Propeller Shaft Earthing System

If the ship has a system of cathodic protection, whether it is sacrificial anodes or an impressed current cathodic protection system, the shaft insulation will prevent the propeller and the boss from receiving protection.

The electrical potential between shaft and hull can also cause a heavy current to flow in bearings when the oil film breaks down or is contaminated with seawater.This current can cause deep pitting of the bearing surface. Excessive wear on the shaft bearings can often be traced to this cause.Trouble can be avoided and cathodic protection extended to the propeller if the shaft is properly earthed with a shaft earthing system.

Propeller Shaft Earthing System Layout

Silver Graphite Bush and Brush Holder

Advantages of a Propeller Shaft Grounding System

• Serves for a short circuit between the rotating propeller shaft and the ship’s hull
• Can prevent the micro pitting marks at the propeller, on the sliding surfaces of crankshaft journalsand main bearings of the engines to be assumed as spark erosion
• Ensures an excellent potential decomposition and the contact brushes ensure lubrication and long life
• A remote indicator system in order to achieve a continuous control the effectiveness of the wholesystem
• A continuous slip ring cleaning device to prevent an increase of the residual potential during operation

Propeller Shaft Grounding System consists of the following

• Slip Ring – Elevated silver band reduce dirt for best possible contact.
• Brush Holders – Double and single brush holders for grounding and measurement. Strong springs for proper brush pressure
• Silver slip band – Reliable contact. Easy installation
• Silver brushes – High purity silver brushes for proper shaft grounding
• Monitoring Meter- Continuously monitoring the shaft potential. (Remote Indicator)