If you’re into the kind of boats we do, you’re probably are into the kind of navigating we do: Global positioning and automatic chart plotters are great. But nothing beats working up a good old-fashioned dead reckoning. Sit down, break out the throw-back paper chart, estimate how far you’ve gone, at what speed, and in roughly what direction. And, after some basic calculations, you know where you probably are. But dead reckonings pose a strange 21st-century challenge: Doing the calculations reliably. In boats, traditional cheap electronic calculators can’t seem to stop dying from the moister and lack of use. Smartphone […]