I've always been disappointed in the way hull sides have turned out whenthere is no support behind the hull skins. It seems that no matter how carefulI try to be you can still see ripples in the sides of the hull. If thesedefects were scaled up to full size, I think the ship owners would be demandingtheir money back from the builders. So, at the scale that we work on in paper models the hulls should appearperfectly smooth with no warps or wrinkles. To accomplish this requires some support behind the hull skins. There are many ways to do this: florist foampieces, balsa pieces, Styrofoam pieces etc.., all squeezed between frames andsmoothed to frame lines. Here is anotherway that I'm trying as an experiment. This is not my idea - I got it from Hiob at Paper Modelers where he usedthis technique to build a 1:200 Kursk model that is nearly five feet long. This process lookedinteresting so I decided to try it. Photo5 I had a model of a Polish destroyer in progress so this would be my guineapig. One thing that I always do is tocolor the edges of my hull stiffeners with black magic markers. After coloring, I soak the edges with superglue which when cured gives a hard workable surface. And when you are sanding down a softer fillerbetween frames, the black shows through when you reach the frame and the hardersuper glue surface prevents you from sanding away too much from the frames. Photo 6 and 7 The expandable foam is the same stuff you can buy in the hardwarestore to seal wall cracks and stop air leak and it comes in a spray cans. Using Hilti expandable foam in a can, Ifilled in the spaces between frames and allowed the foamed skeleton to cure for24 hours. It ain't pretty and this stuff is hard to work with in an open space.It is sticky and gets all over everything. My wife said it looked more like a dessert than a ship. I thought itlooked like something more disgusting especially if it was painted brown. Shesaid "How can you make a ship out of that mess?" I replied "It's simple. I'll just cutaway everything that doesn't look like a ship." So next I'll hack away at the foam and seewhat we end up with.