Marine Police have been notified, the boat's former owner, who goes by his nickname ‘Sando’, told The Phuket News just after midday.
The boat, now registered as Dragon Boy, is better known as the 80-foot (about 24.3 metres long) Lady Andaman.
The boat was valued at about B6 million and was recently sold, Sando said.
“But it had no insurance because the boat was already under contract and had been sold. It was just waiting to go into dry dock in two to three weeks to be converted into a liveaboard dive boat for the coming high season,” he explained.
The boat sank at about 11am, Sando told The Phuket News.
“Police say they have been told that a man was seen taking a dinghy out to the boat and boarding it at about 8am,” he said.
“We went out later this morning to fix the bilge pumps because we were told that the boat was taking on water. We came back on shore and then I got a call telling me that the boat had sunk,” he added.
“Police have checked CCTV but there is no coverage in that area,” Sando said, adding that police were continuing their investigation with one suspect in particular in mind.
The boat last made headlines in 2014 as the Lady Andaman when it sank in Chalong Bay after it struck a concrete mooring block placed in the middle of the approach channel to Chalong Pier. (See story here.)
The same concrete mooring block sank another tour boat with 19 Russians on board for a ‘booze cruise’ nearly a year earlier, with the Phuket Marine Office defending the location of where the morring block had been placed. (See story here.)