2006 Johnson SD 30 HP 4 Stroke Outboards Service Manual, PN 5006592, Page 55Get this manual
MAINTENANCE ENGINE SIDE COVERS
ENGINE SIDE COVERS
Remove four (4) screws and the port side cover
ANTICORROSION PROTECTION
Sacrificial Anodes
Galvanic corrosion occurs in fresh or salt waterSalt, brackish, and polluted water can accelerate corrosion"Sacrificial" anodes are intended to protect the underwater metal components of the outboard from galvanic corrosionInspect anodes and metal components below the water levelErosion of anodes is normal and indicates that the anodes are functioning properly