In Woodbridge, Deben Sailing Club, Deben Watersports Association and Woodbridge School all suffered the loss of an engine last Tuesday. It is believed the motors are being exported to eastern Europe where they are quickly sold on the black market.

The thefts have meant that dozens of children's summer holidays sailing courses have had to be cancelled.

At Alton Water, sailing and windsurfing has been severely restricted, while the general public were prohibited from taking to the water on Friday. Police forensics teams have already scoured the boats from which the motors were taken.

‘These people know what they are doing,’ said Adrian Slim, from Deben Water Sports Centre. ‘The problem we have is that there are school children on their summer holidays who are supposed to be enjoying courses.’

The question is do we go and buy more engines and risk losing them, he asked?

‘The insurers will not replace the engines at the full value. Instead they will give us the value of a second hand engine, so this will cost us thousands.’

The theft of the engine at Deben Sailing Club means the club is now more than £15,000 out of pocket. Lawrence Metcalfe, from the club, said: ‘This is the second engine we have had stolen. The first was worth £9,500, while the second is worth £5,900.’

It's the same gang, he said. The way in which they are stealing the engines is almost a copycat to last time. ‘All the boats were on moorings,’ he said. ‘They steal a dinghy, row out, break the boat free of the mooring and then take it around the corner to Kyson Point.

‘They wait for the tide to go out until the boats are sitting on the mud and then they remove the engines and make off.’

Police confirmed the thefts and said investigations were continuing. Anyone with information should contact PC Alison Bonham-Carter at Woodbridge police station on 01473 613500 or Crimestoppers on 0800 555111.