Sacrificial anodes
Sacrificial anodes – think zinc!
The River Hamble Harbour Authority has been helping to support PhD student Aldous Rees from Southampton Solent University in investigating the variety of corrosion rates of sacrificial anodes seen in the Hamble Estuary.
Read an extract of the study's findings
The hints and tips summarised will go some way to help boat owners ensure not only that are they using anodes correctly to best protect their vessels, but also to help reduce the significant volume of zinc that is found within the water here. Already some users have been able to reduce their costs.
Tips for using sacrificial anodes
- Replace annually. Sacrificial anodes are designed to last 1 year with normal wear being 40-60%. The proportion of zinc in anodes may vary so choose your brand carefully.
- For anodes to protect the cathode they have to be in physical contact or connected via a wire.
- Switching to aluminium anodes may be of benefit, especially if moored in the mid to upper reaches. They may last 1.5 years instead of zinc’s 1 year, and will help to reduce zinc levels in the water.
- Stray currents due to ‘common earth’ wire in marina power supplies may accelerate corrosion. Fit a galvanic isolator to break current flow or unplug when not aboard your vessel.
- Salinity and stray currents should not cause complete anode corrosion over the course of a year. If so, seek advice from a marine engineer as there may be an issue with the vessel e.g. wiring.
- If you continue to experience any anode issues contact an anode supplier for advice on the type and size of anodes suitable for your vessel.
- Appropriate use of anodes will help reduce zinc concentrations in the estuary which are currently very close to the limit allowed under Environment Quality Standards.
