Mark David Moylan, 42, was last seen on Saturday, January 25, in a small dinghy in waters off Gravelly Beach marina.

Inspector Darren Hopkins, of Northern District Support Services, said if Mr Moylan had entered the water, officers were looking for his body.

But he said there was also a chance that he could still be alive and onshore.

Police divers, State Emergency Service volunteers and a Search and Rescue helicopter crew searched waters in Rose Bay, in the Gravelly Beach area on Friday, but found no trace of Mr Moylan.

Beaconsfield and Exeter police continued mobile patrols along the foreshore yesterday, with the police vessel expected to head out this morning for several hours.

Inspector Hopkins said police were working on the theory that Mr Moylan had fallen into the water.

"His dinghy turned up partly filled with water," he said.

"Considering that there had been no rain and the aluminium dinghy was not leaking, we can only assume the dinghy may have toppled over and Mr Moylan has gone into the water.

"We only hope we can find him close by."

Mr Moylan was last seen between 8pm and 9pm on January 25, rowing his dinghy from the Gravelly Beach marina to his vessel.

His boat, in which he lived, was moored in the bay directly outside the marina.

Police later found Mr Moylan's dinghy and oar washed up onshore towards George Town, about four kilometres north of his last known location.

Mr Moylan is 170 centimetres tall, of slim build, with a tanned complexion and short brown wavy hair.

Police urge anyone who knows the whereabouts of Mr Moylan, or who believe they have found any of his possessions, to call Beaconsfield Police Station on 6383 2002 or Tasmania Police on 131 444.