Another what prop question

[k5guy38]

Hi guys I have a 1975 harris float boat 20'. The toon has a 1976 johnson 85hp on her. Up till last weekend it had a 13.75 x 15 prop on her which pushed the boat great. Unfortunatly in the world of low water it lost a huge chunk out of it. Now I know they can be repaired but I would like to put a new one on. My question do you guys think a different prop would better suit my vessel. I average 5 adults and a cooler plus 12 gal of gas. I don't have a tach but it seems she isn't running as high rpms as she should. Sorry for the long post and thanks for you time and info Denny.

[curtiscapk]

You really need a tach to get it right and to save your motor Even though it doesn't sound high it could be...

[k5guy38]

Thats where I have a lil problem cause the old prop needs repair before I would even attempt to run it.

[ronb]

In that case I think you are stuck buying another one of the same dimensions for the simple reason that it hasn't caused any problems but you also aren't sure what your RPM is, whether you are lugging or overspeed.

-ron

[Bamaman]

If the old prop felt right to you, just buy another duplicate.

[k5guy38]

My local options are 13.5x15 and 13.75x13 the old one was 13.75x15. I have no clue how close or far these are from each other. I would wait but it's supposed to be 106 tomarrow and I would love to have her back on the water. If ya know what I mean lol.

[ronb]

To get back on the water I would go with the 13.5 x 15p (it's only .25 difference in diameter and the same pitch) dropping to the 13.5 x 13p would be less pitch which would let the motor spin more freely (or over rev more freely), which may be good for heavy loads but if you've been happy with the performance so far, you may not want to be slower...

just my .02
-ron

[k5guy38]

Just to update my friends went and bought the 13 pitch prop. WOW what a difference The boat gets up and goes alot quicker and seemed to use less fuel. It also doesn't seem to be over reving but until my tach comes I set the cable just a touch under wide open to be safe. Thanks for the help guys. Now to get the old one fixed.