BC Ferries has two Spirit Class vessels that were built in the early 1990s for the Tsawwassen-Swartz Bay route. (CBC)

BC Ferries passengers faced delays Saturday on the busy route between Tsawwassen and Swartz Bay after a vessel was pulled out of service Friday because of a fire.

The Spirit of Vancouver Island was sidelined early Friday after a standby generator caught fire.

No one was injured, but BC Ferries said the vessel — one of four on that route across the Strait of Georgia — is expected to be out of service for at least a week.

The problem caused significant delays for passengers Friday and continued to cause long waits for passengers Saturday, even though BC Ferries added sailings to handle the backlog over the Thanksgiving holiday weekend.

For most of the day, there was a three-sailing wait for passengers going from Tsawwassen on the mainland to Swartz Bay on Vancouver Island.

Heading the other way, passengers travelling from Vancouver Island to Metro Vancouver faced only one-sailing waits for most of the day.

BC Ferries said it would add additional sailings as necessary until the vessel is back in service.

On Sunday and Monday, an extra 10 p.m. sailing was added on the route from Tsawwassen to Swartz Bay, and an 8 p.m. sailing was added from Swartz Bay to Tsawwassen.

In a release, the company said it would not be accepting assured loading tickets on the Tsawwassen-Swartz Bay route on Monday because of the reduced capacity.

The Spirit of Vancouver Island is one of four ferries on the route, which connects Metro Vancouver with Victoria on Vancouver Island, but one of only two Spirit Class vessels, the largest in the fleet.

They were built in the early 1990s to sail the Tsawwassen-Swartz Bay route. Each can carry 410 vehicles and 2,100 passengers. The vessels underwent extensive refits in 2005 and 2006.