Prop spacing from back board

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Basin_Runner355
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Prop spacing from back board

Postby Basin_Runner355 » Tue Jan 17, 2017 7:15 pm

Bought a boat right before hunting season 14 ft diamond back hull really measured 13.5 zz4 355. 2:1 reduction. With a 2 blade psr whirlwind blade . Boat does decent can run the ground as long it not that sticky **** then I have to rudder. I was wondering if in themoff season would it be worth it to move my engine stand back say 2-3 inches. Right now my blades are 7-8 inches from the back board and I can't measure cause boat is in shop right now. But was wondering if that would make it run the ground better and make it stop taping in the deep water
14ft diamond back zz4 355sbc 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

SWAMPHUNTER45
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Re: Prop spacing from back board

Postby SWAMPHUNTER45 » Tue Jan 17, 2017 8:32 pm

Moving the weight back will more than likely make your hopping condition worse. Sounds like it is set up properly now, the old time rule was a beer can from blade to transom.

Basin_Runner355
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Re: Prop spacing from back board

Postby Basin_Runner355 » Wed Jan 18, 2017 6:49 am

Yea that's what heard Im get it back today hopefully and get a good measurement
14ft diamond back zz4 355sbc 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

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Rick McC.
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Re: Prop spacing from back board

Postby Rick McC. » Mon Jan 23, 2017 4:45 pm

My second car engine boat years ago (350 buick DD) was bad to porpoise at full throttle.

We moved the engine stand/seat frame (everything but the cage & rudders) forward two inches, and it ran perfect.

It doesn't take much movement to make a big difference in weight distribution. Same thing with moving the axles on a trailer.
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Basin_Runner355
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Re: Prop spacing from back board

Postby Basin_Runner355 » Mon Jan 23, 2017 5:21 pm

From the leasding edge to back board is 9 inches
To trailing edge is 7.5 but I don't know if moving it back would hurt more than help and that's a lot of trouble
14ft diamond back zz4 355sbc 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

Basin_Runner355
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Re: Prop spacing from back board

Postby Basin_Runner355 » Thu Feb 02, 2017 8:12 pm

Any new info on this
14ft diamond back zz4 355sbc 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

happy harold
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Re: Prop spacing from back board

Postby happy harold » Fri Feb 03, 2017 8:14 am

you have lots of options besides moving the engine stand and drilling yet more holes in an already weak spot in about all airboats. move gas tank, beer cooler, gas cans, fat riders up front, and so on. the closer to the back of the boat you get your weight, the more likely you will get to see if you have really good life jackets. and later you can tell your friends "i couldn't believe that much water could come over the transom that fast."

Basin_Runner355
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Re: Prop spacing from back board

Postby Basin_Runner355 » Fri Feb 03, 2017 9:08 am

I was just wondering if it would make it run the ground better bieng closer to the back board can't really
Move tank it's in a tight spot
14ft diamond back zz4 355sbc 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

br,lc,LA
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Re: Prop spacing from back board

Postby br,lc,LA » Fri Feb 03, 2017 7:58 pm

Moving it wont change ground performance. Weight is weight and thrust is thrust. Moving dont change either but may make it worse if it changes distribution of all weight further back. Got a porpose then bend then back lip down at the transom. Want ground performance make more hp or drop some #!
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JAMES
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Re: Prop spacing from back board

Postby JAMES » Sun Feb 05, 2017 12:47 pm

br,lc,LA wrote:Moving it wont change ground performance. Weight is weight and thrust is thrust. Moving dont change either but may make it worse if it changes distribution of all weight further back. Got a porpose then bend then back lip down at the transom. Want ground performance make more hp or drop some #!

I respectfully disagree with that It's always best to keep the weight off the nose of the boat regardless of the porpoise engine angle plays a lot in that matter as well as a trim tab jacks etc. I also suggest a three blade prop over the 2 Zz4 is a great motor With 2.1 reduction is fine if combined it to the right prop although it still will be limited and should do pretty good on the ground how old are all of them from all timers is a soda can down and a soda can out from the transom although my last tall I built the motor real low the prop was maybe 3 inches off of the stringers did not lose nothing ran excellent
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br,lc,LA
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Re: Prop spacing from back board

Postby br,lc,LA » Sun Feb 05, 2017 9:11 pm

I appreciate the respectful disagreement. But he doesnt seem to have an issue with plowing or the boat would not porpose... now if he makes an engine angle adjustment prop down and he feels the bow plow in the water or the ass lift when he is running dry then yep i would agree move some weight backwards.

And yes ive told him to go to a shorter prop and let that motor run up in some good rpms vs swinging a big sticks thats not matched to that 2:1.
2016 American Airboat's AirRanger pushed by an Airboat Pros 2015 1.4L GM Ecotec... "Nothin' as Fine as Hearing a Turbo Whine"

Basin_Runner355
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Re: Prop spacing from back board

Postby Basin_Runner355 » Mon Feb 06, 2017 10:33 am

Money don't grow on trees I'm trying to find a smaller prop/hub
14ft diamond back zz4 355sbc 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

Basin_Runner355
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Re: Prop spacing from back board

Postby Basin_Runner355 » Mon Feb 06, 2017 10:34 am

I called whirlwind they said that they can cut a inch off each blade that wound bring it down to almost a 78 inch
14ft diamond back zz4 355sbc 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

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406 JAMIE
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Re: Prop spacing from back board

Postby 406 JAMIE » Mon Feb 06, 2017 11:26 am

i had a 13'6x7'6 deepsided diamond back 1998 heavy old school boat loved it.i ran a 350ci/330hp crate eng GM performance nothing fancy with 750cfm elda brock qith rotator gearbox 1998yr 2.1ratio with a whisper tip EX 3bld 79in that prop worked great with all steel sbc and all steel bbc i built for it later on 414ci bbc and that prop worked great for both at 79in and 414bbc was at 500hp&trq.boat had 6bld wrapdrive 80in when i got it would not run dry for love nor money lol but as soon as that 3bld went on it with sbc would run dry no problem so its all in the way u have it set up.hope this helps bubba y all besafe plz have a blessed day. :rebel:
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Basin_Runner355
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Re: Prop spacing from back board

Postby Basin_Runner355 » Mon Feb 06, 2017 12:42 pm

See my boat is that same year a 98 I wanna say it's got a 3/16 bottom that's the ad thing with airboat to manny variables just gota test and tune. I can run the ground decent to me the engine it to far forward
14ft diamond back zz4 355sbc 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

Basin_Runner355
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Re: Prop spacing from back board

Postby Basin_Runner355 » Mon Feb 06, 2017 7:21 pm

I found me a medium hub that will make my blades 78 gonna put them on later this week and try it out
14ft diamond back zz4 355sbc 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200


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