Mariner and boatyard shorthand for sacrificial anodes, whatever alloy they are, because zinc is the classic anode metal. They are bolted to hulls, propeller shafts, rudders, outdrives and engine heat exchangers to corrode in place of bronze and aluminum fittings. Mechanics change them at about half consumed; zincs that stay shiny and intact usually mean they are painted over, poorly connected or the wrong alloy for the water.
Haul-out list: bottom paint, cutless bearing and new zincs on the shaft, the old ones are down to nubs.
Zinc goes passive in fresh water. Boats that live in lakes and rivers need magnesium, and brackish water usually calls for aluminum.
Also heard as
- zinc anodes
- zinc
- pencil zincs
Related terms
Sacrificial anode
Block of a more active metal such as magnesium, zinc or aluminum that corrodes to protect connected steel.
Galvanic corrosion
Accelerated corrosion of the more active metal when two dissimilar metals touch in a shared electrolyte.
Mag anode
Field name for a magnesium sacrificial anode, the high-voltage choice for high-resistivity soils.