DSK wrote:

DSK wrote:

Sailboats have a thingamajig sticking down into the water, like a blade,
which goes easily through the water forwards (or backwards) but resists
moving to the side.



Nav wrote:
It's called a keel.


Not always. Sometimes it is called a centerboard or daggerboard or leeboard or
bilgeboard, or in the case of windsurfers, a skeg.

Those are keels too! Keel is an all encompassing term for a plate
projecting from the bottom of a vessel.


A 'keel' is also a structural member...

It's also a mark.

Cheers