SS Prop recommendations?-gctid374776

[Guest]

In the interest of beating a dead horse, here is another thread regarding stainless steel props.

Here's my situation. I have a 2011 185 bowrider with the 3.0 carb engine. With a typical load, I can pull almost 5000 rpms, that's too high and needs to be lower. My current prop is a 21" factory standard aluminum three blade and I want to switch to SS to get a lil better hole shot for skiing, but I need to be sure that my max rpm's drop in the process. I'm not concerned at all about top speed, I can hit 42-43 now but rarely go over 30-35.

I'm thinking a switch to a 21" SS will drop the max rpm's 100-200 due to less flexing of the blades.

Here's my questions to all the experts here:

1) Do you agree with me that switching to a 21" SS will drop the max rpm's a bit?

2) What SS props do you run and are you happy with them? I used to run a Michigan Wheel Rapture on an old Sea Ray with the 3.0 years ago and loved it, but they no longer make that prop.

3) Anyone run a 4-blade SS on a boat/engine similar to mine and like it? I think a 20" 4-blade SS would also drop my max rpm's a bit and provide a better hole shot too.

4) There are many different models of SS props from Mercury Marine, do any of you run one of them on a boat/engine similar to mine? Would like to hear from first-hand experience.

Thanks!

[smitty477]

I have received very good results posting prop questions on the iboats prop board, suggest you post there.

There are a couple of experts on there that have nailed the problems I was searching to fix on larger outboard applications.

During that process (but on outboards) we did switch from factory 3 blade Al to both Al and SS 4 blade props.

We learned that 4 blades are much better for what you desire in your description.

SS is more efficient than Al and especially so above about 30 mph.

We needed to drop a full 2" going from a 3 blade by 21" to a 4 blade 19" when starting at a full rpm test (6,000) on the stock blade.

Obviuosly a different application but they are somewhat similar.

We also learned that the Mercury SS props are very good but there exists slighly less 'perfect' props for about half the cost in Solas.

Hope this helps

[Mocoondo]

I run a Mercury Vengeance prop on mine. This will be my 10th season with the same prop (knock on wood) and I wouldn't change a thing.It's a great prop. Excellent holeshot even when fully loaded and the boat tops out in the very high 50's according to my GPS.Mine is a 23P, but I have a slightly different boat and engine. I believe Mercury has a prop selector somewhere on their website. You can input all the information about your boat and it will tell you what diameter and pitch you need.

[img]/media/kunena/attachments/vb/678274=26846-PC070028.jpg[/img]

[Guest]

jhenkel wrote:
In the interest of beating a dead horse, here is another thread regarding stainless steel props.

Here's my situation. I have a 2011 185 bowrider with the 3.0 carb engine. With a typical load, I can pull almost 5000 rpms, that's too high and needs to be lower. My current prop is a 21" factory standard aluminum three blade and I want to switch to SS to get a lil better hole shot for skiing, but I need to be sure that my max rpm's drop in the process. I'm not concerned at all about top speed, I can hit 42-43 now but rarely go over 30-35.

I'm thinking a switch to a 21" SS will drop the max rpm's 100-200 due to less flexing of the blades.

Here's my questions to all the experts here:

1) Do you agree with me that switching to a 21" SS will drop the max rpm's a bit?

2) What SS props do you run and are you happy with them? I used to run a Michigan Wheel Rapture on an old Sea Ray with the 3.0 years ago and loved it, but they no longer make that prop.

3) Anyone run a 4-blade SS on a boat/engine similar to mine and like it? I think a 20" 4-blade SS would also drop my max rpm's a bit and provide a better hole shot too.

4) There are many different models of SS props from Mercury Marine, do any of you run one of them on a boat/engine similar to mine? Would like to hear from first-hand experience.

Thanks!

I have this exact boat (2011 185 with 3.0 engine)

I bought this prop off amazon "Turning Point Propeller PA-1421"

and one of these from West Marine (letter E):

http://www.westmarine.com/webapp/wcs...classNum=50239

our boats are to small to really get the full benefit of a 4 blade prop so you may just be spending more $$ for no real benefit

take a look at this article

http://www.solarnavigator.net/propellers.htm

lots of good info.

with the aluminium prop I was getting on plane anywhere between 18 -22mph now with the SS I get up on plane about 16-18mph and have noticed that when running at 3100 -3300 rpm I gained 2mph from the aluminium.

also when reversing (could just be me) it feels "stronger" and like the boat really digs in and I get great control in reverse.

good luck.

