Real Time Thrust Tests with Complete Boats

Torque - something that produces or tends to produce torsion or rotation; the moment of a force or system of forces tending to cause rotation. Why would you be looking at thrust to the amount of HP the motor makes?
 
since HP = TORQUE x RPM ÷ 5252
then by rearranging the equation:
TORQUE = HP x 5252 ÷ RPM
you can do it any way you want too 8)
 
plumcrazy said:
the best thrust of all the boats y'all have tested so far is boat f...... let me explain myself before y'all call me nuts,
boat f is a 220 ground power, i have a pdf on my computer of a dyno of a fresh new built motor at 2800 rpms this engine makes 185 hp that's it ......boat f has a water walker signature series prop 74 inch, it produce a paltry 740 lbs of thrust not much till you do the math........
740 divided by 185 = 4 pounds of thrust per hp......... now take any boat on this test and do the math.

example; lsa supercharged 550 made 1481 lbs of thrust......
the math ; 1481 divided by 550=2.69lbs of thrust per hp 8) i love math

this is a good thread but it would be cool to see, some variety of props maybe a whirl wind or a water walker that is unless this is a sensenich infomercial and so far the water walker is the only prop in the 4 pound club :wink:
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Based on this can you make an educated guess what thrust you would get from a 800HP Honda 2.2L Turbo motor at 8800 RPM with the proper gear ratio and prop?
 
I guess I should have added the contrast for that one. My bad.

Then do the same for a 600+ cubic inch BBC making 800HP at 5400 RPM.
 
Well according to what you were doing. The will both make the same thrust and less thrust per HP because they make more HP than the first two. So you would expect maybe 2.24lbs per HP. That is based on the 33% loss from the 297% power jump from 185hp to 550 and then taking that 800 which is about half the increase at 145%, so that would be about a 15% loss (I did a little rounding). That would only be about 1795lbs total, but the Honda will never make that much thrust since it is only making 477lbs of torque at that HP and will not make enough at lower rpm to even get a prop that big to turn up anyways. The BBC on the other hand may make that because it is making 778lbs of torque at that same exact HP and is make plenty down low also. Torque is the twisting force that is turning the prop, so you would speak in the term because it's the one that matters most. You could say that the 220 makes 137,954watts and the LSA makes 410,134watts, but why would you do that? The person thing I can think of is maybe an electrical engineer that didn't have firm grasp on torque, but it's still not right.
 
my point in this is efficiency . you can keep putting more hp and tq to a prop and make more thrust , but after a point your just wastin energy, i want a boat that will do what it needs to do no matter the size or if its a/c or carmotor with the most amount of thrust for the least amount of energy, now if your flat out drag racin then you can throw that out the window you want all the power you can put to the prop in a second, with todays gas prices and the legendary gas gussiling ability of the average airboat im looking for every mpg i can get.....
 
poobought said:
Speaking of gas milage, would 3 miles per gallon be considerd good, average or bad for an airboat.
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All depends on where and wind and what boat? No wind,lots of skinny water and it is not all that impressive. A day of mixed riding including running a little dry,deep water,your boat and it would be pretty good.
 
I’ll have to say, I’m a little disappointed in the 220-GPU data.
I guess I was expecting/hoping for a little better results there.

I think it would be safe to assume the 220-GPU used for this testing was basically stock, with stock intake manifold and zenith carb and a single mag.

I’m building a 220-GPU and I was certainly hoping to get a little better performance than what I’ve seen here..

I know there’s only so much HP & Torque you can get out of one of these but,,,, oh well,, wishful thinking I guess…
 

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helms24 said:
i wiil run fuel milage with any body that has a 14 boat...i have a W/T 418 and i have had lots of aircraft boats... when i cruse i sip and when everyone wants to line up i have the power to go.. thats to Dave and Shawn have tuned my motor perfict and at cruse speed it sips but when im in it it will burn it too....so my opinon is that to each there own we all want good fuel burn boats but getting the power to do what u want will cost somthing..
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What is your (average) fuel burn in gallons per hour, or miles per gallon?

Is your 418 fuel injected?
 
In the Glades my 15' Scorpion sled with a carbureted WT 500 HP averaged between 3.00 to 3.25 miles per gallon according to the odometer on my GPS. I'm assuming the GPS odometers are fairly accurate. I felt like this was pretty good mileage for a carbureted engine.
 
flying fish said:
helms24 said:
i wiil run fuel milage with any body that has a 14 boat...i have a W/T 418 and i have had lots of aircraft boats... when i cruse i sip and when everyone wants to line up i have the power to go.. thats to Dave and Shawn have tuned my motor perfict and at cruse speed it sips but when im in it it will burn it too....so my opinon is that to each there own we all want good fuel burn boats but getting the power to do what u want will cost somthing..
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What is your (average) fuel burn in gallons per hour, or miles per gallon?

