new guy here vw powered catamaran Mini

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Watterbug
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new guy here vw powered catamaran Mini

Post by Watterbug »

Image
Still needs some work.
Gota move every thing to the back to try and lift the nose.
:alien:

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kwanjangnihm
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Re: new guy here vw powered catamaran Mini

Post by kwanjangnihm »

Watterbug welcome to SA! I embedded your video! :salute:

Be safe out there........
He'll cut your throat, baby, stick you in the back, drive off in your Cadillac.
He's more trouble than you think, he'll kill your sugar, leave you in the drink.

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Watterbug
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Re: new guy here vw powered catamaran Mini

Post by Watterbug »

Thanks
When I get a minute I'll explain my build/problem.
We have 2 mud boats too....
:alien:

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Re: new guy here vw powered catamaran Mini

Post by Slidin Gator »

Watterbug,

Consider me mind blown :bom:

I can explain your problem, but first please explain the build. What is the goal of the Cat style hull? I see a Utah style cage but no info on location. What are you trying to run that makes the Cat hull an advantage?

I'm a dog guy so here is my logic. I'm thinking a boat that can haul a mush team across water and then hook up the crew to haul the boat and riders across snow. Just wondering.

Otherwise, pitch the prop up for starters, then ditch the flotation pods if it still floats OK. Move the driver back as a last move. You are running light in the video, it should lift your butt out of the water and plane out without moving weight. With those flotation pods you should be able to pitch the prop up a lot and still run flat without porpoising.
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.

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Watterbug
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Re: new guy here vw powered catamaran Mini

Post by Watterbug »

Ok the short story.
I had no plans when I started with flat sheets of 0.0625 5052 aluminum.
I did a lot of research and decided a cat may work for us.
I had the 1600cc vw that ran well but never has been rebuilt so it is as.
I wanted to use a snowmobile clutch drive to run the prop to keep the motor as low as we could.
The clutch I found was an OLD Johnson I hoped that the RPM factor would work the best , they only ran at around 3000,4000 rpm.
I used the belt to a center shaft then chain to the prop, hoping to be able to adjust the ratio if needed at that point.
I have a 2 blade wooden 64" 32 prop and a 3 blade 54" composite with pitch blocks. The wood one seams to push the best.
I was thinking "Cat" to make it easer to "walk" over obstacles in small stream beads like mounds or larger rocks rather then have to slide the enterer boat over them, and less friction on the ice.
I'm thinking that I should have stayed with a flat bottom.
I have 3, 4' wide strips of hdpe on each cat to help slid and save the Al.
Another thought that is not working as well as I had hoped.
I do not weld AL so every thing had to be farmed out or I had to use steel and do my own welding.
The boat got heaver then I had planed when I figured out the displacement.
That is the reason for the pods.
With out them when I unload the boat in to the water with out them I fill the boat with water...
The belt drive did not work out so to salvage my project I now run #50 chain in both parts of the drive.
Nosier but it seams to run true, I do miss the clutch, the prop is "Live" now and drives all the time .
I have elevators in between the rudders that are moved electronically with a switch on the steering bares,
But don't seam to lift the bow much, the motor/drive is adjustable and I can "pitch" it up or down about an inch and a half.
But.
What I'm experiencing is exactly what your brining up.
I'm thinking If I move the seat to just in front of the cage and move the 15 gal gas tank to between the two seats, and lift the back of the motor/drive an inch or more maybe It will get the bow up and kinda plane out.

Any vision to help me short of scraping the hull and starting over?


The plan is to use the boat to run very small creeks and duck production lakes full of cat tails and reeds.
We use the mud boats now but the very slow and cant use them on 2" deep gravel bottom streams and rivers.
This is solely a hunting boat, We live in Montana.
:alien:

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Re: new guy here vw powered catamaran Mini

Post by Aeon »

Imho you went the wrong direction. Cat hulls were tried back in the Vietnam War days " google air cat"

I would look at the dragonfly airboat for inspiration.

Given what you want to do i think you might be in for disappointment. It takes a lot of power to run dry. Even over gravel and to push through cat tails takes almost as much or more.

You have a guy just south of you that builds nice boats, "widowmaker boats" in salt lake.
17x8 Circle H powered by a TurnKey LS3, 2.55 ox box and 82" 3 blade JX

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Watterbug
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Re: new guy here vw powered catamaran Mini

Post by Watterbug »

Looking more and more like a wash out to me too, DANG!

The Motor cage and drive is about 400 pounds.

