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Swapping props on the Diamondback airboat

b0b@_dr1nk

New member
Joined
Jul 15, 2025
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4
help us out here! My brother and I are looking at swapping props on our Diamondback airboats to boost performance and help the engines last.

My setup is 13' x 7'6" Diamondback, 355 SBC (300+hp), CH2 2:1 belt drive. I'm running an 80" R series 2blade (13" wide, new hub), pitched at 13. Hits 5000 RPM WOT, cruises at 3400 RPM.

And my brother's rig is 14' x 7'6" Diamondback, CT350 (602 crate, 350hp), CH3 2.3:1 belt drive. He's got a 78" R series 2blade (12" wide, old hub/blades), pitched almost max at 3. Also hits 5000 RPM WOT, cruises at 3400 RPM.
Both engines are fresh, only one season on 'em.

So, for performance and longevity, should we swap props? My 80" onto his 14' (more power, 2.3:1 reduction), and his 78" onto my 13' (2:1 ratio)? What do you guys think?
 
I think you guys will be alright. Swapping props sounds like a good move, your brother's setup with more power and a 2.3:1 drive should handle your 80" prop better, and your 13' boat with the 2:1 drive might run smoother and a bit easier with his 78". It could help both rigs with performance and take some load off the engines. Worth trying the swap and checking how the RPMs and temps look after a run.
 
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