ACME Prop for surfing

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Fellow surfers,

A quick update from the summer of surf in Lake Tahoe... We have been trying different setups on our wakesetter LSV 23 2008. See other posts (Wake surfing - lessons from summer...). Anyhow, one of the things that's been bugging us is the fact that the boat doesn't always get up to speed when we have a lot of weight... We have the Monsoon 5.7L. The boat can get to 10 mph but sometimes struggles to get to the 12 mph we like to ride at - it usually can't get past 3300 RPM with WOT. The boat is very sensitive to trim. We usually put 400+ lbs up front (and move everyone forward until we are up to speed) to get the boat to get to 12 mph. Anyhow, I decided to talk with the ACME prop guys and see what they thought. They said that the boat needed to be running at 4000 RPM+ to get into the power band for that motor. I was using a ACME 1235 prop which has a 14.25 diameter and a 14 degree pitch. Jim from ACME recommended that we get the prop modified - reduce the pitch to 12.5 degrees - that way the motor will be at 3800 - 4000 at 12 mph... So I did. We used Thomasmarinepropeller to make the mods. They did a nice job.

I am psyched to see the results - putting the boat back in the water on Saturday and will post an update...

Question - has anyone else made this mod to the prop for wake surfing? Any feedback?

Thanks,

[CrazyTegger]

Fellow surfers,

A quick update from the summer of surf in Lake Tahoe... We have been trying different setups on our wakesetter LSV 23 2008. See other posts (Wake surfing - lessons from summer...). Anyhow, one of the things that's been bugging us is the fact that the boat doesn't always get up to speed when we have a lot of weight... We have the Monsoon 5.7L. The boat can get to 10 mph but sometimes struggles to get to the 12 mph we like to ride at - it usually can't get past 3300 RPM with WOT. The boat is very sensitive to trim. We usually put 400+ lbs up front (and move everyone forward until we are up to speed) to get the boat to get to 12 mph. Anyhow, I decided to talk with the ACME prop guys and see what they thought. They said that the boat needed to be running at 4000 RPM+ to get into the power band for that motor. I was using a ACME 1235 prop which has a 14.25 diameter and a 14 degree pitch. Jim from ACME recommended that we get the prop modified - reduce the pitch to 12.5 degrees - that way the motor will be at 3800 - 4000 at 12 mph... So I did. We used Thomasmarinepropeller to make the mods. They did a nice job.

I am psyched to see the results - putting the boat back in the water on Saturday and will post an update...

Question - has anyone else made this mod to the prop for wake surfing? Any feedback?

Thanks,

Wow, that's a lotta weight to require a lower pitch than the 1235!

[PowPowPatrol]

Wow, that's a lotta weight to require a lower pitch than the 1235!

Oh, we are surfing at an elevation of 6,000 ft. Apparently it reduces the power of the engine by about 20%...

[MalibuTime]

Wow, that's a lotta weight to require a lower pitch than the 1235!

Oh, we are surfing at an elevation of 6,000 ft. Apparently it reduces the power of the engine by about 20%...

Time for a supercharger!

Do you mean reducing the prop from 14 inches of pitch to 12.5 inches? I have not of prop pitch described as degrees.

[PowPowPatrol]

Wow, that's a lotta weight to require a lower pitch than the 1235!

Oh, we are surfing at an elevation of 6,000 ft. Apparently it reduces the power of the engine by about 20%...

Time for a supercharger!

Do you mean reducing the prop from 14 inches of pitch to 12.5 inches? I have not of prop pitch described as degrees.

Yes I mean inches. I was under the impression that a degree = an inch - is that right?

[Bobby Light]

Wow, that's a lotta weight to require a lower pitch than the 1235!

Oh, we are surfing at an elevation of 6,000 ft. Apparently it reduces the power of the engine by about 20%...

Time for a supercharger!

Do you mean reducing the prop from 14 inches of pitch to 12.5 inches? I have not of prop pitch described as degrees.

Yes I mean inches. I was under the impression that a degree = an inch - is that right?

No the 14.25 is the diameter and 14 degrees was the pitch. They changed the pitch not cut an inch off all the blades.

[PowPowPatrol]

Yes I mean inches. I was under the impression that a degree = an inch - is that right?

No the 14.25 is the diameter and 14 degrees was the pitch. They changed the pitch not cut an inch off all the blades.

Yes. They reduced the pitch from 14.041" to 12.5". No change to the CUP.

[Bobby Light]

There is a difference between diameter, pitch, and cup.

[MalibuTime]

Right, I was just commenting that I had not seen pitch referred to in degrees. For example, and OJ 475 is 14.25 X 14.5 .090 CUP. 14.25 inch diameter, 14.5 inch pitch, meaning the theoretical distance the prop will go in one rotation is 14.5", and cup, which since I haven't really looked to closely, but would guess the cup extends .090 inches above the blade.

I would be curious to know how they are changing the pitch so much on a cnc'd prop, what the process is to do that.

[PowPowPatrol]

Yes. They reduced the pitch from 14.041" to 12.5". No change to the CUP.

Here's a couple of photos of the prop after the propscan work...

[PowPowPatrol]

I am psyched to see the results - putting the boat back in the water on Saturday and will post an update...

Thanks,

OK, here is the update... The modified prop makes a big difference. We have been surfing for 3 days and the boat has been able to get up to speed every time. At surfing speed (12 mph) the boat is doing 3500 RPM and the engine sounds a lot happier. Prior to the change we were at about 3000 RPM for the same speed. It took some getting used to... Its really fast out of the gate - we had to slow down the takeoff...

We also tested the speed at 5000 RPM - approx 32 MPH.

Interestingly, Jim Thelen from ACME props (who is an awesome resource...) said that they were going to create a new prop for this use case. The prop will be available in a few months and will be called ACME part # 1873. Contact Jim at [email protected].

Highly recommended for wake surfing.

[Ndawg12]

I am psyched to see the results - putting the boat back in the water on Saturday and will post an update...

Thanks,

OK, here is the update... The modified prop makes a big difference. We have been surfing for 3 days and the boat has been able to get up to speed every time. At surfing speed (12 mph) the boat is doing 3500 RPM and the engine sounds a lot happier. Prior to the change we were at about 3000 RPM for the same speed. It took some getting used to... Its really fast out of the gate - we had to slow down the takeoff...

We also tested the speed at 5000 RPM - approx 32 MPH.

Interestingly, Jim Thelen from ACME props (who is an awesome resource...) said that they were going to create a new prop for this use case. The prop will be available in a few months and will be called ACME part # 1873. Contact Jim at [email protected].

Highly recommended for wake surfing.

Wow, I know these aren't speed boats, but 32mph???!!

[Bobby Light]

Dang my boat loaded down at 12 mph gps verified is running at 2500 rpm with HH and acme 537. I think I will stick to my setup.

[PowPowPatrol]

Dang my boat loaded down at 12 mph gps verified is running at 2500 rpm with HH and acme 537. I think I will stick to my setup.

OK... But what Jim from ACME said was that its not so good for the engine to be at low RPM when its under heavy loads...

[Bobby Light]

Dang my boat loaded down at 12 mph gps verified is running at 2500 rpm with HH and acme 537. I think I will stick to my setup.

OK... But what Jim from ACME said was that its not so good for the engine to be at low RPM when its under heavy loads...

Interesting I'll have to look into that but mine seems to be doing fine. I'd hate to see what happens to the fuel consumption if I went down on the prop. I don't think I could handle only going 30-32 either. I can hit 46-50 mph depending on water conditions.

Edited August 12, 2009 by 06vlx