More information than you needed:-

"The Galvanic Isolator Explained" at
http://www.yandina.com/galvanicIsolator.htm

"Does my galvanic isolator need a capacitor to conduct AC?" at
http://www.yandina.com/GIsolCap.html

"A non technical education on boat electrolysis" at
http://www.yandina.com/electrolysis.htm