I was walking to my boat along the dock when my diver motored by and yelled, "Hey Bob, what are ya doing different?" The question was a little confusing, and he asked me if I had seen his note. I usually look at his tag after my hull cleaning, but this time I had pulled it off the bow rail and tossed it away. He said that my perrrywinkle zinc at the end of the shaft was nearly gone, but it had been fine during the last cleaning only a couple of weeks before. Because I have been using the space heater in the boat the last month as the temperatures have been dropping, it seems safe to assume that this accounts for my problem with electrolysis.
When I bought my boat I noticed all the thru-hulls were bonded together with copper wire. I have read that since all my thru-hulls are insulated from the rest of the boat with plastic or rubber hose that this is unnecesssary. So I removed the bonding wires. Was this a good idea? And for some reason when I use a high-wattage heater I am eating up the prop zinc quickly. Can you suggest some things to look at to rectify this situation? The only other AC I have is the outlets, the battery charger, and a florescent light. There is a small ground plate about three inches by six inches on the outside of the hull on the port quarter, but nothing is wired to it.
Sue & Larry respond:
Thanks for the question. Electrolysis is always a difficult issue. It appears that your diver has been doing a good job and has noted a change in the electrolysis pattern on board your boat. Between the two of you, it seems that youve identified the space heater and use of 110 volts as the culprit. When AC wiring and connections are not in perfect condition, they can be the cause of stray current. You need to thoroughly inspect everything on your boat. A wire may have been skinned or a connection knocked out, or not properly made in the first place.
To complicate matters even further, your electrolysis could have nothing to do with your boat whatsoever. A neighboring boat in your marina could also be the cause of your problems. We were once in a marina for just 24 hours, and our prop zinc was eaten away by almost 50 percent! We didnt even have 110-volt power on board at the time.
For safety factors and to expeditiously identify and correct your problem, we think it would be wise to employ the talents of a good marine electrician. If you are not familiar with 110-volt wiring, and particularly how it should be run on a boat, it can be a dangerous thing to play with. This especially holds true given the damp environment of boats.
As far as your thru-hulls are concerned, its a good idea any time you change the bonding profile of any of your underwater metals to closely monitor the potential result of your actions. You may solve, or create yet another problem with this action alone. Here's wishing you the best of luck resolving your problem.