Me, the boatbuilder, currently building 100 year-old boat designs -
guesses that if they look like copper then they are copper. Bronze is
often used in boats - but more for bolts and screws than for nails.
Copper is typically used for nails because the nails are usually
either clinched (bent over) or hammered to form rivet heads. Copper
is much more amenable to either of these two treatments than bronze
or brass which are harder to bend and/or to rivet without cracking.
The cross-section of the nails is a clue also - Square ones are meant
to be rivetted. Ones that taper to a rectangular cross- section near
the pointy end are meant to be clinched.
If they just look like ordinary round-shafted common nails with a
point on the end - then look to see if they have rings around the
shaft, looking sort of like screw threads, but running straight
across the shaft rather than in a helix like screw threads would.
These rings would be cut in the full length of the shaft, not just a
little bit near the head end. Then it is just possible they are
bronze - but if the shafts are smooth then they’re likely copper.
I’m not even sure they had ring nails available back then. And if
they did, it would have been damned hard for your friend to pull them
out in good shape - unless the wood was totally rotted - in which
case he’s got a tough job.
Of course, ya never know what some poor ignorant boatbuilder in
Eastern North Carolina might have done all those years ago. It’s no
wonder his creations have to be re-built after only a hundred and
ten years working in the shad fishery. Too bad he’s not around to
Anyway, I’d still guess, sight unseen, that you’ve got copper nails
there. Have a good time!
Marty in Victoria BC, where I’m still using copper nails.