I found this at http://skepdic.com/comments/noahcom.html
Anybody who's worked on wooden boats will tell you that you can't just seal their seams with pitch but must painstakingly caulk (drive pitch-soaked yarn into) every external seam; they'll also tell you that joining the pieces of wood together takes skill and (in the Bronze Age rare and very expensive) metal fasteners, at least for non-trivial vessels.