An ongoing argument like the CF anchor
I agree mostly with Jamels sentiments. I'm old school
and have used sextant without GPS but probably wont use a sextant again since GPS is pretty reliable -but not infallible.
Having said that for offshore
use I would carry at least three independent GPS, being so cheap
, with at least one in protected storage
- perhaps in the grab bag .
I'd also suggest one knowing how to take at least a noon site and carry, if not a sextant, then at least instructions to make one and a crude 'almanac' table of sun zeniths printed/written down. One could if desperate construct a primitive shadow type astrolab from a few bits of timber. Together with a little maths, a shadow measurement of say 5mm at a metre length equates to ~ 15nm mile lat. diff -enough to get by with in that unlikely event of WWIII or all 3 GPS failing.
I think I'm right in saying OpenCPN
now has a celestial nav plugin available but I suppose if the GPS is dead then its likely the netbook is too. Theres plenty of celestial stuff available online.