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On 15 Feb 2005 14:34:42 -0800, wrote:
Brian Whatcott wrote:
After numerous ship losses, Plimsoll legislated a hull mark
in Parliament, the "Plimsoll Line" which accounts for salt and fresh,
warm n cool water, beyond which a commercial vessel must not be
loaded. Unaccounted ship losses were much reduced thereafter.
The difference between salt and freshwater displacement and waterlines
makes sense to me, since the salt increases the density of the water,
right? But why is there a difference between summer and winter?
Thanks, Brent
Warm water is less dense than cold water. Water expands more with
temperature than the metals, so a ship sits lower in hot water.
Moreover, water's rate of expansion increases as the temperature
rises. Another factor: water like oil, gets considerably less
viscous when warm, so a hull might be expected to be livelier, and
maybe the swell higher....
Brian Whatcott Altus OK
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