24 ft pontoon 50 hp merc outboard prop question

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davidwjacob

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Aug 25, 2008
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What prop would you recommend for this motor for a 24 ft pontoon?

i dont know what pitch to get or size. dont think prop on it now was original or the proper one.

here is the motor serial number
1985 merc 50 hp outboard

M9DdHc9OGd5yxoD2At8Og9bA8NlI1uPTYCNBalNggrLsNLYV_8uncZeArm03sz5vxNqKedWjBZzi7nTobbgLcEIWMC1b_UPZh05Rxc-EII5-B_BqRgB6nZxQYtmEoXXQvH-PtjUPpIUlGGyc9rcQn8elGdSxycvfBbm_kdtCYNmqLAwE6USfERM3tey-JxnpIOUrRAwW5nN90ihW1fcoIw6NbIs3NGZ-_nzPQcovGFEwuFJkYOtTOSI-Ar9ATdn0k-e1I4q_hHljru2nuySy0OgM_z5N9Ul0IXnSRKF9_HUjtepTih4a3XHxZx_dlT4JfsgJ-af-E-TXDL0Bjr-ZvM0PdykvkBVt9v89Vh2om3i-0snu2NPK04MvjlGbAZDqZNW-mYy-GCRN0mT0jBj1Ct04oXjPQBU4y3M8mD_BsE0uIdz7dn4GkJs1hGpA_1AggB0OF6BuP2YmDpNPGnVh9Weo69mqLmdR5RZTY68dadQ0EpEBIpa8oWhZ_9PLB6L-xTBsm07cd1EX60QnIbMOP5BSTD3kbm4hgBAO3esyLIfauVfvnujlO6GAO_n7Hv97a3WCDtD9h-AJvh8IH_R3Jwzd5H8-M0A=w490-h872-no


Thank you
Dave
 

HotTommy

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There is an entire forum here dedicated to prop selection. You might get a better answer there. .... There are prop selector websites that can suggest prop specs. I use the Mercury site.
 

davidwjacob

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i thought i would get a better answer here due to its for a pontoon and not a boat that goes on plane.

Thanks
Dave
 

ahicks

Captain
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Sep 16, 2013
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Dave, to be any help at all, would need to know how many rpm the engine is turning the prop at wide open throttle now, and what the engine's suggested max rpm is. Without accurate rpm info, you're asking for a shot in the dark. In addition, it sometimes helps to get an idea of how fast the boat is capable of going at wide open throttle. This is easily established by taking a portable GPS for a ride.
 

HotTommy

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David,
Using my best guesses about your engine, the websites I mentioned suggest you run a 3-blade 12.5" diameter prop with 8" pitch. A speed caluclator website predicts that prop on an engine turning 5000 RPM with a 1.83 gear ratio and 35% slip will top out around 13 MPH.
 
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MH Hawker

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Jul 13, 2011
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a 9, 11 or 13 are common pitches look and see what you have and see what RPM you have, do not guess or you risk blowing the motor
 
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Silvertip

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It doesn't matter if you have a planing hull or a barge. Prop selection requires some basic data as you will see using any prop calculator. Engine rpm, gear ratio, WOT speed, etc. Without this data prop selection is a crap shoot. You should also be looking at "pontoon-specific" props. These props have large, rounded blades that provide the push a pontoon or work boat requires. They also help with reverse gear maneuvering. They are available in three or four blade versions. Your best bet is to work with a prop shop that will let you try various props.
 

rutcutter

Seaman
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Jul 12, 2010
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David, I think that HotTommy is very close. I have a 20 foot with a Mercury 50 hp and that is what I run (3 blade, 12.5 diameter, 8 pitch). The main thing is to get your wide open throttle RPM's within where they should be for your motor.
 

jbcurt00

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Old topic by member who hasnt been on iboats since late July when he posted this topic

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