The crew were travelling on a barge carrying construction materials and a backhoe from Ao Makham in Phuket to Koh Racha Yai when it disappeared in heavy seas with waves of up to four metres.
After receiving the report that the boat was missing, the Navy search began scouring the seas at 4:30am by helicopter.
The search continues to the east of Koh Racha Yai.
The Phuket Marine Office yesterday ordered all small boats to stay ashore to avoid the storm conditions at sea. Larger vessels were allowed to transit, but their captains were urged to proceed with caution.
The Thai Meteorological Department this morning issued another weather warning for Phuket and the Andaman region.
“The strong southwest monsoon prevails across the Andaman Sea, the South and the Gulf of Thailand. More rain is likely in the South and the East, with isolated heavy rain in Chanthaburi, Trat, Ranong and Phang Nga. People should beware of heavy rain,” read the warning.
“The strong wind waves are expected in the Andaman Sea and the Gulf of Thailand with waves 2-4 meters high. All ships should proceed with caution and small boats keep ashore until 13 July.”