle the faith that he brought to Scotland so many years ago. I call it a spiritual odyssey, a kind of missionary voyage."

I looked at his weathered face, framed by distinguished silvery hair, and his brush-like moustache. For a moment he seemed less like a monk than a kind of nautical sheriff, with his posse of missionary desperados, riding back into town to clean the place up.

Curraghs had been the transport of choice for seafaring friars for the same reason they remained in use among Irish fishermen: they were light and manoeuvrable and swift through the water. "All the Celtic nations used them," said Robin Ruddock, our experienced skipper and boatbuilder from the North Antrim coast. "It didn't make sense to have wooden boats where there were no real harbours. You needed a boat you could carry ashore." His only concession to the modern age in building Colmcille had been to use canvas instead of animal skins, which smelt terrible.

I found Robin a reassuring presence. His buzz-cut hair and barked orders could have got him mistaken for a paramilitary in the wrong kind of Belfast pub, but in fact his passion was peacemaking through outdoor pursuits. His day job was to put young groups of Protestants and Catholics in a curragh together and persuade them pull in the same direction.

"Right lads, keep rowing hard!" he yelled now, as we bounced through the tidal race of Dorus Mor. "Don't let the white water worry you." Steering well clear of the famous whirlpool at Corryvreckan, we turned north, hoisting two ochre sails to catch a south-westerly up the inside of the island of Luing. Our target for that day was the island of Easdale, a stepping stone to Iona some 30 miles away. The freshening wind brought a gust of euphoria as we hooked our oars out of the water and scudded along past low-lying islands. Someone tuned a radio to some Gaelic bagpipe music, while others dug out some authentic sixth-century food.

Easdale was only just an island. It lay about 400 yards from neighbouring Seil, which was itself connected to mainland Argyll by a bridge. Coasting into a sheltered stretch of water between the two, we were greeted at the slate-lined quay by people with wheelbarrows: the local taxi service in a carless place. A short walk from the harbour, children of a wild, grubby, happy demeanour were playing football on a shared green between lines of old terraced quarriers' cottages. A few adults sat chatting on doorsteps in the sun, smiling as we passed. They didn't look to me as if they needed saving.

The Celtic Renewal Service, as Donald was calling it, took place the following evening on a village green in Seil. We donned our robes shortly before seven, observed by locals wearing sympathetic smiles. Most of us looked as if we were wearing picnic rugs tied up with string, though Ernest had pulled out the best of his already legendary wardrobe of period costumes. Today, in addition to his robe, he was wearing a crimson smock over his linen undergarments, and a pair of leather sandals. "This is actually what Celtic monks would have worn," he said proudly. " They loved colour."

"Keep yer hoods up!" whispered somebody, more practically. " It keeps the midgies aff!"

A cluster of perhaps 40 people were watching as we clambered out of the boat on Seil and processed across the car park chanting "Kyrie Eleison" mournfully in time to a cowbell. Donald and Ern led the way, carrying an eight-foot wooden cross. I kept my hood well up.

In the middle of the village green, Alistair sat at a portable organ. The congregation looked friendly if nonplussed. A Reverend Freda Marshall from Oban tapped the microphone. "I don't know about you," she began earnestly, "but I really felt a tingle up my spine seeing the brothers here processing up the beach. I felt sure this was just how it might have happened all those years ago ..."

The ensuing vague murmur of agreement was briefly interrupted by a yelp from a woman as Ern's cross toppled sideways and caught her on the shoulder. Then we progressed into a selection of hymns and choruses sandwiched with Bible readings. Things otherwise proceeded much as they were laid out on the notice sheet, until the first few spots of rain precipitated a crisis. A man leapt forward and covered the electric organ with a feed bag, and the various visiting clergy exchanged glances. "I think with Donald's permission we'll skip forward to the final hymn ..."

"Wait!" said Donald, his face reddening. Several members of the congregation froze in the act of putting on waterproofs. Our leader was standing in the middle of the green with his arms raised to heaven. At first I assumed he was sampling the rain, until I saw his lips moving and realised he was praying against it. There was an uncomfortable moment as the congregation realised this too. Lots of people studied their shoes. " Look, it's passing!" shouted Donald suddenly, lowering his arms. " Praise God, we can continue!'

It was true that the rain had stopped. There was even a well-timed appearance of evening sun which bathed the whole surreal scene in honey-coloured light. But if we had witnessed a miracle, nobody seemed to have noticed it. Instead, someone plucked up the courage to ask for what they really wanted: a ride in an authentic curragh. Then dozens of people poured on to the quay, young, old, permed, bald, many of them requisitioning our robes for the full experience. Robin coached several boat loads back and forth across the harbour.

Ern and Donald looked a little deflated. Even the woman who had been clubbed by Ern's cross declined a healing prayer. Slowly the truth sunk in: the entire gathering had been composed of local churchgoers.

We had been preaching to the converted.

We woke at 5am and left the harbour before the village was awake, losing Easdale quickly in a fine sea mist. It was chilly at first, but the repetitive motion of rowing against the wind soon warmed us up, and we drifted into a collective trance of concentration. Soon we were rising and falling in an Atlantic swell.

It was 11 before we turned northwards around a stumpy lighthouse on the saw-toothed Garvellochs, finally hoisting the sails for a little assistance. Donald excavated the food barrel and passed round a few dates with a block of cheese and some four-day-old smoked fish by way of encouragement.

"Where's the bread?" asked Robin, frowning at what was being offered.

