18 or 19 pitch Stainless? How big of a difference? New Questions

I am really baffled on what to do? Some say I need an 18 pitch while others say I need a 19 pitch? (3 blade)
I am looking for more holeshot and less cavatation in the turns. I have a 2007 90 H/P Merc 4 stroke with a 2:33 gear ratio and it is mounted on a 2006 Lowe 165 Fish & Ski Aluminum boat, I am currently running a aluminum 19 (3 blade) pitch prop but I get a lot of cavatation in the turns which requires lots of trimming down to avoid.
What are the big differences between these 2 props in Stainless? I don't necessarily want to loose too much top end speed but I realize I can't have both, which one would work best? I am really after holeshot and less cavatation, we do a lot of tubing/skiing. Thanks for your help.
I am thinking this one below or I can get a used Merc QuickSilver Stainless 13.25x19 for $250.00?............Irv964

Advantage I Stainless Steel Propeller for Mercury, Mariner, Sea Ray Mercury & Mariner 90 HP (2 & 4-Stroke) (Thru Hub Exhaust & 15 Tooth Spline)


Prop Specifications:

SKU: 11319
Pitch: 19?
Diameter: 13-1/4?
Blades: 3
Rotation: Standard
Material: Stainless Steel

Re: 18 or 19 pitch Stainless? How big of a difference?

Re: 18 or 19 pitch Stainless? How big of a difference?

In order to help you, we need your WOT rpm with your present prop pitch.
The first thing I want to say is maybe your motor is set to high for your boat, I would check where your cavitation plate is in relation to your boat bottom, it should be flush with the bottom, at least for testing purposes, if it is above the bottom too much, this could be your main problem.

Next, I'm gonna speculate, if the 19" pitch 3 blade Alum. prop works for proper rpm range of your motor, you'd need to drop back to a 17" pitch (because it is harder to spin a more rigid SS prop), but you would probably still go faster with less cavitation, because the stainless prop will push more water, being more rigid.

I would think, That 19" stainless prop you found, will probably not let your motor wind out, and overload it.

Re: 18 or 19 pitch Stainless? How big of a difference?

Re: 18 or 19 pitch Stainless? How big of a difference?

MikDee said:

In order to help you, we need your WOT rpm with your present prop pitch.
The first thing I want to say is maybe your motor is set to high for your boat, I would check where your cavitation plate is in relation to your boat bottom, it should be flush with the bottom, at least for testing purposes, if it is above the bottom too much, this could be your main problem.

Next, I'm gonna speculate, if the 19" pitch 3 blade Alum. prop works for proper rpm range of your motor, you'd need to drop back to a 17" pitch (because it is harder to spin a more rigid SS prop), but you would probably still go faster with less cavitation, because the stainless prop will push more water, being more rigid.

I would think, That 19" stainless prop you found, will probably not let your motor wind out, and overload it.

Click to expand...

Thanks Mike, the motor is set as low as possible on my boat and my max. RPM is 6000 which I can reach no problem with my current prop.
Would a 17 pitch not make my motor rev too high?
What difference could I expect if I went with a 19 pitch S.Steel? Would there be enough of a difference to warrant purchasing one? I seen in iboats prop section that they make an 18 pitch SS for my motor but it is the only one to choose from? It is rather pricy at $409.00 plus shipping of $92.00, would this prop be the one to go with?.........Irv964
I have had a few tell me a 17 as well but it gets confusing when others tell me a 18 and some a 19 S.S.? I guess it boils down to trial and error?

Re: 18 or 19 pitch Stainless? How big of a difference?

Re: 18 or 19 pitch Stainless? How big of a difference?

I also asked about this issue last year and there is some very good info in it as well, hence the confusion! The prop TexasMark suggests is no longer available that I can see?.........Irv

http://forums.iboats.com/showthread.php?t=226362&highlight=irv64

Re: 18 or 19 pitch Stainless? How big of a difference?

Re: 18 or 19 pitch Stainless? How big of a difference?

