On Tue, 15 Feb 2005 11:45:49 -0400, Terry Spragg
wrote:

Shippers in the past found out that there must be some reasonable
(there's that word, again) value of vessel size and overall weight
including cargo must be considered as some sort of maximum under
some rule somewhere
....
Terry K

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.

Brian Whatcott Altus OK

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

This is because weather is usually worse in winter therefore higher
freeboard required especially winter North Atlantic
wrote in message
oups.com...
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

That could be a factor but I wonder . . .

It happens that temperature has a greater effect on water
density than salinity.

Dominic wrote:
This is because weather is usually worse in winter therefore higher
freeboard required especially winter North Atlantic

I see you're right. thanks.

http://www.onr.navy.mil/focus/ocean/water/density1.htm

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

Brian
Are you sure about this. It would seem to me that the cold water
would be less dense. It expands as it freezes.
JR

Brian Whatcott wrote:
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

I just did some research on this. Sea water density increases as it get
colder until the temperature hits 4 degrees celsius then expands until
it freezes. So don't take a loaded boat too far north.

JR Gilbreath wrote:

Brian
Are you sure about this. It would seem to me that the cold water
would be less dense. It expands as it freezes.
JR

Brian Whatcott wrote:

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

"JR Gilbreath" wrote in message
...
I just did some research on this. Sea water density increases as it get
colder until the temperature hits 4 degrees celsius then expands until
it freezes. So don't take a loaded boat too far north.
----------snip------------

Winter displacement will be more affected by frozen spray than any variation
due to temperature. Not to mention the required antifreeze for the crew.

surfnturf

We don't have to worry about frozen spray like you do but we still use
the antifreeze just to be on the safe side.


surfnturf wrote:

"JR Gilbreath" wrote in message
...

I just did some research on this. Sea water density increases as it get
colder until the temperature hits 4 degrees celsius then expands until
it freezes. So don't take a loaded boat too far north.

----------snip------------

Winter displacement will be more affected by frozen spray than any variation
due to temperature. Not to mention the required antifreeze for the crew.

surfnturf