My 430mm wide hull glassed on the outside a week ago is now 470mm wide. I hope to sand and glass the inside real soon before my design concept changes from narrow minimum rockered hull to a sea kayak, and before any cracks appear on the inside. Is this amount of movement normal, or is the wood I am using (New Zealand white pine) particularly susceptable to shrink/swell compared with cedar (cedar is very expensive to import here)?