CUPROBAN Propeller Shaft Grounding Systems
For complete protection of ships, it is imperative to electrically ground the shipís propeller to the hull. The propeller shaft being a rotating item needs to be properly grounded to the hull to minimise stern area corrosion and current induced damage to the propeller shaft bearings and gearboxes.
This is achieved, whether the main hull is protected by a sacrificial or impressed current system, by using a Propeller Shaft Grounding System.
Cuprobanís shaft grounding systems consist of a set of silver graphite brushes sliding over a copper slip ring layered in with a silver race mounted on the shaft. The silver brushes on a silver race ensure maximum contact with the least resistance to allow for optimal drainage of the current.
In summary, corrosion can thus be seen to be an electro-chemical phenomenon. Its prevention by cathodic protection is also an electro-chemical process. The principle of cathodic protection is to create a potential gradient opposing the flow of electrons from the surface to be protected.
The silver brushes are held onto the shaft via brush holders, which ensure a constant contact between the brushes and the slip ring. An optional monitoring unit can be provided to monitor the shaft to hull potential and change the brushes when they are worn.