Thailand’s military mobilised helicopters, warships and unmanned drones off its central coast on Tuesday as rescue teams raced against time to find survivors after a navy corvette sank at the weekend in choppy waters.

One marine was rescued alive on Tuesday from the waters of the Gulf of Thailand, the navy said, among dozens who were forced to abandon the HTMS Sukhothai late on Sunday after it was knocked over by four-metre (13 ft) waves and strong winds. Five were found dead.

There were 24 marines still unaccounted for by Tuesday evening. Some were without life vests.

“The latest person was found 41 hours from when the ship sank and he was alive. So we believe that there are those still alive out there...we will continue to search,” said Admiral Chonlathis Navanugraha, the navy’s chief of staff.

Vice Admiral Pichai Lorchusakul, the regional navy commander, said finding the men on Tuesday would be critical given their time exposed to the elements.

Helicopters, two unmanned surveillance aircraft, four warships and a C130 transport plane were deployed to find the marines as weather conditions improved.

The vessel had suffered an engine malfunction as it took on water and went down about 20 nautical miles off Prachuap Khiri Khan province. The US-made corvette, in use since 1987, was carrying 105 military personnel.

Most on board were rescued before the boat sank but dozens had to abandon ship in rafts and life jackets.

‘Fatigued’

Lieutenant Colonel Pichitchai Tuannadee, captain of the sunken ship, said he was in the sea for two hours before he scrambled on to a raft and was found by search teams on Monday.

“To see something as small as a life ring or a person’s head above the surface of the water, it’s very hard to see with the big waves,” he said, adding that the missing sailors were likely to be fatigued by now from having to tread water and make sure those without vests stayed afloat.

One of the marines was found late on Monday clinging to a buoy.

“He was floating in the water for 10 hours. He was still conscious, so we could take him out of the water safely,” said Captain Kraipich Korawee-Paparwit, commander of the HTMS Kraburi, one of search vessels.

Relatives of the missing gathered at rescue centres awaiting news of loved ones.

Malinee Pudphong, aunt of missing marine Saharat Esa, said she spoke to her nephew by phone before the boat went down and was shocked to hear he did not get a life jacket.

“We have no hope as they are floating in the sea with just a life ring and with this kind of wind, you think they will withstand that?” she said.

“It’s a body of a 21-year-old. He’s not strong enough.”

Navy chief Admiral Choengchai Chomchoengpaet said the sinking would be investigated, including reports that there were not enough life jackets on board.