Somehow this feels like a silly sailor joke - but I can't tell. In my first few years of sailing (Hunter 290), I went from one to two zincs and thought it delayed the need to change zincs. Recently, I was told that two zincs will simply deteriorate as fast as one; there's more surface area but no reduction in deterioration. Opinions? Facts? One or two zincs? Or should I go looking for a 2-by-4 puller?
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Zincs
I had the misfortune to have some electrolysis caused presumably by a live 110V shore power cord dropped into the water in an adjacent slip for about a week. I had my strut and a thru hull replaced and ever since, have used two zincs. One on the shaft just where it exits the hull and a second 1/2" in front of the strut. It works for me or at least gives me peace of mind and they do seem to last longer though I routinely change them every year. An added benefit is that if my shaft coulpling were to break or the woodruf key were to break, the shaft cant 'back out' and hit the rudder due to the second zinc just in front of the strut.
I had the misfortune to have some electrolysis caused presumably by a live 110V shore power cord dropped into the water in an adjacent slip for about a week. I had my strut and a thru hull replaced and ever since, have used two zincs. One on the shaft just where it exits the hull and a second 1/2" in front of the strut. It works for me or at least gives me peace of mind and they do seem to last longer though I routinely change them every year. An added benefit is that if my shaft coulpling were to break or the woodruf key were to break, the shaft cant 'back out' and hit the rudder due to the second zinc just in front of the strut.
It won't help
Adding multiple zincs won't help. Think of it this way Paul. I'm sure you've seen automobile battery terminal corrosion - adding a second zinc is like increasing the size of the terminal as a means of curing the problem.That's not a very good analogy but I'm sure you get the point. It won't solve the problem that is causing the galvanic corrosion and some would argue that adding zinc(s) could actually exacerbate the rate of corrosion. Your time would be much better spent using a digital multimeter and trying to find the source of the current leakage and fix it. Some of the things I'd want to check are multiple DC grounds, voltage potential between DC ground and the hull fittings and improper wiring, reversed polarity of DC circuits, etc. - not only on your boat but your neighbors' too. Don
Adding multiple zincs won't help. Think of it this way Paul. I'm sure you've seen automobile battery terminal corrosion - adding a second zinc is like increasing the size of the terminal as a means of curing the problem.That's not a very good analogy but I'm sure you get the point. It won't solve the problem that is causing the galvanic corrosion and some would argue that adding zinc(s) could actually exacerbate the rate of corrosion. Your time would be much better spent using a digital multimeter and trying to find the source of the current leakage and fix it. Some of the things I'd want to check are multiple DC grounds, voltage potential between DC ground and the hull fittings and improper wiring, reversed polarity of DC circuits, etc. - not only on your boat but your neighbors' too. Don
Engine Zincs does it have one.
I have a 1991 Hunter 28 with a fresh water cooled Yanmar 2GM20F diesel. The engine manual shows a zinc behind the cyl. head - it's not there! I'm currently taking a Pwr. Squadron eng. class the instructer said it"s probably screwed in the heat exchanger - it's not there ! - does the eng. even have a zinc?
I have a 1991 Hunter 28 with a fresh water cooled Yanmar 2GM20F diesel. The engine manual shows a zinc behind the cyl. head - it's not there! I'm currently taking a Pwr. Squadron eng. class the instructer said it"s probably screwed in the heat exchanger - it's not there ! - does the eng. even have a zinc?
zincs
Paul, given a constant level of galvanic action, 2 zincs will last much longer than one, so your chances of making it thru a season are much better. the other real benefit is that you have additional zinc in the water if something happens-it doesn't have to be your boat that's causing the problem. We had a problem on our 356 as delivered, and after chasing it down had very little galvanic action. in the last two months last year several new boats moved into my marina and I suddenly lost the tailcone on my prop, a brand new shaft zinc, and a large zinc guppy handing off the stern! not my fault, but certainly my problem if I had damage! it's cheap insurance. and, as stu pointed out, it can keep the shaft in in a coupling failure.
Paul, given a constant level of galvanic action, 2 zincs will last much longer than one, so your chances of making it thru a season are much better. the other real benefit is that you have additional zinc in the water if something happens-it doesn't have to be your boat that's causing the problem. We had a problem on our 356 as delivered, and after chasing it down had very little galvanic action. in the last two months last year several new boats moved into my marina and I suddenly lost the tailcone on my prop, a brand new shaft zinc, and a large zinc guppy handing off the stern! not my fault, but certainly my problem if I had damage! it's cheap insurance. and, as stu pointed out, it can keep the shaft in in a coupling failure.
yanmar zincs
ron, the freshwater cooled yanmars do not have zincs, even though the manual says they do
ron, the freshwater cooled yanmars do not have zincs, even though the manual says they do
The manual shows both models.
I think the problem with the misunderstanding is that the manual shows both models GMxxF and GMxx (no f). The non-f models are raw water cooled and they do have zincs.
I think the problem with the misunderstanding is that the manual shows both models GMxxF and GMxx (no f). The non-f models are raw water cooled and they do have zincs.
Process of elimination
Over the ten years that I have had my boat, I first started with one zinc. It was gone by end season, so I added a second. That seemed to help, but another end season and two were nearly gone. For several seasons, I have used 3 zincs and now satidfied that I have adequate protection. When in doubt, add one. It doesn't hurt!
Over the ten years that I have had my boat, I first started with one zinc. It was gone by end season, so I added a second. That seemed to help, but another end season and two were nearly gone. For several seasons, I have used 3 zincs and now satidfied that I have adequate protection. When in doubt, add one. It doesn't hurt!
Do any of you put a zinc on the mast?
I saw a boat that had the bottom two inches of the mast eaten away to the point where they had to cut it down. I have also seen masts where you can see corrosion in the mast. Do any of you put a zinc on the mast?
I saw a boat that had the bottom two inches of the mast eaten away to the point where they had to cut it down. I have also seen masts where you can see corrosion in the mast. Do any of you put a zinc on the mast?
Thanks for all the comments
There still seems to be a wide range of opinion, but I have to try three zincs this season before I go back to one; I know its not my boat that the source - you should see the rebuilt next to me...I'm surprised the water doesn't glow at night. Again, thanks for the input.
There still seems to be a wide range of opinion, but I have to try three zincs this season before I go back to one; I know its not my boat that the source - you should see the rebuilt next to me...I'm surprised the water doesn't glow at night. Again, thanks for the input.
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