Hundreds of West Midlands marine firms believe they will struggle to stay afloat if the European Union sticks to a plan to more than double the cost of boat fuel.
Boat builders, waterside holiday businesses, and marinas fear the EU's plan to increase the price of their fuel from 40p to £1.05 a litre by the end of next year would paralyse the region's leisure marine industry.
Some 162 managers of the 300 marine companies in the West Midlands would consider abandoning their businesses if the fuel rise went ahead, according to research by the Royal Yachting Association and the British Marine Federation.
At present boat owners buy a fuel known as Red Diesel, which has reduced duty.
Howard Pridding, executive director of the BMF, said: "The leisure marine industry is currently a UK manufacturing success story. Over the past five years it has grown by 36 per cent and in the last year grew by eight per cent.
" The industry puts £2 billion into the British economy with the building of leisure boats, power boats and marine technology.
"However, a fuel rise could put the whole sector under threat. It could mean a lot of people will stop boating, others will use their boats less, and many will fill their boats with foreign fuel.
"In the West Midlands the narrowboat industry is doing particularly well. But this rise could force people who want to have a holiday on a narrowboat to pay £50 more a week in fuel.
"We are urging the Government to continue their support for the marine sector by supporting an extension of the use of reduced duty diesel.
"We would ask those concerned about their businesses or their livelihoods to write to their MPs." Neil Northmore, from the RYA, urged the Government to fight against the EU's plans.
He said: "This could be disastrous for water-based tourism and the communities around the UK that rely heavily on visiting boats to support the local economies."
Mr Northmore estimated that the contribution boaters would make to the British economy would fall from £700 million to £550 million if the diesel price was raised and that many would move their boats abroad.
Representatives from the RYA and the BMF met MPs yesterday for talks about the proposed fuel price rise.