Prop advice

[SuperSam]

I am looking to get a new prop since my boat struggles to plane when running 1000-2000lbs of ballast like I do when surfing. I have a 1989 supra saltare with a 351pcm with1.23x1 transmission the current prop is a 14x14 oj at WOT I run about 4100rpms and around 32 mph with full tank of gas and 500lbs on board.... oj props suggested a 4 blade 13x14 and acme suggested a 3 blade 13x14 what have people experienced? I want to make sure I get an increase in rpms by about 400 and be able to plane out with a full boat. Thanks for the advice!

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[crystal waters]

Get another opinion.
Speak to other prop mftrs and also to SkiDim.
IMHO a four blade will get you out of the hole stronger and quicker but I cannot comment on the increase of Rpms.
If anythng , I would think a three blade would have the potential for higher Rpms .
A bit of an oximoron if you will!

[Salty87]

I agree with Mr Waters. While Acme knows all about their props and the same for OJ an unbiased third party will know about them both.

Nettles Props in Austin is my recommendation. Great folks and very informed.
http://www.nettleprops.com/

[SuperSam]

So I talked to skidim and they they thought the 13x14 would be a good choice but also suggested the acme 470 12.5x15 because a lot of people that own nautiques seem to like it that have the same transmission and engine...I just want to make sure that I get something that can get me up to 24 mph even if I got 2000lbs or more in the boat I dont care about much speed over that. Im not exactly sure out of those three which I leab towards

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[crystal waters]

All you can do is gather all the info you can, then make the best informed decision you can and frankly sometimes your gut feeling counts for a lot having down your homework.
The folks at Ski Dim know their stuff based on all of my experiences with them.
When I went from a 3 blade to a 4 blade I talked to all the major prop suppliers and also Ski Dim.
Then made up my mind and jumped in!
Thrilled with the result I got!

[SuperSam]

All you can do is gather all the info you can, then make the best informed decision you can and frankly sometimes your gut feeling counts for a lot having down your homework.
The folks at Ski Dim know their stuff based on all of my experiences with them.
When I went from a 3 blade to a 4 blade I talked to all the major prop suppliers and also Ski Dim.
Then made up my mind and jumped in!
Thrilled with the result I got!

What are the details of your boat and the changes the 4 blade gave you?did u change pitch as well?if you don't mind me asking

[CJD]

So I talked to skidim and they they thought the 13x14 would be a good choice but also suggested the acme 470 12.5x15 because a lot of people that own nautiques seem to like it that have the same transmission and engine...I just want to make sure that I get something that can get me up to 24 mph even if I got 2000lbs or more in the boat I dont care about much speed over that. Im not exactly sure out of those three which I leab towards

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Don't count on 25mph with a ton of water on board. You might get it, but you start to run into prop cavitation at that speed loaded. That is not based on the prop, but on the load and boat angle.

[crystal waters]

What are the details of your boat and the changes the 4 blade gave you?did u change pitch as well?if you don't mind me asking

I have a 1989 Supra Conbrio open bow.(essentially a comp with open bow)
19 ft 9 inches
351 ford windsor with 1:23 reduction Transmission Right hand rotation

I went from the stock 3 blade 13 inch to an ACME 422 model 4 blade rt hand prop with 12.5 x 15.5 blades.
Better hole shot
top speed seems unaffected
Reduces any Cavitation.
It is felt that a four blade helps with any cavitation issues.

Pasted below is SKIDIMs reply to my original query re same:

For the '89 comp, we really like to drop down and add a blade. OJ 13 X 16 4-bld (item #23107), OJ XMP 13 X 15.5 4-bld (Item 102005), or Acme 12.5 X 15.5 4-bld (item# 2034). The XMP & Acme are CNC machined and perfectly balanced. These props will give you better hole shot, be smoother, and it will be easier to hold your speed.

[SuperSam]

I have a 1989 Supra Conbrio open bow.(essentially a comp with open bow)
19 ft 9 inches
351 ford windsor with 1:23 reduction Transmission Right hand rotation

I went from the stock 3 blade 13 inch to an ACME 422 model 4 blade rt hand prop with 12.5 x 15.5 blades.
Better hole shot
top speed seems unaffected
Reduces any Cavitation.
It is felt that a four blade helps with any cavitation issues.

