Optimizing The Prop

[JimS123]

Brand new Mercury 150 4-stroke outboard. Black Max aluminum 14.5x19 prop. 19' Bowrider - 3000 lbs wet. RPMs near max spec, hole shot good, speed good, no complaints. So what's the issue? Nothing - just want a SS prop for betteer durability. (haven't run alum in 40 years)

I guess more stern lift to keep the bow even further down on acceleration, plus better mid range fuel economy would be nice. Top speed is of no concern. This is a pleasure cruiser....water sports ended when the kids graduated from College.

Mercury has some nice offerings.... Enertia, High Five, Vensura, Revolution 4. 3 blades, 4 or 5? Any other manufacturers come to mind?

I'm running a Vengeance on my Whaler and like the performance. The last prop I bought before that was a Michigan.

What say y'all?

 

[QBhoy]

Good to be able to try them out first as each boat responds differently, as you will know...but personally I can’t see by the incredible enertia right now. I have one on an 18ft inboard bowrider. More HP than your set up, but I’d still imagine it would be blindingly good on yours too. Keep the same pitch or the advantage with the enertia is that it has 1” increments, so can get it dialled right in. Stay away from the hi 5 unless you want to do towing sports constantly. It will likely lose speed compared to even your standard Ally prop. Good for hole shot, but nothing else.

 

[QBhoy]

Also if you are impressed with the vengeance, you’ll be amazed by the real performance props like the enertia, laser 2, tempest etc. The vengeance is just a shiny version of a standard black max. Often reported to lose speed compared to the Ally black max of same pitch.

 

[dingbat]

Pretty impressed with how the Enertia performs on my boat

 

[jimmbo]

For 13 yrs I have been saying the Enertia is a Great Prop. Nice to see others saying the same thing

 

[JimS123]

Well, that's 3 strikes for Enertia. That was one of my potential choices as well.

So, going from a Black Max to an Enertia, would the pitch need to be different?

 

[dingbat]

So, going from a Black Max to an Enertia, would the pitch need to be different?

Depends on your current RPM. The Enertia is available in 1" pitch increments.

 

[JimS123]

Depends on your current RPM. The Enertia is available in 1" pitch increments.

Yes, I understand. My question was not worded correctly.

If RPM is OK, should the Enertia have the same pitch? Or, in other words, what is the difference in RPMs comparing a Black Max alum vs. a SS Enertia of the same pitch?

 

[dingbat]

Yes, I understand. My question was not worded correctly.

If RPM is OK, should the Enertia have the same pitch? Or, in other words, what is the difference in RPMs comparing a Black Max alum vs. a SS Enertia of the same pitch?

i went from a 14.25 x 17, 4 blade to a 15x15 Enertia. Picked up @ 400 rpm.
Pitch and blade drop rules seemed to hold true

 

[QBhoy]

Hi. The enertia was strangely behaved on my boat in terms of rpm and what is considered the norm. I can’t tell you what it’s like compared to the same pitch ally but when going from the same pitch laser 2, it saw slightly higher rpm at the top (I think because of the extra lift it had and because it is much lighter) but slightly lower rpm cruising. Bigger diameter I think.
Generally you will see a drop of around 100 rpm or so from ally to stainless but not always. As many will tell you it’s a funny old thing, the way props behave on different boats. It’s great that the enertia can come in 1” sizes. I’m thinking of going up an inch to see how she goes.