As a member over on the baylinerownersclub.com I have asked some of their electrical minds about this. This is called ESD, Electrical Shock Drowning. The story at BoatUS was about some kids that were killed because of stray AC currents in their marina. A sad story.
Too add to all this I know a couple of boating friends that have had corrision problems on their boat at our marina so I thought I would check this all out. By NO means am I an expert on all this but I did learn alot!
So I went out and bought a clamp meter. Now I could of spent up to 3 or 4 hundred dollars on a very good one but went the more budget minded with a 20 dollar clamp meter from Harbor Freight. Went up and down our dock with the clamp meter checking. What it does is.... check for any escaping AC voltage. This is only the first step for this problem. I sent my clamped gauge over the shorepower cord where it plugs into the pedestal to see if I got any leakage. All around my boat's slip I got zero's which is good cause that means your ground, black or white in your shorepower cord is not leaking. About 7 or 8 boat slips out away from my slip I started to get readings of .01, .1 and all the way up to 1.1 on my meter. But nothing higher than the 1.1.What do you do with this information? 1.1 is low on the scale in the Boatus article.
Added info........Now what I have learned from the guys over at the bayliner site is that the AC current leakage will shock you but the DC current leakage(your 12v or 6v batteries) will cause corrision problems on your metals on your boat. So if your outdrives are getting pitted, check your anodes first but you have a DC leak somewhere.
Now back to the AC problem.I just got the first part of all this done. Now if you find a AC leakage what line is it coming from? Your ground, black(Hot and it would be yellow if you have a newer boat) or white. You have to seperate these wires to find out which line is leaking, which I did not do. I just told the owners of the boat about their reading and left it at that.
That is all I did. I have been told that there is a device to seperate the wires so you can figure what is leaking. Also I was told that you should have all your ac devices turned on when testing. There is alot to this.
So that is my story where I got my feet wet on this problem of ESD.