First Airboat = Hull

[arbtmn]

I am starting a new project. I want to configure an airboat. I will be buying a 290 for the power plant and I will have the hull custom made. I would like to start out a little underpowered and later reconfigure with something like a lycoming 320 or 360. So first can anyone suggest the right propeller for this 290 set up? Next, I don't have a clue on the dimensions the hull needs to be. Does the propeller diameter determine the bottom of boat width? Help is much appreciated. I built one one made of wood with a 30 hp engine. I was way underpowered and my hull was way to heavy. This time I think I am headed in the right direction. Again, Thanks

[glades cat]

Congrats on your new project.
You might want to slow down a bit and follow a logical order in acquiring the necessary components for a successful build.
The terrain you ride and the payload you carry will determine the hull you need. That will determine the power requirements, which will dictate the props that are best suited. Leave the prop for last. Talk to your favorite hull builder first and they'll advise you on their hull capabilities and what combinations best meet your needs.

[arbtmn]

Roger that. I am kind of going with the engine 290 as a baseline. I now was assuming that the prop would be next thing after the motor just to properly go with the 290 and go from there. I would let this determine my weight carrying. So now me 150 pounds and maybe one more and some gear. I hear the prop diameter should be not more thank the bottom width? I would like a shorter prop if this is the case to keep the boat a little narrower - say 5 feet rather than 7 feet or so and making the boat a little longer - cantilever effect in water? I am kind of guessing. thank you oh i forgot. I won't necessarily be in shallow water most of the time.

[glades cat]

If you could indicate where you are located it will give the readers a better understanding of how to advise you correctly.
Deep water and narrow low freeboard airboats aren't very compatible. 5" is very…too narrow.
I will reiterate, get together with a hull builder if you're really set on building one from scratch.
Look in the classified and see if there is anything that resembles what you would like.

[Crazy Frog]

X2 Glades!! defiantly don't start narrow ...especially 5 ft. Figure 70'' max on a 290 and that's with a flat prop. I'm running a 66x32 on a 7'6"x11 lite hull/sled and it's amazing how well the 290 works with this combo. You did mention a future upgrade 320 or 360 so I personally would keep it wide!

[arbtmn]

Wow thanks guys. Thats why I came here. Man 7 ft 6 in is wide. So your running the 290? Would that be about 125 to 130hp right? What do you mean by "lite". Is this a lighter gauge aluminum or something? By the way, I am located in Louisiana southern portion. Lots of deep bayous and marsh both Anybody can give me an idea about a trailer? I don't have one yet

[arbtmn]

I am now trying to figure out what type of prop would go will with the lycoming 290. I really don't like wood props. I would want to stick with composite. So three blade or 2? fat props - skinny? I have had good luck with an IVO prop 3 blade but that was put on only a 30 hp engine.

[Deano]

Five feet is far to canoe like, as the narrower it is the lower it will sit in the water and less chance it will have with a 290. You may not need 7 1/2 feet, but you will want at least 6 1/2 if you are going to upgrade the power later. Five feet maybe an ok beam for a small john boat, it is not for an airboat with another 100 hp and a much elevated center of gravity.

I am now trying to figure out what type of prop would go will with the lycoming 290. I really don't like wood props. I would want to stick with composite. So three blade or 2? fat props - skinny? I have had good luck with an IVO prop 3 blade but that was put on only a 30 hp engine.

Forget about an IVO and forget about 3 blades.
An IVO is debatably the worst choice to be made for a real airboat. Do a search, you will see for yourself.
No need for the additional weight and parasitic drag of a third blade when two will hold the motor back.
I agree with avoiding wood if you monetarily can, for a number of reasons. All three of the major carbon prop manufacturers have blades that will work nicely now and later, although you may need a bigger hub if you go with an O360. In this regard there is nothing special about a 290, it really is a complete non-issue.
However, IMO and as was already said, you are putting the cart before the horse, your prop should come last.

On a different note, I would encourage you to do your research and exercise due diligence before you pull the trigger on committing to a 290. It may have a lower acquisition cost than a 320, but there are justifiable reasons for that. Some of us already know (even if you don't) that you very likely will want to upgrade. A 320 may cost more up front than a 290, but in the end it will cost less than buying both of them and having a heartburn along the way.

[arbtmn]

Hey thanks for that advice. I am committing to at least 7 foot width and I really want to go 12 feet long. The whirlwind folks told me that for that engine a 2 bladed 10 inch wide prop called the whisper would work well with it. I feel like this would be the correct fit. I know what you mean about the 290. But I do intend to go small horsepower as I learn this stuff and either sell this rig or just swap out motors and sell the 290 after I go bigger. How high do you think the sides need to be while knowing that I may put the heavier 320 or 360 engine in it?

[mojoe]

Figure out what you want to end up with, and build it once.

[arbtmn]

After speaking with different people concerning my hull project it realized some people use the top beam as the "width" and not necessarily the bottom. So if a boat is described to me as 7'6" would this be to beam or bottom width? Aslo I think I will change up from a 290 to a 320. This I feel is better. I have an opportunity to buy one that was red tagged and supposedly never run in the first place.

[Griff]

Hay arbtmn how far r u from raceland?

[arbtmn]

I am in Slidell. Is Raceland near Houma? It looks like I will have Alumitech build the hull for me minus a few things like seating, some rigging that I will do myself.

[arbtmn]

How high should sides be for a my 12'6"x7'6" ? Any general rule of thumb. I will be running in deep water too.

[arbtmn]

Can someone give me an idea how a 360 will run on a 12'6" x 7'6" hull? 150 hp. I have seen many pics of these hulls with big 540s on them. I just want to make sure I am not getting too heavy with the hull.

[Griff]

Hay bud I sent u a pm hit
Me up when ya chek ya pm

[arbtmn]

i will

[Southern Style]

Yea... Agree.. You getting the parts in the wrong order.. First figure out what engine u want.. then the hull..... prop can come last.. that can be a number of them depending on what your doing and hauling... Good advise above.. good luck..

[arbtmn]

Ok I think I got it now. Lets talk about this now. I like for an airboat to look kind of sleek. First could I put the cage just around the prop and not the whole engine? Maybe that would save on weight too? And can you make the flare on the sides a little more straight up and down? And how about making the front area a little more pointed?

[arbtmn]

I am also undecided about the polymer at the bottom. I am trying to keep my boat as light as possible but I like the idea of a protected bottom. Is it necessary to have this? Can the regular bottom take a stump or rock here and there if I don't hit it to fast? I don't even plan on going on dry land.

[Duckhunter_012003]

If you're gonna be running in any sort of heavy cypress timber swamp like anywhere near or around the pearl river you're gonna want a full cage, and a polymer bottom.

Jeff

[arbtmn]

ok. advise taken for sure