Want to replace the prop on a alpha one 5.7 mercruiser

gica

Petty Officer 1st Class
Joined
Feb 24, 2016
Messages
375
The 4 blade RH aluminum one that's in there bent to hell for lowering the drive in the sand so I need to replace, it has a 14.5X18P prop in there now on a 15 spline hub. What can I replace it with? Can I use a different number combo like 14X19 or 18 or 17 if I get the Alpha One Hub kit? Thanks
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
The important number is the pitch, in your case 18. That's the one you need to keep constant. If your happy with the performance and it keeps the full throttle revs in the specified range, stay with that size.

Chris. ....
 

harringtondav

Commander
Joined
May 26, 2018
Messages
2,438
I can't add much to archis . If you go with a smaller than 18P your boat will jump out of the water faster with a full throttle hole shot pulling up a skier or wake boarder, but it may cause your engine to over rpm at full throttle. 4600-4800 tends to be the max rpm. If you choose a higher P, your boat may be more doggy out of the hole, but will cruise faster at max. engine rpm. That is the performance issue, but do not over speed your engine. Your choice of prop. manufacturer, hub kit, or solid hub is your and your wallet's choice. There are plenty of choices out there, and they all perform fine. I recommend carrying a spare. Just like a spare tire.
 
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gica

Petty Officer 1st Class
Joined
Feb 24, 2016
Messages
375
So you're saying I can use any combination as long as the pitch is 18P no need for the 14.5 one, can use 14 or 14.25 (they all have hub kits)etc. The spline axe is universal?
Mine goes 40mph with the screwed up prop 18P so if I get the same it should be smoother
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Can use any prop pitch as long the engine revs safely inside its min and max wot rpm range factory stated. As haven't posted any wot rpm run impossible to know if the engine was revving happily inside that range as loaded with current shot prop. That's the data you need to know and then go from there.

Happy Boating
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Diameter number is what the prop manufacturer wants to put, more important is pitch and the max wot revs it produces as currently loaded. Be aware of this situation or risk over revving or lugging the engine badly...

Happy Boating
 
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