Strut zinc, yes or no.
All, Some of you might remember my bringing this subject up a number of years ago but when I bought our boat in South Carolina and had her trucked out here to the west coast, I slapped a coat of bottom paint on before dropping her in the water. A friend was with me at the time to help celebrate my purchase, etc and suggested that I add a pair of dollar zinc's to the strut in addition to the shaft zinc already there. I drilled the strut and added them. The result was that bottom paint started burning off the hull around where the strut joined it and also around the sintered(sp?) bronze ground plate located in the bottom of the forward port hanging locker. I might add that the plate was bonded to a lot of through hull fittings, the engine and the mast but not to the strut. When I told what was happening by the diver, I immediately called my dive service asking for help. The owner explained to me that it's possible to be over zinced and that the burning of the paint was a sure sign of it. He called it being "too hot" with zincs. His suggestion was that I remove one of the dollar zincs, leaving the other in place and of course continue to use the shaft zinc. Time passed, maybe 6-8 months and I asked for a report. The burning was still present but much reduced from the original. It was at that point that I had them remove the second dollar zinc, effectively returning the boat to her original state before I started screwing with the mix. Imagine my shock when years later I hauled out in June, 2006 for a total refit of the boat only to discover the burning as bad or worse as it had ever been. A quick look at the strut explained all. Obviously another employee had seen the 1/4" hole in the strut and had fitted a pair of dollar zincs, starting the entire mess all over again. I removed them reinserted the bronze screw and nut and peened the beegeebers out of the threads so it sent a clear message to anyone in the future not to try to fit any zincs. I might add that somewhere prior to that haul out, I had removed all of the bare copper bonding wire from the entire boat and that oddly enough didn't seem to have any result positive or negative on the burning, nor has it had on the lack of even a trace of burning to date. Hope this helps somebody, Glyn Judson, E31 hull #55, Marina del Rey, CA
All, Some of you might remember my bringing this subject up a number of years ago but when I bought our boat in South Carolina and had her trucked out here to the west coast, I slapped a coat of bottom paint on before dropping her in the water. A friend was with me at the time to help celebrate my purchase, etc and suggested that I add a pair of dollar zinc's to the strut in addition to the shaft zinc already there. I drilled the strut and added them. The result was that bottom paint started burning off the hull around where the strut joined it and also around the sintered(sp?) bronze ground plate located in the bottom of the forward port hanging locker. I might add that the plate was bonded to a lot of through hull fittings, the engine and the mast but not to the strut. When I told what was happening by the diver, I immediately called my dive service asking for help. The owner explained to me that it's possible to be over zinced and that the burning of the paint was a sure sign of it. He called it being "too hot" with zincs. His suggestion was that I remove one of the dollar zincs, leaving the other in place and of course continue to use the shaft zinc. Time passed, maybe 6-8 months and I asked for a report. The burning was still present but much reduced from the original. It was at that point that I had them remove the second dollar zinc, effectively returning the boat to her original state before I started screwing with the mix. Imagine my shock when years later I hauled out in June, 2006 for a total refit of the boat only to discover the burning as bad or worse as it had ever been. A quick look at the strut explained all. Obviously another employee had seen the 1/4" hole in the strut and had fitted a pair of dollar zincs, starting the entire mess all over again. I removed them reinserted the bronze screw and nut and peened the beegeebers out of the threads so it sent a clear message to anyone in the future not to try to fit any zincs. I might add that somewhere prior to that haul out, I had removed all of the bare copper bonding wire from the entire boat and that oddly enough didn't seem to have any result positive or negative on the burning, nor has it had on the lack of even a trace of burning to date. Hope this helps somebody, Glyn Judson, E31 hull #55, Marina del Rey, CA