Queen of Oak Bay lost power to its engines just as it was approaching the ferry terminal at Horseshoe Bay. Investigators are examining the possibility that a missing bolt may have caused the engines to run faster than normal, thereby tripping a mechanism designed to prevent the engines from revving too high.
No one was injured in the June 30 accident, but 27 boats at the marina were damaged or destroyed as Queen of Oak Bay came ashore bow first. The ferry sustained damage to a fender and propeller.
Canadian Coast Guard divers spent three hours searching for people who may have been at the marina, but everyone was able to get out of the ferry’s path safely.
The 457-foot 6,968-gt Queen of Oak Bay was entering Horseshoe Bay, north of Vancouver, on its return trip from Nanaimo, Vancouver Island. The incident occurred at 1010 when, according to British Columbia Ferry Services, a bolt connecting the engines’ governor to the fuel rack fell out. Without the governor, the fuel supply to the engines increased and the engines began to turn faster. The overspeed mechanisms then engaged and shut down the engines.
When the engines shut down, the vessel was approaching its landing pen at Horseshoe Bay. Investigators are trying to determine the exact distance of the ferry from shore when the engines stopped.
“It couldn’t have happened at a worse point of the voyage,” said Deborah Marshall, director of media relations at BC Ferries. “He was probably within two minutes of docking.”
The ferry drifted to the right of the berth and struck neighboring Sewell’s Marina at a speed of 4 knots. The marina “is right next to the dock,” Marshall said.
Queen of Oak Bay was carrying 544 passengers, 34 crewmembers and 184 vehicles at the time. Nobody aboard the vessel was injured.
The ferry’s master warned passengers to brace themselves for impact and sounded the horn multiple times to warn those ashore, Marshall said.
“There were a few people on the (ferry’s) dock,” she said. “They heeded the warning and ran off the dock.”
The vessel had been back on its regularly scheduled run for 13 days, following six months in a shipyard. The $35 million “mid-life upgrade” to the 24-year-old vessel included “major mechanical work,” according to a company press release.
An investigation found that a cotter pin that normally held the nut onto the connecting bolt was missing. An investigation is underway to determine if the pin was removed or lost during the shipyard period.
“That piece of machinery was worked on during the refit,” Marshall said. “We didn’t find the pin after the incident. It wasn’t laying on the deck or anything.”
Passengers remained onboard for nine hours following the incident while divers searched the water and conducted inspections of the ferry’s hull.
The vessel was moved with the assistance of tugs to its berth at 1730, and then to Vancouver Drydock at 2100.
The double-ended 11,840-hp ferry lost both of its engines almost simultaneously. It has two opposing main engines running into two interconnected gearboxes. The gearboxes turn two shafts, each running to opposite ends of the vessel.
The vessel, which has controllable-pitch propellers, was in its constant-speed mode as it approached its berth, said Mark Collins, vice president of engineering at BC Ferries. In that mode, “both engines, gearboxes and props are rigidly interconnected” at a low rpm, and the propellers are used to adjust the vessel’s speed.
Although the bolt connected the governor and the fuel rack on the working aft end of the vessel, the pneumatically controlled mode that kept the engines in sync shut them both down within seconds of each other as the system tried to compensate for the ungoverned engine and open fuel rack.
“It just carried the whole propulsion system (into overspeed),” Collins said.
Repairs to the ferry included the replacement of one propeller blade, the “cow catcher” bow fender that touched bottom and some scratched paint on the hull.
BC Ferries operates a fleet of 35 ferries between lower British Columbia and the 12,000-square-mile Vancouver Island.