I've got a Yanmar 3YM20. It was installed in 2008. I switched over to the Campbell Sailer as it came highly recommended and I have seen comparable Catalina 30's walk away from me with one.Elysium, what motor do you have, I have a universal xp25, best I can get is about 5.4 on a extendo prop...
So far I have tested it out twice - glass calm (marginal current) I was able to do 6.1kts at 3000RPM, and then under reasonable current and winds I was doing mid 5's. Both were while towing a heavy Walker Bay RIB with a 7.5 on it, so I am quite happy!
Still, it's going to take a loooooong time to recoup the cost of the prop. But that's OK.