Hi chips. Great boats, those chico 30's. I did a auckland
to gisboune race
on chubasco (a wooden chico 30) when I was 15, and the delivery
up from napier. It was a great trip with a good crew that I will never forget.
Anyway, ive used trim tab windvanes on three boats. They work fine for open water offshore
but tended to oversteer downwind, and arent quite as precise as a servo pendulum in shifty conditions. I would be slightly worried about oversteering on the fin keeled chico. Two of the boats I sailed on where long keeled, and the other had an auxilary rudder system exactly the same as pinguino's (also made by Ini). So all had better natural damping than you will have.
Dont let this completely put you off, but I wouldnt modify the rudder too much initially. Look at something like the quartermaster trim tab system which is all above water
and just clamps onto the top of the rudder. If you make the trim tab hinge up it would be easy to lift
out of the water for motoring. This stops any vibration and heavy steering
that the trim tab can cause, and also stops weed growing on it when leaving the boat.
Some tricks are to use bungy to help limit the rudder oversteer downwind, and make the feedback adjustable so you can desensitise it for downwind.
Have you thought about just building a belcher OGT. With only the horizontal windvane
direct to the tiller. Simple and no underwater parts
. It would be easy to modify into a wind
unit for a trim tab, or servo pendulum if you decided you needed more power down the track. I recall
the chico rudder being very nicely balanced so it would be perfect for this system.
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