simple kayak or jonboat/bateau using coroplast?

[richg99]

I have need of a very light-weight --human powered-- small boat for fishing. I am considering using coroplast to keep the weight down. I can purchase the coro for $15.00 per 4 x 8 ft sheet. It is, apparently, also available in 12 foot x 4 ft pieces. If I can get the 12's I would keep the boat's length down to utilize the material.

Has anyone here used Coroplast for light-weight boat building? I have some experience using it for construction of small radio controlled model airplanes. thanks Rich

[srimes]

well, I made a cardboard boat so I'm sure coroplast could work. For how long is the question.

How will you join it? That'd be the tricky part. Can it be welded with heat or solvents? For my cardboard boat I layered it with the ribs running opposite directions and I'd do the same with coroplast. I might have to try this too...

[richg99]

Well, Coro, when used in the r/c planes, is joined by
#1 using C.A. (Super Glue) after properly preparing the surface ( that is a whole other discussion.)
2. Polyurethane (Gorilla/Borden's) after "peckering" the surfaces with a "woodpecker" tool. That tool punches small holes and allows the poly-glue to expand and form "rivets" on the interior of both surfaces. I believe that 3M5200 is a form of Polyurethane glue. 3M 5200 would be great, I'd think.
#3 Contact cement has been mentioned with some good and some bad results.
#4 Hot melt glue with the head of the glue gun pressed against the Coro until it almost melts the plastic. The correct hot melt glue stick seems to be necessary. The older yellowish material seems better than the new "multi-temp" milky white sticks.
5. Most any of the above glues along with "stitching" two sheets together with line. I'd use Kevlar based fishing line ( Power-Pro ) if I went that way.
#6 Epoxy is mentioned last, since two different fellows have had two different results. I'd suspect that, with proper preperation; epxoy would work just fine, but I'd have to do some tests first.

I found one internet entry of a fellow gluing, then stitching two sheets of 4 x 8 together and then covering the final seams with waterproof tape. He made a small kayak that would be a model for me.

I have a call coming from my local Coro supplier about the 12 foot lengths. It seems that they are available, but I don't know the price yet. For reference, the 4 mill 4 x 8 coro is only $16.50 in a variety of colors and only $14.50 for white. The 10 mil sheet in white only is $33.62. Not bad at all, I thought.

Coroplast is impervious to water but one does have to deal with the empty "flutes"that are the core of the material. I believe a swipe of 5200 would seal the tubes off. If not, bamboo food skewers are often used to stiffen local areas for airplane building. Small pieces stuffed into the flutes and then glued would surely seal it.

Neat stuff. I hope I can use it as it is so light and strong. regards, Rich

[gonzo]

You can seal the edges with tape.

[richg99]

For those who are not familar with Coro-plast..it is the material often used for Political and real estate signs.