I have read “The Rime of the Ancient Mariner” a few times now, and each time, although he implicitly denies it at the beginning of part four, I am left with the lingering sense that the Mariner is preternaturally old, perhaps immortal. I could never quite put my finger on what left me with that impression, and it is entirely possible that I’m the only one to read it that way; if that’s the case, please tell me so. Regardless, I now have some theories on where I got the idea.
Firstly, we as readers never get a sense of the purpose of the ship’s voyage. It doesn’t appear to be a warship, so we cannot pin it to any war; it does not appear to be a whaling ship, which would have marked the voyage as relatively recent. There is no destination given, so if it’s a trade ship, we cannot use knowledge of trade patterns to place it in time. The technology is also very vague — the ship could belong to any number of centuries, and is entirely consistent with those of 1797. The use of the crossbow, though, rather than a musket, seems to indicate that it takes place no later than the sixteenth century.
Looking that far back, other aspects of the poem start to stand out: the language is somewhat archaic, even for the late eighteenth century, with Shakespearean-sounding “loveth”s and “thou”s and nautical terminology that was already far outdated by Coleridge’s time. More telling, though, is the marginalia: the brief summaries in the margins were a common feature of early printed books, circa the turn of the sixteenth century. As books became easier, faster, and cheaper to produce, more and more people were able to buy them, resulting in increased literacy rates. Those margin summaries were effectively waymarkers for new, slow readers: if they had to stop and lost track of where they were, it was faster to work through those summaries and then move back into the main text than to start from the beginning.
So, linguistically, technologically, and structurally, I would place the voyage sometime in the late 1500s. For 200 years, the Mariner has been wandering the world, stuck under the dominion of Life-in-Death. I’m sure actual researchers who actually know what they’re talking about have done a better job with this question, but I’m at least satisfied to have a basis for my longstanding gut feeling.