A 12-meter (40-foot) catamaran found drifting off Australia's Great Barrier Reef had sails up, engines running and food on the table, but no crew, officials said Friday after launching a massive search for the missing men.
A coastal patrol aircraft spotted the vessel Kaz II on Wednesday but rescue workers only reached the boat early Friday, confirming there was no one aboard.
Officials said they were puzzled by what they found.
"They got on board and said the engine was running, the computers were running, there was a laptop set up on the table which was running, the radio was working ... and there was food and utensils set on the table ready to eat, but no sign of the crew," said Jon Hall, a spokesman for Queensland state's Emergency Management office.
"It was a bit strange," he said.
The vessel's emergency beacon and three life jackets were still on board, along with a dinghy.
The catamaran's sails were up, but the headsail was "shredded," according to Warwick Bracken of the Australian Maritime Safety Authority.
There was no indication of any other damage or that the vessel had capsized.
Queensland police confirmed that three men - all Australians, aged 56, 63 and 69 - were missing, and that a massive sea and air search was under way Friday from Airlie Beach to the northeastern city of Townsville.
Nine planes and two helicopters were searching an area spanning some 700 nautical miles, along with four volunteer rescue boats, police and maritime officials said.
Marine police were also towing the vessel back to shore for further investigation.
The men had set out from Airlie Beach on Sunday, and were planning to sail around northern Australia to Western Australia state, according to Sharon Davidson of the Australian Maritime Safety Authority.
Greg Connor, a forecaster with the Bureau of Meteorology, said the sailors would have faced moderate southeasterly winds of about 35 kph (22 mph), typical weather for this time of year.
"It would have been excellent sailing conditions," he said. "There's no reason to believe this is a weather related incident."