Electrolysis on new outboard engine

[Markroby]

I have a new boat and even though it's only been in the water for two weeks I have noticed the anodes have deteriorated a lot ie it has a lot of pitting considering the short time it's been in the water. I have always had boats and normally replace the anodes on my outboard every two years or so, therefore I suspect there is some sort of electricity flow around my boat. The boat moored just beside mine has a shore supply and I suspect this is causing the electrolytic problem!
my question is even though I totally shut down my batteries when I leave would there be any way my own boat could be producing this electric current or am I right suspecting my neighbour's boat with shore supply?

thanks everyone for your help.