Does this make sense?

[Irv964]

I have a 2006 165 F&S Lowe with an 07 90 Merc. 4 stroke (max rpm 5000-6000rpm) and this past week-end I tested an older Quicksilver SS prop with the same pitch(19) and all I obtained was a lot less cavitation. My rpm increased from max rpm of 5800-5900 running a stock 19 pitch aluminum to over 6000 easily running the 19 pitch SS but my mph decreased by 1 or 2mph? The holeshot didn't seem any better either although I was not towing anyone or did I have anyone else in the boat.
From what I have learned, my holeshot and top speed should have improved and my rpm decrease but those 2 things didn't happen?? Am I correct in thinking this? Would have I noticed a better holeshot if the boat was loaded or pulling a tuber/skier?
If I were to go to a 17 pitch aluminum or SS will my rpm's not increase even more? I know I should definitely get a better holeshot but at what cost top end and at what rpm? Any help would be greatly appreciated.......Thanks

 

[rndn]

Re: Does this make sense?

As a general rule of thumb, you do not want it propped where you can over rev the motor, so propping with less pitch is not the way to go. Hole shot can be improved with Smart Tabs, or maybe even a 4 blade prop. Smart tabs will be cheaper than a new SS prop so you may want to look into a set. Some people do end up propping their boat too low to improve holeshot and then have to remember to not give it full throttle with a light load.

 

[Irv964]

Re: Does this make sense?

As a general rule of thumb, you do not want it propped where you can over rev the motor, so propping with less pitch is not the way to go. Hole shot can be improved with Smart Tabs, or maybe even a 4 blade prop. Smart tabs will be cheaper than a new SS prop so you may want to look into a set. Some people do end up propping their boat too low to improve holeshot and then have to remember to not give it full throttle with a light load.

Thanks rndn, not quite sure what smart tabs are?? Where exactly do they go?Do you think the Qucksilver prop, being older technology has anything to do with my results? Would a Stilleto SS Advantage-1 be much different? I am also considering a TurningPoint aluminum prop (Hustler/Legacy in 19 or 17 pitch?) I have heard a few good things about them? I am thinking of keeping my stocker for cruising and obtaining a 17 Turnpoint for water sports? Good Idea? I know I will have to watch my revs but I want a better holeshot. I would like to try a 4 blade as well but I have been told to stay away from them? Just a side note, my motor has a 2:33 gear ratio and I understand the older Mercs have a 1:64 to 2:0 gear case. I was really hoping the older Quicksilver would work but it did everything opposite of what it should have done other than correct my cavitation? Thanks.........Irv

 

[rndn]

Re: Does this make sense?

A link to the Smart tabs.

http://www.nauticusinc.com/

 

[Irv964]

Re: Does this make sense?

A link to the Smart tabs.

http://www.nauticusinc.com/

Thanks for the link, I can't say I have seen them on any aluminum fishing boats before though? Doesn't mean they wouldn't work, I am just curious how necessary they are?..........Irv

 

[rndn]

Re: Does this make sense?

They can fix a lot of issues such as excessive bow rise, slow holeshot, lowering minimum planing speed.

 

[walleyehed]

Re: Does this make sense?

I test props on a LOT of aluminum boats, and any boat I have used, now has smart-tabs on it.
The older Quicksilver prop "may" have some wear...which usually affects the cupped portion first. This will drop efficiency and produce numbers such as you are seeing with it. The early quicksilver was round-eared and just a step-up from aluminum. This later was re-designed by Merc and is now the Vengeance.
Your brain is working quite well if you're considering a Stiletto, which is one of the highest tech props for the money you can buy....and, they are available right here at iboats.

 

[Irv964]

Re: Does this make sense?

I test props on a LOT of aluminum boats, and any boat I have used, now has smart-tabs on it.
The older Quicksilver prop "may" have some wear...which usually affects the cupped portion first. This will drop efficiency and produce numbers such as you are seeing with it. The early quicksilver was round-eared and just a step-up from aluminum. This later was re-designed by Merc and is now the Vengeance.
Your brain is working quite well if you're considering a Stiletto, which is one of the highest tech props for the money you can buy....and, they are available right here at iboats.

