I have a 1999 Merc 9.9. I had standard Merc aluminum prop. I have it on a 1996 Avon 12 foot RIB. The boat is short but very heavy; Hypalon with a thick hull. With standard prop I got 21 to 22 mph on my Garmin good hole shot and quick to plane despite being very stern heavy. With this stainless Solas 11 pitch whole shot not as good, but top end now 27 mph. I was very impressed. Why do I need a stainless prop on my dingy...that is something else entirely. Very well made prop. This is actually the second Solas Saturn I have owned.