Dinghies may have been stolen to order after five were taken in one night.
The dinghies had all been stored securely in a rack in an area of Blackwater Sailing Club.
Donald Baines, 69, a retired lecturer at Anglia Ruskin University, was one of those whose dinghy was stolen.
Mr Baines, of High Street, Maldon, said: “It was an inflatable dinghy which I used to get out to my boat when I go off sailing.
“At the club we had a purpose built rack to store the dinghies under cover.
“I would padlock the dinghy to the rack and take the oars home.
“It’s very identifiable, I’ve had it for 11 years and always kept it there and it has been fine."
Police say besides Mr Baines’ grey 2.65metre Waveline dinghy, a Quicksilver dinghy worth £800, a black Avon rubber dinghy worth £200 and a pvc dinghy worth £100 were all removed from Blackwater Sailing Club, Basin Road, between 8pm on August 6 and 12pm on August 7.