Fishing Lines: I'm going skating on the sea bottom

Imagine deliberately setting out to catch a fish that will end up costing a fortune in physiotherapy bills. This weekend's dumb idea is to drive more than 400 miles to Oban in Argyll and head out in a boat for hours of pain.

It hasn't been easy to fill the boat. All those who have done it before have cried off with a variety of unlikely excuses. "I've just pulled a muscle in my leg," or "I've just found out that I've got to go to Spain with work," and "It's my next-door neighbour's 50th birthday party, and he's asked me to make a speech" are three of the more likely ones. I was even expecting someone to say: "I've got to wash my hair that weekend."

Still, I can't blame them. They know what's afoot. The four "virgins" who will join me aboard Adrian Lauder's boat Gannet are smiling now. They may not look quite so happy come Sunday night.

Our quarry is the common skate. Imagine a triangular dining-room table for 20, stick on a few fins and a long tail, and you've got a skate.

Their flat shape tells you that they live on the bottom, where they hoover up crabs and smaller fish. In their case, home is 500 feet down. When you hook a skate in a fast-flowing tide, it's as if you've snagged a giant rock. Only the fact that the rock moves tells you it's a fish. And that's when the fun starts.

Skate might not have too many GCSEs, but they know that if they point their huge bodies downwards at the right angle, they are almost immovable. Adrian told me a story of a boatload of anglers who hooked a very big one, and took turns trying to haul it up.

Nearly 10 hours later, the party leader, fearing he was going to be on the boat all night, broke the line.

How big do they grow? Well, a small one is 100lb. The British record is 227lb, but Adrian reckons they grow to more than 500lb. The reason that the big ones are never caught is that they are just too strong. In a tug of war with something that big, anglers invariably come second.

On my last trip, I caught fish of 165lb and 140lb - and lost a big one. It was on for nearly an hour, and I had gained about 40 feet of line. At that rate, I worked out, I would get it near the boat about 3am.Then it came off. I wasn't too sorry. Five minutes later, my rod pulled again. "Go away!" I shouted, every part of my body aching.

This is a sport for super-masochists. It makes your arms, legs, back and all the bits in between groan for days. On our last trip, one of the party didn't catch one. "I'm really sorry you didn't get a skate," I said. "On the contrary," he replied. "When I saw what they were doing to everyone else, I was praying that one wouldn't take my bait. I'm the only person who's not going to hobble to the car."

And guess what? If you manage to bring a skate up those 500 feet or so, the final stage is to put a tag in, so that its movements can be traced by Glasgow University. Then you let it go.

I must be crackers.