The Marine Department has revoked the licences and operating permits for tour boats Phoenix and Sereniga, which capsized in a heavy storm off Phuket on Thursday, killing at least 42 and leaving 14 missing.
Jirut Wisanjit, director-general of the department, said the certificates of knowledge and ability issued to the skippers of the two boats have also been revoked.
He said department officials have been instructed to provide full cooperation for the search and rescue operation.
The department's patrol boat 1301 has been assigned to scour an area northwest of Phi Phi Don island, about 20 nautical miles (37 kilometres) from where the boat accidents occurred, where the missing might have been swept to in the current.
Mr Jirut said the sky over Phuket was cloudly and the sea waves moderate, posing no obstacles to the search.