NavList:

There are a few low tech solutions to help the small craft sailor save hand held electronic devices.  

If any battery powered device gets exposed or submerged by water then as quickly as possible shut off, remove batteries, dry with paper towels, drop into a zip lock bag full of rice for 24 hours.

If lighning is approaching then double wrap electronic hand helds in aluminum foil to act as a make shift Faraday cage. 

Greg Rudzinski 

From: Lu Abel
Date: 2017 Sep 8, 17:14 +0000

1.   How about a hand-held GPS sealed in a water-tight bag?  Cheaper, quicker and more accurate than a sextant.

2.  As Bob points out, most massive electrical failures are due to water incursion into the boat (and before someone "corrects" me, yes, lighting strikes can be even worse).   What saves Nautical Almanacs, sight reduction tables, etc, etc, from being ruined by the same water incursion?  

If I were going offshore, I'd certainly carry a sextant.   But that would be part of a larger package of considered and thought-out navigational backup choices.