Propeller pitch for a 1965 Johnson 9.5 hp

[jfp245]

What is the factory installed pitch for a propeller on a 1965 Johnson 9.5 hp? Is there any good reason to go up or down on the factory pitch should I want to replace the prop?

 

[F_R]

Re: Propeller pitch for a 1965 Johnson 9.5 hp

Good question, my 1965 parts book is scrambled. However, 1967 shows part number 377635, 8 1/4 x 8 1/2. The factory stock prop was chosen to be acceptable for the average boat the motor was likely to be used on. Unless you have an exceptionally heavy or exceptionally light boat, stick with the stock prop. It probably has been superseded by now anyway.

 

[cowbyupnow]

I have a '67 Johnson 9.5. My stock prop is an 8 1/4x8 1/2 and i do tend to pull a heavier load when my buddy and i head out. We are both pretty heafty...plus all our gear usually puts us around 700 lbs not counting the weight of the boat, which is a 1436 jon. We do a pretty good job of distributing weight, but still doesnt get on plane... Could pitch be a problem? What would anyone reccomend? I have seen larger heavier boats and loads plane out with same engine.

 

[Sea Rider]

Welcome to Iboats,

Cowbyupnow, you probably need just a prop maximization, go for a wot spin you alone with engine well trimmed on flat, calm no wind water conditions and check achieved max rpm. Compare them to your factory stated min.max wot rpm so to know if inside/outside the ideal safe range. Check how far away you are from them.

One issue is pitching with you alone, other with mate and added weight, for the latter will need to drop more pitch than with you alone to rev up that engine back to ideal/safe range. Must install an induction tach for the wot test. Anyway, what's the max transom rated HP engine for that boat size ?

Some boaters states you gain/lose 150-200 rpm per pitch change, others states 200-300 or even up to 400, don't have a clue for that.

Happy Boating

 

[steelespike]

factory prop was 8 1/4 X 8 1/2.