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Thread: General Prop Discussion

  1. #21
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: General Prop Discussion

    Quote Originally Posted by buster
    Duane,

    That was a lot of questions for a guy with CRS to remember, but I'll try!

    The Arrowprop Reduction came with an adaptor for the IVO Prop. However, After I tried installing it using the bolts that came with the prop, I found out that they must have sent the wrong bolts. (The instructions state: Use only the hardware supplied with the prop.) Anyway, I thought they were turning hard, but I figured that was so they would not loosen in use! They also bottomed out before they tightened up. I broke two of them off, and was not able to remove them.

    Long story short, I ordered a new adaptor from Arrowprop and went to American Fastener, and they supplied the correct bolts.

    I just bolted the prop on and did not attempt to adjust pitch before starting it up. I have an electric fuel pump beside the tank, and even on three cylinders, I think it would have turned well past 4,000 if I would have tried.

    I can't tell you what the pitch was. My goal this time was to get the engine to run. After it runs right, I'll get around to adjusting prop pitch.

    When we started it up, the boat was sitting in the pole barn (shop) with the prop blowing out the big door. The noise (Edit: I meant - sound!) did not seem bad at all, although I don't have a decibal meter.

    Dave

    Buster,

    I have a similar but different problem. In my case, the prop bolts are smaller than the holes in the adapter. Correct pattern, but the bolts are too small. (1/4 vs 5/16 ?).

    I'm going to give Don Miller a call tomorrow... Maybe he can make the same adapter, but threaded smaller.

    Duane
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  2. #22
    Senior Geezer buster's Avatar
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    Re: General Prop Discussion

    Duane,

    It's too bad we can't get all the parts we need from one source. Then at least we would know who to complain to

    Dave
    IF YOU WON'T STAND BEHIND OUR TROOPS, THEN JUST STAND IN FRONT OF THEM!

  3. #23
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: General Prop Discussion

    Buster,

    Yeah, that'd be nice...

    I called Don Miller today, and we figured out what I need, so he's making it for me. He said he'd ship it Thursday.

    Duane
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  4. #24
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: General Prop Discussion

    Buster,

    We learn something new every day....

    While I had Don Miller on the phone today, I also asked about his experience with props / reductions / on a 4A084. He told me that he'd seen the best performance with his reduction drive with one of his 60" wide chord 2 blade props, with a 28" pitch.

    28" pitch? Not a 3 blade?

    That goes against some things I've heard. What I gathered from the conversation was that when it comes to pitch, people are not always comparing apples to apples.

    There was a lot more to the conversation than I could relate properly here,

    For budget reasons I'm still going to start out with my 66" GSC adjustable pitch wooden prop, (that I already have) but expect that I'll be going back to Don at Arrow Props for a 60" wide chord 2 blade fixed pitch prop. Pitch to be determined later.

    Thanks,

    Duane
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  5. #25
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    Re: General Prop Discussion

    Ron is running a 6038 on his 084. His drive is one of the first ones Don built and it is a 1.89 to 1 ratio and he is also running a 31 solex carb. I think Don was using the stock carb.
    Thanks, Chuck

  6. #26
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    Re: General Prop Discussion

    Wow... from a 28 to a 38 with the same basic block and guts. Is the 38 one of Don's as well for apples to apples?
    Mike - Eastern NE

    We live on the surface of a rock hurling through space...some things are bound to happen.

  7. #27
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: General Prop Discussion

    Wildfowl,

    A good part of the difference may be because Don was talking about one of his "wide chord" props. Those blades are considerably wider than an average prop. Another part of it is that everyone doesn't measure pitch the same way.

    But still, there's a lot of difference between 28 and 38...

    Don also told me that the 4A084 is sensitive to disk loading and performs much better with a 2 blade wooden prop than it does with a 3 blade wooden prop.

    We were talking about wooden props, which are heavier than the composites, and have different disk loading characteristics.

    I'm looking forward to seeing how Buster's prop works out.

    Thanks,

    Duane
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  8. #28
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    Re: General Prop Discussion

    Ron's Prop was made by Florida Airboat Propellers. It is just as wide as the 6028 we got from Arrowprop It also has SS leading edges and tips. It is a heavy duty prop.
    Thanks, Chuck

  9. #29
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: General Prop Discussion

    Chuck,

    You know that I'm not arguing with you, right? I know that there's a lot of mystery and magic to finding the right prop for a given hull, engine, reduction combination...

