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SME Group has been working closely with shipowners and operators in this complex area of underwater hull maintenance for more than 20 years. One of the most debated topics in our industry—discussed daily in our Nantong workshop and on calls worldwide—is whether to use copper ion or chlorination for biofouling control. Both technologies have proven themselves, but have key differences in how they work. First, it is important to understand these differences in order to optimise the performance of a vessel and to minimise long term operating expenses.
The Science Behind the Systems
Copper ion anodes release positively charged copper ions into the seawater, damaging the cell membranes of algae, barnacle larvae and other marine life. This provides a place where fouling will not easily attach to the surface. Copper ion systems have limitations, however, in terms of water salinity, flow rate and the particular alloy employed in the anodes. At SME, technical support engineers remind clients that copper ion systems are suitable for ships in consistently saline waters, and that they must be monitored regularly to ensure proper ion release rates.
Electrolysis of seawater, on the other hand, produces sodium hypochlorite. The chlorine that is released in the water acts as a strong oxidizer, eliminating larvae and spores before they can multiply. Chlorine is also distributed rapidly with no residual heavy metals in the discharge water, an important consideration with stricter environmental laws. The corrosion potential of chlorine to some piping and valve materials however, should not be overlooked. We often fix failed copper or chlorination systems in our 5000 m² workshop and the common cause of failure is linked to material incompatibility or wrong size systems.
Performance and Environmental Impact
Technically, both systems can provide a high degree of fouling prevention if designed and operated properly. Copper ion systems are highly effective for long term, low dose protection and especially soft on rubber seals and non-metallic parts. However, they do add copper to the marine environment and this is a topic of concern to port authorities and environmental agencies. Our international partners now enquire about the regulatory issues related to copper discharge, particularly in ecologically sensitive areas, and this is where SME gets involved.
Chlorination has a less “green” profile, with the generation of trihalomethanes (THMs) and other disinfection byproducts (DBPs) which could be regulated. Most importantly, if unbalanced, chlorine's oxidizing effect can speed up the corrosion of the steel hull fittings and heat exchangers. This is why, before proposing a solution, SME's service team will always conduct a thorough material audit. There have been too many instances of a good chlorination system being short lived because the original pipework in the vessel was not designed for oxidative demand.
Operational Considerations and Lifecycle Costs
When our clients ask the question of which system is “better,” we turn towards operational reality. The anode is made of copper ion and will need to be replaced on a regular basis, which is a simple, but regular expense. They also do not perform well in brackish water or freshwater and may require more consistent chlorination throughout the year if ships operate between ocean and riverine ports. Chlorination systems are less expensive to operate, but require more attention to calibration and to testing the chlorine residual. In our experience, total cost of ownership often levels out over five years – mostly due to the familiarity of the crew with this technology and the availability of on-site technical support.
SME Group is a technology neutral organisation. We carry replacement parts for both systems and our electrical and mechanical technicians are capable of diagnosing all of the major control panels, anode assemblies and electrolytic cells. We have retrofit and repaired more than 500 systems each year and continually discover that a poorly managed chlorination system will result in more downtime than a well-managed copper ion system – and vice versa. It doesn't matter what system you use, the important part is how well you maintain it.
Why Professional Service Matters More Than the Technology
In the end, it's all about installation, commissioning and after-sales service. The wrong anode spacing or a point too close to a sensitive heat exchanger will result in a system that does not perform as well as it should. This is why SME warrants the engineering integrity of the entire project service in addition to parts for 12 months. We have more than 100 dedicated professionals working directly with superintendents and chief engineers to create a customized maintenance schedule for any vessel, no matter where it is sailing, whether in the Baltic Sea or the South China Sea.
We have also noticed a trend toward the hybrid (low dose copper ion with periodic shock chlorination) solutions among our more seasoned customers. SME does not offer generic solution, but has been able to tailor the control logic in order to provide the necessary control to a number of global partners and have successfully designed and integrated both types to provide a balance of environmental compliance, corrosion control and efficacy of the antifouling system. Technical support engineers are always able to think outside the box, as evidenced by these custom projects.
Conclusion: Aim Beyond Your Concern
At SME Group, we don't offer a universal solution to the copper ion vs chlorination issue. We believe in knowing you and your vessel's trading profile, its material composition, crew competency, and regulatory exposure. Our ISO 9001, 14001 & 45001 certification, along with our global shipyard service capability in particular within mainland China, puts us in a position to provide you with fast and responsible solutions, wherever you are. Please reach out to the team of services for an assessment aboard. Help you think beyond your concern with a biofouling control strategy that's technically feasible, operationally sustainable and cost-effective long-term. At SME, we are not just about a technology, we are about your vessel's uninterrupted performance.