which backup aluminum prop should I buy?

[bruceb58]

You may want to post your question on pontoonforums.com

Someone might actually have a similar set up to yours.

 

[achris]

Normally when going from an Alum. to SS prop, you drop down a pitch size usually 2 increments, so vice versa when going back to aluminum. Plus, Have you seen a Mirage prop? (I have) It is pretty big, with good size blades, & heavy as it is. IMO,The Black Max in 15" pitch being smaller, & lighter, may overrev,, whereas the 17" pitch should actually pick up a few rpm's and be just right.

Mik,

As already pointed out on many threads, wrong information, again. Have you ever had a Mirage propeller on your boat? No, I suspected not. I have, and I know the characteristics of these props. You can't compare a Mirage (or Mirage Plus) to a standard aluminium propeller. That are that different. As Bruceb58 has pointed out, the Merc propeller calculator is very good (one of the best I've seen), and it so totally disagrees with your 'recommendation'....

Also, when moving between aluminium and SS with the same pitch and diameter there will be a very slight change in revs, not worthy of a 2" pitch change.

I will ask you again. If you have no relevant, current and up to date knowledge of a subject, look and learn. You can not receive when you are transmitting.

Chris.........
(I am doing this in the open forum because you are not responding to PMs)

 

[MikDee]

Chris,
No I haven't had a Mirage on my boat, But I have held one in my hand, so I know how different they are compared to an aluminum prop. Plus, You, & I know, the rule of thumb is to decrease pitch when going from an Alum. to S.S. prop. By the way, I'm having trouble figuring out how to reply to a message, each time I go there I have to figure it out all over again (not like the old system), so I'm not eager to use it.

 

[trout74]

I feel as though I may have started an unintentional fight. I'm sorry! Just trying to figure out what pitch to buy. I think I'll buy a 15 and see what happens. Sorry for the drama. We can close this thread. Thanks for your time.

 

[bruceb58]

You, & I know, the rule of thumb is to decrease pitch when going from an Alum. to S.S. prop.

Seriously?

...and the Black max is only 14" diam.

Also, where in the thread did the OP say he was going to buy a 14" diameter Black Max prop.

 

[bruceb58]

I feel as though I may have started an unintentional fight. I'm sorry! Just trying to figure out what pitch to buy. I think I'll buy a 15 and see what happens. Sorry for the drama. We can close this thread. Thanks for your time.

Not your fault. I would wait to see how your new prop works first unless you can make a deal with the dealer to bring back the prop after using it. Another option is buy the 15" pitch and if it is also a dog, resell it or take it to a prop guy who can drop an inch of pitch if needed.

 

[achris]

I feel as though I may have started an unintentional fight. I'm sorry! Just trying to figure out what pitch to buy. I think I'll buy a 15 and see what happens. Sorry for the drama. We can close this thread. Thanks for your time.

trout74. You have done nothing wrong, and we will continue to assist you in any way we can. The best place to find a starting point for a Merc prop is their own calculator site.

 

[jestor68]

Edit: Post removed. Poster not receiving PMs for me to explain.

 

[trout74]

Good news! My new prop is here early, I'm picking it up Sunday, and will test it the same day and report back Sunday night.

 

[trout74]

Update!

I got the Enertia put on the toon on Sunday and took it out. I am happy to report, that the 15P Enertia worked flawlessly. I couldn't be happier. I got 5600 RPMs' by myself and could get 5400 with all the kids and wife and gear on board. I also got 35.8 MPH on the GPS with a full boat! Very happy with the results.

Thanks
Trout

 

[MikDee]

Glad the Enertia prop worked out perfect for you! Thanks for letting us know! Did you ever order, or get the Black Max backup prop?

 

[walleyehed]

And you keep on saying this wrong information. With an identical shaped prop of the same pitch, when you switch from alum to SS, the SS will have slightly higher RPMs.

This is incorrect information posted above. In ALL modern technology propellers, with the exception of turning point aluminum, when using "X" pitch SS it would require 2" MORE pitch in aluminum to achieve the same (or near the same) RPM although the alum will more than likely be slower. The Blade geometry in SS is impossible to reproduce in aluminum due to the thickness required for strength to make it work.
If you have an SS prop that runs the same or more RPM as alum in the same pitch you have a very worn, old or inefficient SS design.

