Pitching prop

A general, non-powerplant specific, discussion on airboat technology, ie., hulls, rigging, polymer, etc..
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TC66
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Pitching prop

Post by TC66 » Thu Dec 19, 2019 8:06 am

My 0540 is turning 3100rpms when I stand on it. I am swinging a 2 blade prop and it is set at #1 on the hub marks. Boat runs dry like a beast but not making much top end. Should I adjust prop to reduce Rpms and how many rpms is tolerable?
14'x7' lazer with av0540&72"Q series.
If I can't be at work I might as well slide!! :old_glory: :texas:

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digginfool
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Re: Pitching prop

Post by digginfool » Thu Dec 19, 2019 8:24 am

Shoot for 2,600 on the trailer. Should give you 2,700 on the water.
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GeeLeDouche
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Re: Pitching prop

Post by GeeLeDouche » Thu Dec 19, 2019 10:57 am

agreed with digging.
16x8 Utah style hull With a Waterthunder motor W/ 2.3 CH3 reduction swinging a 3 blade 78" R.
&
17-51 Legend craft w/pods pushed by a MB HD7000

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John Fenner
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Re: Pitching prop

Post by John Fenner » Thu Dec 19, 2019 12:19 pm

Use the numbers on the blades as a reference, go buy a husky digital level, fine tune the blades with it.
I never finish anyth,,,.

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Slidin Gator
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Re: Pitching prop

Post by Slidin Gator » Fri Dec 20, 2019 12:14 am

TC66 wrote:
Thu Dec 19, 2019 8:06 am
My 0540 is turning 3100rpms when I stand on it. I am swinging a 2 blade prop and it is set at #1 on the hub marks. Boat runs dry like a beast but not making much top end. Should I adjust prop to reduce Rpms and how many rpms is tolerable?
TC,

It would be useful to have more details, specific prop and hub/diameter. O540 is a carbureted, Parallel Valve (Straight Valve) engine that should make 240-250 Hp with ease. The 3100 figure on #1 pitch is not out of range but you need more pitch. She runs ground well now because she jumps quick.

Assuming you are running a 72" prop, you should increase pitch (Turn down Trailer RPM) tuning for 2,850 RPM Max for optimum performance on ground. For free running on water tune more pitch as Diggin advises towards 2,600 minimum. You should find your happy home in that range.

#2 pitch should be your starting point for running ground, #3 pitch for free running. :thumbleft:
I grew up thinking I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540, 72” NGQ. A Bob Stossel original.

Gary S
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Re: Pitching prop

Post by Gary S » Fri Dec 20, 2019 6:27 am

You can also download a level for your phone that is amazingly accurate.

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Slidin Gator
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Re: Pitching prop

Post by Slidin Gator » Fri Dec 20, 2019 10:37 pm

Gary S wrote:
Fri Dec 20, 2019 6:27 am
You can also download a level for your phone that is amazingly accurate.
Isn't that wild!

I'd like to build a 12 inch crescent wrench with a hammer on the back (already got that) plus a cell phone built in.

Built right, the screen won't crack when I drop it...
I grew up thinking I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540, 72” NGQ. A Bob Stossel original.

Gary S
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Re: Pitching prop

Post by Gary S » Sat Dec 21, 2019 6:15 am

I bet I could crack it.

TC66
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Re: Pitching prop

Post by TC66 » Sat Dec 21, 2019 9:27 am

Thanks for input guys! Engine is an av 0540 and yes it's a 72" two blade. Got it to 2600 now and used a piece of stiff wire attached to a valve cover bolt to get it tuned just right. No vibration and super smooth.
14'x7' lazer with av0540&72"Q series.
If I can't be at work I might as well slide!! :old_glory: :texas:

TC66
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Location: Jasper tx

Re: Pitching prop

Post by TC66 » Sun Dec 22, 2019 9:47 am

What is average top speed for a boat that runs dry very well. My boat made 50mph and crosses the sand very good. I run the river and no boat launch. I unload at the top of the river bank then run across the sand to the water. Sometimes big elevation change to get out.
14'x7' lazer with av0540&72"Q series.
If I can't be at work I might as well slide!! :old_glory: :texas:

Gary S
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Re: Pitching prop

Post by Gary S » Mon Dec 23, 2019 6:28 am

Boat runs dry like a beast an runs 50 MPH. What are you looking to get out of it. Lot of people would kill to have what you have.

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