Thread: Zincs
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Old 02-22-2013, 03:09 PM   #33
Phil Fill
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City: Everett Wa
Vessel Name: Eagle
Vessel Model: Roughwater 58 pilot house
Join Date: Oct 2007
Posts: 2,919
If you had a galvanic table it would be clearer. Metal mfg companies for centuries have used the galvanic table. The lower rate metal will protect the high rated metals, and the larger the spread the better the protection. Sure their might be an aluminum magnesium that has a little lower galvanic rating then zinc, but on the table magnesium is the lowest.

If the zincs are lasting to long then magnesium, which has the lowest galvanic rating should be used. If the zincs where not lasting long enough there are two choices. 1) added a additional/bigger zinc and/or 2) change to aluminum with a HIGHER galvanic rating which would still protect the metal with higher galvanic rating. When we moved to Everett, brackish, the bow thrust zincs where not lasting, so I hung a grouper zinc over the side which help prolong the thruster zincs and additional protection. When we pulled I had a big diver dream, license plate size, installed for the bow thruster.


Lastly if you are still unsure, then ask the boats around you what they use and how long they are lasting.
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