Every now and then, dysfunctional families need a different type of holiday. Not the sort of trip that they can brag about in the playground, that involves a new bikini, but a gluing-the-family-back-together-again sort of break, that comes after a particularly stressful school term and a stream of shouting matches. It comes when you realise that you can no longer stand the sight of each other, and the thought of spending any more time confined together in your Victorian terrace makes you want to wear a false beard and leave the country immediately.

That is the moment, the precise time, when I recommend the least likely holiday on your agenda – a narrowboat in Wales. It’s not trendy, it’s not sexy, and there is no activity or swimming involved, despite being surrounded by water, but you will all (grudgingly) love each other again by the end. I promise. It’s impossible not to.

As Stephen Bleach wrote in the Sunday Times, “If you wanted to sort out a lot of the world’s problems, you’d take George Bush and Mahmoud Ahmadinejad and send them on a canal holiday.” He maintains “you are incapable of doing an unkind thing or thinking a negative thought on the water”. I would argue that was because he didn’t take his family with him. If you do, it may take a little longer and need Scream Therapy to reach nirvana.

Demonstrated by Liza Minelli under a railway bridge in the movie Cabaret, Scream Therapy is legitimised screaming at your partner as he attempts to steer a 69ft “bathtub” down a narrow canal without breaking every glass and child’s head on board. Don’t let anyone tell you that steering a 12-tonne lump of metal is easy. Remember how long it took you to overcome the fear of motorways when you learned to drive? Well taking the tiller of a narrowboat is similar.

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• Slide show: Emma Mahony and family boating in Wales

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OK, admittedly you are only travelling at 4mph, fast walking pace, but when you are motoring towards a lump of stone that your darling heart can’t see because he is too busy looking in his jacket for his fags, you really need to use your lungs above the engine noise to tell him to “Sto-o-o-op!”. It took me half a day to realise that he was only smiling at the back of the boat when I was shouting “For Chrissake you ID-I-OT! there’s a boat coming around the CORNER!” because he couldn’t hear me. As it was, I felt miles better having vented all that pent-up frustration, and he thought I was waving affectionately at him.

However, as any armchair shrink will tell you, Scream Therapy is not enough to glue a family together. For that you also need the necessary factors of fear, followed by teamwork to overcome the imaginary enemy. Fear and the enemy came within half a mile of setting sail. As the guide stepped off the boat a few minutes away from Chirk Marina, we approached the Chirk Tunnel, also known as “Darkie tunnel”, although we had no clue of that then.

For 1,377ft we were plunged into total darkness, with more scream therapy from the children in complete blackness inside the boat, and terror from me that fingers would be scraped off the ceiling as we put our hands to our ears to protect ourselves from the sparks flying and noise of metal on rock as we ricocheted through the gloom. As we emerged into the light, thankful to be alive, we were reborn. Then we saw a narrow strip of water with a 70ft drop either side, Chirk Aqueduct, and motored unstoppably towards it.

This was scary. As we entered the metal channel, the children could have fallen from the top or side of the boat to certain death in one friendly push. But they were clinging to each other and us, with none of us daring to look down, as we moved sedately alongside the beautiful railway arches. The bonding had begun.

Having fought off death, the pub seemed the only answer. To moor the boat, the children jumped off and chucked ropes to each other, taking it in turns to hit the big spikes with satisfying low-tech metal hammers. Food was the usual rubbish pub fare, but for once, nobody complained. In fact, Millie turned cartwheels, Michael pointed out the herons, and my eldest Humphrey totted up the number of ducklings he had witnessed following us (they became confused temporarily and thought we were their mother).

The usual low hum of continuous moaning had been replaced by the hum of the boat’s engine, and we were all surprised to find that we were rather enjoying ourselves. The telly didn’t work, we had forgotten to bring DVDs, there was no iPod facilities, but none of us seemed to care. We had a few bits of paper to write and draw on, a few books to read, and the sunshine. Amazingly, it was enough.

By day two, the children ran alongside the boat for entertainment, and we all gazed like meditating Buddhists at the stunning Shropshire countryside as it rolled by, occasionally waving at other canal boat users, like long lost friends. Uncle Dominic and his fiancé Sarah drove down from Manchester to meet us in another pub, and begged for a ride on the boat. The children had transformed from whinging whiners into a crack team of round-the-world-sailors – showing off with the ropes and the tiller, and pushing the boat off to get going.

“I’m quite jealous of your barge”, said Sarah, as we stopped to let them jump off and head back to their car “I wish we could stay”. And at that moment, I realised that I would not sell my two nights on board for the best five-star hotel in the world. Perhaps next time we’ll invite Bush and Ahmadinejad for lunch.

Need to Know

For ideas on how best to enjoy Britain’s waterways, look at Waterscape (www.waterscape.com ) or visit British Waterways (www.britishwaterways.co.uk ). Drifters (www.drifters.co.uk ) a consortium of boat companies, including Black Prince Holidays (01527 575115, www.black-prince.com), which we travelled with, is offering Times Online Travel readers a special incentive to try out a holiday on canals in England, Wales or Scotland with £50 off a part week, £100 off a full week, and £250 off two weeks. Cite the Times Online Travel and Castle Wharf Promotions offer when you call.

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