Propeller Replacement

[Duck Heaven]

Hi Group!
I just recently purchased a 1973 Rinker Runabout/Tri-Hull with a 1973 65hp. Johnson. Currently, the boat out-of-the-hole is quite slow and at top end may only acheive 23-27 mph. I've been told the existing prop is generally used for trolling. There are no manufacturing names on the prop ... other than the number 2020. I'am confident ... the prop has been changed many times over the years and there is no-way to identify if the existing prop was the correct choice to begin with. I want to replace the existing aluminum propeller with a stainless steel. What diameter and pitch would be a good choice for overall performance? Thank You!

"Doc"

 

[Texasmark]

Re: Propeller Replacement

Don't know how long, heavy, nor transom area hull shape of your boat. Back in that era when buddies of mine ran that kind of setup (60-65 hp Johnnyrudes) on 15' trihulls, with pretty flat to slight v transom area hulls, OEM alum 17P was the norm and 15P if you wanted to have folks in the boat and pull skis.

35 was a great top end for the 17P with light load, and 30 and below for the 15P with 2-3 in the boat as I remember.

Had another buddy with a 16' Kingfisher bass boat which had a pretty flat bottom, not used for skiing and one occupant normal load. With a 65 Johnny ran a 19P SS and could do 37-38. I remember this as I had a boat (different altogether) that could do 39 (never could get that magic 40) and I could just barely leave him.

Mark

 

[Duck Heaven]

Re: Propeller Replacement

Mark ...

Yepper Yepper!

I am leaning toward the 15 pitch .... for the majority of information collected so far and recommendations from prop manufacturers have me convinced this will provide overall great usage.

Thanks buddie ... and have a great boating season!

Doc

 

[Texasmark]

Re: Propeller Replacement

Good luck. Course if you can find a seller that will loan you one to test to see if it is the right answer, you are miles ahead. May cost you a few bucks more, but what is "getting it right" worth?

Mark