A recent MCA review of Thames passenger vessels suggested both older and newer vessels needed to be updated with a more modern safety legislation system.
But boat operators fear that in some cases, the work needed to bring their vessels in line with the new standards could be costly enough to put them out of business.
Danny Collier, a skipper, and owner of Colliers Launches, said his boats are specially designed to operate on the Thames to cope with the low tides and low bridges.
Mr Collier said: “Over the years we have invested a lot of money into our draft – almost tens of thousands of pounds to make improvements.
“Should the consultation implementations go ahead, then I will have to provide the inspector with a brand-new plan.
“I have no intention of doing so because I already invest a lot of money to make sure my vessels are safe and adhere to passenger safety.
“If I don’t submit new plans then I could be out of business as early as January 2020.”
The MCA review came as a direct result of the Thames Safety Inquiry held in 2000, following the fatal Marchioness boat accident that happened in 1989, with the decision made to modernise passenger safety standards for older passenger-boat vessels that could hold 12 or more people.
Mr Collier’s vessels include The Princess Freda, renowned for rescuing British Troops at Dunkirk in 1940, as well as The Queen Elizabeth, which was used in the Queen’s Diamond Jubilee celebrations in 2012.
Over 20 passenger-boat operators who operate from Richmond, Kew, Hampton Court Palace and Westminster have joined Mr Collier in rejecting the proposals as they believe their vessels are safe and built for purpose.
Twickenham MP, Vince Cable, said: “I have been in touch with the government on the leisure boats issue and the flourishing ship repair business on Eel Pie Island which is potentially affected if the boats go out of business.
“Priority must be given to passengers safety and the issue is whether the proposed changes are proportionate which is a technical not a political issue.
“The PLA, the Port of London Authority has now come out with a strong statement of support for the changes which has to be taken seriously.
“I think that the key issue in practice is to have a safety regime which is appropriate for the dangerous and crowded waters lower down the river around Westminster but also allows for boats to operate on the Richmond-Hampton Court stretch where the challenges are different.”
The MCA have announced that the new regulations will begin in the Autumn and that passenger-boat operators will be given a two-year grace period to ensure that they will be able to comply with the new consultation proposals.
A spokesperson for the MCA said: “There’s been some controversy as a few – five maximum, of the Little Ships – as they’re known, may be affected by the proposals.
“We would like to reassure people that the vast majority of the Dunkirk Little Ships do not fall into this category- probably only two to three per cent out of 198 ships are expected to be affected.
“All passenger ships including those which went to Dunkirk are certified against the appropriate standards and are subject to annual checks by the Maritime & Coastguard Agency.
“We cannot use wartime operational service – however noble – from nearly 80 years ago as standard against which to asses currently operating passenger ships.”
The MCA have also stated that it will welcome any future ‘exemption requests’ for the Dunkirk Little Ship and other vessels which will be handled on a case by case basis.