In article ,
wrote:

What Marty said is correct most books will have some reference to this lift.
The boats underbody is mainly used to create lateral resistance and helps
push the boat forward when beating and reaching.

But remember the keel/fin/centerboard are symmetrical in shape so you get
equal lift on both tacks. So the keel's lift is negated. There are boats
which have been designed with asymmetrical underbodies which are great for
one tack. I remember a speed record was set using this method. Others have
designed asymmetrical bilge boards and catamaran hulls to give greater lift.

The keel's lift is *not* negated. A symmetrical foil can produce lift
just fine. Some aerobatic planes have symmetrical airfoils.

The moment the boat starts to move a little sideways in addition to
forward, the keel will have a positive angle of attack and it will
produce lift.


Do not sweat it - just sail and enjoy
stu



"Mike" wrote in message
...
In books about sailing, I have read that the keel, going through water,
produces lift in a similar way to a sail. Given that water is a
non-compressible medium, I wonder how this can be so. Has it ever been
documented?


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Michael Hobbs
Minneapolis, Minnesota







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Alan Baker
Vancouver, British Columbia
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