Remember Your Anodes

By Don Casey

Revised by BoatUS editors in April 2012

Anode needs replacement

Anode needs replacement

Anode on outboard

Anode on outboard

The rule of thumb on underwater sacrificial anodes is to check them at least once a year, but if you dry-store your boat, inspecting the anodes should be part of your wash-down routine. The anodes on outboards and stern drives can last a long time if the motor's lower end is out of the water when not in use, but a few days or even a few hours in a "hot" marina can silently dissolve the anodes and leave your engine under protected.

Outboards and stern drives are typically fitted with at least three anodes, often more, and every one is essential. When 50% of an anode has been lost to corrosion, replace it. If you do your boating in salt or brackish water, use zinc or aluminum anodes. If you boat only in freshwater, use magnesium anodes.

 

Don Casey has been one of the most consulted experts on boat care and upgrades for 30 years, and a panelist on our "Ask The Experts" website for a decade. He and his wife cruise aboard their 30-footer part of the year in the eastern Caribbean. His books include Don Casey’s Complete Illustrated Sailboat Maintenance Manual, and the recently updated This Old Boat, the bible for do-it-yourself boaters.

 

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