If you are having cavitation problems in turns then you should probably switch to a 4 blade prop. I switched for this very reason and I am very happy with it, as I used to loose speed in turns if I didnt trim down. People say you may loose a little speed and RPM's when switching to a 4 blade, however I kept the same wot speed and RPM's, by using the same pitch 4 blade prop, of course this may be because I went from aluminum to stainless and the added benefits of the stainless countered the negatives of the 4 blade. On top of not loosing speed in turns, I now get lower plaining speeds.

I cant tell you which 4 blade to go with, as I have an OMC and bought and OMC 4 blade. Just my $.02.

Re: 18 or 19 pitch Stainless? How big of a difference?

Re: 18 or 19 pitch Stainless? How big of a difference?

Irv964 said:

Thanks Mike, the motor is set as low as possible on my boat and my max. RPM is 6000 which I can reach no problem with my current prop.
Would a 17 pitch not make my motor rev too high?
What difference could I expect if I went with a 19 pitch S.Steel? Would there be enough of a difference to warrant purchasing one? I seen in iboats prop section that they make an 18 pitch SS for my motor but it is the only one to choose from? It is rather pricy at $409.00 plus shipping of $92.00, would this prop be the one to go with?.........Irv964
I have had a few tell me a 17 as well but it gets confusing when others tell me a 18 and some a 19 S.S.? I guess it boils down to trial and error?

Click to expand...

A Stainless prop is Heavy, and Rigid, it does not flex like the Alum prop you have on there, meaning it will Bite better, and keep it's pitch more true, and make your motor work harder, But the net result is usually more speed because it pushes more water per rpm, and with the usual built in cup, will grab more water, & cavitate less, in skinny water. That's why I recommend a 17" pitch Stainless.

One final thought, to help you understand, as an example: Your 19" pitch Alum prop flexing back to 16" pitch under load at WOT, versus, A 17" pitch Stainless prop, with no flex under load, & thinner blades at WOT, Which do you think would produce more speed? The SS! as long as your engine has the power to keep the rpm's up.

This is my opinion, from what I've found, your results may vary

Re: 18 or 19 pitch Stainless? How big of a difference?

Re: 18 or 19 pitch Stainless? How big of a difference?

Thanks again Mike, I phoned Merc. Consumer help line and the gentleman I was talking to recommended a 18 or 19 pitch stainless for my application. He stated with the rpm's and my boat, a 17 would tend to over rev my maximum rpm? He stated it was perfect to be just under (5800-5900ish)
If I am going to go with a Stiletto I myself am thinking a 19 as well? I have read quite a few reviews on them and they are different than most other SS props due to their cup design? iboats only list a L/H Stiletto, no R/H? I wish they had one as I would order one now.
I am going to try and see if I can borrow a few props this coming long week-end from my dealer and hopefully I can finally see for myself which prop will fulfill what I am after? Thanks again for all your help, it is greatly appreciated........Irv964

Re: 18 or 19 pitch Stainless? How big of a difference? New Questions

Will this prop make a noticable difference over my 19 pitch aluminum? It is an older SS and the numbers are QuickSilver 48 72762 A5 19P.
How much difference between this prop and a new SS as in the Stiletto Advantage-1 19P prop? Thanks.........Irv964

Re: 18 or 19 pitch Stainless? How big of a difference? New Questions

Irv964 said:

Will this prop make a noticable difference over my 19 pitch aluminum? It is an older SS and the numbers are QuickSilver 48 72762 A5 19P.
How much difference between this prop and a new SS as in the Stiletto Advantage-1 19P prop? Thanks.........Irv964

Click to expand...

Any answers to the above question??
This is what I found out this past week-end, I tried the above mentioned prop (19 pitch Quicksilver above) Not a whole lot if any quicker out of the hole??, reaching 6000 rpm was very easy, I could probably go over quite easy as well which is not a good thing imo?? I lost 1 mph on the top end using my speedo?? The only benefit was way less or no cavatation, I could turn very sharp turns and didn't need to trim down near as much as I use to.

From what I discovered about this older QuickSilver was that my only benefit going to this 19 pitch SS was no or way less cavatation. Would a newer technology SS prop be quite a bit better than this older SS tech prop? Would the Stiletto 19 P Advantage-1 prop be in an entirely different league than this Qucksilver? Thanks..........Irv