Since you already have the tape on, you can take some craft paper and place on the inside of the hull against the tape. You want to make sure your form is very stiff, and I mean stiff. You can use foam, poster board, cardboard, etc. You have to make sure you have the form correct. Do not use such heavy glass in your first lay-up since you have the tape on. You should start with a very light glass, 1 ounce will do, glass small sections at a time, maybe a twelve inch square at a time. The reason for this is to make sure you start the form and keep it without the tape or other material sagging. Once you have the hull shaped and cured with the light glass, you will notice that it is still flexible. Repeat the process. Once you have the hull nice and rigid, THEN you can lay it up with heavier cloth. If this is a hull for humans, you certainly have to build it for that. If it is a model, then you will need to plan ahead and glass in the pieces you need to build the model. I would use a couple of layers of 4 ouce cloth, or 5, or 6, to get the solid hull you want. Be sure to glass in your transom while you are doing the hull. You don't want to add that after the fact. Happy building!