On 28 Feb 2006 09:59:34 -0800, wrote:

So a leeboard is a good idea. Maybe something like this:

http://www.abdn.ac.uk/~ltu006/images...s/leeboard.htm

That's what is referred to as a daggerboard. It will work fine as
long as its vertical position remains reasonably rigid when pushed
down into the water and under sail.

Or using a spare paddle like this:

http://www.sailboatstogo.com/img/cat...stabilizer.jpg

Spare paddle will work too, although the rig shown is pretty
elaborate. A simple clamping arrangement that will allow you to pivot
(lower) the board into the water and have it remain fixed in that
position is all that is required. I would prefer a pivoting board,
with a teardrop shape. so that if any underwater obstruction is
struck, the board will swing up without damage to either the board or
the boat. You can also raise the board when sailing downwind since it
is not necessary then.
Whatever choice you make, the board should be long enough to remain in
the water when the boat is heeled in the wind.

Or some modifications to the rudder to make it fatter and a little bit
like a centerboard.

Not really a great idea. It would place the turning moment of the
boat too far aft and make it a bear to keep on course. In a moderately
strong breeze it would cause the boat to try to pivot around its own
rudder. If you use a leeboard (or daggerboard), it should be as close
as possible to the center of the boat so as not to introduce
additional turning force. If you make a simple clamping affair with a
pivoting board you should be able to move it fore and aft to help you
find the optimum location on your boat.
--
jimbok