NavList:

>>What people might be looking for is backup navigation, not exactly emergency nav like Tom Sult was suggesting, but something one or 2 steps up from that....what would you carry as a backup to GPS that minimized cost and storage space? <<

I think this is a good idea.  I know, Frank, that you feel passionately that the best backup for a GPS unit is another GPS unit.  But viewing interested people as customers of your course, I can say that a certain percentage of your customers are going to think of GPS - no matter how many handheld devices you have scattered about the cabin - as a single point of navigational failure.  This group really does, rightly or wrongly, think of celestial as a good backup to GPS.

Having said this, do proceed to share your passions around GPS units as being good backups for other GPS units...just flesh that out a bit (if you do not already) with a discussion of Faraday cages.  Far too many people wrap up a piece of electronics in aluminum foil, and then throw it in a baggie.  But electronics-conductor-insulator is the wrong sequence.  You need electronics-insulator-conductor.  So put it in the baggie before wrapping it in aluminum foil.

I find that metal tins for tea, most readily available at a Chinese market, make good Faraday cages...better than aluminum foil because they are more durable.  I also have an enormous tin that came filled with Ritz Crackers.

It is also the case that if you have an electronic watch, and you are concerned about EMP frying the main chips in all your GPS units, it will likely fry the watch too unless you have THAT in a Faraday cage.

So maybe teach the celestial they want as a backup navigational strategy...and then include a component in your course on how to minimize the NEED for actually USING celestial as a backup, by judicious use of Faraday cages to protect your primary GPS method.

Bob