The niece of an Australian captain whose yacht was found drifting off the Great Barrier Reef said Tuesday she believes he and his crew may have been kidnapped. Police maintain they probably drowned.

Skipper Derek 'Des' Batten, 56, and brothers Peter and James Tunstead, aged 69 and 63, were last seen on April 15 leaving the northeastern town of Airlie Beach, the first leg of a two-month trip around Australia's north coast.

The Kaz II was discovered three days later drifting some 95 miles offshore.

Rescuers who boarded the vessel found food and cutlery laid out for a meal, and the men's clothes folded in neat piles on the rear deck. A laptop computer was charging, the boat's engines were running and navigational equipment was laid out on the table.

An emergency beacon, three life jackets and a dinghy were also found on board. The yacht's headsail was shredded, but there was no other sign of damage.

Investigators who reviewed the boat's global positioning system said it had been drifting with the wind and currents since the day they left Airlie Beach.

On Sunday, police called off an air and sea search for the men, saying the trio were probably swept overboard in rough weather and had likely drowned.

The skipper's niece, Hope Himing, rejected this explanation.

"If it was bad weather why would their fishing line be out? Why would their clothes be piled up?" she told reporters in Brisbane. "If it was that bad that it would have knocked three experienced sailors off, why wouldn't they have put on their lifejackets? It just doesn't add up for us."

Himing said she believed another boat had pulled up alongside the 32-foot catamaran, and that the three men may have been kidnapped.

"The fenders were out on their yacht, and the only reason you ever put them out is when another boat comes aside or if you come to rest against a wharf," she said. "It looks like they've been boarded."

However, police have ruled out foul play, saying there was no suggestion that the men's disappearance was anything other than a tragic accident.

Answering questions about the fenders earlier this week, police inspector Warren Webber said it was not unusual for small-craft sailors to leave their fenders out at sea.

He said there was also no sign that the vessel was ransacked.

Queensland police said Tuesday they would reopen their investigation into the men's disappearance if further information came to light.