# Fishing tip # 672 trim tab zincs



## captken (Feb 24, 2008)

If your boat has Stainless steel trim tabs, they certainly need cathodic protection. All marine stores sell trim tab zincs and usually in pairs for top and bottom. When you change zincs, the bottom piece is generally gone and the bolt head is all that is left below the trim tab. The upper zinc is usually ok but likely not doing much good because it is flopping around because of the loose bolt and not making proper contact. Additionally, there will be a crud build up underneath the zinc that will reduce electrical contact. 
The zinc on the bottom is not used up by galvanic action but by cavitation erosion. Cavitation erosion is not electrical in nature. Instead of buying the little 2" trim tab "Buttons," buy one small rudder zinc and install half of it on top of each trim tab. They will usually last 2 years. Each season or each time you haul your boat, remove all zincs, clean the mating surface under each and wire brush all of the crud off the zinc. Tighten the bolts securely but no so tight you crush the zinc. 
NEVER PAINT ZINCS


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