On our boat we use a Monitor with the corrugated plastic vane (like a reality for sale sign) for wind under 20 knots. It is larger than the standard wood vane and way more sensitive. The issue in light air is boat speed. If the water is not passing the watervane at at least 2 knots there is not enough force to turn the wheel and steer the boat. Of course individual boats could take more or less force to move tiller or wheel.