Maine Sail got me worried about it. That's why I am going to check mine. I am in an inland marina, my best friend is a lineman. We know a lot about the power on our dock and it is not o be trusted. More then once he has corrected problems. A few years ago while at the dock I jumped in to cool off. As I climbed up the ladder and grabbed the stern rail, I felt a tingle. Not much but it was there. I got my volt meter, strip some insulation off a wire and tested for voltage between the lake and my boat. Sure enough there was voltage. Not much but enough to make us go look for a problem.
By the way, thank you Maine Sail for all the great information. I love to read what every one writes, some times when I read the forums I feel like a beginner that has been sailing for 40 years.