prop dumb

[Kent Myers]

my current prop is kinda beat up i want to buy a new one but i dont know what my engine rpm is and do not really know how to find out i have a 16 foot fiberglass v bottom bass boat with a 1979 johnson javlin seahorse 85 hp i do not know what i need to know about hub size pitch or anything all i know is i have one on the motor and dont know anything else

 

[steelespike]

Re: prop dumb

Your prop size is usually marked on the prop barrel -- X -- diameter X pitch.
A prop shop can repair your prop and measure it.
As you have probably read you need your prop size and present max rpm and speed.Without its a crapshoot for performance and motor health.You'll need a tach.A tiny tach is reasonable and easy to install.gps speed is best.
In the meantime you can get your prop repaired and run it.You can also fine tune your setup .Motor vertical height especially.Starting with the antivent plate even with the bottom raise the motor a hole at a time to a point just before venting becomes a problem.carefully adjust trim.

 

[Kent Myers]

Re: prop dumb

a what plate ? dont know what that is

 

[Kent Myers]

Re: prop dumb

and please tell me its not on the inside of the barrel

 

[steelespike]

Re: prop dumb

a what plate ? dont know what that is

The antiventilation plate (sometimes incorrectly refered to as cavitation plate) just above the prop.Ideal starting point for the plate is even with the bottom of the boat.The higher you raise the motor without getting ventilation problems the better your performance.There are a series of holes in the mounting bracket that allow vertical adjustment of the motor.
If motor is too low you drag too much through the water too high you get venting problems just right best performance.There is no set height it depends on the application.You could gain 2 to 3 mph
depending on where you are at now.