Prop selection

sethhartman

Recruit
Joined
May 28, 2012
Messages
3
I have a 21 foot pontoon with a 1997 mercury force power series 40 hp (0E261779). Current prop has numbers but not a part number that I can tell. All it has is (48 8/818 A10 9P ) when measured it's showing a 12 inch diameter. Any advice on what size and pitch I should replace this one with? Thanks
 

b.gagnon

Master Chief Petty Officer
Joined
Apr 28, 2001
Messages
835
It looks like a 9 pitch..... You need to state your WOT rpm to get an answer. If you are turning close to 5500rpm you have the right prop.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Welcome to Iboats,

Firstly, why do you plan, need to change current prop ?

Buying blindly a prop per recommendation, word of mouth, before having tested current one on combo as usually loaded on a wot spin on flat calm, no wind water cond without a tach to know achieved wot rpm is throwing money into the blue.

Happy Boating
 

sethhartman

Recruit
Joined
May 28, 2012
Messages
3
My prop was slightly damaged when I backed into my brick mailbox. Currently my wot in calm water is about 5000-5200 max wot on this motor is 5800. I'm just going to have to try some I guess. What will be the difference between a 9 pitch and a 10.5 pitch?
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
The near cast theory that states +200 wot revs going 1 pitch down will vary depending on how heavy is any combo. You can re pitch current prop 0.5-1 less pitch at a prop shop for OB to rev at max 5250 stated rpm.

Happy Boating
 
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