According to a survey carried out by the three organisations, faced with the massive price rise on red diesel, 52% of the 5,000 respondents would buy their fuel abroad, or move their boats abroad. Another 10% said they would just give up boating altogether.

If the derogation goes, the owner of a 16-17m motor cruiser will have to find around £1,270 more to fill the tanks.

Whichever option the boaters choose, the UK recreational marine industry will lose a tremendous amount of business. And this, says the BMF, will have a devastating effect on an industry that is currently a rare example of UK manufacturing success.

"We estimate the loss of business could be worth around £200m, "said BMF executive director, Howard Pridding. "And if employment dropped by the same proportion it could lead to job losses of up to 6,500."

The immediate action required is to stir up the UK government. "We have to persuade the government this is worth fighting for in Brussels, " said Neil Northmore, the RYA's government affairs adviser. "If our government pushes, the EU will look at it."

Rod Carr, chief executive of the RYA, told BB: "The spring of 2005 is going to be crucial - that's when the debate around the corridors of the EU will be taking place.

The derogation on red diesel is due to end on December 31, 2006.