ESD seems to be a very rare event with conflicting evidence that it occurs only in fresh water. I don't know of many boaters that are unaware a marina full of boats is likely to have some boats leaking current into the water. I suspect marinas take action when tenants complain about eroding zinc or actively monitor stray current. I commend you for trying to warn other boaters but through hearsay, your message was misinterpreted. It would be interesting to hear how marina divers protect themselves against this problem. If I had to go in the water near the marina, I would go in slowly anticipating one would feel the electrical current before you become imobilized.
I'll bet that family from Minnesota would have wished Disney would have put a warning sign about alligators in the lake, but everyone knows there are alligators in Florida right?
There are all sorts of threats we are exposed to every day. Ever seen a sign about the danger of lightning? I've never seen a warning sign at marinas cautioning of the dangers of ESD either. It would be bad for business if your marina was the only one. Unfortunately, marina owners will not voluntarily put signs up unless they are compelled to do so. Like the warning signs on boats of the dangers of carbon monoxide. There just haven't been enough accidents to pass a new law.
). My mother gave me advise long ago that never fails to stick ... she said "if you want value, pay for quality". 
