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Sounds like you know more about Nova Craft that I do, so here's a question, the answer to which might explain things. Does Nova Craft use "closed-top" wood gunwales on the composite boats like most other makers do? These gunwales look "open-top", which as far as I've seen, is always the way it's done with Royalex, regardless of maker. See that thick "seam" sandwiched between the two wood pieces? That's probably the top of the Royalex sheet. On every composite boat I've ever seen, there's a fine rabbet on one of the two gunwale pieces which hides the hull material from view, and it also makes a very fine seam that probably couldn't be seen in such poor-quality photos as these.
If it IS fiberglass, those creases on the bow could be the joints where the float tank joins the hull, but why would there be two creases instead of one?
Of course, if the original poster wants to buy the boat, he'll ask the seller what the hull is made of. Heck, he could be the seller for all we know, in which case he already knows.
I'm not especially crazy about the rails being screwed through the outwales full length.
There are also a couple of details in the third photo that might make me agree with papav. Way to the left it looks like there might be a tank, and that funny shadow in the middle could be the edge of the core.
FWIW, I would have said Royalex at first glance.