Hello,
As a C47 owner I do the following:
When going to windward 38-50° AWA:
boat speed 0-5kn, both boards 100% down.
boat speed 5-7kn, both boards 75% down.
boat speed >7kn, both boards 50% down
Max boat speed at 40°AWA is around 9kn.
If choppy conditions I raise them a bit earlier. The risk is not tripping the cat, but to brake the boards.
Both boards should be set symetrically and you might need to luff (25-30° AWA) a bit to lower the
water pressure on them before adjusting. Especially if saling thight and faster than 6-7kn.
50-180° AWA: both boards fully raised. If the
wind is light and boat speed low, I keep them down until 60°AWA to reduce leeway. In high following seas I lower them 30-50% to help the
autopilot.
When
anchoring or manouvering in thight quarters with some
wind, I always put the boards down. Sometimes I keep them down at
anchor to limit the cat to swing. She will stay in the wind like a
monohull.
This might seem like a lot of hassel but in fact most of the time I set them once and this small effort makes the sailing so much more pleasant.
While motoring one day in very flat seas I totaly lowered both boards to messure the loss of speed, only 0,1kn.
Enjoy the ride.
Thomas