Practical Sailor · video

What this video covers

Sacrificial anodes protect underwater metal components like prop shafts, rudders, and keel bolts from galvanic corrosion by providing a path for stray electrical currents. Proper installation requires direct metal-to-metal contact with the boat's grounding system; mounting anodes on fiberglass or painted surfaces renders them ineffective. When selecting material, use magnesium for freshwater, while aluminum serves as a versatile, long-lasting alternative for salt and brackish water. Zinc remains a traditional choice for saltwater but carries environmental concerns regarding toxin release. Mixing different anode materials on the same vessel reduces effectiveness and should be avoided. Rapid anode deterioration often indicates stray current from shore power connections, either from the boat itself or neighboring vessels in the marina. Inspect anodes regularly and replace them before they lose significant surface volume, as their protective capacity diminishes as they erode. If pitting appears on protected metal parts, install larger or additional anodes to increase the sacrificial surface area.

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