80-year-old Puget Sound ferries forced out of service by cracks in their hullsJan 16, 2008 12:00 AM
Klickitat, one of four Steel Electric-class ferries, leaves the Keystone Terminal on Washington's Whidbey Island. Some of the cracking problems may be related to alterations done to the riveted-construction hulls. (Courtesy Washington State Ferries)
The decision was made in response to problems found during the dry-docking of Quinault. As paint was removed from its hull, inspectors found pitting along the keel and numerous hull cracks. The discoveries prompted Washington State Transportation Secretary Paula Hammond to order the other three Steel Electric ferries out of service.
"Our first priority is to assess the full range of hull pitting in each vessel and determine the extent and the cost of needed repairs," she said. "Depending on what is found, the next step will be repair or retirement of the Steel Electrics."
Quinault went into dry dock in mid-2007 following the repair of cracks in the hull and in the propeller shaft tubes of another Steel Electric-class vessel, Illahee. Both Illahee and Quinault were built in the same shipyard. The other two Steel Electrics, Nisqually and Klickitat, are of similar construction. Hammond said it is likely that hull cracking will be found in all of the Steel Electric vessels.
John Boylston, a naval architect based in Dresden, Maine, who inspected the vessels for Washington state, said alterations done to the hulls probably contributed to the cracking.
"The 80-year-old hulls were completely riveted construction when built, but they were connected to a welded sponson structure about 20 years ago," he said. "Because a welded hull flexes less and a riveted hull flexes more, that connection is a high-stress area. The steel structure relieves itself by cracking."
The hulls may have some other potential integrity problems, he said.
"The peened rivet heads are on the outside of the hull, and because peening stressed the metal, it tended to corrode more quickly. A repair made over time, called ring welding, seals any gap between the rivet and the hull plate by welding. It's not really a great fix, because with a shock, such as from hitting a dock or a rock, those rivets could pop inward," Boylston said.
Boylston has recommended cutting off the old hulls and replacing them with new welded hulls and new propulsion machinery as a faster and less expensive alternative to building new ferries.
"I thought swapping the ferries' houses to new hulls would be a good approach because the Steel Electrics' accommodations have been well maintained," he said. He also noted that the U.S. Coast Guard has said that existing electrical cabling in the superstructures "might not exactly meet existing USCG requirements."
The Steel Electrics were built in 1927 for service on San Francisco Bay. They were sold in 1937 to ferry operators on Puget Sound. Under WSF, the vessels have provided daily service on the San Juan Islands routes and the Keystone-to-Port Townsend route. They are the only WSF ferries that can use the Keystone terminal because of channel limitations.
WSF has been able to put a passenger-only ferry into operation on the route. However, with the four vehicle ferries out of service, commuters have been forced to take long detours.
Full service will not return until the Steel Electrics have been repaired or replaced. A decision on what to do with them is expected in early 2008.Edit Module