[Guest]

Davem2421 wrote:
I have this exact boat (2011 185 with 3.0 engine)

I bought this prop off amazon "Turning Point Propeller PA-1421"

and one of these from West Marine (letter E):

http://www.westmarine.com/webapp/wcs...classNum=50239

our boats are to small to really get the full benefit of a 4 blade prop so you may just be spending more $$ for no real benefit

take a look at this article

http://www.solarnavigator.net/propellers.htm

lots of good info.

with the aluminium prop I was getting on plane anywhere between 18 -22mph now with the SS I get up on plane about 16-18mph and have noticed that when running at 3100 -3300 rpm I gained 2mph from the aluminium.

also when reversing (could just be me) it feels "stronger" and like the boat really digs in and I get great control in reverse.

good luck.

When you switched to the SS prop, did your max RPM's drop?

[Guest]

jhenkel wrote:
When you switched to the SS prop, did your max RPM's drop?

yes, it did, I don't remember the exact number at the moment but I did notice that it dropped

[Rocky_Road]

Something to be aware of, so that you don't find yourself unable to go boating the day your new prop arrrives: Many of the SS performance props (like my Stilleto) will require that you file away some of your O.E.M. trim tab for clearance. The best solution is to install the offset performance trim tab sold by Quicksilver.

[img]/media/kunena/attachments/vb/678336=26883-39250_0.gif[/img]Happy boating!

[Mocoondo]

Davem2421 wrote:
yes, it did, I don't remember the exact number at the moment but I did notice that it dropped

If max RPM dropped, you have selected the wrong pitch propeller.

The correct stainless prop will not have the same pitch as the aluminum prop it is replacing.

Aluminum props flex and lose some pitch (pitch flattens out) when underway. Stainless props flex very little and therefore remain a relatively constant pitch while in operation.

If you lost RPM, you need a prop with a lesser pitch.

In an ideal installation, you will reach ~4,800 RPM at WOT at maximum speed. If you are not getting that, then you are not set up right.

[Guest]

Mocoondo wrote:
If max RPM dropped, you have selected the wrong pitch propeller.

The correct stainless prop will not have the same pitch as the aluminum prop it is replacing.

Aluminum props flex and lose some pitch (pitch flattens out) when underway. Stainless props flex very little and therefore remain a relatively constant pitch while in operation.

If you lost RPM, you need a prop with a lesser pitch.

In an ideal installation, you will reach ~4,800 RPM at WOT at maximum speed. If you are not getting that, then you are not set up right.

Thanks, I understand that part. In my case, I NEED my max RPM's to drop a bit because I can pull 5000 now and that's 200 above the max recommended level.

[Guest]

Mocoondo wrote:
If max RPM dropped, you have selected the wrong pitch propeller.

The correct stainless prop will not have the same pitch as the aluminum prop it is replacing.

Aluminum props flex and lose some pitch (pitch flattens out) when underway. Stainless props flex very little and therefore remain a relatively constant pitch while in operation.

If you lost RPM, you need a prop with a lesser pitch.

In an ideal installation, you will reach ~4,800 RPM at WOT at maximum speed. If you are not getting that, then you are not set up right.

I don't understand, I'm achieving the same top end speed and my RPMS are (and I can double check the next time I'm on the water) running about 4500-4600 with the SS why would I want the rpms to stay at 4800 if I'm able to top out in speed at 4600?

can you please explain?

even at 3100rpm's I'm now setting at 27.5mph whereas the aluminium prop at 3200 rpms was setting me at about 25.5-26mph

also I replaced the proper with the exact size of my aluminium.

14x21

the rake is higher on the SS hence the offset anode but I picked up a prop that was the same numbers as the aluminium

[Guest]

Davem2421 wrote:
I don't understand, I'm achieving the same top end speed and my RPMS are (and I can double check the next time I'm on the water) running about 4500-4600 with the SS why would I want the rpms to stay at 4800 if I'm able to top out in speed at 4600?

can you please explain?

even at 3100rpm's I'm now setting at 27.5mph whereas the aluminium prop at 3200 rpms was setting me at about 25.5-26mph

also I replaced the proper with the exact size of my aluminium.

14x21

the rake is higher on the SS hence the offset anode but I picked up a prop that was the same numbers as the aluminium

I think 4600 is just fine, generally you want to be in the top half of the recommended range which I believe would be 4600-4800.

The rationale behind this, as I understand it, is that if you are unable to achieve say 4500+, then the prop is probably 'overpitched' which means that your engine doesn't have enough power to turn it as fast as it should, and there could be higher than usual load placed on the entire drive train at any given speed.

