Fears for yachtsman missing off NSW coast

It's unlikely a man feared to have fallen off a yacht found abandoned off the NSW north coast is alive, police say.

Marine rescuers officially suspended their search for the 48-year-old Tasmanian man on Wednesday evening.

The man's eight-metre vessel, known as FireFly, was found a day earlier in waters just off Samurai beach, a popular nudist spot in Port Stephens.

Stephen Leahy, CEO at Westpac Life Saver Rescue Helicopters, told AAP it appears the man was living on the yacht and "there is a suggestion that he may have fallen overboard".

But an extensive search covering a large area from Fingal Bay to Stockton and five nautical miles out to sea has failed to find the man.

"Due to conditions of the water, it is unlikely the 48-year-old man was able to survive," a NSW Police spokesman said.

Rescue crews will resume their search on Thursday morning.

Detectives are also looking into reports the boat was seen around Lemon Tree Passage on Tuesday morning.