The skipper was identified as Samran Pipatpalsakul, 36.
Chaiya district police a shipyard owner, Mr Patpong Laopreechakul, skipper Samran and another friend who was not identified set sail in the yacht from Ban Don estuary to the sea about 1.8 miles from the shoreline with a plan to sail to Koh Tao and Koh Pa-ngan on Wednesday for sight-seeing.
Patpong and a friend did not stay overnight on the vessel but spent the night at a beach resort while the skipper was supposed to be on the yacht anchoring about 1.8 miles from the beach.
Patpong said when he returned to the spot where the yacht dropped anchor, it was not there along with the skipper who went missing.
The yacht was however found capsizing in the sea with a rubber raft went missing with the skipper.
A search was mounted by a team of divers and rescue workers, but they failed to locate the skipper.