[Mocoondo]

Davem2421 wrote:
I don't understand, I'm achieving the same top end speed and my RPMS are (and I can double check the next time I'm on the water) running about 4500-4600 with the SS why would I want the rpms to stay at 4800 if I'm able to top out in speed at 4600?

can you please explain?

even at 3100rpm's I'm now setting at 27.5mph whereas the aluminium prop at 3200 rpms was setting me at about 25.5-26mph

also I replaced the proper with the exact size of my aluminium.

14x21

the rake is higher on the SS hence the offset anode but I picked up a prop that was the same numbers as the aluminium

I still think you have the wrong prop.

A properly chosen prop will allow the RPM to travel through the entire normal range which is 0 to approximately 4800 RPM in a Mercruiser installation. If you are not achieving 4800 RPM at WOT, you are overpropped.

As an example, a 23 pitch aluminum prop is effectively a 21 pitch prop because when underway, the aluminum prop flexes and you lose some pitch. So even though you may have a 23 pitch aluminum prop, it is actually a 21 pitch prop (and this is just an example...the numbers are not important). Now say you purchase a 23 pitch stainless prop and bolt it on. Stainless does not flex like aluminum does so if it's a 23 pitch prop, you're getting a 23 pitch when underway. Now your RPM suffers because the pitch is greater than ideal.

Another alternative is to choose a lesser diameter prop when you go stainless.

Using my boat and engine combination, the appropriate stainless prop is a 13 1/2 x 23P. The appropriate Black Max aluminum prop is 14 x 23P.

In other words, I am able to achieve the same maximum RPM when I went to a stainless prop by installing a prop that is the same pitch but 1/2" less diameter.

I think if you would have chosen a 13 1/2 x 21P, that would have been a better prop choice for you.

You can try this tool to see what works best for you: http://www.mercurymarine.com/propell...elector/#step1

[Guest]

Thanks for the explanation I appreciate it and Thanks jhenkel.

Thanks!

***edit***

Interesting that website shows that I should have had a 14x23 prop for both SS and aluminum but when I bought it

The factory had a 14x21 aluminum on it.

[Guest]

Davem2421 wrote:
I have this exact boat (2011 185 with 3.0 engine)

I bought this prop off amazon "Turning Point Propeller PA-1421"

and one of these from West Marine (letter E):

http://www.westmarine.com/webapp/wcs...classNum=50239

our boats are to small to really get the full benefit of a 4 blade prop so you may just be spending more $$ for no real benefit

take a look at this article

http://www.solarnavigator.net/propellers.htm

lots of good info.

with the aluminium prop I was getting on plane anywhere between 18 -22mph now with the SS I get up on plane about 16-18mph and have noticed that when running at 3100 -3300 rpm I gained 2mph from the aluminium.

also when reversing (could just be me) it feels "stronger" and like the boat really digs in and I get great control in reverse.

good luck.

Been running this prop since 2000 and LOVE what it does for my boat.

Performance of SS without the $$ or risk to my gears !

BTW WOT 4700 ....... New trim tab IS required (High performance)

A quite unique design for a AL prop.

Several here on the board use it.

[smitty477]

"Interesting that website shows that I should have had a 14x23 prop for both SS and aluminum but when I bought it

The factory had a 14x21 aluminum on it."

The Mercury website is somewhat noted for suggesting a prop on the more agressive end of the range. On the i-boats prop forum this has been numerous times and most often they say to use one size smaller in pitch then recommended with that calculator. Other things that were brought up there include the selection of boat type (hull), overall weight being estimated low, rpm range being in the mid range, and the lack of the calculator to asses for boat lenght and beam (key elements). Some of the folks on that site have 1,000 of posts just on the subject of propellers with a few in the 10's of 1,000''s based upon there years and experiences with selling and trying various propellers. It is notable how the propeller market has varied just in the past few years as technology has offered up improvements in design, materials and casting techniques.

FWIW the merc website suggested a 21" - 22" prop for our 19' , 1,700# , 115hp 4 stroke Yamaha outboard as well and we ended up with a great match at 19".

Especially with your application noted for skiing, mid range, and not focused on top speed.

BTW - as a result of the above I do have a like new condition 21" Solas 4 blade Al 15 spline prop for sale.

I was told I would be better off at 19" but that is not what I bought after the initial excercise.

"Performance of SS without the $$ or risk to my gears !""I bought this prop off amazon "Turning Point Propeller PA-1421"

FWIW - This is listed as a 3 blade stainless steel prop

Hope this helps