new prop or hub??

[truax42]

89 evinrude 120 pushing a 18' stratos 279 fs:<br /><br />after a few minutes on plane, my motor will act as if its slipping until i back off the throttle then it does it again. mechanic feels the hub is spinning. havent checked yet. its my understanding that too much prop will cause the motor to "spin" i am running a 17x22 prop ( i think, cant remember for sure without going back to the boat. what is a proper size pro for this setup and would it be wiser to purchase a new prop or what??/

 

[ob]

Re: new prop or hub??

The right prop is the one that will allow your engine to run in the upper limits of the factory recommended wide open throttle operating range.For your engine that is around 5800 rpm w/light load.I'd say off hand that a 22" pitch is a bit steep for that setup.I can say with confidence that the diameter of your current prop is not 17".

 

[truax42]

Re: new prop or hub??

you're right ob. that number should have been 13 1/4

 

[Dhadley]

Re: new prop or hub??

Not sure I understand what you mean by "too much prop will cause the motor to "spin". A lot depends on what brand/style and condition your prop is in now. <br /><br />When the prop is hooked up, what is your top rpm with an average load? Are you sure its a 17" diameter?

 

[Dhadley]

Re: new prop or hub??

Sorry --- I need to learn to type faster.......

 

[truax42]

Re: new prop or hub??

not sure what the rpms are or should be. this is only the first time i have had this boat onplane since i bought it. i was so aggravated at the time, i did not pay attention to the tach. guessing i would say i had it around 4000 then it started slipping.

 

[Dhadley]

Re: new prop or hub??

Does the prop look to be in good shape otherwise?

 

[truax42]

Re: new prop or hub??

the prop loks great....no bends and just 1 small scratch

 

[truax42]

Re: new prop or hub??

another problem i am having is to have to get someone up towards the bow to get the boat to level out under throttle......would the prop cause this as well?<br />i just checked the prop and its a 13 1/14 by 21

 

[Dhadley]

Re: new prop or hub??

Are you trimming all the way down to take off? Is there a tilt pin preventing the motor from tucking under?

 

[truax42]

Re: new prop or hub??

yes i am all theway down on take off......i am not an experienced boater, should i be tilting up when the boat comes up on plane?

 

[Solittle]

Re: new prop or hub??

I would suggest getting your prop rehubbed. If it turns out that you want to run with a different one you could keep the one you have for a spare.<br /><br />When you get it back on the boat take some time and try various settings to see which works best. You can also have the pitch on the prop you have now changed by a good prop shop - saves some bucks over buying new.

 

[truax42]

Re: new prop or hub??

what would be the lowest pitch and still be efficient?