Better prop size?

[SuthernBowRush]

I'm running a 13 1/2 x 15 stalos prop on a 70hp evinrude (old faithful) on a 17ft fiberglass cajun.  My pistons are 140 across the board.  At 5500 rpms my guage says I'm doing about 31/32mph.  I know this prob aint accurate, just wanted to ask a question..

I was told I could use what they call an old speed prop...2 blade.  It wouldn't have any holeshot or pulling power...but it would give me better top speed.  Has anyone found this to be accurate? 

If not, what are my options..I would give up some acceleration to gain some top speed...also, I plan on putting a fin on it so bowhigh takeoffs and porpoising shouldn't be a problem. 

Thanks for any advice!

[Mike Cork]

That's probably max RPM for that motor. Probably don't have a jack plate either?

If you could bring the motor up some, you could go up in pitch on the prop. You'll loose hole shot but may pick up some top end. It's not going to be significant though. Maybe a couple MPH.

By going with a bigger pitch prop, you'll lose RPM, but if you can raise the motor up you'll gain some of that back.

I don't know the first thing about a 2 blade prop but I'm thinking I've only seen them on speed boats that don't have to plane out and without the lift of at least three blades you'd have some handling problems with a 2 blade.

The best prop I've ever used with Evirude/Johnsons is the Raker.