Visual checks recommended

Anodes should be replaced when they are 50% wasted

Industry Database

The end of season lift out is a good time to check the condition of your anodes, says Toby Biddlecombe of MG Duff.

The company’s marine cathodic protection systems prevent corrosion that occurs in all types of water and has catastrophic impact on boats and coastal structures. 

MG Duff recommends regular visual checks of anodes and to replace the anode when it is 50% wasted. “Boat owners need to ensure the anodes will last until the next time the boat is lifted and not risk leaving the vessel unprotected,” says Toby.

Without anodes steel and aluminium corrodes resulting in localised pitting in areas including the hull plate, rudder and bilge keel. General wastage of the bilge keel also occurs below the paint coating.

“The impact of corrosion can be disastrous and very expensive,” Toby added. “General wastage can critically weaken the hull and localised pitting can lead to complete penetration of the hull below the waterline.”

Wooden and GRP boats also suffer with corrosion on stern gear including propellers, shafts, shaft brackets, stern tubes and rudders.

Using the right type of anode depends on the water with zinc or aluminium anodes for seawater and magnesium for fresh water. “It’s also important to check the bonding between the anode and what it is protecting,” says Toby. “Check the resistance in the bonding using a standard multi meter and aim for less than 0.5 ohms resistance between the anode and cathode.”

Content extracted from