My WindPilot Pacific Plus auxillary rudder vane will steer the boat almost from zero knots on up. I fabricated a corrugated plastic 8"x4' wind vane for light air use cause the plywood vane wasn't sensitive enough in light air. Uncanny how little wind and boat speed it works in.

My old Westsail with an Aires would also self steer with almost no way on or wind. Pendulum servo vanes work very well with tilller steering because there is no wasted effort from the drag of all the pulleys and wire of a typical wheel system.

Depending on how well your rudder is balanced and drag on the wheel system, a pendulum servo may or may not work well with a wheel. The Monitor that I originally had on my Pearson 35 didn't work for beans in light air with the boats unbalanced barn door rudder. Had to get boat speed up to about 4kn to get enough water flow over the servo rudder to turn the wheel and steer the boat. Know if I'd had a tiller, the vane would've worked just fine. Other boats up to 50' or more have reported they steered fine with a pendulum servo system and a wheel.
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