[gurps] underwater sails

[Travis Watkins]

Generally speaking when you are using a sail, you have two parts that
work together to propel you in the direction you wish to go: the keel
and the sail
The keel is much smaller and less obvious because the density of water
is so much higher than that of air, but you are still using the
pressure on one to push against the other and get movement in the
direction you want.

If you were to try to use this same principle under water, you would
need to be at a place where there are two currents moving in different
directions

On the other hand, you could just go with a parachute style propulsion
to be carried along if you are in a water flow that is already going
the correct direction.

There are some 'submersible gliders' as well, but I believe those
mostly just use ballast and changing dive planes to move forward:
http://www.impactlab.com/2008/02/12/submersible-glider-powered-by-thermal-changes/

So I guess it really depends on what you mean by 'sail'

  -Travis

On Tue, Jan 13, 2009 at 4:59 AM, Tom Sparks <tom_a_sparks at yahoo.com.au> wrote:
> Could underwater sails be practically use for propulsion?
>
>
>
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