ALUMINUM STERN ANODE

Function and technical context

The stern aluminum anode is a cathodic protection element that is installed on the outside of the boat, specifically in the stern area, to protect submerged metal components against galvanic corrosion. It acts as a sacrificial metal, oxidizing in a controlled manner instead of the nobler metals of the assembly (tail shaft, propeller, gearbox or trim). This type of aluminum anode is especially suitable for navigation in brackish or mixed waters, where conventional zinc anodes have lower performance. Without effective cathodic protection, galvanic corrosion can deteriorate critical stern structures in a single sailing season, leading to costly breakdowns and compromising driveline integrity.

When to replace this part?

The clearest indicator that the anode should be replaced is a reduction in mass of more than 50%, a porous or disintegrated visual appearance, or the presence of visible corrosion on the metals it should be protecting (pitting on the shaft, erosion on the powerplant housing or stern surfaces). It is recommended to inspect the condition of the anode at each beaching and replace it at least once a season, regardless of its degree of apparent wear, since a depleted anode silently leaves the components unprotected. Replacing it preventively at the beginning of each season is the most widespread practice among naval mechanics and represents a minimal cost compared to repairing a corroded tailshaft or propeller.