Swimmers cooling off in the Exeter Ship Canal and boats speeding in the estuary are making Exeter City Council hot under the collar.

Badly-behaved bathers have been clambering over boats so they can dive into the water, and security patrols have been drafted in to curb some of the antics.

A report for the city’s harbour board spells out the hot-weather headaches.

In his quarterly report, harbourmaster Grahame Forshaw writes: “The canal manager reports that swimmers in the canal during warm spells of weather continue to be a problem.

“The water quality in the canal is not overly good and bathers are oblivious to this. The behaviour of young people swimming is particularly worrying at the Basin during the school holidays.

“Boats are being climbed over and jumped off, as are the rowing club and Haven Banks pontoons.

“The situation at Clapperbrook bridge and Double Locks has got so bad that we have contracted Marsh Barton Security Services to stop by these areas three times per day.”

The report also reveals that the authority has recorded 79 speeding boat incidents this summer, despite only being able to mount limited patrols.

Mr Forshaw’s report says a patrol boat has been out every weekend bar one, when the weather was too bad, but has rarely been out on weekdays.

He says: “What the team see, or is reported to us, only represents a fraction of the true number of incidents that occur.”

Engine breakdowns and navigation errors are the other most likely incidents, while patrols have also dealt with two sinkings, two groundings, a collision and a man overboard.