Prop recommendation for C90 TLRY Yamaha.

I just bought a 17' 4" Sailfish center console with a mod-v hull. The boat has a C90 TLRY Yamaha 2 stroke engine that runs like a top. The prop on the motor is pretty worn out and I am new to boating and would like recommendations on what prop I should purchase to put on it. With two people in the boat, 30 gal of gas plus moderate fishing gear the boat tops out at 4500 RPMs going 28.9 knts. I am told that I should be up around 5000 or better RPMs WOT. The prop on it now is a solas 13.25 x 17 aluminum prop. Any suggestions would be greatly appreciated.

Re: Prop recommendation for C90 TLRY Yamaha.

Your WOT rpm range being 4500-5500; I'd say that you would benefit from a 15" pitch prop. You can expect to gain 300-400 rpm. Your motor's horse power is rated at 5000 rpm.

Another Solas aluminum would be a good choice.

Re: Prop recommendation for C90 TLRY Yamaha.

Would you recommend the aluminum over a stainless prop?

Re: Prop recommendation for C90 TLRY Yamaha.

moultrieboater said:

Would you recommend the aluminum over a stainless prop?

Click to expand...

Solas squeeze cast aluminum props work as well as some SS props, at a fraction of the cost.

Re: Prop recommendation for C90 TLRY Yamaha.

A quick check of your setup it appears a 90 should run around 5400 rpm and speeds 39-44 mph.
Of course your beat up prop could be slowing things down but it does appear a 17" prop is closer to normal for
for all up weights 1225 to about 2400.

Re: Prop recommendation for C90 TLRY Yamaha.

steelespike said:

A quick check of your setup it appears a 90 should run around 5400 rpm and speeds 39-44 mph.
Of course your beat up prop could be slowing things down but it does appear a 17" prop is closer to normal for
for all up weights 1225 to about 2400.

Click to expand...

Is there anything else besides the prop that could cause it to run at lower RPMs? Even with the worn prop, shouldn't I be able to reach the 5400 RPMs if it is pitched correctly?

Re: Prop recommendation for C90 TLRY Yamaha.

There's lots of things that could cause poor performance.
I do think you should start with a new 17" prop The Solas Amita 3 blade has a good reputation.
Check that the throttle opens all the way.You could do a compression check.Minimum 100 psi and within 10% between cylinders.
The antivent plate (just above the prop) should be even with or slightly above the bottom of the transom.
Does the boat respond to up trim?
Does the boat seem to lay down like its glued to the water?
Is there a hydro foil(whale tail) on the motor
Sometimes as a boat ages the Flotation foam under the floor absorbs water.
Boat may seem to sit low in the water and hole shot seem to be slow.