Pasted below is SKIDIMs reply to my original query re same:

For the '89 comp, we really like to drop down and add a blade. OJ 13 X 16 4-bld (item #23107), OJ XMP 13 X 15.5 4-bld (Item 102005), or Acme 12.5 X 15.5 4-bld (item# 2034). The XMP & Acme are CNC machined and perfectly balanced. These props will give you better hole shot, be smoother, and it will be easier to hold your speed.
Thanks for the details its nice to hear what people are running with the same motor and transmission

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[SuperSam]

Don't count on 25mph with a ton of water on board. You might get it, but you start to run into prop cavitation at that speed loaded. That is not based on the prop, but on the load and boat angle.
I would hope that they would make the boat so that it could get on plane with it full of people though and that is the goal... whether its people weight or water weight when there is 1500lbs onboard I wanna be able to get on plane

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[CJD]

I would hope that they would make the boat so that it could get on plane with it full of people though and that is the goal... whether its people weight or water weight when there is 1500lbs onboard I wanna be able to get on plane

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I thought the goal of ballast was a good wake?? What wake sport are you planning to do that you need to run 25? I'm just saying...25 with a ton of water is not a practical goal. It'll do it, but you are working both the motor and the hull a lot harder than they're designed for. A great wake at 10-18 is a goal.

[SuperSam]

I thought the goal of ballast was a good wake?? What wake sport are you planning to do that you need to run 25? I'm just saying...25 with a ton of water is not a practical goal. A great wake at 10-18 is a goal.
Most people ride at 18 to 24 mph wakeboarding I dont wanna be wot when wakeboardin at 22mph with a good amount of weight so would be nice to be able to get a few mph over that... for surfing with full ballast yes thats fine

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[CJD]

I stand corrected...I've never pulled that fast, but a quick search says a lot do.

So, to your original question, a 4 blade 14X13 will pull easily loaded to 30mph. It will cavitate if you do any maneuvering at that speed/power. If you are currently running an older generation prop (like 10+ years), you will notice much better pulling with the new props, and little change in top speed. The new props are much better designed for a wide range of loads and speeds. Your engine will work less to get the boat out of the hole. WIth 300hp, you should be able to reach 5k rpm with that prop.

[SuperSam]

So a couple thoughts first is I have the 351 in my saltare with the 1.23x1 transmission so I am at about 250hp and so would u still suggest a 13x14 4 blade or should I get another 3 cause my old prop is the hand made 3 blade 14x14... Second would I just be better off keeping the diameter and only dropping the pitch and go to a 14x13? Or doing the opposite and drop to a 13x14?all opinions welcome

[Salty87]

Call Nettles. Inboards are very common in Austin as are old Supras and Saltares. Skidim is great and they are also very informed but they don't specialize in props like a prop shop does. I think I've read other forum members were able to try a prop and swap it out for another if they weren't happy...I'm not certain but it's worth a call.

[CJD]

So a couple thoughts first is I have the 351 in my saltare with the 1.23x1 transmission so I am at about 250hp and so would u still suggest a 13x14 4 blade or should I get another 3 cause my old prop is the hand made 3 blade 14x14... Second would I just be better off keeping the diameter and only dropping the pitch and go to a 14x13? Or doing the opposite and drop to a 13x14?all opinions welcome

Drop the pitch to help come out of the hole better when loaded. It should also unload the engine so you raise the max rpm...with the result of better pull with little top end loss. 4 blades help come out of the hole stronger, but add more drag at speed.

These are just generalities. It would be best if someone with your engine/tranny combo would chime in for specifics. Have you looked through the prop sticky?

[SquamInboards]

would I just be better off keeping the diameter and only dropping the pitch and go to a 14x13? Or doing the opposite and drop to a 13x14?all opinions welcome

One thing to keep in mind switching from an older-style prop to a newer one is that the overall surface area of a brand-new CNC prop is much greater than that of an older prop. So, even if you went for a new prop of the EXACT same specs, you would have a very different prop. I went from a 14x16 4-blade (I'm ignoring cup for simplicity) to a 14.25x12.5 CNC Acme and had about the same WOT RPM. Other aspects of performance were of course different, but the point is I had to drop way down in pitch to get the same RPM.

What I'm saying is, it's hard to compare an old hand-made prop to a new, CNC prop. It's relatively easy to compare among the CNC props because they're so precise. So the IDEAL situation is, as someone mentioned, finding a shop that might give you a 'best guess' but allow you to exchange it if you don't like it (and don't damage it). That is how I arrived at my current prop, it wasn't what Acme suggested originally. But I worked at an Acme dealer at the time, so the exchange was simple. Once you have a known benchmark with a CNC prop, it's much easier for someone to recommend a change from there. It's a little bit of a chicken-egg issue, I know.

Also check out the sticky prop thread, as CJD just mentioned. As people add to that thread, it will be the best resource for people like you to compare actual real-world use of CNC props on comparable boats with comparable loads and activities.

In any case, best of luck and you'll love your new prop once you get it sorted out, I'm sure of that.

[SuperSam]

Thanks for the advice/experienced thats very helpful.

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