Hi Melanie: Easy part first – servo pendulum wind vanes are the most powerful and what we have preferred ourselves (much more on the subject of wind vanes in our Offshore Cruising Encyclopedia).

As to what would be best for an O’Day 22, that is a tougher question. Because of the small size you might need to find something a little different – the typical wind vane might be too big. I’d check with some of the vendors to see what they recommend. One of them is Scanmar at http://www.selfsteer.com/ Good Luck – Steve