Thanks for the reply Mark- we have taked readings with a low voltage meter, at the dock ,and away from the other boats at dock, but not with 100' of cable out. That would be interesting to see the difference. Pos/Neg voltage discharge is very obvious in a marina, where some anodes will corrode quickly, and others will never need to be changed. ProTroll has a pretty good explanation on line...........worth a look. - Jack http://www.protroll.com/books/?id=5 copy & paste this site.