Prop trouble for my boat

[tigerhawk]

How do i know which prop is the right propfor my boat, I keep hearing about this pictch or degree camforing cup and angle and some other crap thats suppose to make it better or worse. How do I figure this out ?

 

[ob]

Re: Prop trouble for my boat

First you'll need to either post what engine is in question or find out what the recommended wide open throttle operating range is for the engine.This data coupled with what the engine is pushing dictates the diameter and pitch prop is best suited for your engine.

Example: Lets say you have a 60 hp engine and it's recommended WOT operating range is 5500-6000.Lets assume that the prop on that engine is a 13" dia by 19" pitch prop pushing a 16 ft tri-hull boat and is capable of attaining 5000 rpm at wide open throttle.That would be considered an overpropped engine and it would be recommended to decrease the dia and prop pitch to say a 13 1/2" dia by 15" pitch to reduce engine load and allow the engine to attain it's recommended rpms at full throttle. If the engine was attaining rpms in excess of the rpm range limits,then you would want to increase the prop pitch.And of course ,only a water test monitoring rpms can dictate the final prop choice.

Then there's engine mounting height options that work in conjunction with prop selection which will optimize overall boat and motor performance.

 

[tigerhawk]

Re: Prop trouble for my boat

Well I got a Johnson 140 with electric start, tilt, and trim, and the boat is 18'6" Deep V Sylvan aluminun ski and fish style.from the bottom of the stern to prop center is aprox 7" inches. presently the tripple bladded prop thats on it now is kinda chued up and looks like it has seen better days, I personally would rather buy a new one over trying to add something to whats already missing if you get my drift, "fixing this one" maybe better to just replace and start over "yup" ! anyway that all I can tell you for now other that the engine in question is an 1982 Johnson 140 HP Electric tilt, trim, and start. she runs great since we've done alot to acheive that. only now we want to finish what we started and give it some new to move us with. it aint got to be the most exspensive stainless prop out there, just the cheaper imatation will do, of course one with the right attitude of course.
Any info greatly appreciated !

tigerhawk

 

[OBJ]

Re: Prop trouble for my boat

Moving to Prop Topics and Questions.