Problems with keel and bulkheads

[modelmaker 2001]

I am wondering what should I use to make the false "keel" and the bulkead "ribs" that make the basic shape of a cardpaper model boat? I have had some trouble in the past with the keel ending up a little crooked and the bulkheads sometimes not being truly squared off and perpindicular to the keel. Should I replace the cardboard keel and the bukheads with thin sheets of balsa or some other wood? Could it be the glue? (I was using Elmers white glue)

[Siwi]

You could try balsa. Another solution (if not already included in the kit) is to cut some right angled pieces to make all the joins exactly squared off, or if your measuring is good, whole rectangles of card to maintain the shape. Below you can see this technique used aircraft, exactly the same principle: