[GBurton]

The point that I was trying to make, is that the jumper cables provide a path to "ground" as well. You may have a well bonded system with an external plate etc. but this will not guarantee that you will not sustain damage from a hit. The energy transferred to the boat may be enough to overwhelm a "grounded" system and cause a lot of damage.

I suspect what a lot of people are talking about here is not a grounded system at all, it is just a bonded system.

Wrapping the anchor chain around the mast would not be a good thing to do imho