Hmmm...."Faraday Cage" I wonder if an old metal (unused) paint can would work as a Faraday Cage for my backup GPS and the handheld radio.
A lightning strike CAN destroy a magnetic compass. Also a lightning strike can magnetize a lot of the previously non-magnetic metal in the boat, thereby making the compass act totally whacked out. This happens in airplanes pretty often.
Windvanes don't depend upon electrons to steer. That's the REAL reason I use one.
As for the electrical budget, I think Jim has a point, but on the other hand the RC needs to go to some sort of lengths to ensure that people have at least thought about major issues, and filling out the form and seeing if there's some glaring discrepancy can't hurt. It's pretty painless. Of course, it only makes sense to have backups.
Regarding electrical systems....I've said this a million times so here goes a million and one. In 1996 I got to Hanalei on two fully charged batteries and a four-hour charge run with my Lightning generator on about day 12. I had no solar panels. I carried a LOT of AA and C batteries!
The GPS's were all handhelds.
The Navik windvane did the steering.
I didn't use Navigation lights, but I did have a masthead strobe.
Other strobes in the rigging were armband strobes.
I didn't talk to anybody for 16 days on the radio.
I essentially never ran cabin lights.
That taught me a lesson. You can go a LONG way with a totally dead house electrical system if you just have independent systems that don't depend on house electrons to run the boat.
1968 Selmer Series 9 B-flat and A clarinets
1962 Buesher "Aristocrat" tenor saxophone
Piper One Design 24, Hull #35; "Alpha"