Colonel Tareq al-Hassan, a spokesman for the interior ministry, said late on Saturday that the ship's owner had applied for a licence but never completed the procedures.
"The owner of the ship had applied for a licence in December 2005. He was asked to meet the regulations, the conditions, and he was given a list of regulations that were required," al-Hassan said.
"He went away to complete the regulations but never came back to be licensed. So the ship is not licensed to be a sailing ship but it is registered as a fishing boat."
At least 57 people died, mostly foreigners, when the dhow went down late last Thursday. The boat trip was sponsored by companies involved in a construction project in Bahrain, including South African construction firm Murray & Roberts, its local partner Nass and subcontractors.
The authorities have detained the boat's captain for questioning after concerns arose about his qualifications and whether the boat was overloaded.
Officials have said 126 people were believed to have been on board. Tourism sources said the vessel had a capacity of 100.
The dead were 21 Indians, 13 Britons, five South Africans, five Filipinos, four Singaporeans, four Pakistanis, two Thais, a German, an Irish citizen and a South Korean.