Homemade mini pontoon project

[mfu5324]

Have a new project this spring. Been looking for mini pontoon boat 12 footers to.get into the shallow rivers. The ones I have found they want 4 to 6k for them.. logoboats.com and prostrike bother make them...
So for.christmas I got me a klutch mig welder with aluminum spool gun...spent a few days learning to weld.aluminum.. and placed the order for some aluminum

Here is a sneak peek at one of the pontoons.. going to provide many updates and instructions and pics over next several.weeks... so stay tuned

 

[stinkfoot]

Awesome. Looking forward to your build. I have two f/g cats a 10 foot and a 14 foot Livingston. I would love an aluminum one. They are so stable for standing and fishing and also great in rough water.

 

[Jim]

Awesome man! Loving this!


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[KMixson]

Nice! Looks like you have a plan. I can't wait to see the finished product.

 

[Hanr3]

Have you thought about compartmentalizing those toons? What will happen if you spring a leak in one of them without compartments? the whole toon will become full of water. I'd think it would be best to compartmentalize each toon for safeties sake.

 

[stinkfoot]

Have you thought about compartmentalizing those toons? What will happen if you spring a leak in one of them without compartments? the whole toon will become full of water. I'd think it would be best to compartmentalize each toon for safeties sake.

Or you could fill with foam.

 

[mfu5324]

wow.. hard to get time to update this.... first in response to compartmentize the pontoons.... my plan is to fill them with closed cell eps foam (those big white foam blocks you see used for docks). surprisingly, I can get all the foam I need for about $70... ill have pics for this later...
So here are the "plans" I came up with to build the actual pontoons:

I purchased 4, 4 x10 sheets of .100 guauge aluminum ($160/sheet). I decided it would be impossible to bend these on my own given the 10 foot length so I didn't attempt to make a brake to do it. I had them bent at a local shop for $400 total.

2 of the sheets were bent as follows:
- 1 inch bend on each end lengthwise (to provide rivet/bolt lip for top)
- then 12 inces down each side, made another bend
- so the profile is: 1 inch lip (facing out), 12 inch sides and 22 inch width across the bottom. the width across the top is 24 inches
Here is a profile view


And here is what the 4x10 bends looked like (bends in red)


1 4x10 sheet simply cut down the middle to get 2 - 2x10 pieces.
These pieces will be used for the top of the bent sheets above. Rivet (or maybe use stainless steel bolts) to connect these tops using the lip of the bent pieces


Finally, the two front sections of each pontoon
I had the final 4x10 sheet, cut down to 84 inches long and bent the same way as the first 2 sheets were. once bent, I then cut this 48x84 inch in half to get 2 48x42 inch pieces. These pieces will be welded to the10 foot pieces to serve as the front part of the pontoon. ** the remaining piece from this sheet will be cut in half and used for the tops for the front pontoon pieces.


Now on these 2 front pieces, I cut them to get the upward slope angle for the front of the pontoons. i cut the angle as you can see, then I cut the bottom piece 1 inch up from the bottom so i could keep the lip/bend (the blue shaded area)....i then used this piece to weld to the angle piece I cut.... worked perfectly and didn't wast materials


in this pic u can kind of see how I welded this bottom piece to the 10 foot toon.


and here are the bent toons when I got them home

ok... off to bed... ill update much more over the weekend...

 

[Weldorthemagnificent]

I've built a few round ones, I've also seen it done this way. Another plus to compartments is stiffening especially crossways. These square pontoons will flex with load, bottom contact and temperature. Even if you don't make compartments water tight, I'd weld a stiffener in there and a small angle or two on the bottom for a keel if you plan on dragging it on shore or shallow water use. A 1/4" pipe coupling on the bottom of the back for a drain and one up top for a vent. These things will really move when they warm up, especially after a cool night and then the sun hits them. You'll be able to heard them pop and ping. Lol. Looks like you're off to a great start and if you need any advice on the welding, let me know, it's what I do for a living.


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[mfu5324]

Welderthemagficant..... oh I wish I would started this post before I started. I could have definitely used your advice on the welding. alum welding sucks to get use too and I am sure you could have helped me avoid all my trial and errors..... when I first started I used wire that just didn't work.. the 5356 wire... I practiced and practiced and just fought the whole spool... then I finally put in the 4043 wire and it was night and day.....


