Mini Air Boat Question/Info needed

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Hello all.
My wife mentioned to me that she would like an air boat (go figure) so I'm set with the task of gaining information as such. I have been boating all my life but never using an air boat. I have been on a few long ago and I have some questions in hopes of guiding me to the right way to go on a possible build (if I can).

Sorry if this isn't the place to post this but I figured it was general stuff.

So here is what is in my mind and I need some direction.

1. 11'-12'L max. x7'w-max. Not sure what is needed but I would like some width if possible. Running in skinny water and some lakes/everglades maybe. Might get some salt water but very limited if that.
2. Two people-200lbs each we will just say. Plus fuel (I was thinking 15gl).
3. Smooth hull bottom. Maybe some slick paint or poly.
4. I would like to use a car engine. What is the best way to go/HP/Size/MFG etc. Don't want to get to crazy.
5. If I don't use a car engine, what would be the engine I would need to look at if possible.
6. Gear reduction box (if applicable)?
7. Prop, cheapest possible for starters. I have seen some 5 blade thin style props and my thinking (even though I don't know anything) is if one needs to be replaced it might be cheaper than a large prop. I have seen some wooden ones as well.
8. Can be able to move on land (not a big must but very helpful).
9. I think that's all for now to help me get pointed in the right direction.

Thanks again for the help,
Jim

[Rollbar]

Found this today. Ultralight plane. Rebuilt motor. Dual carbs.
Wondering if the Rotax 582/66hp would be enough with a smaller boat?













Thanks,
Jim


Sent from my iPhone 4S

[Rollbar]

Sent from my iPhone 4S

[Bart]

a couple of questions, how long ago was it rebuilt? a couple of things you will want to check is the compression, the rubber boot seals around the carbs, for cracks, and if it has been sitting to long, check the seals on the crank shaft, need to make sure that they are not sucking any fresh air, into the crank case when it is running. another thing is to check the jetting, 2 strokes are very dependent on temperature and elevation for what size of jet that needs to be used.
there should be a chart of what is needed for the elevation and ambient air temp.
I might be wrong but the 582 is an older motor, but parts are still available for it. with it operating upside down, you will need to always carry a couple of spare sets of sparkplugs, to trade out for when they foul, but that is the case with all 2 strokes, even the fuel injected ones they make now.
let me know sometime what they are asking for it. I know what they are worth new.
good luck and have fun
but if it starts up and runs, and the price is right. it

[Bart]

one more item to inspect is the gear box, see what the oil looks like and check for play in any of the shafts. if the gears have any slop, depending on what gear box it is, the replacement gears can be a little bit, bearings and seals are cheep.
I have a gear box on a Cuyuna 460-F4 motor, and they don't make gears for it anymore, and it had been ran dry. luckly only the bearings needed replaced.
I purchased it sight unseen. but everything was salvageable. and is working now. this motor puts out about 45 hp.
the Rotax with 65 hp. should be good, if you decide to go that route, but if you do not understand how the 2-stroke motor works. there is a learning curve.

[Rollbar]

a couple of questions, how long ago was it rebuilt? a couple of things you will want to check is the compression, the rubber boot seals around the carbs, for cracks, and if it has been sitting to long, check the seals on the crank shaft, need to make sure that they are not sucking any fresh air, into the crank case when it is running. another thing is to check the jetting, 2 strokes are very dependent on temperature and elevation for what size of jet that needs to be used.
there should be a chart of what is needed for the elevation and ambient air temp.
I might be wrong but the 582 is an older motor, but parts are still available for it. with it operating upside down, you will need to always carry a couple of spare sets of sparkplugs, to trade out for when they foul, but that is the case with all 2 strokes, even the fuel injected ones they make now.
let me know sometime what they are asking for it. I know what they are worth new.
good luck and have fun
but if it starts up and runs, and the price is right. it

All very good questions and I don't have answers right now. Just went to see it this morning.
The entire ulta light less the wings for 1K but I probably can get him down to 7/800. Has the frame, two seater, wheels, gauges, repair books etc.
Just not sure of this motor and I'm a car guy so I would feel better w/a car engine or ?

