Tourism bosses say extra public money is needed to offset losses incurred by businesses because of a 10mph speed limit imposed on Windermere.
The limit is being enforced using hi-tech speed cameras
Cumbria Tourist Board claims the area is losing millions of pounds because of the limit imposed by the Lake District National Park Authority (LDNPA).
The board says two surveys have confirmed tourism businesses are facing serious problems.
The LDNPA says it has a duty to protect the landscape for the public.
National park bosses imposed the limit, which effectively bans high-powered water craft and skiers, in March, to bring tranquillity back to the lake.
But tourist board officials say two surveys of firms in the area revealed over half said a fall in profitability and visitors during 2005 was down to the speed limit.
Chief executive Ian Stephens said it would now be seeking extra funding from the North West Regional Development Agency to help tourism firms and boost the profile of the area following the ban.
He said: "It is now clear that although speedboaters represent a small percentage of visitors to the national park, they are high spenders.
"Attracting new high spending markets is a very difficult task in the extremely competitive tourism market. Of course Windermere has the potential, but businesses, especially small businesses need help to adjust to the new circumstances."
The LDNPA said the tourist board and local businesses had five years' notice of the imposition of the speed limit.
It urged the tourist board to do more to aid the economic regeneration of the area and better support its members.