Watch Your Zincs — Make sure you know where all of the sacrificial anodes ( which may be made from aluminum, magnesium or zinc) are throughout your boat, and replace them if they are degraded. These zinc "tabs" are commonly found on the engine lower unit and transom, but they can also be found inside the engine compartment, as part of your running gear, and elsewhere. Check your boat and engine owner's manual to confirm how many there are and where they are. Zincs are made to be eaten away over time; by doing so they "sacrifice" themselves to protect other metallic components against galvanic corrosion. If they are neglected and wear away, they cannot perform this protective function.