Ah, map reading.
In the days when portable GPS units were still to be found in company helicopters in Nigeria, had one die on me while on deck the platform offshore while the new-in-country (but otherwise experienced) expat copilot was outside supervising the deck activities. This was somewhere offshore Andoni or thereabouts if memory serves. Once he clambered back aboard I shared these glad tidings.
However were we to get back?
I proposed if we were to take up a compass heading West by Nor by West or thereabouts we might find ourselves with a panoramic view of the Nigerian Coast presently where we might identify say Bonny, and thence Cawthorne Channel or summat and pick our way up to Samki and thence to the aerodrome where we might have a word with the greenies about the state of the GPS. We might even tune up the POT VOR or an ADF or some such for confirmation if the things were working.
When I later brought up this cautionary tale about the precarious battery life of the portable GPS, several pilots in the crew lounge looked at me as if I were a sorcerer... or worse.