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Need Airboat design advice

C

COLD

Well-known member
I live close to the river and nobody uses it except a few river boats. I have always been interested in airboats however that intensified when we went to Lousiana a few years ago. A buddy gave me a donor car for the project recently and another buddy who owns a machine shop has signed onto the project. Because of the price of gas I chose a Toyota 4 cyl FI engine with about 100 HP and 145 F/LB's torque at 4400 RPM. I plan on building a long belt drive with a reduction of somewhere around 2:1. I need information about prop length and any other tips you could provide. My thoughts were longer multiblade with not to much pitch to reduce noise and improve acceleration. I would also like the prop to handle more HP should I think 100 HP sucks. Thanks
 
Cold: I don't want any of this to be negatively taken. First of all 100hp will suck unless you make a very small boat. It is gonna sound stupid but try talking to the prop manufact. listed on the directory link on this site. They really do want you happy because then you will tell others how great they are. Longer and slower is quieter most of the time. Hull size is going to be very important and you have to have some idea of where and how you are going to use the boat to really decide that one. " The RIVER" doesn't help much what kind of river is it fast slow shallow deep rocky sandy grassy ..so need more info. HOWEVER the most important thing is to get going on it and even if the first one is not what you want it will be enough to get the hook set in your butt just like the rest of us. LET THE FUN BEGIN, once the sport gets your heart your wallet will follow.
 
Shorter wider prop with more pitch (less rpm) is quieter.

You probably want more like 3:1 reduction for torque multiplication with the 4 cyl

Keep your hull short and light

Should be a fun boat and cheap to run
 
This is a good start, I know of only one airboat up here (rescue when the river is frozen). The river is shallow and flows at about 5-7 MPH. Gravel and sand for the most part. I want to keep it as light as possible. I know one boat can't do everything (I also have a lake boat) and the jet boaters suck rocks and spend lots on thier pumps. What size of hull should I stay towards for the first one?
 
I was basing m,y advice on conversations this week with whirlwind props. Like I said call the prop folks and let them advise you on that choice once you decide what power plant setup you are going to use with what type of hull. I would probably go with a 12 x 7 aluminum if you can afford it. There usually are one or two for sale on airboattrader.com.

hey red: when you gonna get your boat runnin and show up at a run with it. I missed meeting you at the dock when you stopped by. Fatboy told me you were there. Look forward to seeing all theses innovative ideas in action on your boat. Till then .. keep the ideas flowing.
 
Cold, you've come to the right place. Airboats were born and bred here in Florida, but they've proven themselves all over the planet since then.

Cntry141, MarshMaster Pat, Swampjet, Sniper, Thunder .... the list goes on and on. They've all got thousands of combined hours in blowboats, and they'll all be more than willing to help.

Ask questions, and when you get answers, listen. These guys know what they're talkin' about. Best of luck with your project!

Ken
 
WELCOME COLD
Just a remineder there is on dumb or stupid questions when it comes to thes things. The folks here will keep you going the right way. Get it built bring it to Fla. for a mouthly ride. Or on vaction.
 
So people are running aircraft O-200 and O-230's in airboats, they are about the same HP as I was planning. I figure I can get another 20 HP out of this toyota easy enough. What size of boat are they typically running? What kind of speed do they get out of thier machines and how much load do they carry. My target is as light as possible so what does a typical O-230 boat weigh?
 
cntry141iq":1kivq2xd said:
hey red: when you gonna get your boat runnin and show up at a run with it. I missed meeting you at the dock when you stopped by. Fatboy told me you were there. Look forward to seeing all theses innovative ideas in action on your boat.
Click to expand...

I should have it ready in a month. If you come to the big shindig in Lochloosa on New Years, I will have the boat there, maaaayybe I can have at a run if there is one in Dec,

Fatboy must have been mistaken or someone is impersonating me? :?
 
COLD-EH'":20e9ipzh said:
So people are running aircraft O-200 and O-230's in airboats, they are about the same HP as I was planning.
Click to expand...

But I'm sure that the Toyota doesn't make peak power at 2800-3000 RPM like the O-200 and O-230

See, torque is the ability to do work, and then when we space that work out over time (measured in RPM) then we get horsepower.

There's a way to make up for that and that is with reduction.
 
Yeah I know that. I already have my propeller bearing assy. to do a long belt Polychain and I know how I am going to build the crank bearing assy. I know the prop tips can't reach the speed of sound "i'm also a private pilot" so I want opionions as to best max prop rpm. I can spin the engine at 6000 RPM while achieving a 2700 RPM prop speed with a 2.2/1 reduction and end up with about 300 foot pounds of torque after reduction losses. I know, I AM phoning the prop manufacture.
 
