DiY pontoons.

[Catrease01]

Thats interesting. I never thought of the pressure on the submerged part

 

[HotTommy]

One of the basic laws of physics is that if a force is applied to an object, it will move in the direction of that force unless some other force is pushing back. A 1,500 pound boat is being pulled toward the bottom of the lake by gravity. The only thing that keeps it from going to the bottom is the force of the water (called buoyancy) pushing back against it. If you add up all the small upward forces the water applies to the toons and everything else it touches, it will come to 1,500 pounds. But, as was mentioned above, the water also pushes sideways on the toons, and the deeper it is the harder it pushes. ... Think about it - if you get a leak an inch below the water line it will be noticeable but not too bad. If you get the same size leak a foot lower, water will gush in. So when you build your box shaped toon, imagine a thousand small wood working clamps placed all over the toon, trying to squeeze the sides inward, and the bottom up. That's why I and others here have suggested you will need bulkheads (braces) inside your toons to keep them from distorting or being crushed by the force of the water.

 

[Catrease01]

I was planning bracing them .

 

[Catrease01]

Should i use 2x4 or eip 2x4a into 2x2s? I was thinkingbod turning the 2x4 horizontal on thw bottom side of the toon to help deal with thise prwssure beneath the water.

 

[HotTommy]

Here is how one builder did it:

 

[Catrease01]

I like that method alot. Simple but strong. I was thinking of making it 8ft long to keep simplicity at hand.

 

[HotTommy]

Catrease01,
There really is a lot more to this than what you implied in your very first post. That is why you will be much better off copying most or all of what someone else has already done rather than starting from scratch. You won't have to learn as much about buoyancy, balance, waterproofing, and many other things if you just copy what has worked for someone who's already done it successfully. .... Or, as I said earlier, you can do it from scratch and learn a lot ..... the hard way. It's up to you.

 

[Georgesalmon]

Many years ago I built a redwood canoe. It was covered with some light cloth and clear epoxy resin. Lasted about 2o years with little care. So,,,,why not build two canoe's, put tops on them, connect them together and you got yourself a pontoon. Lots of wood canoe plans that have all the engineering already done as far as water forces etc.

 

[Jeep Man]

I like that method alot. Simple but strong. I was thinking of making it 8ft long to keep simplicity at hand.

8 ft. is very short. What do you plan on using it for? Longer will allow it to ride better and give you a bit more room.

 

[BrianMc]

I wouldn't go less than 16' on a pontoon. If two people stood on one corner of a 8' toon you'd likely tip it over. The dual canoe idea is a good one. Just cap them off. It would gluide through the water. Go out next weekend and rent a canoe somewhere. Both of you could sit on one end of it to get a feel for the buoyancy needed for people walking around on the deck.