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Zincs on shaft
- Thread starter KWD
- Start date
I placed a 5" dia. zinc on each trim tab and on each rudder. I have the large plate on the stern, and I placed one zinc on each shaft. 3/4 through the season, I dove down to take a look at the zincs. They all looked like I would expect except for the shaft zincs. I only had 25% of the shaft zincs left. I installed one more on each shaft. I will not make that mistake again, I will put two on each shaft. I did check my bonding and everything is OK.
- Joined
- Feb 18, 2003
- RO Number
- 11165
- Messages
- 82
Zincs are cheap. Have you priced a new shaft plus labor lately?
I will try the hammer method. The original zincs were on the boat for 9 years with no problem until last year they started slipping. I replaced them in April,they slipped 2"-4". I tightened them with a rachet drive. Another problem was the screws rusted.The previous screws were fine after 9 years.I purchased them at West Marine. Could they be using Chinese stainless screws in there zincs?
quote:
Originally posted by KWD
what is the purpose of hitting the zincs with a hammer. Hit them where
There should be two pins on the inside of the shaft zincs (at least there is on mine) that when hit hard will pin themself against the shafts for good contact.
The latest Canada Metal Martyr shaft anodes (made in China) sold by WM and other stores, no longer have those copper contacts on the inside. I understand that those copper ball-bearings sometimes prevented positive full contact of the anode to the shaft. The anode now has a locking mechanism to ensure it will maintain full contact and not slip, if properly fitted...no banging required!
I've just had a diver fit them to my Bay 3587 and I plan to haul the boat in the spring, so I should be able to comment on their efficacy then.
David
I've just had a diver fit them to my Bay 3587 and I plan to haul the boat in the spring, so I should be able to comment on their efficacy then.
David
Its not uncommon for Zincs to last a long time in fresh water. Sometimes though, at least with I/Os that have lots of aluminum (in fresh water), they do not do an adequate job, and you should change out to magnesium.
My last boat was an I/O, and had zincs over 6 years old, and were just a bit corroded, but at the same time, there was also some corrosion on the drives. When I changed out to magnesium, the anodes lasted only one season because they are more active, which means they did a much better job at protecting the drives. This is why you cannot use magnesium in salt water - they would only last a short period of time.
My 325 is 12 years old and I bet they also have the original zincs. There is some evidence of dissolving, but not a whole lot. But with the inboard engine, stainless and bronze are pretty close on the nobility scale I think, so I don't think there is as much galvanic activity as there would be if there were lots of aluminum around.
Anyway, one of the do-to things on my list is to try and locate magnesium anodes.
By the way, I boat in fresh water on Lake Michigan.
One last thought about zincs is that I also clean them every year. One issue with zincs is that over time, they can form an oxide on their surface that essentially electrically isolates them from the water. So every year, I use a Norton or Wolfcraft brand fibrous "wire" wheel to clean them up. I would not want to use any metal wheel, because that might make them less effective.
Well, thats about all I know about zinc anodes.
My last boat was an I/O, and had zincs over 6 years old, and were just a bit corroded, but at the same time, there was also some corrosion on the drives. When I changed out to magnesium, the anodes lasted only one season because they are more active, which means they did a much better job at protecting the drives. This is why you cannot use magnesium in salt water - they would only last a short period of time.
My 325 is 12 years old and I bet they also have the original zincs. There is some evidence of dissolving, but not a whole lot. But with the inboard engine, stainless and bronze are pretty close on the nobility scale I think, so I don't think there is as much galvanic activity as there would be if there were lots of aluminum around.
Anyway, one of the do-to things on my list is to try and locate magnesium anodes.
By the way, I boat in fresh water on Lake Michigan.
One last thought about zincs is that I also clean them every year. One issue with zincs is that over time, they can form an oxide on their surface that essentially electrically isolates them from the water. So every year, I use a Norton or Wolfcraft brand fibrous "wire" wheel to clean them up. I would not want to use any metal wheel, because that might make them less effective.
Well, thats about all I know about zinc anodes.