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Sunday, November 14, 2010

Stability and Trim 101

Pop Quiz time!

When is it a good idea to try to correct a permanent list with variable and unpredictable cargo?

a) When the vessel will be typically sailing on a run with 6'+ seas and 30+ knot winds on the beam, such as a Washington State ferry on the Port Townsend to Coupeville run crossing Admiralty Inlet.

b) When the previous vessel on the same run was notorious for running with the car decks awash due to the sea state, thereby ensuring maximum free-surface effect.

c) When the last vessel of the same type and same name operating in the same state sank due to unseaworthiness. I'm not kidding

d) When hell freezes over.

To be fair, c) is less about stability and trim and more about superstition. But, still, really?

Why does the new state ferry list?
 (Seattle Post-Intelligencer)

Should they call it the Chetzemoka or the "I-Lean"?
The state's much-celebrated new ferry, the m/v Chetzemoka, lists to one side due to the way the vessel was designed, according to the state ferry system.
Washington State Ferries spokeswoman Marta Coursey told Seattle PI the list is due to the location of a single stairway tower on one side. "When the ferry is fully loaded, there is no list," she said.
The Chetzemoka was designed to maximize the number of trucks and oversize vehicles it can carry, she said.
The Whidbey News-Times, which had a thorough report on the new $79 million boat, reports the list is noticeable enough that crew members have nicknamed it the "I-Lean."
The ferry service says the vessel is safe and has passed a "stability test" with the U.S. Coast Guard.
Full Article

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