best prop for GT40 with PCM trans.

My friend here has one of this MC hulls they make here in Argentina, and Prostar 195 I think, it has PCM mechanics, Ford GT40 with the power plus transmission 1.23:1. what are the best ACME propeller options for this setup for pulling around 3000lbs?

What year?

Hey Karl, you're the guy for this task, it's the Prostar hull from 1997 I think, the one a bit shorter than what became the first X-Star, the thing is this one is with the PCM reduction gearbox, what my friend needs to find out yet is the shaft diameter and the cleareance between the tip of the shaft to hull.

This on3 is odd. I also need to know the clearance between the tip of the shaft and the rudder. This is one of the boats that can be difficult. On a few they used a slightly longer shaft that presents clearance issues. Malibu and CC both did the same thing in the same era - during the change over from 1" to 1.125" shafts.

Karl, I'm still waiting for my friend to confirm but I'm pretty sure they copied (as they did with the hull) all measurements from the MC, they just changed the engine/tranny combo.
They had some turning issues with this particular boat (they didnt count with the tranny reversing prop rotation) so this one was the only ever made with this setup.
Yet I'm waiting for my friend to confirm actual propeller size.

Actual propeller is an OJ 13.7x15.5

Distance from prop bore to hull is a little bit over 8 inches.
From prop to rudder 4 inches.

Boat actually develops 3200rpm at 23.5mph with over 2800lbs. Top end isnt important, could use better holeshot and turn some more rpms at boarding speed (+200)

Right hand or left hand prop? You can tell by which way the prop spins to propel the boat forward at the top of the swing. Since you reported it as a opposite rotation, it would likely be a RH rotation.

Likely 1579 would be the best match.

Karl, what would be the difference between the 1579 and the 1631? I have another friend considering those for his Malibu V-ride.

best bet for you guys is to call acme, before i bought my prop i spent a long while on the phone with them and they were beyond helpful even though i wasn't ordering a prop from them directly. best of luck.

Jeff

oops. RH - 1464 for the 195 under discussion.

the 1631 has more cup. Cup is like extra pitch at higher RPMs. Say you want low end hole shot and still want to barefoot or slalom, you get extra cup. Not a perfect solution, but is is a good compromise. Cup begins to be noticed at about 2,000 prop rpms.

I am an ACME dealer. One of the top 10 by volume.

Karl, it would be an RH since it has a PCM 1.23:1 reduction gear, it does reverse prop rotation right?

You are a propeller guru!!!

Yes. If you back up and the stern of the boat goes left, you have a RH prop. If your boat goes to the right, you have a left hand prop.

Do you prefer this 1464 or 1236 over the 470 ACME reccomends?

call skidim they will have every answer for you.

Completely different approaches. The 470 is a 1" bore. Please verify. The boat is in the transition era and it could be either.

Assuming a 1" bore - the 1598 would be my choice. I tend to me more aggressive than Acme in my approach to wakeboarding.

Increased diameter increases the load on the motor. Increased pitch increases the load on the motor. Increased pitch increases the load on the motor. You also gain thrust and speed. Bigger diameter props, within the torque curve, allow you to keep the speed constant than a smaller diameter prop. It is a curve, and not a linear progression, however.

That is why you can talk to three prop experts and get four different opinions. All will be "correct" to a point. The last 3% is up to you to determine how it feels on your boat.

My advantage is that I have been a wakeboarder since 1983.

Karl I'm sorry for all this mix up, bore is 1 1/8. 13.7x15.5 RH 4blade(OJ 444 I think) is what my friend just tore apart.

I'm leaning towards 1236 or 1464.

Dhtige, Karl is the propeller guru on this site, he has proven more knowledgeable than the people who make this props more times than I remember.
He sells this props, but he always steps out to help, like this time, and in any post he tried to sell me one. thanks Karl.

13.50 x 14.25 .150 cup - 1236
13.50 x 14.25 .105 cup - 1464

I would recommend the 1464. The bigger cup I think would be too much for your engine.