The last-minute discovery of a problem with the steel welding on a Washington State ferry serving the San Juan Islands has delayed boat swaps that would have affected both the Triangle and Bremerton routes, according to the Washington State Department of Transportation (WSDOT) Ferries Division.

Previously, the ferry system had planned to loan the Tillikum from the Southworth-Vashon-Fauntleroy route to the Bremerton-Seattle route while the 124-car Kitsap went into dry dock for a “week of scheduled maintenance.” However, the move was postponed after a problem was discovered Friday with the ferry Hiyu that will delay its return to full time service in the San Juan Islands.

The Hiyu has been undergoing maintenance and steel hull repair since December and was preparing to travel north to the San Juan Islands on Sunday when vessel crews discovered a damp area in one of the void spaces on the vessel.

“While the Hiyu was in dry dock, workers welded in new steel hull plates and repaired areas of steel corrosion,” said Paul Brodeur, WSF’s director of vessel preservation, maintenance and engineering. “When we drydock the vessel again and get a better look, we will be able to determine the cause of this new problem.”

Today, the Hiyu was expected to return to dry dock for inspection and repairs, which are expected to take several days. Once repairs are completed, the Hiyu will begin operating on the San Juan Islands inter-island route until mid-May.

Hiyu’s delayed return postpon-ed the other repairs because its absence left “no spare vessels in the system.”

Changes to previously announ-ced service adjustments in-clude:

• Anacortes/San Juan Islands: Until the Hiyu is available, the 87-car Klahowya will continue to provide service on the San Juan Islands inter-island route.

• Fauntleroy/Vashon/Southworth: Because the Klahowya is not available to run on the Fauntleroy/Vashon/Southworth route, the 87-car Tillikum will remain on the route.

• Seattle/Bremerton: Planned maintenance on the 124-car Kitsap will be postponed so the Kitsap can continue to operate on the Seattle/Bremerton route. The 188-car Walla Walla will also remain on Seattle/Bremerton, maintaining the route’s normal vehicle capacity.

Riders are encouraged to check the Web site, www.wsdot.wa.gov/ferries, or call (888) 808-7977 for the latest information.