The offenders – none of them from Hayling Island – were hauled before Portsmouth magistrates after ignoring warnings to slow down.

Langstone Harbour Board, which brought the prosecutions, said the fines should serve as a warning that speeding will not be tolerated, and warned more prosecutions would follow.

The offenders were fined between £125 and £350, depending on the severity of the speeding. Each had to pay between £100 and £150 costs.

All were travelling at more than 15 knots which is five knots over the harbour speed limit of 10 knots.

Harbourmaster Nigel Jardine said a minority of people were flouting the rules and travelling recklessly at up to 50mph.

Jet-skiing is now big business in Langstone Harbour – with many skiers using the stretch of water between Eastney and Hayling.

Many travel down from London to enjoy the sport, but the harbourmaster said some people were putting lives in danger.

He said: "We patrol the harbour constantly and during the course of the year speak to thousands of individuals and ask them to calm down. The vast majority do just that.

"But there is a significant minority who exceed the speed limit. We have to get the message out there that the harbour needs to be a safe environment.

"If you break the rules we will prosecute. You are not immune."

The five prosecutions were from offences over the summer. The harbour board is planning to take seven more people to court in December

The five were: Wayne Jowers, of Meadow Edge, Widley, fined £125, plus £100 costs; Daniel Edwards, of Hill View, Horndean, fined £150, plus £100 costs; Michael Bacon, of Queens Crescent, Horndean, fined £285, plus £150 costs; Ben Sharpe, of Lime Grove, Paulsgrove, fined £200, plus £100 costs; Ricky Crowe, from High Wycombe, fined £350, plus £150 costs.

JUDGE'S ASBO WARNING
Nuisance jet-skiers could be handed Antis-Social Behaviour Orders (Asbos) after a test case in Gosport.

A top judge has said orders may be given to riders caught zooming around "no jet-ski" zones where people are swimming.

The ruling came after a man was taken to court by Gosport council for riding recklessly at Stokes Bay.

The authority wanted an Asbo slapped on him, but that was dismissed as 'frivolous' by a judge at Fareham Magistrates' Court.

In the High Court, Mr Justice Bean said the man did not deserve an Asbo as there had been no swimmers present when he offended.

But he added that jet-skiers could be eligible for Asbos in the future if they rode irresponsibly while there was at least one person in the water.