Stainless prop

Is it true if I go from an aluminum prop to a SS, I have to go down 1 pitch? and why?. Thanks, Jerry

Re: Stainless prop

my 2 cents tells me that the SS has much less flex so you're getting more of a true pitch rating under full power, whereas the alum likely flexes somewhat under full power, effectively reducing pitch.

Re: Stainless prop

Stainless props are also most often cupped which in theory can be like adding pitch.

Re: Stainless prop

Well, close. A ss prop is more efficient and therefore can, generally speaking, be run at a higher X dimension. So, if you're going from an alum prop to a ss and not going to adjust the set up, then yes you need to go down in pitch. If you're going to adjust the set up to take advantage of the technology you paid for, stay with the same pitch. Don't be shocked if you end up going up in pitch with a max set up.

Re: Stainless prop

Due to the fact that when you go from an aluminum prop to a stainless prop you are: 1 - turning more weight, 2 - the prop has less flex and 3 - usually has more cupping of the blades it will lower the RPM of your motor. You want your motor to operate at it's highest RPM as determined by the manufacturer without exceeding it and to not operate below the lowest RPM as determined by the manufacturer. So to counteract this you usually drop down one pitch in your blade selection to raise the RPMs back up. Remember this is not an exact science and does not apply in all cases.

Re: Stainless prop

In my case, I went with the exact same pitch and the RPMs stayed exactly the same. But, the overall diameter was a little smaller and the new SS prop I have is not cupped or raked, so that has a lot to do with it as well.

Re: Stainless prop

My dealer told me once you find out what aluminum works for you and you like the performance you keep the same #'s and go to SS.

I just bought a new SS prop for my new bayliner that is exactly the same size and pitch as whats on the boat since the performance is killer.

So, from what I read here if it lowers my rpms does that mean I need a bit more open throttle to get to the same RPM but I may actually increase my top speed? Or does it mean that at the same throttle position I will keep the same RPM but increase my top speed?

I can wait to see when the prop comes next week but Id like to know your thoughts since I staied the same as my aluminum!

Vic

Re: Stainless prop

BAYLINER185 said:

My dealer told me once you find out what aluminum works for you and you like the performance you keep the same #'s and go to SS.

I just bought a new SS prop for my new bayliner that is exactly the same size and pitch as whats on the boat since the performance is killer.

So, from what I read here if it lowers my rpms does that mean I need a bit more open throttle to get to the same RPM but I may actually increase my top speed? Or does it mean that at the same throttle position I will keep the same RPM but increase my top speed?

I can wait to see when the prop comes next week but Id like to know your thoughts since I staied the same as my aluminum!

Vic

Click to expand...

What engine do you have? What prop did you order (size/brand)? Let us know how it worked out for you.

Re: Stainless prop

I have the 4.3 Mercruser V6...The baoat('07 Bayliner 185) has the stock 14 X 23 picth and I bought the Stiletto advantage II SS in the same exact size.

I should have my boat back fromt the dealer this week, I bought it brand new but the carpet was ripped so they are finally replacing it. The prop should be here Monday and I plan on getting out on the lake as soon as the work is done and the prop is on so as soon as I get it back in the water I'll post my experiance.

Right now I can run to 52MPH at 5000RPM with the stock Mercury 14 X 23 prop so Im interested to see where my #'s go with the SS prop

heres the link to my new prop:
http://iboats.com/mall/propfinder/?...id=448&**********=962660589&*******=644118672

Re: Stainless prop

Not the guy with the experience as some of the participants herein, but I was having a non-speed related problem and decided to go to an alum prop in an attempt to solve the problem.

I was running a 24P SS XP prop and bought a Hustler alum which was supposed to (does) have a lot of the things SS has (except identical material......which has it's advantages and disadvantages). I dropped the pitch to 23 figuring that the alum would not get me the perf of the SS and I didn't want to load up the engine (dropping rpm's).

Well, the alum should have increased rpm's as it was 1" less pitch (both had cupped trailing edges) but it cost me 600 rpm's and 3 mph.

So in retrospect, had I gone the other way initially (upgraded), from the alum to the SS, increasing the pitch (23P alum to 24P XP SS) would have bought me an increase in rpm's AND speed and the only thing I can think of is that, as D said, the SS was more efficient due in part (at least) to thin, sharp, blades.

The other variable is the boat. Sometimes, getting more whoopie from your driving source (including prop) causes the boat's speed to increase which causes the boat to rise out of the water, reducing drag, which makes for more rpm's AND speed when you probably expected one to increase and the other decrease.

But as many have said many times, it's all a SWAG till you install it and run it.

Mark

Re: Stainless prop

I just went through this same thing. I was coming from an Aluminum 21 Pitch Hustler Prop. My boat is a 94 Crowline 196BR with a 5.0 Mercruiser, thru hull exhaust and an Alpha 1 with 1.65 gears and a 2bbl carb.

With the Hustler I 21 pitch, I could turn this motor up to 5000 rpms, no matter how loaded the boat was. I was running right at 50mph also.

I just purchased a 21 Pitch REV 4 prop and installed this. This is a much larger prop than the Hustler for sure. I was trying to get my RPMS down to around 4600, so I was hoping this would work. Well from what everyone had told me, they said my little motor should not push the 21 pitch, and that I would need probably a 17 pitch. Well I put the prop on, and I could turn it to 4300 RPMS with no trim. When I trimmed up just over half, I could get up to about 4700 or just over RPMS. So My Rpms were at the very top of my range. This was also with 4 people on the boat and a full tank of gas. The boat was running right at 49 MPH.

So the moral of my story is, you have to test. No one can tell you how one prop will work and perform on your boat. Its all trial and error, like most other things. Once you get it right, you will know it.

I am still looking for more props to test on mine, to see what I can really get out of here. By the Prop selectors, I should beable to get it to 56 or so, pushing a 21 pitch prop that many RPMS.

Bryan

Re: Stainless prop

I just got my stilleto today..WOW this is a pretty nice shiney prop and its heavier then my aluminum.

I also notice that out of the box this prop looks physically bigger then the aluminum and they are both 14 X 23.

My boat is still at the shop getting new carpet put in and now I am going nutz waiting around for it to get done so I can install this chrome sexxy prop and see what the 4.3 mercruser does with it on the drive.

Ill let you all know next week!