Prop cupping

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captjimjr
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Prop cupping

Post by captjimjr »

Can anyone elaborate on cupping for 16×16 3 blade props. I see the chart calls for cupped props but doesn't mention light, medium or heavy, is there a standard cupping for our marinette proppping
1988 32`Fisherman
Twin 360`s
Curtice OH
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Tuggle
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Re: Prop cupping

Post by Tuggle »

Contact Bblades, 920-295-4435, have used them for years on my hot rod boat. There's a little art and voodoo that goes into prop tuning, much like welding "anyone" can do it but few have the true talent.
Last edited by Tuggle on Wed Jun 10, 2020 3:23 pm, edited 1 time in total.
"Deplorable", 1975 32' Express, Twin 318's, Raw Water Cooled, Lake Lanier, Ga.
Fastjeff
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Re: Prop cupping

Post by Fastjeff »

You're signing from my hymnal!

The one time gurus of Marinette, Sir John his-self (I'm a southerner now, y'all) was instrumental in the industry what cup is and how it's defined (while he worked for Michigan Wheel). Hard to 'splain in print, but an example might hep yew out:

My old 32 footer was running 16 x 16 3 blader on the Port side, with a 16 x 15 3 blader on the other'n That the 16 x 16 had a mild cup--barely visible--where the 16 x 15 had a heavy cup (pounded in by a guy in my presence). Both engines operated the SAME.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington
captjimjr
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Re: Prop cupping

Post by captjimjr »

I see, had a guy try talking me into a 4 blade 15 inch with pitch and cupping to match or excede my 16×16's. And the ones I could match up from acme which where he said he went is a 15.50×15 4 blade. Jeff does this sound like something that would work out.
1988 32`Fisherman
Twin 360`s
Curtice OH
Fastjeff
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Re: Prop cupping

Post by Fastjeff »

Sounds reasonable. A 3 blade 16 pitch is similar to a 4 blade 15 pitch (ODs being similar).

The bottom line is that our beloved Marinettes JUMP onto plane compared to plastic boats, so you can use far more prop on them than is customary (and get better gas mileage).

The eyes of my plastic boat buddy bulged when i planed my 32 footer of--easily--at only 1/2 throttle. His 28 foot Sea Ray (454) required all it had to make plane, and dropped off under 3,000 rpm. And when he saw mine hold plane a 2,000--and after making a tight, 360 degree turn--he was stunned!

Marinettes rule!

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington
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bcassedy
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Re: Prop cupping

Post by bcassedy »

Amen, Jeff!!!
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