"Heavy wind"

[JumbleDuck]

' everything except wave making drag '; I know some Test Pilots and Flight Test Engineers who could do with that tatooed on their foreheads !

It's generally considered a Bad Thing for aircraft to create wave drag, or indeed waves.

 

[Seajet]

It's generally considered a Bad Thing for aircraft to create wave drag, or indeed waves.

http://www.youtube.com/watch?v=zcf4aUdaG0o

 

[JumbleDuck]

http://www.youtube.com/watch?v=zcf4aUdaG0o

Wow. That's what I call a ground loop.

 

[Fantasie 19]

Winsbury,

yes it was called ' sharkskin ' for that reason; don't know about Aussie swimmers, maybe that's their natural finish !

Back in the day when I windsurfed far to much the shaper for the Tiga manufacturer was a guy called Hugues de Turckheim - he produced boards for a fair few years with what was called the Tiga Turbo moulded into the bottom of the board... basically a small step/indentation that was designed to feed in air under the board and supposedly improve speed*... certainly the same kind of thinking as sharkskin......

*I never noticed a difference.... that may have been more to do with my ability though....

 

[alant]

Water density also decreases with temperature so as sea temperature drops presumably the hull will move fractionally easier through it too.

According to this http://www2.volstate.edu/CHEM/Density_of_Water.htm
as temperature drops, density increases.

 

[alahol2]

Except from about 4deg down to zero, which is why water freezes from the surface rather than from the bottom.

 

[alan_d]

According to this http://www2.volstate.edu/CHEM/Density_of_Water.htm
as temperature drops, density increases.

Yes, hence my post #30 above.

I think the phrase "decreases with temperature" may be confusing, some people taking it to mean "decreases as temperature rises" (which is true) while others seem to think it means "decreases as temperature decreases" (which is false). Saying "varies inversely with temperature" would avoid the ambiguity.

Density is mass per unit volume, and as most things expand when they get hotter the same volume contains less mass when the temperature rises (all other things remaining equal), so in general density falls as temperature rises.

 

[JumbleDuck]

Saying "varies inversely with temperature" would avoid the ambiguity.

A pedant writes:

That would imply a 1/T relationship. "Decreases with increasing temperature" would resolve the ambiguity.