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Ducted fan on jon boat 14x36 will it work?

Kelly1

Member
:texas: new to airboat world I have fan off of a hovercraft and 14x36 boat on hand will be running shallow river sandy bottom Mudd motor is a no go! All advice is welcome budget is limited
 
In searching mini airboat forum for air john projects you will find very few success stories. Johnboats typically are too narrow, have ribbed bottoms and will not perform like an airboat. You might consider finding a light weight used airboat hull and trying your fan motor to move it on water. Don't expect too much in the way of speed.
 
I am going to try it and stay as light as I can and see how it goes this summer will try and find a aluminum airboat Hull and do it the right way the materials I have to work with are on hand already if it works I will brag about it if it doesn't we won't talk about it I was just hoping somebody had more knowledge about hovercraft ducted fans and thrust then I have I'm not wanting to go fast or run dry up heels just needed to plane and Hall about 400 lb payload
 
The key in mini airboats is light weight and displacement. There are threads on ducted fan applications. Use search function in the mini airboat category and avoid sure to fail time wasters. This is my opinion after costly trial and error, as well as research for nine years in chasing mini airboat projects. Good luck!
 
Kelly1 said:
I have fan off of a hovercraft
do you know the size of fan/prop or horsepower of engine you are planning to use?
agree with the above users, most setups couldn't pull a pickle out of a pile of cat-sheite, mush less push 400lbs down the river :violent1:
 
It's a 32" fan with a 277 rotax that I can upgrade to bigger rotax 503. May just use reduction drive and go with a prop instead
 
Your 503 Rotax with a B box would spin a bigger prop for sure. However, your prop should NEVER be longer than your hull's width!!! Do some homework in the mini airboat section of this site. My mini is a12' x 7' Alumitec with a 583 Rotax C box 2 blade Razor X Core weighing just under 500#. It would haul your 400# load with ease and barely sip gas.
 
That is what I want to achieve. Good fuel economy, and to get me to my hunting spot river here is all smooth sand and unreliable depth. More than likely going to prop this motor and scratch anything with the fan!!!
 
There is a company in the UK with ducted fan airboats, but I think a 32" fan will be way to small. I have been playing with a Hovercraft of my own design for awhile now, and what I can tell you is you would be better off to find you a used Ivo prop and forget the ducted fan as 32" fan is what they mainly use for lift fans and not thrust. here is the link to the UK airboat site. http://www.airboatuk.com/?fbclid=IwAR1OxbsYykuxejoM2v6ZT0iUfN7hJxdr9cSYOECHgBNRI5R1MzBXxa1V-G8
 
Ducts and fans I know about because I am into hovercrafts.
To find out lots about fans,required hp and static thrust produced go to Hoverhawk .
Ducts are a waste of time unless they are made correctly. Universal hovercraft has plans for them. The specs need to be followed to the letter or don't even bother. If its done right about a 15% increase in static thrust can be gained if your talking about 48 inch dia. props.
Once you get into ducted 5 and 6 foot dia. props the parasitic drag and weight becomes greater and gains in thrust are lost when moving wide open throttle.
 
I have abandoned the ducted fan for sure ! Now trying to figure out if I can get enough push from a prop to plane out with 22 hp 14x36 jon boat . There's not many airboats in West Texas for sale I did not want to have to drive to Florida to pick up a hull. I still have a 277 rotax from the hovercraft I can use it has a belt reduction on it already not real sure which way to go with it now
 
Find an airboat hull and slap a jet ski motor in it. I have a 12x7 with a yamaha 760 in it, it will run 2 inches of sand bottom all day until you stop, then you need at least 8" to pop back on a plane. Great gas mileage, electric start,stick steering, low maintenance, can build for pretty cheap.
 
I built a jet Jon a couple of months ago it goes real good and gets good fuel mileage don't know if you have discovered this or not but if you're going to cross real shallow sand it can suck itself to the bottom and it stops on a dime throwing everything it's not tied down to the front of the boat or out of the boat and it just about broke both my knees I still run it on the river just real cautious when you're crossing the sand bars with it
 
The river I run on have 6 foot long underwater grass. Would that be a problem for a jet pump drive because I would go the pump route over the airboat idea if the weeds aren't a problem
 
It is a vacuum and will suck up anything loose for sure. As long as the grass is on the bottom and you have a couple inches of Clearwater jet ski motor will work a cruise on a Sandy Bottom River usually in less than 3 to 4 in of water and I am not sucking up sand in rocks I have a 55 horse rotax and can plain off with three people usually within 15 feet
 
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