Real Time Thrust Tests with Complete Boats

Roxy sorry if i ruffled some feathers buddy , been doing some testing my self in the last week and can appreciate the hard work and the infomercial thing was wrong shouldn't have said it and your test is very enlightening to me and helpful to many here. wish i was closer would love to to bring some boat s that way :salute:
 
Ruagatr said:
Plum you are taking the horsepower numbers from a "dyno sheet" for an engine that has never been tested and trying to prove a prop makes x thrust with it...right? I dont think that is realistic or factual.

Maddog[/quote its all i can do charles, but it is realistic to assume the 220 makes 185 hp at 2800 when i have a dyno sheet on a new factory engine running with a peak tune.. and it may even be realistic to assume that the actual engine in the test may have less hp due to age and wear, and that would make the signature have greater thrust #s , its just food for thought buddy its got you thinkin right... bet you got you calculator out huh! :D
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Skinny, we know there is lots of things that can be done differently but the fact of it all is we are testing these boats the way we want to run them. Remeber we have only been testing our personel boats set up the way we like to run them. We know there is alot of other things that could be done differently and may be done differently at some point but for know this is what we have. Meant very respectfully."


Of course I understand what you mean. I like this stuff and would love to have the resources to work at it like y'all have been. The search for knowledge is a fun one. I can get very analytical about this stuff.

I would love to see you test some other props. Maybe if the manufacturers won't provide props. The big time supporters would. Need make sure you use the most ideal prop on each combination to be fair of course.

Thanks again for all the research!
 
It's simple physics 101. The bigger the prop the less efficient it will be. Also the wider the prop the more induced drag it has. A small two blade A/C prop by far will be the most efficient. I bet you can take a mini airboat Koller lawn mower motor and win the most pounds of thrust per HP.
 
Waterthunder said:
It's simple physics 101. The bigger the prop the less efficient it will be. Also the wider the prop the more induced drag it has. A small two blade A/C prop by far will be the most efficient. I bet you can take a mini airboat Koller lawn mower motor and win the most pounds of thrust per HP.
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thunder you made a statement years ago about diminishing returns, it is physics 101 with the horse power you have the knowledge to make you would have to have a 14 ft wide boat to use a prop that would be efficient . don't think a lawn mower engine will get her done, but i have come to the conclusion that a variable pitch prop can make a big difference on a ride boat 8)
 
Plum, it was great to finally meet you today at the bus. I would have liked to talked to you more but that other fella wouldn't shut the hell up. Maybe next time!
 
yea dont like getting wet and had to get back to the thing for kirby you got a sweet ride brother, it was good meeting you to . raised a lot of money for a airboater in need, that what its all about , we will meet again , it was cool you had them yougins with ya teaching another generation of aiboaters :cheers:
 
Good analysis Plum, so if the lsa would be as an efficient combination as the 220 it would be in the 2200 lb thrust range, as it is it appears to be equal to an efficient 370 horse engine.
 
I'm not gonna pretend to be a prop guru by I think it stands to reason that if the LSA was spinning its prop at 2800 to 3000 rpm then we may not be having this conversation. That would have to equal the thrust to horse power numbers. Now, I could be wrong but I don't really think so. Regardless of what the max thrust number is on the LSA it is very impressive how fast it gets to that max number.
 
stan said:
Good analysis Plum, so if the lsa would be as an efficient combination as the 220 it would be in the 2200 lb thrust range, as it is it appears to be equal to an efficient 370 horse engine.
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well you cntry and others figured alot out about thrust years ago i learned alot from your testing back then , theres is a lot of info in this thread and i enjoy reading it and analizing the numbers,
my hats of to these guys workin there ass off and sharing it with SA site for old and new airboaters to look at
 
My hats off to them as well for the work they have down and the information they they have shared. I myself am concerned about the way that the price of fuel will effect my life style and I am looking for ways to improve the efficiency of the things I use. My airboat as it sits is in that 2lbs thrust/hp category if in some way i am able to increase that efficientcy say to 4 lbs It would be like doubling my mileage or cutting my fuel bill in half. The answer maybe to sell the Cadillac and put a gpu on the old boat as discovered in the provided data.
 
Plum, been gigging catfish of late 4 nights of gigging a total of 20 hours never once got on plane and burned 50 gallons of fuel. Also considering Waterthunders statement about the efficiency of a kohler. Is there some way to set one up as an auxiliary unit? Thrust testers keep the data coming.
 
Waterthunder said:
It's simple physics 101. The bigger the prop the less efficient it will be. Also the wider the prop the more induced drag it has. A small two blade A/C prop by far will be the most efficient. I bet you can take a mini airboat Koller lawn mower motor and win the most pounds of thrust per HP.
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well you just might be onto something there Dave .. LOL of course my thrust tester isn't very fancy but it is consistent and when compared to what the big boats blew .. yep the Kohler or briggs wins hand down goin away as thrust per hp .. aint even close .. it literally would make you sick trying to get that power per hp out of a car engine ... if you could ??? a 200 hp engine would be all you would need ...
 
Is the 2 blade NGH going to happen on the 540 with the right pitch? Just for conversation, we have taken a signature and a Q off of a ground power 6 and 4 cylinder that barley would push the boat on dry, change the blades to NGH using the same hub, and would strike out with 2 guys in it. No BS!
 
fl cracker said:
Is the 2 blade NGH going to happen on the 540 with the right pitch? Just for conversation, we have taken a signature and a Q off of a ground power 6 and 4 cylinder that barley would push the boat on dry, change the blades to NGH using the same hub, and would strike out with 2 guys in it. No BS!
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We didn't do the two blade on the 0540 but we did on the 0520 conversion and I don't remember the exact numbers but the two blade Q and the NGH 3 blade had better numbers. The NGH 2 blade and Q blade was tested as a 74'' and the 3 NGHs were 72''. I really like the NGH blades. If I had a AC boat it would have them on it .
 
Speaking of geared A/C, i would like to thrust test mine with my 3bld R and compare a 4bld R and a Saber if you have them. With my gear ratio (1.73)@ 3500rpm, i spin the prop the same RPM as these C/M at 5450rpm with the 2.68s. PM me if interested. Thanks
 
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