Thanks for the help/info,
Jim

[Rollbar]

one more item to inspect is the gear box, see what the oil looks like and check for play in any of the shafts. if the gears have any slop, depending on what gear box it is, the replacement gears can be a little bit, bearings and seals are cheep.
I have a gear box on a Cuyuna 460-F4 motor, and they don't make gears for it anymore, and it had been ran dry. luckly only the bearings needed replaced.
I purchased it sight unseen. but everything was salvageable. and is working now. this motor puts out about 45 hp.
the Rotax with 65 hp. should be good, if you decide to go that route, but if you do not understand how the 2-stroke motor works. there is a learning curve.

Thanks, I did turn the prop and I just went one click and stopped and it didn't feel like play but then again I didn't look for that. I spun it clockwise and then tried to move it back and it wouldn't go. Hum, not sure, more Info is needed-Thank you,

[Rollbar]

Here us the tag that was in the frame above the motor.
Not sure if this helps with the reduction gear info or ?
One picture above in the original post read Bombardier on the back side and Rotax on the other side of the aluminum.






Sent from my iPhone 4S

[Bart]

I understand your dilemma. I have played with 2 stroke motor on snowmobiles since the early 90's and have rebuilt many of them, manly worked on Polaris,
Rotax is the brand of the motor, and it is made by Bombardier, which has a big interest in ultralite airplanes.
the motor has both a pull starter rope, and an electric starter also.
I am not to familiar with the gear box. the newer ones I think have a clutch in them to help reduce the damage when the prop strikes an hard object like the ground

use the pull rope that is behind the seat to see if it will turn over. if there is any resistance besides the compression. pull the plugs. fuel may have leaked out of the carbs over time, and you will be trying to compress fluid,
you will see 2 spark plugs per cylinder, this is the double redundant system they put in. so there is always a back up.

if it still will not pull over, then that opens it up to a lot more questions.

I know the questions that are going through your mind,
good luck with what you decide to do,

[Rollbar]

I understand your dilemma. I have played with 2 stroke motor on snowmobiles since the early 90's and have rebuilt many of them, manly worked on Polaris,
Rotax is the brand of the motor, and it is made by Bombardier, which has a big interest in ultralite airplanes.
the motor has both a pull starter rope, and an electric starter also.
I am not to familiar with the gear box. the newer ones I think have a clutch in them to help reduce the damage when the prop strikes an hard object like the ground

use the pull rope that is behind the seat to see if it will turn over. if there is any resistance besides the compression. pull the plugs. fuel may have leaked out of the carbs over time, and you will be trying to compress fluid,
you will see 2 spark plugs per cylinder, this is the double redundant system they put in. so there is always a back up.

if it still will not pull over, then that opens it up to a lot more questions.

I know the questions that are going through your mind,
good luck with what you decide to do,

Awesome Bart, Thank you very much. I'll see if I can get back over there after I check a few things/research etc.

[WBS]

Also would like to know what you guys feel are good engine choices and preferred size or a 35 to 100 hp project. Also, what diameter prop seems about right and not too big and how much thrust is essential.

[Papee]

If you feel comfortable with a two stroke by all means go for it. There are plenty of guys running that setup with good results.

[Papee]

Also would like to know what you guys feel are good engine choices and preferred size or a 35 to 100 hp project. Also, what diameter prop seems about right and not too big and how much thrust is essential.

the only thrust numbers we have to go by is from the aircraft guys running the same setups. I can't remember any numbers. The lawnmower type engines just don't last in my opinion and can cost some big money to get to run right compared to the popular choices like the rotex or the 4A084. Prop size depends on the engine, running direct drive or reduction drive. I would think with a shroud you would want a shorter and wider prop to cut down on the shroud mass. Hull design is another key. Some hull designs are faster but harder to control than others.

[Rollbar]

Found this today. Ultralight plane. Rebuilt motor. Dual carbs.
Wondering if the Rotax 582/66hp would be enough with a smaller boat?

Question, can I use this prop or would I have to get another one for a 12'x7' boat? Use meaning, does it have enough meat to push or ?