Sorry for the late reply walleyehed, been busy and trying to get logged backed in here! LOL. Anyways I am glad to hear that you speak highly of the Stiletto props, the advantage-1 has been in my top choice ever since TexasMark suggested one late last year.
After doing a lot of reading on here I have come to the conclusion though, and that is just because one prop of a certain size/pitch works well on some boat and motor combos doesn't mean that one will get the same results on theirs? I just read another post about the turning point prop where a man gained 3mph and his rpm stayed and another lost mph and rpm running the same prop? I now know, with what ever prop I choose, I may or may not like the results it gives me? Hopefully the Stiletto 19P SS will come a lot closer to what I am after than that older Quicksilver did? I guess it is a crap shoot. Thanks for all your help and assistance with this matter, it was greatly appreciated!!...........Irv964.

 

[walleyehed]

Re: Does this make sense?

The Stiletto Advantage series has a knack for over-coming a lot of obstacles that allow this prop to "slide-in" to applications that are more critical with other props...it's a very good design.

 

[Irv964]

Re: Does this make sense?

The Stiletto Advantage series has a knack for over-coming a lot of obstacles that allow this prop to "slide-in" to applications that are more critical with other props...it's a very good design.

Thanks Walleyehed, would you stick with the same pitch as what I am currently running? (stock/factory 19P Alum.) I am really thinking the Stiletto Advantage-1 SS is the prop for me? Would this prop be worlds above my aluminum as far as holeshot goes? I know it would definitely help my cavitation but what sort of numbers can I expect to see at WOT (5500-6000?) as far as speed and rpm goes (07 90Merc 4 stroke) Thanks again.......Irv

 

[walleyehed]

Re: Does this make sense?

To be perfectly honest, 4-stroke and good hole-shot are not used in the same sentence much...but I really think you will see about 5900 and a few more MPH over-all. I think you'll also notice a bit better fuel economy as well. I would stay with the 19P-same as your aluminum and go from there.
We do have a few other tricks we can pull if needed to get the R's up a tad without messing with the prop. (the Stiletto)

 

[jay_merrill]

Re: Does this make sense?

I went from an aluminum, 3 blade, 15" prop on my boat to a SS, 3 blade, cupped 15" prop. I picked up a little bit over 100 rpm and about 1.5mph at WOT. To me, the more important difference is in less than WOT performance. My boat will remain on plane at lower rpm settings than with the aluminum wheel, and it gets better speed/fuel economy at various rpm settings below WOT.

I think the reason for all of this relates to a couple of things. First, the SS wheel is a stiffer prop, which results in less blade flex and flutter. Second, the SS wheel has more unobstructed area within the hub, which allows the motor to eject exhaust more efficiently. Better exhaust scavenging = better volumetric efficiency = more power. Simply put, the more spent gases you can get out of the cylinders, the more fuel/air mixture you can get into them.

 

[Irv964]

Re: Does this make sense?

Thanks walleyehed and Jay, great info about SS and the Stiletto!
I just had an opportunity to check out 2 newer SS props from Merc. One was a Lazer 2 21P and the other was an Enertia 19P. I noticed 2 distinct differences between them and that older Quicksilver prop that I still have but haven't purchased (not now for sure!) First I couldn't believe the weight difference between the new Enertia and the old QuickSilver!(Probably due to the older brass hub versus the newer plastic hub?) The quicksilver felt twice as heavy as the new enertia and the enertia was the bigger of the 2 props (enerita was 14 diameter 19P and the quicksilver is 13.25 19P) Secondly I know see what walleyehed was talking about as far as the ear design/cupping goes! That new Enertia was a more sleek fin designed compard to my big eared quicksilver plus the cupping on the new enertia made that quicksilver look like it had none! What a difference, just looking at the new style props one could tell how much more effective/efficent they would be compared to the older quicksilver. (both of these new props are for a 150 Merc Optimax 2 stroke) After seeing these 2 new props any thoughts of keeping that older quicksilver were quickly gone! I think the Stiletto will be ordered soon.........Irv964