The 43-year-old man - who would only give his first name as Peter - scraped one of his knuckles while trying to save his 25-feet fibreglass craft from sinking.

He was rescued unhurt from the lock but says he has "lost everything I own" and that his £3,000 boat is a write-off. It is only insured for fire and theft.

The painter and decorator, who rents a room in a house in Frome, was travelling towards Bath when he entered the lock at the canal wharf.

"I was trying to go through the lock with a hire boat and told the user that two boats were allowed to go through together.

"But he closed the lock. I asked him to open it but he stopped me and I didn't have the lock key."

Peter was being helped by two friends, Tom and Gene, but they couldn't hear what he was trying to do.

"I shouted at them to put the lock paddles back down but they couldn't hear me.

"The rope on the boat was too short and it was getting tighter and I jumped down onto the boat to cut it.

"I tried to cut the rope with a hammer, which is all I had, but it was too late and the boat sank. It was a complete accident."

His sunken boat has blocked the lock near the B3109 Frome Road and the canal wharf services.

Other canal users are now unable to pass through until the boat is removed by a specialist contractor.

Fire crews from Bradford on Avon and Trowbridge, plus a specialist water rescue unit from Trowbridge fire station, were called out to assist Peter but were unable to save his boat from sinking.

The accident happened between 6pm and 7pm. Peter said he was planning to moor up at Avoncliff after passing through.

The Canal and River Trust, the charity which runs the canal, has been informed.