SS 13 1/4 x 19 - Workable on Johnson 70

[johnjsa]

I have a 15 1/2 Bomber Bassmaster with a Johnson 70 HP on it. Currently the prop is a 17 & was wondering if a stainless 13 1/4 x 19 would work.

 

[11rufus11]

Re: SS 13 1/4 x 19 - Workable on Johnson 70

What are you wot rpm's with the 17 pitch?

 

[johnjsa]

Re: SS 13 1/4 x 19 - Workable on Johnson 70

If my tach is correct, 5900.

 

[Dhadley]

Re: SS 13 1/4 x 19 - Workable on Johnson 70

Assuming the tach is correct you are right where you need to be. Reading between the lines we assume you have a 17 aluminum and are asking about going to a 19 ss. That may be do-able but you will have to improve the set up. Even if you have a ss 17 now, you'll have to adjust the set up to take advantage of the higher pitch.

Lots of variables when you don't know what 2 props we're comparing and know nothing about the set up.

 

[Sandhammaren05]

Re: SS 13 1/4 x 19 - Workable on Johnson 70

How high is the cavitation plate above the pad (measured with a straightedge), and how much offset is there? 5900 RPM is ok, but if the cvitation plate's beneath the pad then you need to jack up the motor and cup the prop (maybe cup it more, if already cupped).

With a 35 Johnson on a 15' Allison bass boat, I get less than than 1 mph speed difference between a thin, 14" correctly cupped Stiletto and a thick OMC aluminum 13" pitched prop cupped the same way (the 14" pitch Stiletto has the same pitch as a 13" OMC, measured via a Rundquist pitch gauge).

If my tach is correct, 5900.