How did Pytheas not get lost?

Tidying up the boat for the winter, we've packed up all the pilotage books, maps and guides, and brought them home to keep them dry. This, and a comment made by a recent visitor, make me reflect on how on earth Pytheas found his way around these isles more than two thousand years ago.

The visitor, when I said we'd been at sea for about 90 days this summer, expressed amazement at how we manage to avoid rocks and navigate around the coast. I told her that, in addition to Bill, who with decades of lobster hunting experience seems to have his own unique underwater sensors, we have a stack of charts and pilotage books. The Clyde Cruising Club, in particular, produce brilliant books detailing thousands of harbours and anchorages, with detailed maps and directions and all kinds of useful information about hazards.

We also have a depth sounder, which helps, although I still trust my plumbline  more than I do the electronics. I always think of Pytheas as I dangle the bit of lead on a string down into shallows, as this technology without doubt goes all the way back to the iron age and beyond.

But Pytheas didn't have pilotage books. Or did he? Incredibly, even as far back as the sixth century BC there was a written guide to mariners in the Mediterranean, called a 'periplus', containing detailed sailing directions to Massalia (where Pytheas lived). And there were even written accounts of journeying out into the Atlantic, one by a Carthaginian called Himilco, who possibly sailed far west (conceivably even to the Sargasso sea) in the fifth century BC. Pytheas' own book, On the Ocean, was widely quoted and used as a source of travel information, not least by Rufus Avienus, the Roman author of Ora Maritima, a collection of sea lore tracing a journey from a northern part of the Atlantic coast back into the Mediterranean.

Avienus wrote his account in the form of a poem. The pilotage books we use today are staunchly prosaic, but I like to think that back in Pytheas' day, a great deal of navigation information would have been in the form of poetry. Most coastal lore and sailing directions would have been passed on orally, probably from generation to generation of navigators, and therefore it was probably full of songs, rhymes and good stories to help it be as memorable as possible. Just as indigenous Australians have 'song lines' to enable them to find their way vast distances across the outback, I imagine sea captains of Pytheas' day could well have sung their way around dangerous headlands and told their children folk tales to help them to remember sea hazards like rocks and strong currents.

So I reckon Pytheas found his way by joining the voyages of experienced seamen and women who held their pilotage know-how in their heads as songs and poems. Anyone for some poetic versions of the Clyde Cruising Club books, or a setting of Reeds Almanac to some rousing tunes?