Lets talk prop

[bryancm]

I know this topic has been covered in great lengths, so I apologize for the yawner of a discussion.

I currently have an acme 515 - LH 1 1/8 13x12 on my 21V. It is a big banged up and I am about to buy a new one.

We don't do much except for surf and cruise. I usually surf at around 2400-2500 rpms, ~11mph, 1500lbs plus a few peps and I feel like my boat is straining a bit sometimes. I am almost certain that I have the black v-drive. I am not sure if a new prop will help, but it seems like I could get something with a little less pitch, run slightly higher rpms, and take some of the resistance off the drive.

Also, my current prop was bent up a bit and I fixed it somewhat with a crescent. How hard on the shaft packing and drive shaft is it when a prop is out of true?

Does anyone have any thought on this or recommendations for a good surfing prop?

Thanks and happy 4th!

[duffymahoney]

I would say acme 911 is the best surf prop for 1:1 v-drives which you have if you are running a 515. You should always get props repaired if they are damaged. They will wear the shaft strut and packing quicker.

[chpthril]

The ACME 653 (13 x 11.5 w/.060 cup) is a good upgrade to the 515. But its always a good idea to confirm what your final drive ration is (probably 1:1 since you have a 3-blade on there now). It never hurts to also contact the experts at ACME for their suggestions. They will ask all the basic questions about boat size, HP, how you use it and elevation of the lake(s) you run on. From there, they can give you some options.

[bryancm]

Great stuff. Those two are what I have been debating. I boat around 700ft, 350 mag (315 hp), 21fter, black 1:1 v-drive.

Has anyone ever felt a weird, intermittent, faint vibration with subtle noise when surfing? I cant say I have ever noticed it before, but I am running with a bit more weight lately. That is why I have been hoping a new prop with less pitch could fix that problem. You can't hear or feel a thing when running at any RPM without ballast and surfing.

Thanks

[laserfish]

I only feel that vibration when we are on rougher water. Assume it is air coming under the boat with the waves. Never feel it on smooth water.

[bryancm]

Interesting! Now that you mention it, I have only noticed it yesterday when it was very busy and rough and another time on Lake Travis, again pretty rough. Hmmm, you might be on to something there.

Thanks!

[bigdaddy_houseboater]

The ACME 653 (13 x 11.5 w/.060 cup) is a good upgrade to the 515. But its always a good idea to confirm what your final drive ration is (probably 1:1 since you have a 3-blade on there now). It never hurts to also contact the experts at ACME for their suggestions. They will ask all the basic questions about boat size, HP, how you use it and elevation of the lake(s) you run on. From there, they can give you some options.

Cheap is right. The V-drive will love the 13x11.5, unless you need 40 mph for footin or something like that. Better surfing, good low-end torque.

[bryancm]

I'm pretty torn between which prop to buy. I plan to go pick one up today. I called, hoping only one would be in stock to ease my decision, but they have both. I can return it though, so no biggie. Does anyone know the difference in RPMs one would notice going from a 515 to the 653 to the 911? Also, do you think I will notice much difference going from 12" to 11.5" pitch with the cupping change difference of only .02(515->653)?

[bigdaddy_houseboater]

I'm pretty torn between which prop to buy. I plan to go pick one up today. I called, hoping only one would be in stock to ease my decision, but they have both. I can return it though, so no biggie. Does anyone know the difference in RPMs one would notice going from a 515 to the 653 to the 911? Also, do you think I will notice much difference going from 12" to 11.5" pitch with the cupping change difference of only .02(515->653)?

FiveFlat should know, or at least be able to guess pretty close. he made a very similar change.

[Fiveflat]

I went from a 13.5X13 to the ACME 911. I have the 1:1 Vdrive. I used to surf at around 2600RPM at 11.5MPH Now with the 911 I'm up around 3200. I might have just a little more ballast than I did before, but that's because this new prop allows me to. I couldn't run the kinda ballast I have now with my old prop.

Wakeboarding, my son doesn't use any ballast... yet. He used to ride at about 2400RPM, now he's at 2900RPM at 22.5MPH.

[bryancm]

Thanks FiveF, That helps a lot. It would appear you gain roughly a +200rpm increase per 1" of pitch decrease. If you went from a 13" to 10.5" and it wasn't too crazy, I might go with the 911.

[Fiveflat]

When I cruise home from riding I usually just run up around 3000 RPM (emptied ballast etc.) and I'm cruising at around 28MPH.

If you don't care about going much over 35MPH and want to get out of the hole in a hurry when weighted, get the 911.
But like CHP mentioned - make certain that you have the black 1:1 vdrive first!

[bryancm]

I definitely have the 1:1 and I'm rarely in much of a hurry. Also, I will still have the 515 that is getting repaired for a backup.