Is a 16 foot 48" ,70" beam Jon hull a better option?
They weigh about 280 pounds and most ill carry 1100 pounds .
I know a smooth FLAT bottom Is the right type of hull but up here there non existent.
But there is a lot of Jon hulls with out motors around for like $600 .

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Re: new guy here vw powered catamaran Mini

Post by Slidin Gator »

You don't want a jon boat hull, they are too narrow. I have a hard time imagining what the value of a cat hull is unless you are building a 100+ mph boat and looking for lift. The cat hull has less water plane area, so it's gonna need more power than a flat hull to plane out, your primary issue is lack of power. Those motors are only 50-60 Hp. You could get more out of 2x Briggs motors and 2x 4' props.

Swap that VW and drive train out for a 160 Hp or higher aviation motor and she might run. If not, at least you will have a motor for your future airboat.
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.

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Watterbug
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Re: new guy here vw powered catamaran Mini

Post by Watterbug »

HUMMM ..

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Slidin Gator
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Re: new guy here vw powered catamaran Mini

Post by Slidin Gator »

But, before you go there, find out what you have will do. Move all the weight aft, pitch the prop up as much as possible and make sure you are getting all your power. What is the reduction ratio total and what RPM are you making on the motor? How much does the whole thing weigh? Length and Width?

Worst case, a little more Aluminum and some welding/grinding you can turn that Cat into a rigid flat bottom hull. Gain back all that flotation and ditch the mud boat pods so it will plane out and turn.
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.

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Watterbug
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Re: new guy here vw powered catamaran Mini

Post by Watterbug »

That's what I'm going to try. I can move the motor/drive and cage back another 9" that will shift 400 + pounds back.
When I do that I can raise the prop end of the drive/motor a few inches. I'm going to try that first it will be WAY easer then to move all the controls and seating, wiring and gauges.
Fuel tank is simple.
I have chine and sprockets that drive the prop. Right now my "drive" sprocket is 19 teeth and the prop sprocket is 21.
I'll try a 15 on the drive. I can only get to 2400 rpm on the motor and the max HP comes at 3000.
I did go to a mechanical distributor and set the advance to ( I think) 28* at 3000 rpm no load, as per the VW guys .
That helped a lot with just that I got the boat to move on the ice.
If I can get the attitude of the boat corrected , a two barrel carb will give me 10 or 15 hp.
The more $$$ I spend the more HP I can get up to around 100 out of a 1600cc, Way more if I spend a BUNCH.
First things first.

:alien:

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Watterbug
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Re: new guy here vw powered catamaran Mini

Post by Watterbug »

I didn't say the size sorry.
The boat is 13' by 7', not counting the pods in back.
the actual "water" size is each cat. 10' by 2' that's 40 Sq. feet in all not counting the two 24x 26 pods another 8.66 sq'

weight I have no idea, 800 pounds empty ?
:alien:

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Re: new guy here vw powered catamaran Mini

Post by Slidin Gator »

Dude, that's all I can think of, Dude.

Please take this for what it is, constructive criticism. I'm trying to help you salvage your project and make something that will run.

You went through all of that crap just to get a 21/19 = 1.1 gear reduction? Chain drive is just damn dangerous. When, not if, When that chain breaks and goes through the prop, there is no telling what else is going with that swinging chain.

You need to ditch the whole damn reduction system and bolt a prop straight to that motor, assuming you want to use that motor. From what I read the 1,600 VW makes 80 ft-lbf at 2,200 and 53 hp at 4,000 RPM.

Right now you are only making 2,400 RPM on the motor, so just past peak Torque, but no where near peak Hp. I bet if you get rid of all that 1.1 reduction system the motor will make at least 2,200 RPM direct drive on the same prop, less weight. Beyond that you need less prop, you need a narrow blade 66 or smaller and spin it to 3,000.

7' Cat hull is gonna be stable, no way that little VW motor is gonna cause stability problems direct drive, look how high we mount everything, you guys want to huddle in the warm boat. Get rid of that reduction system and you can move the motor and prop way back and still float better. Move all the other stuff like you said. Try it again with the same prop.

Then you are looking for a direct drive VW prop with less pitch than you have right now. Spin it to 3,000 direct drive. That is the formula from the old days. Those VW motors make good torque low, run out of steam up high. They make good Airboat motors, just low power. :banghead:
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.

