With regards to the stiffness test - that's not a very scientifc way to go about it. Were the beams on the Nacra seated? I removed my hulls and bedded my beams in epoxy (mostly to get rid of the squeeking noises! ). However, most of the flex measured by lifting the hull is generated within the beams themselves, very little the hull to beam joint, and practically none of it by the hull itself. You should see practically no hull flexure on any cat by lifting the bow. This kind of flex characteristic indicated by your test has to do with the length and type of cross beams. Impressive, yes...but still not the whole picture.