Replace my bent aluminum prop on my Mariah 22 footer with a 5.7 mercruiser and Alpha one outdrive... holy cow.. What a big difference that was... I didn't know if 21p would be too much for it or not since it would be grabbing a ton more water but it planes nearly immediately and accelerates quickly... My only concern is it tops out about 4400 maybe 4500 rpm(if my tach is correct). Stays on plane down to about 20 mph... Love the prop, service was great and shipping was fast. From Cali to Arkansas in only 3 days Fed Ex ground.