Mr Fieldhouse said he would be appealing against the ruling

The limit was introduced on England's largest natural lake in March by the Lake District National Park Authority.

Windermere businessman and waterskiing enthusiast Nick Fieldhouse denied breaking the limit in June.

On Tuesday at Kendal Magistrates Court he was told to pay a �200 fine and �300 costs after being found guilty.

Two lake wardens claimed that in June they saw Mr Fieldhouse driving a powerboat towing another man at about 20mph.

He denied that and said the wardens had been more than two miles away.

After being found guilty, he said he would be appealing.