shouldn't optimized designs be "salt" OR "fresh" water?

shouldn't optimized designs be "salt" OR "fresh" water due the substantial differences in density? It seem quite noticeable in a kayak or rowing scull.

Do nautical CAD programs make calculations for both, and what tends to happen when the numbers get re-crunched?

In related news, I don't see a lot of 'air' in those sails on Peru's Lake Titicaca at 12,500 ft.

 

There is a density differetial but it is not a big one, only two and one half percent. I am pretty sure that the skippers of big vessels like tankers or bulkers take account of the difference. A ship entering the St. Lawrence seaway from the east would begin to draw more water as they progressed toward some great lakes destination. A dinghy or other small boat would not notice much difference I suspect.

I take your remarks about kayaks in fresh versus salt water as a point of interest. A kayak that displaced...say 240 pounds would have a tiny bit more wetted surface in fresh water than in salt. The difference would be insignifigant at 165 cubic inches of displaced volume. Most kayaks would have a surface difference of about one half square foot of surface. The boat would feel a difference of 6 pounds of weight more or less. An expert paddler would feel the difference. Klutz paddlers, like me, probably would not

 

See article on page 2, "Performance differences in fresh and salt water":

http://www.hydrocompinc.com/knowledge/techexchange/tex0502.pdf

Regards,

Don MacPherson
HydroComp, Inc.

 

Hmm, no. That was a link to "Effects of SHALLOW water", not FRESH/SALT.

Have you got another link?

 

See page 2 of the PDF.

Don MacPherson