NavList:

Chris Maness, you wrote:
"...instructions on one side and the table on the other laminated to put in your lifeboat. You can also make a compact Sun ephemeris the same way. A small Ageton's table + Sun Ephemeris + Davis Mk3 you have a basic idea of your lat/lon +/- 5nm pretty easily. Within easy sighting of a flare gun from a plane. But I suppose EPIRB makes this irrelevant unless the EPIRB is not working."

Yes, EPIRBs have largely made these "lifeboat" scenarios irrelevant fictions. They're "thought experiments" in the modern world...

Also, look at the middle part of your story here... You get your position within 5nm. OK. Stop there for a minute. What use is that? Is your imaginary lifeboat also equipped with a short wave radio transmitter (but it doesn't have an EPIRB?)? If no radio, then what's the point of determining your position with a sextant? One possible answer: it will provide distraction.

Setting aside the "lifeboat" scenarios, there are plenty of gradual degradation scenarios that are worth exploring. The simplest case is a major increase in GPS problems during an international crisis. But the key here is that it's rarely all-or-nothing. If I lose my GPS signals and still have a functioning computing device (iPad, e.g.) and solar power to keep it charged, then what should I do? Or suppose my built-in nav system is fried by an electrical problem, but I still have a functioning smartphone. Then what?

And consider: if you can store a "small Ageton" in your minimal celestial kit, then why not store a cheap solar-powered calculator? That's what I teach in my celestial navigation workshops: direct solution for lat and lon without plotting using a cheap, solar scientific calculator.

But I will say that I agree with you on Ageton versus the Nautical Almanac's included sight reduction method. The H.O. 211 tables (and kin) are excellent, and if you enjoy such tabular methods, they're a great choice! :) And yes, the problematic cases are a minor practical concern.

Frank Reed