Just wanted to pass along something new I learned about crawdads & ram-x plastic. I did a search on how repair any holes on Coleman boats that have the ram-x. It said to use plastic milk crate & melt it with a blow torch. Let me tell you it worked great! I held a piece of milk crate with a pair of pliers over the boat & heated it with a blow torch. Let it drip onto the area that need patching. Its best to do a little at a time, let it cool & harden. Then continue to add more if needed. 

no holes in my crawdiddy yet but its good to know, especially some of the crap i drag it over...

how do you keep it smooth? also, do you put it inside and out?

I put it on the outside. The boat is pretty beat up so, I wasn't concerned about it being smooth. Also, it was very small hole. The melted plastic didn't harden right away. You could try smoothing it with a flat scraper or putty knife?