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Apologies for drifting off-topic here...

There's another way to do automatic navigation: you let the satellite find
YOU. Ships at sea are easy to detect. A handful of satellites can track
every vessel on the face of the Earth assuming they're emitting some radio
noise (the electrical systems of any modern ship's engine produce enough
radio noise). Then when you need your position, you call up the satellite
and ask. And needless to say, you can ask it to tell you where your
"friends" are, too. There have been reports of such systems in actual use
for years. There are sets of satellites, supposedly operated by the US NRO,
that travel together in small groups. It's a bit eery: you can see three
little "stars" gliding across the sky together in a triangle a few degrees
across if you know where and when to look (google "NOSS trios").

Speaking of satellites, how about using them for small-craft navigation?
And, no, not GPS satellites. I'm talking about visual observations of low
orbit satellites. Satellite positions are as predictable as the Moon's, as
long as you avoid objects which maneuver frequently, like the International
Space Station. And if using a computer isn't cheating, then you can get a
line of position by observing a satellite's position in the sky (I'm
picturing tracking it with binoculars and looking for close approaches to
moderately bright stars). If I observe a satellite that's 500 nautical miles
above me, and if I can get its position relative to some star accurate to a
tenth of a degree, which should be possible, then I can get a line of
position accurate to about 1 nautical mile. If I have a rough DR position to
start with, there shouldn't be any problem with mistaken satellite
identities.

 -FER

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