New 258′ cable ferry for British Columbia

In late November, BC Ferries began work on a new cable ferry at Seaspan’s Vancouver Shipyards in North Vancouver, British Columbia. 

The new 258’×56′ vessel has room for 50 vehicles and 150 passengers, which is the same capacity as the 36-year-old, conventionally powered Quinitsa, which it will replace on the run between Buckley Bay and Denman Island on the eastern shore of Vancouver Island.

BC Ferries says the new cable ferry will be capable of a top speed of 8.5 knots with a normal service speed of 7.5 knots and it will save about $2 million per year in fuel and labor costs, and over $80 million over the life of the boat compared to the Quinitsa. The Quinitsa is operated by a crew of six, while the new ferry will only require a crew of three.

With a crossing of 1,900 meters (1.2 miles), the cable ferry operation will be the longest of its kind in the world. It will also be the first cable ferry operated by BC Ferries, although there are 65 others in operation in Canada, including several in British Columbia. 

The new cable ferry will have two guide cables, one on each side, and one drive cable in the center, all 1 5/8″ in diameter. All three cables are secured, under tension, at each end of the run. The cables lie on the seabed and rise and fall with the ferry as it crosses.  

The drive cable, also known as the traction cable, wraps around a bull wheel in the center of the boat. The bull wheel is turned by hydraulic motors powered by one of two 400-hp diesel engines. As the wheel turns, the cable stays stationary and the boat moves. “It’s like a horizontal elevator,” said John Waterhouse, a naval architect at Elliott Bay Design Group, Seattle, which designed the ferry’s mechanical and electrical systems. EYE Marine Consultants, Dartmouth, Nova Scotia, is the primary naval architect for the project.

Waterhouse said that cable propulsion is very efficient. “You can move a cable ferry with about half the power that you need for a regular propeller boat because you’re not taking mechanical power and converting it to propeller thrust to move the boat,” he said. “Typically, propeller efficiency is 50 to 60 percent, but 100 percent of the mechanical power of the engine is being used to move the boat along the cable.”

The lack of propellers and rudders also reduces underwater drag, making the hull movement more efficient.

BC Ferries says it expects its one and only cable ferry to go into service in the summer. 

— Bruce Buls 

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