Cathodic Protection for Boats Explained

What is it and why do you need Galvanic protection for your boat?

Common metals used in marine applications generate voltage in water. Galvanic corrosion can occur when there are 2 or more dissimilar metals in water. The water provides the means for metal ions to move from the anode to the cathode.

Cathodic Protection (CP) is a technique used to control corrosion of a metal surface by connecting the metal to be protected to a more easily corroded metal, “anode”.

When a vessel is connected to shore power it is also connected to the shore earth grounding system through the shore power cable. All vessels connected to the same shore power are all interconnected to the shore earth.

How to protect your boat?

Have one of our professional marine engineers check or install your Cathodic Protection Bonding System.

A correctly operating bonding system will provide protection by wiring all the vessels below water metals together to carry a low voltage galvanic current. The voltage generated in water are equalised.

Ensure that your bonding system is working effectively and that there are no breaks or faulty connections that will leave the vessel inadequately protected. Install an earth blocker to protect your boat from other vessels or any marina shore power faults.

Left unchecked there is a risk of the under water paint systems including prop speed failing or falling off. Metal components on your boat such as props, shafts, rudders, hull, metal fittings, through hull fittings etc maybe subject to destructive corrosion.

Find here some documentation about corrosion and cathodic protection.

The next steps to protect your boat

Gage Roads Marine offer a complete Corrosion Control service to boat owners and marina managers.
Including boat and marina surveys, bonding and MPS Maddox anode installation and sales.

Boat Surveys

A comprehensive cathodic protection survey utilising testing equipment is conducted with the boat in the water, at its usual pen or mooring. Once complete you will receive a written report with findings, conclusions and recommendations.

  • Corrosion preventative requirements.
  • Cause and type of corrosion.
  • Environmental influences on cathodic protection.
  • Electrical and electronic fault finding.
  • Bonding system check.
  • Cathodic Protection.
  • Advice or correct anode placement and composition.

Survey Checklist

Prior to the Cathodic Protection survey ensure the shore power is switched OFF and all leads are disconnected. Turn all battery switches to OFF position. turn all AC and DC circuits to OFF. Isolate any solar or wind charging equipment.

Comprehensive Cathodic Protection
testing & survey enquires

Please fill in the form if you have a request concerning
corrosion issues on your boat. Gage Roads Marine can assess those common problems and install a Cathodic Bonding Systems on your yacht.
Contact us


Gage Roads Marine provides surveys to control the corrosion level of your boat. Our Marine engineers are skilled and highly trained to offer you the best boat service in Western Australia and the Perth region. Our services include Cathodic Bonding Systems installation as well as boat surveys and marina surveys to make sure your boat has galvanic protection.