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3 blade vs. 4 blade GPH

Old 04-25-2007, 01:17 PM
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Default 3 blade vs. 4 blade GPH

3 blade vs. 4 blade GPH-

What is the difference? I know 4 blades have a better cruise but what are we really talking- 5%, 10%, 25%?

I am running twin 300XS's 5800RPM, 3MPG, 44GPH, 65MPH (was still in break in..) with 24 Bravo I 4 blades.

I want a "day-to-day" prop (26 Bravo I?) and then a "fast" poker run prop (25 Mirage Plus labbed?) but if there is not much cruise difference I would go with a non-labbed day to day prop (25 Mirage +?) and then a labbed poker run prop (same 25 Mirage + labbed or labbed Tempest or ___?)
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Old 04-25-2007, 02:37 PM
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Location: St. Cloud, FL
My Boats: 1995 Allison Grand Sport & 1990 30' Velocity
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This is more of an extreme condition, but I'll give you my real world example.

On my Allison, I run a 28" 3-blade for top end, but I wanted something that would carry a load a little bit better since I usually have my family with me and I'm rarely in the boat by myself.

Anyway, I bought a 24" OT-X 4-blade from Hydromotive for this purpose and at around 5000 rpms, I was cruising at just shy of 60 mph, which wourked out to about 4-5% slip. My 3-blade 28" runs about 2-3 mph faster at the same RPM, but comes in around 10-12% slip. If my 3-blade prop was a 24" based on my results I would cruise at least 3 mph slower with the 3-blade at the same RPM.

Of course this is with my boat and these 2 particular props, but you can get the idea of how your fuel efficiency may go up or down depending on the prop you're running.

Your efficiency depends on a number of things and the only real way to know what the differences will be is to try different combinations.
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Old 04-25-2007, 03:49 PM
Join Date: May 2002
Location: Tampabay Florida
My Boats: Renegade 29
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I run a 25" Hydromotive Quad 4 by Throttle Up on a 29Renegade. This worked better than the Bravo 4 & Mirage in general. The CC consoles need their tails lifted & the Quad 4 lifted the stern, allowing us to get better overall results. Matt & Julie actually cut the blade down a little as we were getting too much lift. Call Throttle Up & try a Quad 4
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