Is your 418 fuel injected?
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Careful there fish you might start a old verses new war LOL
 
pax1ton said:
flying fish said:
helms24 said:
i wiil run fuel milage with any body that has a 14 boat...i have a W/T 418 and i have had lots of aircraft boats... when i cruse i sip and when everyone wants to line up i have the power to go.. thats to Dave and Shawn have tuned my motor perfict and at cruse speed it sips but when im in it it will burn it too....so my opinon is that to each there own we all want good fuel burn boats but getting the power to do what u want will cost somthing..
Click to expand...

What is your (average) fuel burn in gallons per hour, or miles per gallon?

Is your 418 fuel injected?
Click to expand...

Careful there fish you might start a old verses new war LOL
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Just curious Willy. :)
I sure hear good things about the W/T 418 EFI.

poobought-
Thanks for the info. Without GPS, I do not know miles per gallon. I am checking the burn per hour on my new set up.
The first time out on my new set up, I ran all skinny water and was just under 6 GPH fuel burn. last weekend I ran all deep water due to rain and run off into the river, and averaged right @ 8 GPH for 3 hours run time.
My cruise was 28-2900 RPM in deep water, no wind. 31-3200 in deep water and 10-15 MPH head wind.
My max governed RPM is 4950 RPM with a 2.52 ratio reduction and a 3 blade 82" Sirius prop. She runs ground real good, but seems a bit tied down @4950 governed RPM. She is laboring. I can hear it. Sure wanting to take pitch out and govern her @ 52-5300, but am guessing will hurt fuel burn and I need no more out of the boat. Need absolutely nothing. She ain't fast. Is real quiet, and moves on the ground rather easy. So quiet my fishing buddies telling me she is the loudest boat on the river. At cruise RPM, real easy to carry on a conversation with person sitting in passenger seat. I hate to screw it up by taking pitch out. Fighting the go fast side of my brain. That part of my brain saying to govern the good breathing piece @ 5500RPM :)
 
plumcrazy said:
my point in this is efficiency . you can keep putting more hp and tq to a prop and make more thrust , but after a point your just wastin energy, i want a boat that will do what it needs to do no matter the size or if its a/c or carmotor with the most amount of thrust for the least amount of energy, now if your flat out drag racin then you can throw that out the window you want all the power you can put to the prop in a second, with todays gas prices and the legendary gas gussiling ability of the average airboat im looking for every mpg i can get.....
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The most fuel efficient was to see the woods, is on the discovery channel or setting on a porch somewhere. Now if your just worried about it because of cost riding on a friends dollar could work, but that way just isn't right. LOL

I'd say on of the most efficient motor combinations would be a liquid cooled aircraft motor. Since they are light and use low rpm they are great, but because they are air cooled they need more fuel in chamber than a car motor to run right. I'd like to see how lean you could run one.

So, we should be looking at thrust vs torque and then the fuel need to make that torque. For the final of thrust vs fuel burned.
 
you water thunder guys are the bomb after all you have water thunder boats you have drank the coolaid what else can i say you have the best airboats ever built . congrats fellers :salute: 8) dont get no better than that, now that i agree with you let me just say this there something to be said about sliding around on something that makes more tq at half the rpms but hell what do i know. :dontknow:
 
helms24 said:
dont know fuel burn by hr but i know i am about equal with alot of the aircraft that i run with in the woods....but i have the 418FI and i am running 1500 rpm cruse with the water the way it is....A/C are running 1100 to 1200 rpm depending on the boat....but when my peddel hits the floor see ya.....i run 93 711 finest..if u think u cant have hp and fuel milage call WaterThunder he proved me wrong..i think it nice that diffrent props and combos are tested..
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Cruising around in skinny water @ 1500 RPM is just incredible. Impressive to say the least.
Maybe you could get an average fuel burn per hour and post the results. Truly I wish I could cruise @ 1500 RPM and still hit 5000+ WOT RPM. You got it going on. :) Nice!!!
 
Helms what your turning wot? I know when I turn 5600 I cruise about 500rpm higher than when I set it for fuel mileage at 5000. And if I remember right your turning 5600 so if you choked yours down you may cruise even lower.... I thought my boat cruised good at 2500 til I saw yours! Btw my next hull will be a scorpion!
 
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