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Old 07-04-2019, 01:02 PM   #1
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prop size

I own a 1981 mainship 1 34ft ,200hp perkins eng. need new prop, now have 23x19 ,1-3/8 . was told by prop shop I could only get a 23in prop with 1-1/2 in or bigger. was told could go with 22in wheel but to add 1in of pitch (22x20). does this sound about right? I don't guess it will make a heck of a lot of difference either way,just wondering .
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Old 07-04-2019, 01:36 PM   #2
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We need to know what RPMs you are turning with the current prop.
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Old 07-04-2019, 02:50 PM   #3
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If your existing prop allowed you to reach max rpm at WOT then dropping dia 1" and add 1" of pitch shouldn't make a huge difference. But... Rule of thumb says you add 1 1/2 - 2" of pitch. So it might be a couple of hundred rpm off.

Just make it clear to prop shop that final acceptance is subject to sea trial and if you can't reach max rpm or max speed then they will repitch it.
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Old 07-04-2019, 03:55 PM   #4
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If all is well with current prop, get the 1-1/2 and a bushing. They are cheap enough and work fine. Maybe get a new prop shop...


https://www.deepblueyachtsupply.com/...n-bore-reducer
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Old 07-04-2019, 05:13 PM   #5
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I ran a 24 inch wheel on an 1 3/8 shaft for years so am surprised the prop shop says you can't get one. I will say 1 3/8 shaft is too small for a 24 inch prop. Chewed up 3-4 shafts until I installed an aquadrive.
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Old 07-05-2019, 10:49 AM   #6
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prop size

I thought I had heard years ago that 1in of dia equaled 2in of pitch,depending on prop size, as far as using a bronze bushing , I used one years ago and didn't care for it. also the prop shop is not the only place that says you can't get a 23in prop with 1-3/8 bore, if you look at the Michigan w-site you will see that the biggest wheel they offer with 1-3/8 is 22in also I want to stay with a mich dyna quad. my old prop has a fair amount pitting near the hub. it's about 25 yrs old! I don't need a blade going through the bottom! I will keep looking on line ,don't think I will find much more info.
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Old 07-05-2019, 10:58 AM   #7
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Contact Michigan. They used to machine custom bore sizes on special order.

A lot of prop shops will try to sell what they have in stock, even if it is not the correct prop.
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Old 07-06-2019, 04:31 PM   #8
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going to check with them mon.
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