August 19, 2010
WSDOT fixes ferry vibration problem
Changes to propulsion-control software have eliminated unwanted vibrations on the new, 64-vehicle ferry Chetzemoka, the Washington State Department of Transportation Ferries Division said yesterday.
A new date for the Chetzemoka's inaugural sailing between Port Townsend and Keystone has not yet been set, but may occur in October after a minimum of six weeks of crew training are completed.
"In working with Todd Shipyards, we fine-tuned and refined the operating system to ensure that the propulsion components work together for optimal performance," said David Moseley, assistant secretary for Washington State Ferries. "We have a boat that we're confident meets our operating requirements, can stop in the required distances and will provide safe and reliable service."
Refinements to the propulsion-control system software, tested in eight hours of sea trials Wednesday, provided greater control over engine "ramping," which allows the bow propeller to slow the ship as it approaches the dock. Now, the propeller speed is gradually ramped up, as opposed to a more sudden and quick thrust of power. The change eliminated the unwanted vibrations.
"Now we need to get the vessel in the hands of our crews for familiarization and training," Moseley said. This will occur in about a week, he said, after Todd Pacific Shipyards, builder of the ferry, addresses what are described as "a few additional minor items." Then, the state will take formal delivery of the ferry.
Moseley said a minimum of six weeks of intensive training will be used for captains, engineers and crews to become familiar with this new class of ferries, to continue testing its operating capabilities and to practice a variety of emergency and security drills, among other things.
"We believe we have resolved the issue of vibrations, and we'll be looking to confirm that as the Chetzemoka is put through all kinds of maneuvers and situations by our crews," Moseley said. "We're excited to put this wonderful new ferry into service in the Pacific Northwest."