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Expert Help please Prop 21 foot Boat

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Old 05-14-2012 | 05:37 PM
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CRG
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Cool Expert Help please Prop 21 foot Boat

Have project boat(1989 scarab excel) that is almost done, came with fresh alpha drive and 19 pitch 3 blade ss prop. Motor was cracked, so got short block 383 , with BM MOTOWN 23° ALUMINUM HEADS, demon 650 , stock merc dist. , thru hull corsa exhaust. Just need advise on prop size, I run the local river , with myself and one other person. Would like to see top end in the 64-66 range. Thanks in advance. I have a 4 blade ss set off my Formula 24 pitch.....too much for an alpha?
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Old 05-14-2012 | 05:53 PM
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I think a 3 blade high rake SS prop will serve you best. Try the one you have and let us know if you wish to test any others.

Brett
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Old 05-17-2012 | 03:58 AM
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Default test run results

boat ran 53 mph on gps with 3/4 tank of fuel, 650 lbs of people , looks like I need to go to a 23 pitch. Still plenty of power left in the stick
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Old 05-17-2012 | 11:14 AM
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Let us know if you need some test props.

Brett
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Old 05-18-2012 | 03:09 PM
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you have a PM
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Old 04-24-2013 | 06:55 AM
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Default go up in prop size? 21 foot with 383cu 23 pitch mirage

ran yesterday on the bay, WOT is 55 on the gps, 3/4 tank and two guys , can't trim too much at all, loosing bite at higher rpm's. can I run a 4 blade? maybe 24 on the alpha? Thanks
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Old 04-24-2013 | 06:57 AM
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What is your RPM at WOT?
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Old 04-24-2013 | 09:53 PM
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5000k thanks
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Old 04-26-2013 | 05:14 PM
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So you are at 5000 rpm with a 23" pitch prop and 55 mph gps?

What is your drive ratio?
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Old 04-29-2013 | 02:13 PM
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CRG,
did you send me a PM?

Sorry, I was at Desert storm for the last week and I want to make sure I didn't miss anything.

Brett
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