First Hull - rigging

A general, non-powerplant specific, discussion on airboat technology, ie., hulls, rigging, polymer, etc..
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arbtmn
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First Hull - rigging

Post by arbtmn »

I am very new at this so bare with me please. I am starting out with a 12'6" x 7'6" hull. (Top measurements) In deep water how high should the sides be? What does polymer weigh? I am trying to keep the boat light as possible. I like the pancake type caging. The look pretty strong to me so long as you properly reinforce it with bracing towards the front as well. Just placing the cage part around the prop. Now the rudders. Can I shorten them to be 1/2 the diameter of the prop? I forgot to mention that I will be running a 360 180 hp lycoming on it. Thanks
Marty

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Deano
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Re: First Hull - rigging

Post by Deano »

As far as the sides go, let your builder make that determination. He already knows the answer, and why.
Just make sure that you convey to him what you're using for power and how and where you will using the boat.

As far as the polymer goes, I don't know exactly what it weighs but it is pretty much neutrally buoyant, so it will not really add weight while you are in the water. The bolts, etc. will add some dead weight but is well worth it my my opinion. You said in a different thread you were not going to be running dry, so I would not perceive the weight of the polymer to be deleterious to how the porposed boat would perform overall. Your 360 is a much better choice than would have been the 290, especially in this case, as every weight in your tackle box will not make a difference.

Nothing wrong with a pancake cage if you are not running through the woods and/or running small, overgrown trails. The main objective of the full cage is to push such brush back out of the way rather than getting hooked on the cage. If there will never be any such brush and/or consideration then there may be no need for the extra weight and/or subsequent loss of otherwise usable space.

As for as the rudders, you could, with a loss of maneuverability, make them shorter; but why?
Realize that most of the air column coming off the prop is not at the tips and/or at the dead center at the hub.
With standard 4 foot rudders at a typical 24" spacing, they optimally deflect the most air given they are each covering near the entire height of the thrust column. For these reasons, this has become a time proven standard. You may see bigger on a big boat with a big prop, but you will very rarely see them smaller.
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
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Duckhunter_012003
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Re: First Hull - rigging

Post by Duckhunter_012003 »

I already recommended it to you once, if you ever run in any sort of heavy cypress swamp down here, full cage, you think it's a coincidence that you never see any airboats in south La without a full cage ?

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Deano
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Re: First Hull - rigging

Post by Deano »

x2 on all that.

I reckon that's another example where putting your location in your profile would help.
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
- Carl Sagan

woods and water
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Re: First Hull - rigging

Post by woods and water »

I have built hundreds of set of metalwork for people over the years and i try to talk them out of pancakes for theirs safety the bars in a pancake to a 3/4 cage are about 8 inch longer so it ends up about 88 inches in all not much wieght for a whole lot of safety

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Re: First Hull - rigging

Post by Duckhunter_012003 »

Yeah but you can't ever fix stupid

arbtmn
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Re: First Hull - rigging

Post by arbtmn »

Thanks for all of that input. I will update my profile to include my location which is Slidell, LA. I understand the rudder issue you mentioned and I will go with the 48" (swinging a 70 inch prop) rudders as recommended by the outfit that is building my boat. I also let him pick the sides which is going to be 22 inches.
Marty

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