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.
Cheers Ben
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