The hull of a ship is protected against corrosion with a coating. However, this is only passive corrosion protection. In the event of a coating problem, the corrosion process will still start.
For this reason, ships have been protected for more than a hundred years with galvanic anodes made of zinc or aluminum.
However, current ships use cathodic protection by means of impressed current. These impressed current systems have a much longer lifespan because the material consumption is up to 1000 times lower with inert anodes.
Below the water level, a series of inert anodes, usually activated titanium, are distributed over both sides of the ship’s hull. A larger proportion of anodes are mounted at the stern and propeller. Because different metals are used here, corrosion is also greatest on this side of the ship.
The impressed current system uses an external power source, a rectifier-transformer, to supply power to the anodes. This direct current ensures that the anodes produce a direct current that is sent to the wall, the propeller, etc. to create a protection potential. To provide the correct current, a feedback system is used by means of zinc electrodes that will adjust the current according to the electrical conductivity of the water, the speed of the ship, etc.
A cathodic protection system on board a ship can be monitored remotely via the internet. The Scotty communication system, developed by Anotec, has everything to give the customer the right information about his corrosion protection system. The Scotty module is the only communication system worldwide that indicates, in the event of an anomaly, which part has gone wrong: anodes, cathode cable, reference electrode, rectifier or power supply. This simplifies the repair on board the ship and can also be monitored from the service provider or help desk.
