Need some prop advice

[Skeeter00185]

I have a 1997 50tlrv on a landau 1650 side console aluminum boat. Dry weight is 600lbs for just the hull. I don’t run real heavy. When I got the boat it had a 9 pitch pitch prop that would do 6000+rpm at 25mph. I recently replaced with a 11x12 pitch propr which increased speed to 33mph but I did not bring rpm down at all. I want max rpm to be in the 5500 range and hoping to gain a little speed. Boat jumps right on plane. These are all aluminum props. I was thinking of going to a 11x16 pitch or 11x17. Would this be to big of a jump?

[Jason2tpa]

Rule of thumb for gauging pitch....1" pitch = 200rpm. Increasing pitch decreases rpms and vice versa. I would disregard speed in your effort to dial in the prop since speed is affected by uncon*****able factors such as the environment. You only need to drop 500 rpms, so theoretically going up 4" in pitch should get you there.

[brian3006]

^^^ good Advise^^^^ 16 or 17 sounds about right. might look at cupping the blades as well. helps it hold water at high trim levels or with a jack plate. kinda gives a lil more bite as well.

[99yam40]

since your original prop and the new one both let the motor hit over 6000 RPM, I would think you are hitting a rev limiter .
so you have no real idea what RPM the motor would hit if not hitting the limiter.
but finding someone else with a boat and motor like yours to see what prop they used would be a good idea

or just try another one until you find what you need

I use to be able to find a web site that showed Yamaha performance Bulletins that helped a lot with something like this

[Skeeter00185]

I appreciate all the feedback. I was thinking cause it was limiting it is hard to tell how much to go up, but I thought it was strange going up 3 pitch didn’t bring it down at all.
I am installing a hydraulic jackplate in this setup so I figured it wouldn’t hurt to go up pretty high since I will be able to achieve higher rpm.
also, the 6000rpm is with no trim at all. If I even bump it the boat starts hopping up and down.

[99yam40]

My 1650 Xpress has a C40TLRX on it with a whale tail( or maybe a Dolfin)
I got it in 2008 used.
I took the tail off and ran it once, had to get my 180lb brother to get up on the bow to get the proposing to stop with the motor trimmed all the way in.

I put the tail back on the motor.
to run without the tail I believe I would have had to put some transom wedges in to get the angle of the motor to change enough to keep the bow down