Technology and sailing
Visibility decreasing as we enter the Bay of Biscay Not long ago, when people set sail to cross oceans, they set off with some charts, a sextant, sight reduction tables, pencils, dividers, parallel rules, a compass, a log to measure knots and a clock. If they knew the speed at which they were sailing, and how long they had sailed, they could determine where they were. They would back that up by taking sights on the stars and the sun and calculating their lat and long.