Prop Diameter and Pitch Question

[Greg Fraser]

Hi everyone,

I'm a new boat owner who needs to replace the prop on his 1972-3 Evinrude 65 HP outboard. The iboats website sells many possible props for this motor, and indicates that, in order to make the proper choice, I need to determine the number of blades, the diameter, and the pitch of the propeller. The site suggests that a code should appear on the outer hub of my prop (e.g., 3 x 16 x 18R, where 3 = blade number, 16 = diameter, and 18 = pitch). I searched everywhere on the prop for this code, but couldn't find it. It's a three-blade prop, but I'm not sure about the diameter and the pitch. Any ideas of what I should do next? Thanks for any help.

Greg

 

[junior1113]

Re: Prop Diameter and Pitch Question

nubers at all? ussually on barrel under set screw and thrust waser. may need to take to prop shop to have it measered.

 

[Greg Fraser]

Re: Prop Diameter and Pitch Question

Hi junior113,

Thanks for replying. You mention the set screw and thrust washer. I take it, then, that I have to remove the prop in order to find the numbers? I simply looked while the propeller was still attached. Do I need to know anything important about removing the prop? I've never done this before.

I appreciate your counsel,
Greg

 

[junior1113]

Re: Prop Diameter and Pitch Question

yea the prop might have to be off to see #'s. take off cotter pin, prop nut, thrust washer if there is one and prop should slide right off there is big washer bihind prop that you can leave on. do you know what current wot rpms are with that prop? come back with prop #'s and wot rpms and we'll tell you what u need

 

[Greg Fraser]

Re: Prop Diameter and Pitch Question

Thanks. One question: how do I determine the wide-open-throttle rpms? Do I need to purchase a manual?

 

[steelespike]

Re: Prop Diameter and Pitch Question

The motor developes its hp at 5,000 rpm.Someone may be along with a recommended max rpm.I would guess 5,500.
Hopefully you'll find the prop numbers.And you can give us your actual in operation max rpm and speed at wot(wide open throttle).

 

[skagit17]

Re: Prop Diameter and Pitch Question

this topic is very helpful. i have a 1978 70 hp evinrude and i recently swapped a 13x1/4x15 for a 13x1/4x17. i am interested in seeing how it changes the performance of the boat...my old prop was munched on two of the leading edges and i scored this other prop on a parts motor i bought. i do not have a tachometer, so in reading this thread i am putting a more powerful, less high speed prop on. i hope this adds clarification to the subject, not trying to hijack!