SS Prop

[hardwater55319]

Just wondering if anyone has put a ss prop on a

1725 pro guide w/75hp 4s. Right now I have a 17 p running around 5400 rpm with standard alum prop. I would like to get up on he rpm up to at least 6000 rpm but yet keep up with the speed if possible. Right it gets up on great even with gear and people. anyone with info would be great.

[Kyhl]

What is the recommended RPM range for the motor?

What are you trying to fix?

I don't know that you will gain anything by going SS. SS is heavier and possibly will lose effeciency because of the added mass. Generally, SS props lose RPM at the same pitch as aluminum. So a 17P SS will most likely drop your RPM from where you are now.

[hardwater55319]

Should run at 6200 rpm. Trying to get more rpm. Has a great hole shot to plane no problem. just trying to get a little more rpm.

[delcecchi]

Should run at 6200 rpm. Trying to get more rpm. Has a great hole shot to plane no problem. just trying to get a little more rpm.

Going down to a 15 inch pitch should about do it.

[Kyhl]

Agree with Del. You have 800rpm to work with. A 15P aluminum will probably wake things up good while adding around 400 rpm.

What is the gear ratio of the motor? There are online calculators to calculate the prop's efficiency. Then take that efficiency and plug it back in using the new pitch and estimated rpm to see your new estimated speed. RPM changes about 200rpm per inch of pitch, assuming the change is to a prop of the same design.

In reality, your effeciency may change up or down, and your rpm will be a ballpark swag, but it will give you a guage to see if you might lose speed. It won't be exact but should get you in the ball park.

I also recommend working with a shop/dealer that will allow you to try out different props. I have my third on order from my dealer.

[Down Deep]

Call Jay Soderbloom at Soderbloom's Props in Cromwell, MN. He is the expert on pairing boat-motor-prop. Soderbllom's also carries a large selection of props at competitive pricing.

[Esox_Magnum]

I would find a shop to let you try a 15ss after running ss I won't go back to an aluminum prop...

[Kyhl]

What motor Esox?

I had a 90hp 2 stroke with aluminum and thought it was fine. Moved to a 115hp 4s and found a SS prop marginally better. Wouldn't even think of aluminum with my current 150 4s.

On a 75hp? I'd spend that money on a sweet rod and reel instead of SS. It's not my money though.

[Esox_Magnum]

What motor Esox?

I had a 90hp 2 stroke with aluminum and thought it was fine. Moved to a 115hp 4s and found a SS prop marginally better. Wouldn't even think of aluminum with my current 150 4s.

On a 75hp? I'd spend that money on a sweet rod and reel instead of SS. It's not my money though.

Currently a 115 2 stroke and made a huge difference in my boat. Started with a 17p aluminum then went to a custom worked 17p ss and huge difference currently running a stock 18p ss till I get the 17ss fixed that I roughed up on gravel.

[hardwater55319]

Thanks for all the info. The local prop shop talked me into bringing my alum prop in for some custom work. They basically told me that until you get up in hp you really wont notice much of a difference.

[jjz]

Good things about s.s. props for smaller outboards able to plane at lower speed nice advantage. Biggest advantage is your trolling speed drops while top end stays the same. My 90 went from 2.75 to 2 mph by switching from 17 al to 13 ss durability and all around performance much better well worth the cash. Top speed was basically the same.

good luck