: Hi i am just getting in to this so i hope that i don't sound too dumb.
: i want to copy a kayak by cutting a outer mold of it in styrofome(2 peices)
: and then simply coating the inside of the mold with fiberglass and puting
: the 2 sides of it together. Now this sounds just a little to ez for me so
: what am i missing?

You are missing all the problems and the adventure of solving them

Oh, and you may be missing the ethical consideration of copying someone else's design in this manner. It might be a subject to your concern at least, and a copyright infringement at worst. But, if you have the requisite permission the process should go pretty much as you stated.

If you have solid styrofoam panels I'm not sure how you would carve them to perfectly match the shape you are trying to duplicate, so i'm assuming you are going to use an expanding foam mix. This stuff is a fairly good adhesive, so you will need to prepare your mold so that it does not stick to the foam. Otherwise you won't get your original boat out without tearing large chunks of foam from the mold.

The texture of the foam will transfer to the outside of your copy, but that can be sanded smooth.

Some people use fiberglass to make their molds. There is more money involved, and the molds can be nicely finished, polished and waxed so they cna be reused many times. TIn fact, this is the general process for making fiberglass and kevlar canoes (and kayaks). The original is made of wood strips and is called a "plug". Sometimes the plug spends its life in the shop, and other times it is sealed and taken onto the water for testing. If it passes the testing they make copies in fiberglass. If it doesn't pass, then they might have a bonfire.

You might consider less expensive materials for your mold. Plaster of paris has a very smooth finish, but it is more expensive and also heavy. How about concrete? An 80 pound bag of sandmix costs under $5 typically, and you would need about 5 or 6 of them. Press in some thin wire fencing (chicken wire) for reinforcement and let it set up. That would give you a mold which weighed 400 to 480 pounds -- which is quite a lot to lift -- but you would only need to lift the top half, or 200 to 240 pounds -- which should be manageable by two or three people. The other half stays on the ground. Once the concrete has set up and dried you can coat the rough interior with a few coats of epoxy floor covering (cheaper than the epoxy we use for boat building) and sand and polish that.

Or, you can use the previously mentioned paper mache. Put on thin layers and let them dry completely before adding more.

PGJ