Changing prop from Alu to SS

[roger3645]

I have a 1989 Sprint 265, 16? bass boat, weight of 950 lbs, 6.5? beam. It?s powered by a 1989 Evinrude 88 SPL. ( I added factory power trim) It currently has a 13 X 19 pitch, Michigan Wheel, aluminum propeller.

AT WOT I am running 5300 RPM, with a constant top end of 44 mph (GPS). Every now and then it will hit 45 mph, for just a second. I am considering changing to a stainless steel prop as I am looking for a little more speed.

Will adding a SS prop make that much difference in performance?

If so, I have read that I should drop the pitch to a 17 pitch when using a SS prop. Is this correct?

I have found a used 12.5 x 17 pitch ballistic SS prop for sale locally for $200, would this make a good prop for my setup?

Thanks
Roger

 

[roger3645]

Re: Changing prop from Alu to SS

Have a correction the Ballistic prop is a 13.5 X 17 pitch.

 

[roger3645]

Re: Changing prop from Alu to SS

Must be a stupid question

 

[steelespike]

Re: Changing prop from Alu to SS

Must be a stupid question

Here's the problem any prop change is a bit of a gamble even same pitch to same pitch.
So your wanting to change brand,pitch and material. This introduces all kinds of variables.
Your present setup is at a very acceptable 7% slip.
My info indicates the 88 is rated for 4500 to 5500 rpm.Developing its hp at 5000.
No doubt a 17" prop will improve hole shot and normally would add 300 to 400 rpm.
Usually a ss prop is easier to turn but may load the motor more. Then there is the possibility its affect on the boat could add both rpm and speed.
Doing just a straight calculation 17" adding 400 rpm using 7% slip speed says 42.7 at 5700 rpm.
As you can see I'm doing a lot of tap dancing. My feeling is the 17 will add too much rpm.
Now that I've broken the ice the real hands on guys may jump in.

 

[roger3645]

Re: Changing prop from Alu to SS

Thanks for the reply. My current hole shot is acceptable and I guess I should be satisfied with my current setup, but you know how us boater’s are. My current prop has a few slight dings so I am looking for a replacement and I am just trying to see if I can replace it with something that will give better performance.
Thanks again !