prop pitch?

i have a 17 ft express h51 with 90 hp yamaha. I am currently running 44 mph at 5500 rpms with a 17 pitch prop. If i trim it out right it runs tach up to around 5800+. Asked the guy at the local boat shop about putting a 21 pitch prop on it and he laughed. Said it would take forever to plane out and i would be unsatisfied with the performance. I thought i could put a 21 on it and still run around 5400. But not well educated props.

You would gain more top end and have a loss in your hole shot......
The only real way to find out is to try it.

[mgnorman1956]

21" is probably too much prop. try 19"