He was caught breaking by-laws
Torbay harbour master Adam Parnell confronted the offender with the evidence.
Mr Parnell says he gave the man the option of not using the harbour or facing prosecution.
He said the action had sent “shockwaves” through the jet-ski community.
Mr Parnell said the man was caught on CCTV “being particularly stupid” on a jet-ski in the harbour.
The man admits he was splashing his friend, but says he did not agree to the ban. He added that he often helps the RNLI with his jet ski and wants to get back out on the water.
Details of the incident emerged as Mr Parnell gave an update to Torbay Council’s harbour committee on recent incidents around Torbay.
Councillors were told there were three reported near-misses involving jet-skis in April, including two near swimmers at Broadsands and Torre Abbey.
Mr Parnell said a review of warning signs was due to be carried out alongside a programme of education and information for water users.
A second meeting had taken place of a safety forum bringing together users of jet-skis and power boats with swimmers.