any bad experiances with wheel autopilots?
Paul, one finite limit on what a wheel pilot can take is the building weather helm aboard many boats as the winds build. But as you point out, semi-balanced rudders don''t load up as much and present less force opposing steering control by the pilot. But another source of opposing force is the sea itself as swells roll past the underbody, torque the hull in one direction or another, and also directly impact on the rudder. This becomes especially noticeable in heavy seas on and aft of the beam, and doubly so in cross swell conditions. Rudders are sized to control the hull form, seas act on the larger hull form and its rudder, and lots of force can be generated at the helm.
You asked about experiences with wheel pilots: I found my Navico (now Simrad) wheel pilot to be a big disappointment as multiple copies of the same molded parts didn''t fit and there were contact wiring problems in the push buttons which I finally gave up repairing ''in the field'' and returned to the mfgr. It now sits under the V-berth. I currently use a CPT sold these days by Scanmar, which needed a motor change to operate properly on both tacks, also done by the mfgr. My conclusion from these two experiences is to buy from a source where returns aren''t a problem, work the pilot very thoroughly immediately after purchase, and don''t expect it to handle all conditons. That''s one reason why we also sail using a wind vane.