Fred Rebel - Sailed from Australia to the USA using a VERY fine - home made sextant, long before electronic navigation.
There is also the factor that GPS for civilians has the capability of dithering and 'selective availability' which -who knows- might be potentially accessible to hackers - especially with those GPS ground stations on foreign soil.
>>>>====> I was reading about a blue water, large 'gin palace' sailboat that had to be rescued because of 'failure of navigational equipment'. Oh? I can virtually guarantee that they did not have even a plastic sextant and basic set of tables aboard and the skills to use them for latitude sailing; add a $5.oo E-bay electric watch and you're getting longitude too - better than what Captain Cooke used to map much of the Pacific. Improvised celestial navigation, using what you can make, won't have you safely threading narrow approaches in shallows in the dark but you CAN find specific parts of a continent pretty easily. OTOH - I've read of more than one SKILLED navigator who, when improvised was the only option, used their skills and made a rough, 'sextant-like' sighting protractor. One Russian ROUTINELY used a children's protractor and soda straws to sight horizon and celestial object and he sailed from post-USSR Russia all around the med, Atlantic and Caribbean.
Master skills - once 'owned' skills travel lightly and the rest can often be found, scrounged or made outright.
73 de RadioRay ..._ ._
Ps. For fun and a quick intro, download a 'celestial navigation' app for your smart phone. It's a quick intro. If you can get within 10 miles, you're doing fine, 5 and you're a 'master' of iPhone-waza!