I have a fiberglass boat and run two batteries, two downriggers and a fishfinder. The guy I bought the boat from was doing something with the groundwire on the motor when I bought it. He dosnt know boats. Im worried something may not be right. I had a issue last year of my cannonball snapping off at waterline (wire line) when I hit the switch to retrieve. I dont know how thick the zincs were to start so I dont know if there past 50%. Im not sure how they work and if they are important to keep a eye on? and also the ground wire, what does that do? Can I tell if its grounded right?