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Well you COULD do it that way (can I watch?) But no, with the boat in the slip (engine off) you turn the closed prop to where you want it then climb aboard, go below and mark the shaft. On mine that's where the blades open horizontally, so the gap between them when closed is aligned with the strut.
Then like Pat wrote, when you turn off the engine before your race start, you jump below and turn the shaft so the mark (and closed prop) is where you want it. BTW, I only go to this trouble for an ocean race.
(Massive edit there - I hope this makes sense.)
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