Like I have mentioned, we took a large, direct catastrophic lighting strike that took out all of our fixed electronics, boiled and shorted the house batteries, took out most of our electrics including the inverter and charger and solar regulator - but we still cruised just fine for a while with electronic charts and GPS.

Yes, one could imagine a nuclear-powered EMP that does take out everything, but in that case, my personal worries about my position on earth would not be geographical in nature.

A lightning strike any larger than the one we took would be such that the boat would be sinking around us and, again, navigation would be the least of our worries.

The point is to have so many different electronic means to gain a position fix that you greatly outweigh the odds that they all can be taken down.

It actually doesn't take that many to do so - maybe 3?

BTW, you are a techy Larry - how many GPS devices are on your boat when you are out sailing? Tablets, phones, computers, chartplotters, cameras, handhelds, vhf, etc?

Most of us today are never without a GPS on their person. I laugh when I realize that our underwater camera has a GPS - so we aren't even without one when we are swimming! Our HH vhf does, so we have one on us when we are in the dinghy and walking about somewhere. I imagine soon they will be built into our clothing or something.

Mark