I took an "Intro ti Sailing Course" some years ago and took a sextant sight. I found out I was in the Pacific Ocean alright, but I had the boat on the wrong side of Santa Cruz Island. Not a good result.

Boating around in the 1980's we used LORAN, which was repeatable if you used the same instrument,but you could not transfer the numbers. Early GPS receivers were expensive, but much better, and what is available now is superb.

Currently i use a Foretrex 101, which is cheap, dependable, and reasonably accurate. No map, but I have a good record of distance covered and the ability to backtrack. Works for me. (along with a paper map)......