Thanks a lot for all the help everyone,
Jim

[Bart]

if you have had time to do any looking on the net for this setup,
a couple of things to be wary of, and think about. to purchase a used setup like what you are looking at goes from 5 to 8 thousand. if it is running.

where they have stated the motor has been recently rebuilt, why is it so cheap???
the fun thing about 2-stroke motors, like this last winter, I know of 8 snow machines that have lost the motor, due to bad gas. seems like a detonation issue, water in the fuel, and things like that. the octane rating is very important, if you use ethanol gas, then, I wouldn't touch it.
if you try to start it with old fuel, that is a big no no also
not trying to scare you off, but when you are looking to purchase a 2-stroke used motor, there is no guaranty,
they are a strong simple motor, but they are a high performance motor as well, that is why you always read about why they are always opening the motor up and inspecting all the internal moving parts every couple of hundred hours. when you are in the air, you do not want it to fail.
last year, I failed to open up and replace the pistons in my Polaris 700 RMK, the high performance motors that they are making now, are needing the pistons replaced about every 2000 miles.
this is what happened to it last year.
the piston skirt broke, which broke the cylinder skirt. of coars,e my oldest son was with his friends night riding, and had to try to start it when it quit on them,

(who wants to tow a sled out of the mountains 20 miles)
needless to say, with the metal laying around in the bottom of the crankcase, they forced a ventilation issue. from this I was only able to save the crankshaft, and 1 cylinder, and 2000.00 dollars later, it was running again.

like I said I am not trying to scare you off from a dream,
if I was there looking at it, and he was talked down to the price you were saying, I would pick it up in a heartbeat, as long as my better half would let me. but that is me. and I am a sucker for projects.
I hope that this gives you some ideas to think about, as you are looking for the a power plant to use in your dream,
as I mentioned in my thread, I have 2 different motors that I am working on, a 2-stroke cuyuna 460-F45,and the Teledyne 4A084, both have their good points.
the cuyuna is half the weight, less than 70 lbs. but will burn up to 5 gallons an hour at full throttle. and needs 91 octane, and good quality fuel.
the Teledyne 4A084, 4-stroke is lot more forgiving, yes it weighs a little more, but from what others have posted, you can play all day on under 10 gallons of gas. and that is one big selling point.
the next dilemma that I will be coming up on is the hull that I have really isn't that big. for the lighter motor it would work, but with a hull only 4 feet wide and 10 feet long, I probably will be in the market for building something bigger. just for the safety reason alone, every where you can have problems, it just seems that the playground up here in Alaska can be a little more extreme, and not very forgiving.

I don't mean to preach, or tell you what you need to do, but weigh out your options, and as I have found out, sometimes a real good deal will pay off,
and other times, it is going to cost you a lot more, than what you envisioned. I have been down both roads, but I have learned a lot, and have gained a lot of knowledge from costlier road.
have fun an enjoy the process of reaching the end result.


.

[Rollbar]

Thanks again Bart and thanks for the info and I'm use to preaching as I am one

The ultra light belonged to a pilot, he rebuilt it and flew it a few times and then crashed on landing/not messing up the motor. He is 65ish and his wife said to get rid of it so he gave it to a friend who was going to build an airboat, he is in his early 70's and his grand kids didn't want to build anything so he drove it around his yard for a while then parked it. That is all I know beside him say it was rebuilt. I can clarify who rebuilt it if needed but again, I'm in the discovery stage and looking closer at this. I have looked at the 4A084 but can't seem to find some NOS motors and those who own one want some big bucks etc.
I do like the fact the ultra light has a two plug per cylinder set up and I was told I could probably sell those heads for a single plug set up and have someone go through the motor and maybe them tweak it some for HP etc. Lots to think about and go through and I appreciate all the responses and patience in this learning curve.
Thanks again and I'll look into the information provided,
Jim

[Bart]

this almost sounds this is where we will be, in a blink of an eye,
it is hard for people to have to let go of their dreams, and all they can hope is that someone will pick it up, where they left it.

sounds like if it turns over, there have been a couple of motors that I have had to spend a little time rocking the crank back and forth before things would free up.
if it feels kind of stuck or tight spray some marvel mystery oil where the carbs are to help lube things up a bit. ( it will smoke big time for about 10 minutes after it fires up)
drain the carbs, put fresh gas, and have 2-stroke oil in the oil tank. and it should fire up. I bet the electric start even works, that is a big plus. with the crank shaft seals being hard to get to, the old stand by method to see if they are leaking, is while the motor is running, is to put a very small squirt of starting fluid, (VERY SMALL) at the seal. and if the motor revs up, then you have a leaker, if there is no change in the RPM, then it should be good for a while.
a lot depends on how long it has been sitting, to when the rubber seal starts to dry out due to lack of activity.
usually when a seal starts to leak, the motor will not develop full power, because it is running only the other cylinder, unless both seals are back
check the spark plugs, you can pull up the color charts on the net, and that will tell you a lot
also I see it has EGT plugs on the pipe. if the gauges are hooked up. you can monitor the motor by the exhaust temps. and where you have one for each cylinder that takes so much of the guessing game out of it.
depending on the manufacture, but at the 2 inches from the engine, at full throttle the temps. should never get above 1300 degrees, ( at least for the style I have on one of my snowmachines)
you can pull up the information on the web. to verify what your temps. should be at various stages of the throttle position.

