Mercruiser Zincs
Your engine’s sacrificial anodes (or zincs, as they are often called) are designed to protect the motor’s other submerged metals from galvanic corrosion. When a boat is sitting in water – especially saltwater, or when hooked to shore power – the vessel’s metal parts become a battery of sorts, with minute amounts of current flowing through them. The laws of physics dictate that the softest, most reactive submerged metal in this system will dissolve over time. If your anodes are significantly worn or missing entirely, galvanic corrosion will attack your lower unit or aluminum propeller, which can cause costly damage.
