A captain took four sightings of the sun and saved six lives
Frank Worsley navigated 800 miles of open ocean toward an island he could see maybe four times, for about four seconds each.
In April 1916, six men left Elephant Island in a 22-foot lifeboat called the James Caird, hoping to reach South Georgia before their crew, stranded behind them, ran out of food. The odds of a wooden boat surviving the Southern Ocean's worst waters were bad enough. Missing the island by even a few degrees meant sailing past it into open sea with nothing beyond.
The navigator was Frank Worsley, a New Zealand sea captain with a sextant, a chronometer, and almost no way to use either one. The boat pitched too hard to stand. Cloud hid the sun for days at a stretch. Worsley later estimated he got only four clean sightings across the entire seventeen-day crossing — each one grabbed in the seconds between swells, while a crewmate braced his legs so he wouldn't be thrown overboard mid-calculation.
He landed the boat on South Georgia within a few miles of where he'd aimed, on the correct side of an island roughly a hundred miles long, after seventeen days with no way to check his work until he arrived.
Most of what we call skill is really tolerance for incomplete information, exercised often enough that four bad readings start to beat zero good ones.