2001 Mercury Mariner 50-60HP Factory Service Manual, Page 22Get this manual
MAINTENANCE
Corrosion Control Anode
Your outboard has control anodes at different locationsAn anode helps protect the outboard against galvanic corrosion by sacrificing its metal to be slowly eroded instead of the outboard metalsEach anode requires periodic inspection especially in salt water which will accelerate the erosionTo maintain this corrosion protection, always replace the anode before it is completely erodedNever paint or apply protective coating on the anode as this will reduce effectiveness of the anode1The gear case has two corrosion control anodesAnother anode is installed on the bottom of the transom bracket assemblyaBottom AnodeTrim TabSide Anodes (Big Foot Models Only)