BoatHowTo · video

What this video covers

Excessive galvanic protection causes cathodic disbondment, which strips bottom paint from bronze through-hulls and triggers delignification in wooden hulls.1:14 Replacing zinc anodes with aluminum anodes often increases the total surface area of the sacrificial metal, leading to overprotection.1:03 Nigel Calder recommends using a silver-silver chloride half-cell to measure the voltage potential of the bonding system.1:59 By hanging the half-cell in the water and connecting it to a multimeter, a boat owner can compare the natural voltage of the protected metal against the anode.1:35 A proper protective shift should measure approximately 200 millivolts above the natural voltage of the metal.3:06 Readings of 400 to 600 millivolts indicate excessive protection.3:34 Reducing the total surface area of the installed anodes, such as using one anode instead of two, corrects the overprotection and prevents damage to surrounding materials.3:50

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