COLD - Those 0-200 and 0-230s are disappearing fast from airboats. They work ok in water deep enough to float and when on plane in shallow stuff, but like the 0-320s, just don't have the HP for most boats around 11-12 feet. FUN as you know what, till you get them stuck.

But don't get me wrong, I know of several hulls with 320s and 360s on them that are producing 150 to 180 hp and they run real sweet with one or two people, even run dry in the right conditions. One of the LA guys apparently has a real mean 4 banger Lycoming rig.

One of the issues is that in the river if you get going 25 MPH in shallow water a hit a small rock, there is a great possibility of hull damage. That is why lots of them are adding polymer, for protection. And that adds weight. That is an issue. Hull strength versus weight reduction.

Each of the props and manufacturers have their own best performance RPMs and I would try to get the reduction gear to match that RPM with the engine's peak HP range. But you probably figured that out.

Alaska had (has?) a forum about airboats that had some experienced people on it. Quite a few were home builts, they may have ideas for you and are running in similar conditions.

One last warning. Ice can shred an aluminum hull fairly quickly. But you might know that as well.

Good Luck. I love those toyota R series engines. They can take lots of abuse as mud boat engines.
 
Thanks for the encouragement! I look through this site and see lots of guys overwhelmed with the performance of th BS Vanguard stuff and another group that doesn't consider giving constructive advice for anything under 700 HP. The Vanguard stuff looks like it does as much as I need for my first boat. Sites I have checked claim a top speed of 27 MPH with 31 HP and people tell me I probably wont be able to get my hull on plane with 100 HP and a reduction unit? What gives?
 
Cold, it can be done. It just isn't done often in the horsepower range where you are intending to build. That doesn't mean that you shouldn't try it ...... you might show us all a trick or two when you're finished.

Getting the right prop will be very important to the success of your project, and there are a couple of prop manufacturers that aren't often mentioned on here that might be able to give you some good advice. One of them is Tennessee Propellers (http://www.tn-prop.com). They build a lot of props for the ultralight folks, and they do VERY pretty work. I've used their stuff before and it's top shelf. Another is a company out in Meeker, OK by the name of Arrowprop. They've built several airboats in the past in your HP range using the little 3 cyl. Geo Metro engine on a belt redrive. I bought a prop from them once, and they're real nice folks also.

Talk to those two companies. They'll get ya' headed in the right direction.

Ken
 
COLD - We all have our favorite rig or idea of what is best. Just have to overlook that. Hehehehe.

There are some really sweet fiberglass hull around that are running rotax ultralight engines with reduction gears on them. They are a blast and run really well in most places.

Remember, most of the early airboats have very low HP. And if they didn't work and were not a blast to run, people wouldn't have made so many of them.

I have two opinions on HP -
1) It will get you to places you never visited before. And that is nice.

2) It will get you stuck in places you never visited before. And that is not nice.

I like extra HP, but know I would get myself in a bind sooner than later. Just would have to look at each levee and tall grass flat as a challenge, then take it on.

If that motor is what you have and can put it together, then try it. BUT BEWARE - you can easily get the airboat bug and start wanting more.

Check out that Alaska Gold Forum for airboats. They were doing some unusual things on airboats. Maybe someone there tired it. Good Luck and when you take her out, let us know.
 
Pat, I have a couple of the 24 HP Zenoah 2 cycle ultralight engines that TN Prop sells. When all the other projects are caught up (Yea, right) I intend to build a little 10' one-man airboat that I can slide into the back of my pickup. A little fly fishin' machine.

A guy I know mounted one of these little 2 strokes to an A-frame in the back of a little Mazda pickup and it shoved him up to almost 30mph. They're a lot of fun to play with. I have a re-drive for mine that will swing a 54" prop. but I plan to direct drive a 42" and use it for a rev-limiter also. That will also get me into a 4' wide hull that will fit into my truck bed.

Ken
 
Hey B.F., Now that sounds purty neat, truck bed boat. I'd sure like to see something like that. By the way, do you tie your own flies? Doing wildlife control I sometimes come across some feathers and such. P-cocks, Emus and stuff. Later Cajun
 
Cajun, nice of you to offer that. I don't tie my own anymore. There's so much to know about the Florida waters that I don't know .... natural food sources for the time of year, etc. that I just take the advice of the experts over at the tackle shop. It's worked pretty well so far.

I'm from KY, so fishin' in Florida is like learning all over again for me.

Ken
 
Your welcome. I sent some feathers to some folks in Co. , Miss. , & La. for flies. Have a great day. Cajun
 
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