Posted by: oldsalt1942 | January 27, 2016

Foam Pontoons Redux

I think I suffer from a totally new mental disorder that I’ve labeled SBADD (Shanty Boat Attention Deficit Disorder). It’s akin to ADOLAP disorder (Adult Deficit Oh Look A Puppy!). In other words I vacillate from one idea of how I want to build a shanty boat.

I would truly love to have something like Bryan Lowe’s dream of the H.W. Taunt. Who wouldn’t?

taunt-houseboat1

But the reality is I don’t think I have either the skill level or the physical stamina to build something like that, more’s the pity. The reality is that I’m a nearly 74 year-old guy with 3 stents in his coronary arteries and a lung capacity 34% of normal. I get winded making the bed (wish that was a joke, but it’s not). So as much as I would love to have something like theTaunt it’s just not going to happen.

So, right now I’m back on the idea of a pontoon boat. The shanty boat that I owned in Louisiana was a pontoon boat. It was basically a shack on a pair of 35-foot long by 24″ diameter well casings. Worked pretty well, and I lived on it for almost three years, but I only moved it three times. The first time was from where I’d found it on the Tchefuncta River on the north shore of Lake Pontchartrain down to the Gulf Outlet Marina in Chalmette. a total run of about 42 miles. A couple of years later the starboard pontoon developed a leak and I moved it from the marina to the boatyard where I worked and back around 18 miles round trip.

What had happened was that the pontoon had rusted through in a couple of places right around the waterline. As the boat rocked water would slosh into the pontoon. I was able to drill a hole in the forward part of the pontoon and use a drill motor pump to clear it out. The steel was too thin to weld a patch and there were several holes and almost holes in both pontoons. What I did was to clean the effected areas and put fiberglass patches over them with polyester resin. Then I used 15 gallons of a special epoxy paint. The stuff was really thick. Like runny ketchup. I was able to get three coats of the stuff on the pontoons and it was probably close to 1/4″ thick.

Anyway, I’m not adverse to the idea of using pontoons for floatation. I investigated the possibility of making a raft type shanty using 55-gallon drums. There’s a place in Panama City where you can get metal ones for about $10/each, but then you’d have to ship them 300 miles out here to Boquerón. I checked a lot of places around here but no one had metal drums. The cheapest plastic ones I found were $35/each if I bought 20 of them. Forty five bucks each if I bought fewer than 20.

I’m not going to go cruising with whatever I build but I do want to be able to move it fairly easily and barrel rafts aren’t really great for doing that.

So that brings me to the pontoon idea again. The original idea was to use glass-covered plywood pontoons made in 2X2X4-foot segments and then join them together with bolts and epoxy. Seems like a good idea. After all, they build huge aircraft carriers in segments and join them all together to make a ship.

I’m thinking I’d make them between 20 and 24-feet long. How much could something like that support? Here’s what I figured out for pontoons 28-feet long (refer to previous post of “Resist the Urge” to see about “size creep”).

The pontoons will be 2-feet wide by 2-feet high, and between 24 and 28 feet long.

I decided on the pontoons because of the amount of flotation they offer. Here are the numbers I’ve come up with…

Each pontoon segment will be 2’X2’X4’ = 16 cubic feet

One cubic foot = 7.5 gallons (7.48)

One gallon of water weighs = 8.3453 pounds. One cubic foot = 7.48052 gallons. The weight of one cubic foot of water is 7.48052 gallons times 8.3453 pounds, which equals 62.42 pounds of water per cubic foot. OR, it would take 62.42 lbs. to completely sink a cubic foot container.

SO, 62.42 lbs X 16 cubic feet = 998.72 lbs. displacement for each 4’ pontoon. Minus the weight of the materials each pontoon will support, roughly, 900 lbs.

The sections in the bow would be made like the bow of a barge or scow, sloped up from the bottom to move through the water with less resistance. Figure that each one of those will be roughly half the volume of the regular one for a 28’ long structure overall, or roughly 11,700 lbs. flotation. Whatever kind of house structure I build on top of the pontoon segments plus all the junk that I’d bring aboard certainly isn’t going to amount to five and a half TONS!

If you look as building a raft-type structure using 55-gallon drums the figures look like this:

Now, a 55 gallon drum measures 35” X 24”. A 55 gallon drum will displace 459 lbs.

Because of the odd measurement of 35” you’d need 10 drums to make up each pontoon of a similar size to the plywood pontoons. Now you’re mucking around with non-standard size lumber or going for 10 barrels a side. And how much flotation? Potentially 9,180 lbs., before deducting the weight of the materials needed to contain them. So more than a ton less flotation than the plywood pontoons.

I also toyed with the idea of using closed-cell foam to build the pontoons and encase them with fiberglass in polyester resin. I know a lot of people will say it’s better to use epoxy, but the stuff is terribly expensive down here in Panama. Polyester resin is about a quarter of the price of epoxy, and just think of how many THOUSANDS of boats are floating around made with polyester resin!

Foam would be, of course, a LOT lighter than plywood pontoons would be and easier for me, in my physical condition, to move around. Some people are using foam insulation boards to build with.

pink foam

Foam insulation sheets can be bought at the big box stores like Lowe’s and Home Depot…

Foam2

Eighteen sheets of this stuff would make a pair of 2X2X24-foot pontoons for $270! The problem HERE is they DON’T USE insulation in their construction. Almost everything is cement block construction which does have a bit of built-in insulation value. There’s only one place in all of Panama I’ve found that sells 4X8-foot sheets of closed-cell foam in 1″, 2″,3″, and 4″ thicknesses. When I called about a year ago the 4″ sheets went for $107 a piece. A pair of solid 24′ pontoons would cost $963. And that’s JUST for the foam.

I don’t know what the 1-or-2-inch sheets cost, but I’ll be in Panama City on the 3rd of February and stop at the supplier and find out. But it has got me going in another “what if” direction…

There’s a place in David that sells 2’X4’X1/2″ styrofoam drop ceiling tiles for 50¢ each. What if the 1″ or 2″ closed cell foam sheets were reasonably priced? What if I used THEM like I would if I was building the pontoons with plywood? Then, what if I filled the empty spaces with the ceiling tiles? I’d need 576 of those at a cost of $308.16, tax included. I’d have unsinkable pontoons on which to build the house.

I priced out what the wood costs would be if I built the pontoons with plywood. Wood cost, plywood and framing lumber as of Jan 26 = $806.32 using 3/4″ HDO for the bottoms and 1/2″ regular ply for the sides and top. Using regular ply the lumber would cost $710.02.

In both cases there would be extra costs for the glass cloth and resin.

And THIS is how I spend much of my day!

 

 

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