 

[walleyehed]

Not your fault. I would wait to see how your new prop works first unless you can make a deal with the dealer to bring back the prop after using it. Another option is buy the 15" pitch and if it is also a dog, resell it or take it to a prop guy who can drop an inch of pitch if needed.

Not to pick on ya again...) but you can add efficiency to a prop but you WILL remove it effectively by reducing pitch.

 

[bruceb58]

I guess you missed what I said..."With an identical shaped prop of the same pitch, when you switch from alum to SS, the SS will have slightly higher RPMs."


So...if you look up the Mercury prop selector chart up in post #11 that I pasted, with the data that I put into the calculator with the OP's engine and a pontoon, it came up with the 15-1/4x14" Inertia prop and the 16x13" Black Max prop. The OP ended up getting good results with a 15" Inertia. The OP wants a spare Black Max prop. Why would he want to go higher pitch with a Black Max when the prop selector is telling the exact opposite?

The question at hand is should he get a 16x15" or a 16"x17". I think he should get the 15". I take it you think he should get the 17"?

Not to pick on ya again...) but you can add efficiency to a prop but you WILL remove it effectively by reducing pitch.

I can't argue with you on that. I agree it would be difficult to get the proper shape after a re-pitch.

 

[walleyehed]

A 17P in alum, yes... Unless it's a TP, which I don't believe they cover that size anyway.
Here's the deal, I've ran about 600+ props in testing and some of the tid-bits I've found is that Rule #1 is "X" pitch in 1 brand is not the same in another brand whether it be alum or SS. As you well know, the only true way to find that magic spot is testing another prop which for some folks is just not financially possible.
I contributed a tremendous amount of Data to Merc for their prop calculator and found that many of their props in SS, although stamped the same pitch, vary greatly and pitch alone is now just a really general starting point. Blade geometry has become so high-tech that we now have purpose-built props of near identical diameter, in the same pitch yet may have as much as 400 rpm difference. A week ago I took a bunch of props to lake to test on a friends boat and found that a 19P BRP alum ran the same numbers as a quicksilver SS in 17P then really surprised myself when I put a 15P turbo1 on and had 3.2mph faster speed but the same rpm as the 19Pbrp alum. You well know this but a lot of prop set up is in how open to engine height and set-back is the owner willing to go through to make the best technology work like it was intended. We can install a 600 buck prop and find we can do better with a 100 buck alum in some cases.

 

[trout74]

Bruce, I ordered the 15P in the black max, I actually have it. But I put the Enertia on as I got it earlier than I was told I would get it. I do want to try out the blackmax, but im pretty sure ill leave the enertia on until my back-up is needed. I love the Enertia, it totally changed how my boat performed compared to the Mirage plus of the same pitch. For MY setup its a superior prop. I gained over 500 RPM's, don't ask me how, but the numbers don't lie and my GPS had me going faster too!

Thanks,
Trout

 

[bruceb58]

A 17P in alum, yes... Unless it's a TP, which I don't believe they cover that size anyway.
Here's the deal, I've ran about 600+ props in testing and some of the tid-bits I've found is that Rule #1 is "X" pitch in 1 brand is not the same in another brand whether it be alum or SS. As you well know, the only true way to find that magic spot is testing another prop which for some folks is just not financially possible.

I understand what you are saying and looked back at your previous posts and I see that you have a ton of history with props. As the OP has discovered, his 15" Mirage is quite a bit different than his 15" Intertia and both of them are SS so I totally agree with you that 2 different props of the same pitch(even in the same brand Mercury) will behave completely different.

 

[Tail_Gunner]

I understand what you are saying and looked back at your previous posts and I see that you have a ton of history with props. As the OP has discovered, his 15" Mirage is quite a bit different than his 15" Intertia and both of them are SS so I totally agree with you that 2 different props of the same pitch(even in the same brand Mercury) will behave completely different.

Exactly well said.....by the way tinkering is half the fun of it and marble eye's gets to play a lot....jessh some people's kid's.....