    That's why I decided to start with an adjustable prop, so's it wouldn't cost me hundreds of dollars every time I wanted to tweak it. Plus, I don't want a shop full of exspensive wall hangers. There's not much of a market for used airboat props here in NC.

    Once I've got the right combination tweaked, I may go with a fixed pitch prop. But if I like it, maybe not. Why screw it up once you've got it running like you like it?

    I dunno, I'm still a ways out from that decision....

    Thanks,

    Duane
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  10. #30
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    Re: General Prop Discussion

    Hey Duane, One of the reasons Ron's boat turns the 6038 prop is the drive ratio. It is a 1.89 to1. If he had a 1.69 to 1, his engine would not turn the 6038 prop to where it would get the rpm's he would need to make it run good.
    3700 engine rpm's divided by 1.89 = a prop speed of 1957
    His boat jumps on plane but only runs 30.8 MPH.
    3700 engine rpm's divided by 1.69 = a prop speed of 2189
    His boat would only turn a 6034 with this ratio but might run 35 mph due to the extra prop speed.
    A lower ratio will multiply the torque. If an engine produces 80 ft lbs torque at 3700 rpm's and you put a 1.69 to 1 reduction on it you would multiply 80 x 1.69 = 135.2 ft lbs torque on the prop shaft.
    80 x 1.89 = 151.2 ft lbs torque on the prop shaft.
    The lower ratio produces 16 more ft lbs torque but gives up 232 rpm's on prop speed. The 16 more ft lbs torque will turn a same length prop with more pitch but turns it slower.
    Now some props work better at lower rpm's than others. I like to use the more expensive adjustible props so i can set the pitch to get the rpm's out of the engine where it works the best. I only use a stick prop when i know what length and pitch works best for the engine i am using.
    Note: for every 2 inches shorter in prop length, add 2 inches pitch. So a
    6030 could be replaced by a 5832 or a 6228.
    Thanks, Chuck

  11. #31
    Senior Geezer buster's Avatar
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    Re: General Prop Discussion

    Duane,

    I just got my new plugs today, and I will let you know as soon as I can get around to trying it out, but it may not be until this week end.

    Chuck,

    I adjusted the IVO prop for the max. pitch, which seems to be about 20 degrees, if I am doing everything right. Does that sound about normal?

    Thanks, Dave
    IF YOU WON'T STAND BEHIND OUR TROOPS, THEN JUST STAND IN FRONT OF THEM!

  12. #32
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: General Prop Discussion

    Chuck,

    Phewhy. Now I'm in brain overload.

    I'm gonna' print that out so's I can look it over later. It makes sense, but that doesn't mean that I understand all of it yet. Duh.

    Thank you for "clearing it all up in my mind".

    Duane
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  13. #33
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    Re: General Prop Discussion

    Hey Buster, if you got the 1.89 to 1 ratio then you will be maxed out on pitch. If you got the 1.69 to 1 ratio, you might have to back off a little on the pitch. We haven't run the 1.69 to 1 on the 084. It is a torque motor and may work great with a 1.60 to 1. That would give it more prop speed. Maybe someone will get a smaller bottom pulley and try it.
    Thanks, Chuck

  14. #34
    Senior Geezer buster's Avatar
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    Re: General Prop Discussion

    Chuck,

    If I remember right, I measured the pulleys when I first got the Re-drive, and I think it worked out to about 1.73:1. I guess I'll know how it goes in a few days.

    Thanks, Dave
    IF YOU WON'T STAND BEHIND OUR TROOPS, THEN JUST STAND IN FRONT OF THEM!

  15. #35
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    Re: General Prop Discussion

    Hi Duane, Thanks for the info from Don. Interesting and good to know about the loading factor!

    I have two props for my 400DD both wood. One is a Sensenich standard prop in 72x38 and the other is a Florida Airboat Prop wide blade/wide chord, or AKA "paddle prop" in 72x34. The wide blade prop is my first pick with the best performance all around...In static it turns right at 3000 and I can over spin it when loose on the water but I like the static for getting started off of the sand. Top end speed is also faster with it(I can spin it up to 33-3400 but wont as there is no gain in speed after about 2950 rpm....and I have no desire to spin the rivets out of the tips. ). The Sensenich was the first prop I put on and it worked good enough to keep as a backup, can spin it up to 3200 but just not a lot of guts on this application. So for what it is worth, there is a direct comparison of a straight stick and a paddle/wide prop. The paddle is also much quieter with a pleasing sound signature.