I also finally got enough courage to turn the wire feed speed WAY up.... it was so hard to get use this, but to me the wire speed was the key.......


I went through an entire spool of the crap wire and half a tank of argon before I finally got it to work.....

And GREAT point about the flexing of the square pontoons. When I picked up the bent toons the guy at that shop told me the same thing, that I would need to reinforce them..... so I did do this using 1x1 tube....ill have pics of that as well.........

My research (and logic) tells me the rectangular pontoons provide better floatation vs round ones... since they have more area in the water..... I read that the 22 inch wide rectangle pontoons draft in about 4 inches of water with 400 lbs load..... we have a bass buggy pontoon with 24 inch round toons, it drafts in 9 to 10 inces..... I guess we will see

 

[mfu5324]

Welding process.....
my practice welds


Welding up the front sections


welding the 10 foot sections to the front 40 inch sections


Welding the back plates on


The 1/8" - 1x1 aluminum tube for supports..... 16 inches from the back, then one where the 10 foot section meets the front section and one halfway between the two.....


Finally, welded the front plate on...


Next will be the EPS sytrofoam... we are going to cut those blocks this weekend and get those set into the pontoons..... next week going to try and put the tops on the toons. We decided to use 10-24 1/2 inch stainless steel bolts instead of rivets..... any pros and cons to this? rivets are easy.. but I figure a ss bolt with a nylon lock nut would be stronger?.... look for more updates over the weekend.

 

[user 21876]

I don't know that the EPS Styrofoam is a great choice, it will absorb water and become waterlogged. I have used the garage door foam insulation when building wood boats.

Google Picture

I have weighed a 1' square piece of it and then put it in a small kiddy pool with concrete blocks to hold it under water and after 30 days it had absorbed no water or gained any detectable weight.

 

[mfu5324]

I use that in my jon boats... great stuff.... I was going to use that but the expense and how much it would take to fill each toon was $$$$. I did some research and what I bought is called GeoFoam.. never heard of it, but the research I did says its waterproof .... does not soak up the water. I have my finders crossed ... here is a link to an article about geofoam.....
https://www.waterproofmag.com/back_issues/201604/WATERPROOFING_AND_GEOFOAM.php

 

[Tman]

Where did you purchase the Geofoam? I cant find it anywhere online. The stuff looks cool, people have filled old in ground pools and put concrete over it to keep cost down.

 

[mfu5324]

There is a local supplier in Des moines https://www.iowaepsproducts.com/
My guess is to call around to general contractors they should have a place to get it
Also... they cut it to the exact specs for me

 

[Weldorthemagnificent]

Pontoons won't leak much if they are sealed (hold a glass upside down under water)
What grade aluminum are you using? 3000 series and 6000series weld well with 4043. The silicon content makes for superior wetting. 5000 series aluminum like most boats are made of needs to be welded with 5356 or it may crack later.


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[Weldorthemagnificent]

Welds look good. Good job. For that thickness I like welding down hill with the nozzle pointed slightly downwards. When possible.


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[mfu5324]

I am using .100 " ... 5052 mill finish??? I hope that is ok? Ive used it in the past on my jon boat floors and decks... glad to hear my welds look good.... a lot of practice... your absolutely correct too, I noticed that welding downhill slope is much easier .....

 

[Weldorthemagnificent]

5052 is the only 5000 series aluminum that can be welded with 4043. However 4043 is a little softer and will fatigue faster and will also corrode faster than a weld made with 5356. I feel your pain, 5356 is harder to use initially. It's a harder wire and takes more heat to melt. Slower wire feed and a spray arc (hissing instead of sizzling). That being said, if the 4043 is working for you, go with it. For a guy who went and bought a spool gun and taught himself how to weld aluminum, you're kicking butt!


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[mfu5324]

well I was doing ok with the 5032 and could have probably finished with it. BUT THAT 4043 is so much easier - in your opinion do you think it will be ok? I actually worked for a weld shop 25 years ago for my summer job in college... never did aluminum tho.. and havnt touched a welder since then.....

 

[Weldorthemagnificent]

Basically the only under water seams are at the front. Weld em inside and out, you'll be fine. I prefer 4043 too because it wets and flows so well. Put stiffeners anywhere you think it will flex. YouTube can make a welder out of anyone. Lol, so can a grinder!


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