NavList:

I recall that Greg Rudzinski also posted about rate consistency with a cheapish mechanical watch movement.  I can't remember whether it was here or on his blog.

My "almost all is lost" GPS fallback is a running (sports) watch with GPS that can be charged from a USB cable attached to a small solar charger, stored in a Tupperware-like box. The charger can be charged through the clear plastic lid of the box without taking the lid off and exposing it to salt water.  It takes very little charge to get it going and is then both a watch and GPS receiver independent of other charging systems (except the sun).  But then that too may get fried.  I could fit both the watch and charger inside a metal box in turn inside the plastic box - I hadn't thought of that.

Which leaves me with the "now things are really desperate" Tupperware box containing a quartz watch, a copy of Dr. Kolbe's Long Term Almanac with the Concise tables, a small compass, an $11 scientific calculator, a notebook, forms, plotting sheets and some papers and pencils to go with that, plus my EBBCO Special in the Go-Bag.  Maybe I need to add a wind-up watch.  I like the idea of that - the discipline of winding it daily at sea and checking it against the GPS and WWV during the good times would add mystique for the crew who believe celestial navigation to be one step removed from witchcraft. 

(I have an attractive mechanical clock on the bulkhead at the front of the saloon, together with a matching barometer.  I have never documented its rate of change, but should do so.  That would necessitate keeping it wound continuously which would require frequent trips to the boat on its berth.  But I need no excuse to do that.)

Murray