Sailing in gear or in neutral?
A freewheeling prop is doing what it does best, operating efficiently in a stream of water. This is NOT what you want while sailing. It has a solid grip on the water and is converting energy from your sails into revolutions in the transmission. This spinning robs horsepower from forward motion but can only slow you down if there is JUST ENOUGH wind to make hull speed, or less. If you''re in twenty knot winds, drag or not, you''ll reach top speed. Then you have to concern yourself with what other posters have said: does it have a negative impact on your running gear? That is more than a little possible, but only a truely knowledgable investigation into your transmission can say for sure. For instance, it will not seriously hurt a Hurth gearbox (like mine) but it''s not really good for it, either. Spinning your output shaft, bearing, gears, etc., is just unneeded wear and tear. I leave my gearbox in gear. Reverse, only because that''s what I''ve heard, though it does seem to me that some gearboxes can rotate in gear in the direction opposite their powered drive, for some reason. Maybe ratchet clutches or something. My two cents.