Well, tried my new Quicksilver 12P prop on my boat yesterday, 4 people total weight app. 700#, 15 gal fuel with big cooler, tackle box, etc,etc,,,,, Findings are, the 50hp got us up on plane pretty good & top speed(GPS) was 29/30mph @ 5400rpm, a 400 rpm gain over my old 14 P prop. Funny...