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Found my motor, 2021 Merc 60, 20 inch shaft for my new to me 1987 15 Super Sport. Now the question is what prop and what mounting hole? I am considering aluminum.

Thanks again for any and all suggestions!

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Since you did not specify whether you have a CT gearcase or not, I will do both.

Note - Installing an aluminum prop is like buying a Ferrari and installing tires from a golf cart. The rational about aluminum protecting the gear case is pure bollocks! The modern hubs do the protecting.

Here are the specs:

Non- CT

WOT - 6,000
Gear Ratio - 1.83
Slip - 5%
Target Speed-

Pitch = 13

Mercury Vengence 13-3/8 x 13

Command Thrust Model:

WOT - 6,000
Gear Ratio - 2.33
Slip - 5%
Target Speed- 38 mph

Pitch = 16

Mercury Vengence 13-3/8 x 16

Engine should be mounted at least 2 holes up. Meaning, the top bolts should be in the 3rd hole down from the top.

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Phil, on the "other" website you mentioned a 13 3/8 x 13 prop. What is the difference between 12 and 13 pitch and why the different recommendations?

Thanks

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Presuming the same model of prop, a 13" pitch is "steeper" than a 12" pitch. The larger pitch will result in the prop turning less to travel the same distance.

Prop performance is not locked to size and is not universal across brands and even models of props. This is why recommendations are Make, Model and diameter/pitch.

Does this make sense? Helpful?

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Ok, got that, thanks Phil. So which size and pitch should I look to start with. The Vengance 13 3/8 x 12 or 13/3/8 x 13?


Thanks again