Prop Suggestions

JC21

Cadet
Joined
Sep 9, 2011
Messages
14
Hey guys im new to the forum and would like to ask for some suggestions on my next prop selection. Heres a little info on my setup so you can help me choose. Im running a 1542 flatbottom riveted aluminum boat its aprox (125)lbs with an 85' evinrude 30 hp on it. This is a new set up for me and I want to change props. The current prop is a 10.5x11 aluminum and I use the boat primarliy duck hunting on rivers and flooded timber with me and 2 other guys and gear. I have loaded the boat accordingly and ran it. It ran 26mph and jumped on a plane and seemed to be screaming. I dont have a tach but I could tell the motor was over the rev limit. I borrowed a 10x13 and tried it again pretty much the same except I hit 28mph and the rpms were a bit lower(still seemed very high to me). With all that aside I think I have decided on a 10x15 but I would like your opinion on brands or other sizes you think might be better for my set up. Im looking mostly for top end and dont mind sacrificing a little hole shot for it but still need a decent amount of low end for days I have an extra person in the boat. Thanks for your help and happy boating!!
 

John_S

Rear Admiral
Joined
Jun 21, 2004
Messages
4,269
Re: Prop Suggestions

Welcome to iBoats.

Hard to make a suggestion without current wot rpms. Buy an inductive tach that wil work with your engine.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Prop Suggestions

You shouldn't reprop without a tach. Rpm and speed are critical for best performance and
the health of your motor.Motor is rated for 5,800 max rpm.Estimating rpm is nearly impossible.
Without rpm and speed there is no way to know the best prop.A motor needs to run close to ar at its max rated rpm.
A 1542 is closer to 300lbs.If my math is right a 30 with a 11" prop at 5800 rpm 10% slip will run about 25 mph.Is your speed by gps?It does appear you could use a little more prop.
Again if my math is right at 5500 a 13" prop with 10% slip produces about 28 mph.
While I don't like calculating prop application it does appear a 13" prop is close to what you need.
Just keep in mind there are a lot a variables that affect the final result and the higher the pitch the less power for a load.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,813
Re: Prop Suggestions

I thought I responded to this thread elsewhere a day or so ago!
 
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