pitch question

[hullken]

i don't know what pitch i need. I have a 17 foot tri hull with a 115 merc on it. what pitch do i need for maxium useage.

 

[steelespike]

Re: pitch question

You need to find out your present prop size(should be on the barrel -- X --).
diameter X pitch. Then give us your prop size,and max rpm and speed.Unless someone has your exact boat it is all a crap shoot without the spacs.In the course of things let us know your typical load and activities.
You might read some of the posts it may help you understand prop selection
better.Don't hesitate to ask any questions.

 

[Silvertip]

Re: pitch question

Choosing a prop requires that you know the year of the engine among other things. That provides us with the gear ratio and since a 115 Merc from umpteen years ago may not take the same prop series as a current model. Then there is the issue of how you intend to use the boat most of the time. Then there is the thing about the manufacturers recommended wide open throttle rpm. The best prop for your boat is one that allow the engine to operate at or near the high end of that band with an average load. Since we have no idea how your boat performs now, what prop you have now, and what the observed wide open throttle rpm is we can only guess what prop you should have. I won't make that call.

 

[hullken]

Re: pitch question

Sorry maybe i should explain that i know nothing about boats. How do i get my maximum rpm? What is a barrel? I intend to use the boat for fishing and cruising. There is not a prop on the boat right now so i have no referance.

 

[Silvertip]

Re: pitch question

To get maximum wide open throttle rpm (WOT) you jump in your boat, add a few people if thats what you consider an average load, and go as fast as she will go. When you reach that speed, look at the tach. That reading is WOT rpm. If you don't have a tach, there is no way to tell what RPM the engine is turning and therefore it is difficult to fine tune the setup. The barrel of the prop is the round area to which the blade are attached. The hub of the prop is the area behind the nut and washer. I have no idea what you mean by maximum useage. Since you have no prop and therefore no reference, and we also don't know what year this engine is, it's pretty tough to tell you what prop would get in the ballpark. A wild guess would be 13-1/4 x 19P. But that prop needs to be one that fits your engine -- any old 13-1/4 x 19 isn't a guaranteed fit.