Re: Boy killed by lightning in our anchorage, what would you do?
hellosailor has a point about not needing a perfect faraday cage to get some protection, with a car providing another example. That said, the whole boat as an approximation to a faraday cage only applies if the boat is all metal. The overwhelming majority of recreational sailboats are plastic.
It is more likely that the typical sailor can only get the benefit of a faraday cage that is much smaller, like an oven or an aluminum foil wrap. It can be inconvenient to disconnect and remove your electronics to an oven, so the aluminum foil trick may be more practical, as long as the wiring is disconnected. I agree that just switching off a breaker does not guarantee protection, as I noted in my previous post. But I also noted my personal experience that completely disconnecting your electronics does not provide protection against the electromagnetic pulse from a lightning strike.