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Duma Windy Airboat Need Suggestions

Old 10-11-2015, 01:29 PM
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Hampstead39
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Default Duma Windy Airboat Need Suggestions

Hello all. I am currently building the dumas windy airboat. It is recommended for .09 to .12. I have a os .15 and os 25. I'm stuck on wich motor I should use. I know these small boats have been ran on the 25s but I cannot find any info on how the boat performs. I want it to do well but not over do it. Any advice?
Old 10-11-2015, 02:49 PM
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71dartswinger
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Put the 15 on and if its not fast enough then change to the 25 I have a SI3 20 rated for a 20 and we have put a 46 on one I have a 34 on mine
Old 10-11-2015, 02:56 PM
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Hampstead39
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Well I want the boat to run ok just not too fast to control that's why I figired a 15 woild be ok being a 12 was the biggest dumas recommended. By the way are the selp inflicted airboats still in production?
Old 10-11-2015, 03:59 PM
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1QwkSport2.5r
 
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I'm sure if you got ahold of Chris Selph through Facebook, you could get a kit made or get the plans.

I overpower everything - you can always throttle back. I'd run the big engine, balance properly, and just be careful with the throttle.
Old 10-11-2015, 04:04 PM
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Hampstead39
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I'm slowly getting into boats. And I'm wondering how you go about balancing them. I've flown planes for years and have that down pat just burned out on them. Any rule of thumbs for proper cg?
Old 10-11-2015, 04:17 PM
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Originally Posted by Hampstead39 View Post
I'm slowly getting into boats. And I'm wondering how you go about balancing them. I've flown planes for years and have that down pat just burned out on them. Any rule of thumbs for proper cg?
Start with the prop 1/3 of the hull length as measured from the transom for a tractor configuration. It's usually good for light boats to have it balanced such that if you hold the boat up by the prop, that the bow hangs lower than the transom - think 30-40* angle. It's a good idea when building the engine mount to allow for an inch or more engine movement in either direction. If the bow has insufficient pressure/improper balance, either it will plow water or blow over when you drop off the throttle from WOT.
Old 10-11-2015, 04:21 PM
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Hampstead39
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So balance 30 percent forward from the stern and I should be ok to start
Old 10-11-2015, 04:28 PM
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1QwkSport2.5r
 
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Originally Posted by Hampstead39 View Post
So balance 30 percent forward from the stern and I should be ok to start
That's a good place to start for most average flat bottom boats, yes.
Old 10-12-2015, 03:01 AM
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The Windy does not allow you to adjust the motor position and keep the original pod/rudder. Placement of the servos and receiver battery will be your best means of balancing the boat. A couple ounces of lead can help too.

Stick with the .15 at least at first. That boat does not take too well to huge power, at least the one I played with did not, it became tough to drive. BTW there is a lot of difference between a 3-point hydro and your little flatty, the former can be overpowered and still be controllable. Too, bigger engines need larger diameter props and a .25 prop may not fit. Sure you could go to a 3-blade but start with the .15. This is your first airboat, KISS.


.
Old 10-12-2015, 03:07 AM
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Hampstead39
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Was thinking last night after my last post and I think I will go with the 15. And ill be fine. After this build I'have a dumas big swamp buggy kit waiting to be built I plan on powering it with a os 55 ax. Thanks for all the info. Good stuff. KISS is is the better way. Less head ache
Old 10-12-2015, 05:57 PM
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Hampstead39
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One other thing. I don't know if I'm splitting hairs or not but I sanded a little too much off of 2 of the pieces curving to the bow a little too much. The kit parts were made with a blunt point so they would be easy to remove from the sheet and the instructions stated that they need to be sanded to a point. I don't think it will be a problem. Any inputs?
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Old 10-13-2015, 07:21 AM
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No problem just make sure there are no gaps for water to get in. Painting will cover most minor gaps. Don
Old 10-21-2015, 04:04 AM
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Glue a balsa strip and sand down to size. problem solved

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