Things are moving along with the plan to build a shantyboat. Things go in phases.
The first phase was all the crackpot ideas I’ve come up with over the years. Camper shells on pontoons. Bamboo rafts. I’ve even gone so far as to actually buy plans for one. There were ideas of collecting empty plastic bottles, stuffing them into plastic milk crates that would be lashed together, etc., etc., etc.
I’ve finally decided that the most practical thing to do is to build a pair of pontoons in four-foot sections because they’re small enough that I can man-handle them by myself, and then epoxy them together.
So, I went out and bought some 2’X4′ styrofoam ceiling tiles and started to put together a full-size mockup of a pontoon section. The Sketchup program was had too steep a learning curve and trying to visualize how it should all go together on paper wasn’t working. Doing this, though, was a good lesson and I can see how this is going to have to go together and how pieces of wood need to be cut.
The first photo shows the bottom which will be 2’X4′ as will the top piece. The bottom piece will be 3/4″ ply and the top and sides will be 1/2 inch ply EXCEPT for the very last end piece on each pontoon. The pieces with the squiggly lines are going to be 2X4 set on end. The sides and end pieces will be glued and screwed into these 2X4s. In putting this model together I was right to inset the end carlins 1/2″ in from the ends because the end piece will sit on TOP of the bottom piece. I found out, while putting this together, that the carlins on the sides at the bottom must ALSO be inset 1/2 inch to accept the sides and maintain the 2′ width.
You can see that the end piece sticks up an additional 5-1/2 inches ABOVE the 2′ height. To connect the two pontoons it’s necessary to have pieces spanning the beam of the boat. Except for the very last cross piece I plan on using 2X6 and bolting and gluing them to the ends. When 2 sections come together those “tabs”, if you will, will be 1″ thick. The reason for the 5-1/2″ height is that lumber is trimmed and a 2X6 actually measures 1-1/2″ X 5-1/2″. Plywood, on the other hand is actual size. That is, 3/4″ plywood REALLY IS 3/4 of an inch thick.
Each side piece will have a single carlin at the top so that the top of the pontoon can be glued and screwed securely.
Now, the very LAST end piece of each pontoon will be made up of TWO half-inch pieces of ply epoxied together so that the “tab” will be 1″ thick. But IT will extend 11-1/2″ above the tops of the pontoons and the cross member will be a 2X12 so that it will be strong enough and big enough to accept an outboard motor.
Why make so many 2’X4′ sections instead of one long one? First of all I’m going to be doing practically everything by myself and I’m pretty sure I can manhandle a 2X4′ section on my own. Second, I want to have several watertight segments so that if one part of a pontoon gets holed it won’t sink the boat. I can also buy enough of these 2X4-foot, 1/2″ styrofoam blanks to fill all the pontoons for $385. They come in bales of 35 sheets. Seventeen and a half inches high. If I opted to just put a single bale in each pontoon that would give me potential buoyancy of 746.67 lbs. Certainly good enough to keep from sinking, and it would save me $128 which would buy quite a bit of lumber.