As most of you are aware, Slocum only had a castoff alarm
clock with just the hour hand, no minute or second hand. He used Lunars because that was the only way he could get Longitude without a chronometer. The tables for calculating lunars were taken out of Bowditch and/or the almanacs sometime around the turn of the century, that's the previous century. Accurate chronometers had become relatively cheap
and universally available by that time. Navigators were no longer using lunars and/or being taught how to reduce them.
Doubt that Josh would have used GPS
unless someone gave it to him and the batteries to power it. Why else would he have left without a proper chronometer other than a severe lack of money
and/or extreme frugality? Even though he knew how to get Longitude from Lunars, FWIU they require high level competence in spherical geometry and are arduous and time consuming to calculate. His life would have been much easier with a proper Chronometer. Then again, he may have just been a retro-grouch and preferred to do it the hard way.
Any modern boat should have an electronic log and possibly a taff rail log. I always drag my Walker and compare it against the Raymarine
Log. It gives me damned accurate measurement of distance covered through the water
. Given an accurate compass
and interpretation of the real heading made good, you can get a pretty accurate fix for 24 hours of run, especially if you know the current
. Accuracy degrades drastically beyond 24 hours and/or with strong currents of unknown set. You need dead reckoning to advance your position for getting LOP's from the sun for morning and afternoon shots, as well. Doubt that counting shaft revs would be all that accurate on a yacht, at least one of normal size. A typical yacht just gets tossed around too much with any amount of weather
. Of course, counting revs would be useless on a sailboat except under power.
My definition of navigating in the good old days is "I was always lost
, it was just a matter of how lost