The Spirit of B.C. will be rerouted around Active Pass during strong tides until one of its four engines is repaired. (BC Ferries)

A problem-plagued B.C. ferry that needs a major engine overhaul will not be allowed to travel through a narrow channel during periods of strong tidal currents while it awaits repairs.

The Spirit of B.C. is now operating on only three of its four engines after a breakdown last week, BC Ferries said Tuesday.

Last month the ship had to be taken out of service on the Tsawwassen-Swartz Bay route between the mainland and Vancouver Island to fix a damaged propeller, causing sailing cancellations and delays.

The company says the ship can maintain its schedule on three engines except during certain tides in Active Pass, when for safety reasons the ferry will take a longer route that will add 45 minutes to the trip.

The narrow channel of Active Pass has some of the strongest currents on the south coast, and was identified in a 2007 safety audit of BC Ferries as one of the highest risk areas of operation.

"The route through Active Pass [where typically two Spirit-class vessels are transiting at the same time] is particularly strategic. We recommend that BC Ferries, as part of a formalized risk management process, undertake an assessment of the degree of risk associated with the current practice of BC Ferries' vessels passing simultaneously in Active Pass," former auditor general of British Columbia George Morfitt wrote in the 2007 report.

The ship will be in service during the busy Thanksgiving weekend and then removed for four weeks beginning in mid-November. The Queen of Vancouver will be brought in to replace the Spirit of B.C. during the engine refit, BC Ferries said.

At 167 metres in length, the 15-year-old Spirit of B.C. is one two Spirit class vessels on the Vancouver-Victoria route that are the largest ships in the BC Ferries fleet.

With files from the Canadian Press