new prop for merc 125

badfish888

Seaman Apprentice
Joined
Feb 2, 2012
Messages
43
I wanted to try this again with more info.
The boat is a 20' angler center console, deep v, 80 gallon tank.
the motor is a 2002 mercury 125 saltwater. current prop is a 13x19 black max. with 2 people on the boat, i run about 36kts. but my tach does not work. it does sound like the engine is (winding out) into the upper rpm band. However, my usual load is a full 80 gall, 4 adults, 2 coolers, and gear. With this load, the engine had a hard time jumping out of the hole, and i cannot get my rpms up as high, even trimmed out.

I searched on here for a new prop and looking at the horrible reviews here and else were about my black max prop, ive settles on the hustler prop.

i think id like to stay with 3 blades, so what are your thoughts on dropping to a 17x19?
 

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
Joined
May 19, 2001
Messages
26,039
Re: new prop for merc 125

Unless you have some sort of bionic hearing I would get a tach reading. I would not invest in a prop until I had a verified WOT reading.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: new prop for merc 125

I'll second that.
Is the motor a 2 stroke?
Seems a 125 hp 20 footer is a little underpowered.
Prop calculator only does mph so guessing 41 mph with 2.07 ratio,guessing 6% slip rpm is about 5100.
Too much "guessing" to make a prop change. You would probably have to give up a little top end
but that would depend on the rpm and speed of a test run.
Check out the Tinytach they have a web site.
 
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