read what the manuals say,
I always used to get in trouble because I would be looking at my EGT'S when riding, it can be worse than texting and driving.
have fun.

[Bart]

so I am curious, when he drove it around his yard, was he chasing his grand kids? that sounds like he was having a lot of fun.
at least that would explain why they don't really want anything to do with it.

[Rollbar]

this almost sounds this is where we will be, in a blink of an eye,
it is hard for people to have to let go of their dreams, and all they can hope is that someone will pick it up, where they left it.

sounds like if it turns over, there have been a couple of motors that I have had to spend a little time rocking the crank back and forth before things would free up.
if it feels kind of stuck or tight spray some marvel mystery oil where the carbs are to help lube things up a bit. ( it will smoke big time for about 10 minutes after it fires up)
drain the carbs, put fresh gas, and have 2-stroke oil in the oil tank. and it should fire up. I bet the electric start even works, that is a big plus. with the crank shaft seals being hard to get to, the old stand by method to see if they are leaking, is while the motor is running, is to put a very small squirt of starting fluid, (VERY SMALL) at the seal. and if the motor revs up, then you have a leaker, if there is no change in the RPM, then it should be good for a while.
a lot depends on how long it has been sitting, to when the rubber seal starts to dry out due to lack of activity.
usually when a seal starts to leak, the motor will not develop full power, because it is running only the other cylinder, unless both seals are back
check the spark plugs, you can pull up the color charts on the net, and that will tell you a lot
also I see it has EGT plugs on the pipe. if the gauges are hooked up. you can monitor the motor by the exhaust temps. and where you have one for each cylinder that takes so much of the guessing game out of it.
depending on the manufacture, but at the 2 inches from the engine, at full throttle the temps. should never get above 1300 degrees, ( at least for the style I have on one of my snowmachines)
you can pull up the information on the web. to verify what your temps. should be at various stages of the throttle position.

read what the manuals say,
I always used to get in trouble because I would be looking at my EGT'S when riding, it can be worse than texting and driving.
have fun.

Thank you, I'll get some more info and check next week on these things. He did offer to take the entire tarp off etc and wheel it out but I was just feeling out the situation/$$ to see etc. He did say 1K but did offer and say that he didn't know and for me to make an offer.
I might just make an offer and see after some more research etc.
I'm still wondering if that prop will work on a 12'x7' and 350lbs-people/gear but I still have some calculations to do.

so I am curious, when he drove it around his yard, was he chasing his grand kids? that sounds like he was having a lot of fun.
at least that would explain why they don't really want anything to do with it.

Haha, most likely.

Thanks again,

[Bart]

sounds like you are having fun, if you look on the 2-stroke link in this forum. i see a person that is in one of the links. http://miniairboatassoc.com/forum/me...12924-papajack.
and if you could get in touch with him. from his comments, he has a set up similar to what the direction you are looking at. he probable would be able to give you a lot of sound advise.
there are a couple of others also, that would have more first hand knowledge, of what will work.
but it has been fun & learning experiances, that i have had with the 2-stroke motors, at the moment i have 8 snowmachines, 6 are running, 4 of them were deals to good to pass up. a couple of these have been such a good deal, that i would have to pay someone to take them, now. that might be why when you asked for advise on what to look for on this motor, i am trying to pass on information that i have learned over the years.
i hope some of the more knowledgeable chip in, a lot of the questions that you have, are the same as what i have,
i figure in about 2 to 3 weeks, i'll have my anodizing done on all the parts and pieces. Finish putting the motors together, then building the stand and cage, and maybe by the end of May, i'll be in the water. then the real testing begins. to see if the designs that i choose to go with will work.