Anodes (commonly "zincs") are small but critical parts that protect a boat's underwater metals from corrosion. Neglected, the shaft, propeller and other metals suffer.
What does an anode do?
Underwater, different metals and seawater act like a battery; this causes galvanic corrosion. The anode "sacrifices itself" (hence 'sacrificial anode'), wearing away instead of the valuable metals and protecting them.
When to replace?
General rule: replace an anode when it has eroded to about half. On most boats, check at season start and replace if needed. A fully eroded anode no longer protects.
The right anode
Water type matters: zinc for salt water, aluminium for brackish/mixed water, magnesium for fresh water. The wrong anode doesn't protect.
Anode checking is part of hull maintenance; we check it with haul-out in our winterising and maintenance service. It should also be checked in spring maintenance.
Get a free survey
We inspect your boat on site and send an itemised written quote within 48 hours. No obligation.
Get a Quote on WhatsApp