If you sail a craft on the sea, you might want to consider buying a CelNav kit.
I disagree with the notion that this is a kit that can be used in an emergency by someone who is inexperienced. Oh, it can be used in an emergency, but like a handgun, it's a good idea to know how to use it before you need to.
GPS is a good thing, but you're depending on technology both in space and on your craft. For celestial navigation, all you need for technology are a sextant and a chronometer.
GPS spoofing isn't likely much of a problem in open ocean sailing. A spoofing transmitter has to be close enough to disrupt the signals. But what if someone mounted spoofers on a number of drones and sent them out over the sea?
More likely is, in any sort of conflict, that the GPS network itself is going to become spotty. If you are a cruiser, being caught away from home in an environment where GPS becomes unreliable would be a bad thing.
(I've mentioned this before.
(H/T)
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Wondering the lifespan of a plastic sextant? That plastic, exposed to heat and cold, even in a case, won’t last nearly as long as a metal version. Gonna suck to pull out the plastic sextant and have it snap in your hands when you need it.
Huh. Sea water is not friendly to metal. Talking through my hat here (though I toyed with sextants and have a basic knowledge of coastal navigation with pelorus, map and parallel rules), but I'd imagine that metal (and hideously expensive) sextants are treated with considerable respect and care (and kept away from sea water). If you lavish the same level of care on a plastic sextant, it will probably be fine. And I'd imagine that a half-way decent Casio is damn near as accurate as a Rolex.
As for needing celestial nav, you might read Weber's The Apocalypse Troll wherein an EMP blows away the electronics of a deep water sailor....and drops a woman from 100 years in the future into the sea next to his boat
Not necessarily off-topic: this website I'm still looking at a tad askance, lot of good stuff but some that'll make ya' wonder, but this is an interesting read on our wandering magnetic north, and its acceleration and sudden departure for Siberia ~ https://www.ozy.com/around-the-world/why-the-north-pole-is-moving-faster-than-ever/256395/?utm_source=OZY&utm_medium=Facebook&utm_name=Organic&fbclid=IwAR3VBXbaYHxQDZ7ap9-r8biyQl33byEpjC-ggonq47he-Nc5RVVfgxCkQS4
Most plastics do well around sea water less so in sunlight. Protected from
the sun between uses it will fair for many years. Bigger issue is the field
book and accurate time.
As to metal sextant, the traditional material is brass, it holds up
well around sea water. You pay dearly for that.
Third method of navigation other than compass and dead reckoning, radio
bearing to known coastal stations in the LF (200-500khz) and MW (am broadcast)
are good for a coastal fix to several hundred miles. Still requires some skill
for plotting the stations and angles. Also a decent AM radio, Novatech one one
for the day or a ship board radio with directional loop.
Eck!
True enough on metals, excepting brass, but this is a toss and forget item. I suspect it will fail rather than save after 10-15 years of heat/cold cycles...brass was my thought, and shouldn’t be completely unreasonable for such a kit.
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