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Watterbug
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Re: new guy here vw powered catamaran Mini

Post by Watterbug »

I have a Ultra-Prop I 3 blade ,from competition aircraft I think , it was used .And 3 sets of pitch blocks , maybe 11's 14 and 18 I think. Better choice ?
I'm driving off the back end of the VW. that would be where the clutch and transaxle would hook on, not the generator side, Belt side.
All the redrives I have seen go in front as well as the direct drives.
Set aside the fact it's chain drive how much should I reduce it down.
The ultra prop cant go over 3100 rpm. All the VW guys tell me 3000 rpm mark is the sweet spot for HP on a standard 1600cc.
Not a lot of boats here to look at or people to talk to that have the proper knowledge .

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Re: new guy here vw powered catamaran Mini

Post by Slidin Gator »

Watterbug wrote:
The ultra prop cant go over 3100 rpm. All the VW guys tell me 3000 rpm mark is the sweet spot for HP on a standard 1600cc.

There’s your answer. I can’t help you with fitting prop to motor, but 3,000 rpm is the sweet spot for prop and motor it appears.
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.

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Watterbug
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Re: new guy here vw powered catamaran Mini

Post by Watterbug »

Going to work on it.
I have no shop, tools per say , and very limited budget for my bug project.
Everything takes a ton of time working with a left handed crescent wrench and a metric hammer.
Been in to it 2 1/2 years now, so bear with me . As soon as I get a little head way I'll report back.
maybe some pics, off and on .
Thanks SOOOOO much for the information and your perspective.
Up here in no mans land there is a vacuum of information.
Most the other sight I have talked on are over my head in there information and do a lot of theory talk,
not for a layman like my self. Or simply poopoo me off with no information at all.
Thanks again.
Back to the big sky garage , hope the rain stops soon.
Watterbug
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kwanjangnihm
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Re: new guy here vw powered catamaran Mini

Post by kwanjangnihm »

Watterbug you should make a trip to Florida and experience airboating first hand. We have a lot of rides and events throughout the year and many of us would be glad to take you for a ride!!
He'll cut your throat, baby, stick you in the back, drive off in your Cadillac.
He's more trouble than you think, he'll kill your sugar, leave you in the drink.

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Watterbug
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Re: new guy here vw powered catamaran Mini

Post by Watterbug »

I'll bet.
Come on up and I'll give you a ride on a snowmobile at mock one...

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Re: new guy here vw powered catamaran Mini

Post by Aeon »

Ummmm do you have private property to hunt elk on?
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Watterbug
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Re: new guy here vw powered catamaran Mini

Post by Watterbug »

Aeon wrote:Ummmm do you have private property to hunt elk on?
Sorry no Privet property for us we hunt 99% public lands.
But with several million acers of Public land it is still very huntabal.
We all get an elk every year of one kind or another and deer everywhere
Antelope when we get the draw.
If we don't get one it was we did not see the "One" we wanted...
:alien:

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Re: new guy here vw powered catamaran Mini

Post by daxxe »

Watterbug wrote:
Aeon wrote:Ummmm do you have private property to hunt elk on?
Sorry no Privet property for us we hunt 99% public lands.
But with several million acers of Public land it is still very huntabal.
We all get an elk every year of one kind or another and deer everywhere
Antelope when we get the draw.
If we don't get one it was we did not see the "One" we wanted...
:alien:
Wow that must be a great place to hunt!

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Watterbug
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Re: new guy here vw powered catamaran Mini

Post by Watterbug »

Sure can be.
If it doesn't freeze before the geese come down...
We call coyotes around the lake too. :alien:
The public land is scattered all over the state. :usa:

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Re: new guy here vw powered catamaran Mini

Post by daxxe »

Sounds like there are some good windows for hunting but got to be careful.

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Watterbug
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Re: new guy here vw powered catamaran Mini

Post by Watterbug »

Better still need some more work.

Water test
To bad the wind was 50 mph and cool we would have made some
adjustments on the river bank.
The movement of the motor and other weight back helped a bunch.
I still can move the motor but a lot of effort.
I was going to move it a foot then chickened out and went with 6".
Could have gone 8".
I'm going to lift the prop end another inch I went with 2 the first time.
We had troubles with the 64" prop hitting water as it splashes in the back, It eroded the prop some in a 15-minute test. I could get 3900 rpm with the new gears that put me around 2500 pm on the prop.
We put the 3 blade 59" prop on with the steepest pitch blocks I can get. 4600 motor rpm that's 2900 rpm on the prop.
Max for the prop is 3100, And I don't want to run that many rpm if I don't have to. I'll try a different sprocket I have. I can back off to 1.3 instead of 1.6 ratio. If I can get 3700 on the motor that's 2850 on the prop. About the same and 800 rpm less on the motor.
Here is the test vid.


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