ANODO DISCO POPA 125mm (ZN)

Function and technical context

The 125 mm stern disc anode made of zinc acts as cathodic protection in the stern area of the boat, sacrificing itself electrochemically to preserve the noblest metal parts of the propulsion assembly—such as the tail shaft, propeller and transmission—against galvanic corrosion. This component works within the passive anti-corrosion protection system, that is, it does not require external energy: its effectiveness depends exclusively on the correct fixation to the hull or transmission and continuous electrical contact with the metal parts to be protected. Without active cathodic protection, galvanic corrosion silently and progressively attacks the stainless steel and aluminum components of the propulsion train, generating pitting, material thinning and structural failures that can render the vessel unusable far from port. Zinc is the ideal material for salt and saline waters, where its electrochemical potential guarantees effective protection against marine corrosion in conditions of high water conductivity.

When to replace this part?

Zinc anodes must be visually inspected at the beginning of each nautical season and replaced when they have lost between 50% and 60% of their mass, since below this threshold the cathodic protection is insufficient and adjacent components are exposed to galvanic corrosion. The most obvious symptoms of a depleted or missing anode are the appearance of pitting or rust stains on the tail shaft, propeller or aluminum surfaces of the stern, as well as accelerated and premature aging of submerged metal fittings. Replacing the aft disc anode preventively at the beginning of the season is the most economical and effective maintenance measure to avoid costly repairs to the tailshaft or transmission, interventions that usually require grounding and specialized labor.

Compatibility