Donald flushed and rooted around in a couple of barrels. "Ah, I guess we must have eaten all the bread before we set off," he said sheepishly. "Sorry, guys, no bread. At least there's lots of smoked fish!" He laughed nervously into a silence broken only by the lapping of water at the bow and tinny haze of bagpipe music coming from a radio. Robin stared angrily at the floorboards, then at his watch.

"OK boys," he said, finally. "I'm afraid we're going to have to carry on rowing. The wind isn't strong enough, and if we're still crossing the channel when the tide changes, we'll end up right back where we started."

We rowed silently for the next few hours, the shore of Mull always tantalisingly distant. As our movements became stiff and lopsided Jim the bosun prayed aloud for a following wind. Later, Donald looked back over his shoulder at me, embarrassed that God hadn't done the business yet. "I think it's a test of our patience," he said, in case anyone was beginning to doubt.

"You're telling me," muttered someone.

By four we could hear the faint hiss of breakers on the shore. It was scattered with rocks the size of bowling balls, forming a level shelf which then curved upwards into towering cliffs. Robin coached us in to within 100 yards of the shore, careful to stay on the right side of the breakers. The tide, meanwhile, was already beginning to flow east - and even God seemed unlikely to interfere with that.

"We'll take a break here and wait out the worst of the tide," he said, dropping the anchor.

"Why not hole up on the shore for the night and gather our energies for Iona tomorrow?" said Donald, tentatively. "We could make a shelter and set out first thing in the morning, when we've rested ..."

"We don't have enough food to keep going after tonight!" barked Robin angrily, overruling him. He was genuinely worried.

Donald slumped under the public criticism. In the awkward pause that ensued, someone quipped: "Oh well, if all else fails, there's always the outboard!" There was, indeed, a small outboard motor stowed on the floor of the stern, for emergencies. A few people laughed, including Donald - but he added nervously: "That would kind of undermine the authenticity of the voyage." There was silence.

Thankfully, Peter chose that moment to recall a bag of pasta he had brought all the way from Govan. "We could maybe share this?" he said, fishing it out of his drybag with a generosity that brought a lump to my throat. Jim gave a cheer and began boiling up a billycan of seawater over a Primus he pulled from below the benches. As miracles went, this one was up there with the multiplication of loaves and fishes as far as I was concerned. I shot Donald what I hoped was an encouraging grin. His sunburned face was as red as a baboon's arse, and his grey hair was matted in all sorts of directions. He grinned wearily back at me.

We were anchored in the retreating tide, dragged parallel to the shore by the slow ebb. On the lower slopes a thatch of grey scree and greenery gave the upper crags a silky opal sheen. High above us on a bone-like branch sat two golden eagles, proud, regal, utterly unconstrained by earth or sea.

Peter doled out his pasta and I took a plate each to Robin and Jim at the stern. They were murmuring quietly together, and attaching something to the outside of the boat. It was the emergency outboard motor.

"We may be Irish but we're not stupid," said Robin, winking at me. "The Lord helps those who help themselves, eh?" He pulled the starter cord, and the motor chuntered into life. Donald looked up from his pasta in surprise. He opened his mouth to speak, but Robin cut in first.

"There's no more food or water, Donald, and I've got to get these boys to their beds tonight," he said, tinkering with the petrol input. He played a carefully prepared religious trump card. "Look at it this way: the only reason we wouldn't use the outboard at this stage is out of pride. And you have to learn to swallow your pride where the safety of others is concerned."

We all waited for Donald to object to this moral fait accompli, but he never did. Instead, Robin called the rowers to their seats and slipped the anchor.

In fact, the outboard probably did more for morale than it did for our speed. It was a tinny contraption that spluttered and left the water entirely each time we breasted a wave. We had to row hard for the next four hours against the slowing tide. My muscles felt as twisted as rubber bands. The Torron Rocks drifted past in the mist, as insubstantial as ghosts on our port side, and the light was dying by the time we turned into Tinker's Hole, a passageway between the extremity of Mull and the little island of Erraid. Wordlessly, Robin cut the outboard and lifted it back into the boat.

"Right lads, this is the home strait," he said. "Let's get our habits on, and do ourselves proud."

Pulling out into the Sound of Iona, we could see our destination rising gently against low skies littered with the last violet shreds of day. The tide was flowing as fast as a river in the centre of the channel, dragging us backwards.

"Pull hard, boys!" said Robin. We inched past winking channel markers, towards the lights of houses on the shore of Iona. The lights were multiplying ahead of us. A crowd of people were standing waiting for us at the quayside pub with candles and torches, their cheers and applause pattering across the water.

A motorboat roared out to meet us. "Welcome to Iona!" shouted a female voice.

"Praise God!" Donald shouted back. Many raised pint glasses as we pulled in alongside the ferry ramp, while others caught our lines. Some wanted to shake our hands, ask about the trip, so Donald recounted to anyone who would listen how the hand of the Almighty had been mightily evident. He seemed to glow in the darkness, a man on fire with the spirit and advanced sunburn.

As a final gesture he pronounced a homily while the men launched three captive doves into the sky as symbols of Celtic brotherhood. It was a nervous moment. One flew off while the other two flapped woozily across the beach and escaped to the roof of the pub. We took the hint, ditched our habits and got ourselves inside for last orders.

Nobody mentioned the outboard motor again.

'Adrift In Caledonia: Boat-hitching for the Unenlightened', by Nick Thorpe, is published on 2 March by Little, Brown, £12.99. To order it for the special price of £11.99, inc p&p, call 08700 798897, or visit www.independentbooksdirect.co.uk