The trouble with dating that, is that they have made boats and ships like that for 100's of years (even up to the present or at least, recent past) They don't/didn't use iron nails and spikes for shipgoing vessels, because of course water and salt would quickly corrode iron. So sea-vessels always have brass fittings & nails, to resist corrosion. And trying to guess the age by simply looking at the accumulated wear and corrosion, will not be conclusive either, because something on an ocean beach like that, can be thrust around in the in-out-movement of the sand ebb & flow with the seasonal erosion/buildup cycles, means that random objects can get really pounded in short time frames. For example: you can find memorial pennies from the 1970s that are ABSOLUTELY hammered (can't even read the date, paper thin, etc....). On the other hand, if a coin came out of the higher dry dunes, in a big storm 20 or 30 yrs. ago, coming from dry sand that perhaps hadn't seen erosion/salt water for 200 yrs. prior to that, those coins can come out in nice shape (like you'd expect from a land coin anyhow). I've found seateds and barbers that "just came out of the dunes" (as we perceive from the deeper-in erosion of some storms).
And of course the depth you found it at will also have no bearing on the age, for wet salt beach sand. Because that sand is always coming and going with the seasons. Ie.: a memorial can be 10" deep, while a seated can be right on top, after storms push in and pull out sand.
