Nauta senex

A question: is the Ancient Mariner only ancient as he tells his story to the wedding guest? Or was he ancient back when he was an active sailor? In other words, was he a young sailor who has, since his strange voyage, been pounding the highways and byways, compulsively retelling his adventures, for such a long time that he has grown old? Or was he a greybeard back when he took to the sea?

Here's a 1790 poem by Christopher Bethell, who was at Cambridge the same time and in the same college as Coleridge, and with whom he competed for college prizes in writing verse in Latin and Greek. Bethell went on to become a distinguised churchman, and ended his days Bishop of Bangor, but in his youth he wrote things like this, an exercise in which he is tasked to explain the surprising health of an old horse:

It was published in the second volume of Musae Etonensis (1795), a collection of neo-Latin versifying edited by William Herbert whilst we was still a pupil at Eton, hence the name. Several increasingly expanded editions were issued through the nineteenth-century (I notice there's a copy of the 1795 edition on sale on eBay right now for the lowlow price of £394). The bit that I want to concentrate on for a moment are these lines:

Labitur ut leni vento ratis, arripe portum,
Nauta senex; dubio nec male fide mari:
Мох fera tempestas turbatis saeviat undis;
At tibi jam clavo est et sine fune ratis.
Felix, qui post cuneta maris discrimina, tandem
Ex alto incolumis litore cernit aquas!
Tunc alus cursum monstrat, quae flamina captent;
Quà saxa, et syrtes, quà vada caeca latent. [13-20]

Which means:

When the ancient mariner, soft wind moving his ship,
finally slips into harbour, leaving behind the dubious sea,
the wild and savage tempest, the turbulent waves,
and finally now makes fast the ship's ropes;
he is happy to be safely beyond the sea's hazards,
high up the beach, removed from the water!
pondering might-have-been voyages, forced on by gales
to where rocks and sandbanks and unknown shoals hide.

Bethell's ‘ancient mariner’ is a representative figure for any man who has reached a calm old age and can look back with equanimity on the previous dangers of his life (the next section of the poem does something similar with a senex castra, an ancient soldier; and the poem's last line is ‘hic meritus senium nobile cinxit honor’; we must honour the nobility that old age has gathered to itself). But I wonder if Coleridge's eye settled on that nauta senex, that ancient mariner looking back on his life, and began wondering about the dangers of his might-have-been voyage. It's not much, but it might be something.