B.C. Ferries has cancelled 35 sailings on its busy Swartz Bay-Tsawwassen route through Sunday due to mechanical issues.

The operator says there is a mechanical difficulty with the main engine’s propulsion system on the 60-year-old Queen of New Westminster, which was pulled from service Tuesday.

“We appreciate your patience and apologize for any inconvenience you may experience as a result of these cancellations,” the company said in a service notice.

B.C. Ferries has added two sailings for Wednesday evening — one departing Swartz Bay and one departing Tsawwassen — on another vessel to assist with traffic volumes.

It says people affected by the cancellations will hear from B.C. Ferries’ customer service centre and will be notified if they can be moved to an alternative sailing or if their booking must be cancelled.

Customers will be refunded in the case of a cancellation, according to B.C. Ferries.

B.C. Ferries vessels have experienced various mechanical issues causing cancellations in the past. In early 2024, it announced it was taking steps to ensure all vessels would be set to sail successfully this summer  — after the 2023 season was plagued with cancellations.

The ferry operator said it planned to do annual repairs within a shorter timeframe and would replace problematic rotors in three of its vessels in an attempt to avoid cancellations during the peak summer period.

CBC News has contacted B.C. Ferries for comment.