I'm old enough to remember the days groping around
New England in the
fog using nothing but a depthsounder, a
compass, and DR, plus noting things like how hard the
current is flowing by the lobster pots. We always managed to get to where we wanted to go. Went to Labrador and back that way. I've also made landfall with nothing but a
sextant, some tables, and a chronometer. If you need to you can get most places by just taking noon shots to get your latitude, and then sailing down the latitude to your
destination, which eliminates the need for tables and the time even. If the depthsounder poops out there's the lead line. If the
compass dies you can still take relative bearings on prominent landmarks.