NavList:

The marine sextant was a natural alternative for early airships and flying boats. You could use the sea horizon, and also the top of stratus cloud.  Dip and refraction tables were produced up to considerable heights, so the tables were never a problem.  The main problems were the haziness of the sea horizon at greater distances and finding your accurate height above sea level or stratus cloud so you could use the dip and refraction tables.  In those days, in mid-ocean, unless you were in contact with a passing ship, it was difficult to obtain sea level pressure to set on your altimeter.  Instead, they measured the angle made by the airship’s shadow* with their sextant.  Try it.  Do the maths; it works, especially if you put the Sun on the airsgip's beam.  The trick when you draw your diagram is to draw the rays from the Sun parallel, as they effectively are.  Then the base of the triangle is the length of the airship.

There is conjecture over the name of the chap in in the much-used photograph wearing the leather coat using the Plath from the control cab of the Graf Zeppelin airship.  (? ? Why doesn’t his hat blow off?)  My suggestion after searching press photography surrounding the Graf Zepplin and finding no obvious choice is Max Pruss before he became Commander of the Hindenburg airship and his face was so badly disfigured.**  DaveP

*  ‘The Log of H.M.A. R34 Journey to America and Back’ Maitland: E.M. (Edward Maitland) (Available on Kindle)

** Incidentally, I first made this suggestion about 20 years ago, and I note today (while checking my memory of his hat and coat) that The Smithsonian has also given him the same name.  https://timeandnavigation.si.edu/multimedia-asset/max-pr%C3%BCss-graf-zeppelin-navigator