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Okay....the Yamaha man says my 40hp 4s wot rpms is 6000.

I am getting 5400 tops, but maybe a little more with some trim adjustments.

Prop....a 3 blade SS 10.5X12.

If I am to get another prop, I definitely want a 4 blade.

What say ye, boating Gurus?

Try raising the motor up one hole at a time before you start buying new props.

RC wrote:Try raising the motor up one hole at a time before you start buying new props.

Thanks, I have a jackplate.

Definitely sounds like you could step down some in pitch. I don't know if you have considered it, but I believe a 4 blade might be nice (you are running a tunnel, correct?). If you end up wanting to get rid of the 12p, lmk. I have a f60 with a 15p and it is over propped with a 5200 wot... I know power tech can make their props in a lower pitch than listed. The 4 blade might yield you some additional height as well as less blow out/ better hole shot. Only disadvantage is a top end hit, but you may not be at a loss as you have some revs to work with. FWIW my f60 is making peak torque at 5500... I doubt the 40 is too far off that mark.

Good Luck!

My 17.5' G3 is at 6000rpm with a full load "including two 200+ men" with a 10 1/2 X 14 SS prop from Propco on my f40. I have to watch it when by myself or I will over-rev the motor!! Unless your boat is a lot heavier than mine, you still need to work on getting the trim right "a 12 pitch would blow mine all ta hell and back"
PS: All of their props are cupped and that makes a heck of a difference

Wevans my bote hull weighs over 900 lbs. Add 2 200+lb men, ice chest, tackle, motor, and it's getting on up there. Maybe the weight is the factor in my difference in rpms from yours? You have more pitch, and are turning more rpms. My top speed with 2 lardazzez is 27 on gps.
PT said by the math I should be at 30.1mph.

Is propco where they are all cupped?

Tincan I called PT and got the suggested prop 4 bladed. Then I called Propgods and they quoted me the same PT prop at $60 less!

I am gonna run some more and try a trim trick that Barhopr suggested and get a better fix on my rpms before buying something.

Thanks for the help, and I appreciate any info you can submit!

My hull is 920 lbs, two 200+ men, ice chest, fuel tank in the transom, livewell in the transome, batteries "2" in the transome I average between 28 and 32 mph "depending on wind and water conditions"

Wevans is your motor a 4s ? I called propco and they don't make a 4 blade for a 40hp. She insinuated that the 4 stroke didn't have the power for a 4 bladed prop. I assume she means low-end torgue.

4 stroke, 40, 3 blade SS and I do doubt that it does have the low end torque to turn a 4 blade very well, but then, my 3 blade puts me on plane in 15 to 20 foot by myself and 50 foot with another rider The Bob's Stabilizer plate does wonders for your hole shot

Your hole shot sounds close to mine although mine might take a little longer with the suction from the tunnel.
I was told by one fellow that with the low power motor I might not see my $ worth in changing props.
But now you have me thinking that a Bob's stabnilizer plate may be an answer for me.

The Bob's stabilizer plate I had on my 40 h.p. Merc was awesome.

The man at Propco suggest I get a 12 X 11 3 blade SS. This will give me stern lift (hole shot) and increase my rpms, so says he. This may be the route I take before adding a Bob's plate.

Gonna run the bote again and make sure of the rpms and call Propco back.

birddog wrote:The Bob's stabilizer plate I had on my 40 h.p. Merc was awesome.

Is your avatar a video of when you were a girlyman dancer in college?

Highschool