    As far as the Florida Air Prop goes...I've beat the tar out of it (exhaust manifold bolts, nylon shorts, bottle caps, a wrench, etc) and have sent it in a couple of times for general maintenance and it comes back good as new.

    Chuck...thanks for the equations, very interesting material on the Tq conversions. I have always been scratching my head why they came up with the 1.69 for both the o84 and the twins. I guess I still am, but now I understand the reductions to get the the prop to 3K will have little if any Tq benefit.

    So...the question might be...Is there a prop manufacturer that makes one with good performance characteristics turning 2000-2100 RPM at the hub??? I mean one with some quantitative thrust numbers. If I had to guess it would be the Florida Air Prop???
    Mike - Eastern NE

    We live on the surface of a rock hurling through space...some things are bound to happen.

  16. #36
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: General Prop Discussion

    Wildfowl,

    That's good info also. I still think there's voodoo involved in finding the right engine / hull / reduction / prop combination.

    Another thing that may be misunderstood when people are discussing performance is what they consider good performance. A race boat and a ride boat are not the same thing.... same for a fast ride boat vs a leasurely ride boat. A 25 year old's idea of a good performing ride boat, and a 55 year old's idea may differ a lot.

    Ultimately, I want to be able to get moving, up on plane quickly, and then be able to throttle back to a pleasant enjoyable cruise speed. I have no interest in a FAST ride, but a relatively quiet, economical, leasurely ride.

    Of course, having enough reserve to punch it when you feel like it (or need to) would be nice....

    Thanks,

    Duane
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  17. #37
    Senior Geezer buster's Avatar
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    Re: General Prop Discussion

    We did not get the Aircat 084 in the water yet since we are still re-designing the snowmobile trailer to fit it.

    As the pic' was taken the trailer is just tac welded together for now. My welder buddy Ron volunrteerd to finish welding as soon as it is ready, so that will be done shortly and we can head for the lake!

    Today however, we got the carb adjusted better, and decided to put it on the lawn to see if it will run dry. We ran it up to over 4,000 rpm, and It would not budge even when Hank pushed the nose side to side. The three blade IVO appears to be maxed out on pitch, about 20 degrees if I'm doing it right.

    First, we figured the tach must be wrong, so we tried a hand held unit, and came up with almost the same numbers. I guess I just added too much weight to the hull with all the fiberglass resin I used to straighten the bottom.

    Anyway, the next step is to see how it runs in the water. In this area there is probably not a lot of dry running to be done anyway

    I guess tomorrow I had better get the Minnesota liscense onto the sides, before it goes into the water. An airboat around here will probably attract a lot of attention, maybe the wrong kind, and it will be best to be ready!

    Dave
    IF YOU WON'T STAND BEHIND OUR TROOPS, THEN JUST STAND IN FRONT OF THEM!

  18. #38

    Re: General Prop Discussion

    Well Buster I really hope everything goes well today.
    Such a nice looking ride and with all the work. I'm sure you'll get her pegged.

  19. #39

    Re: General Prop Discussion

    An Idea for everyone; especially Papee,

    I was thinking this morning about my prop situation. Naturally when i get it right i will post the results. What I was thinking was, if everyone would post their combination including engine, direct or % reduction, type prop, pitch etc... this would be a great reference for those building in the future so they can save time, money sanity, etc...

    Now Pappe, Since you don't have enough to do If everyone likes this idea is there a good way to organize this? Would this also work for different carbs and jetting etc...?

    What i am not sure about is; bo all engines/boat combinations work the same. And the static verses running rpm's etc... At least we could get close.

    Just an idea.


    Thanks

  20. #40
    Administrator Papee's Avatar
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    Re: General Prop Discussion

    I could make a reference thread that everyone could post their setup and make a chart from it. Something like:

    USER------HULL SIZE------HULL MAT. -------ENGINE-------REDUCTION MFG--------RATIO--------PROP MFG--------PROP SIZE-------PITCH
    Papee-----13'4" x 66-------Aluminum---------4A084-----------none-----------------none---------Ultra Prop----------57-------------10

    I can also make a form on the main site that when filled out will fill in this info and post it to the list.
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