Police are investigating a fire which forced fire crews to scuttle a $1.5 million cruiser in a Sydney marina packed with millions of dollars worth of boats last night. The 17-metre Riviera motor cruiser, called Chairman Two, became engulfed in flames at the Ferguson’s Marina on the eastern side of the Spit Bridge about 8pm. Robert Bew, manager of Harry’s fish cafe by the bridge, told smh.com.au fire crews arrived at 7.30pm but more than three hours later the boat was still ablaze. “About 11pm I went down to have a look and it was still blazing,” he said. “There was fire coming out of the front of the engine room.” He said the boat kep catching alight. “There was a lot of flame going on and a lot of black smoke and grey smoke.” After getting permission from the boat’s owner and the Port Authority, fire crews deliberately sank the burning vessel to prevent surrounding yachts from succumbing to the same fate. Booms were placed around the scuttled boat to reduce pollution, a NSW Fire Brigade spokesman said. No one was on board the boat at the time of the fire, he said. Forensics experts and fire investigators are continuing their inquiries into the cause of the blaze. Insurance teams are also inspecting the site today.