Battling barnacles

Pipework anti-fouling system can also help stop unwanted mussel growth.

Barnacle and mussel fouling is becoming a bigger problem around the world. “This is one of the unforeseen consequences of having cleaner seawater ? they actually breed more vigorously in cleaner seawater,” says Richard Woolley, publicity manager for Cathelco, which specialises in pipework anti-fouling systems.

He cites the UK?s fishery protection vessels as an example of the problem. “They are having terrible problems with engines overheating,” explains Woolley. It has since been resolved by fitting Cathelco?s seawater pipework anti-fouling system, which has been fitted to more than 10,000 vessels worldwide.

The system eliminates the growth of barnacles and mussels in engine cooling systems which otherwise create blockages resulting in overheating and increased fuel usage.

Typically, Cathelco systems have copper and aluminium anodes that are either mounted in the ship?s seachests or strainers and are supplied with an electric current from a control panel. The copper anode produces ions that are carried throughout the system by the flow of seawater, creating an environment where barnacles and mussels cannot settle or breed. Woolley explains: “The copper ions create an environment which doesn?t kill sea life outright ? it just creates an environment in which they don?t like to live.” The analogy that he uses is that “it is just like us being in a smoky room”. At the same time, a hydroxide floc is produced which builds up on the internal surface of pipes to create an anti-corrosive layer. In this way, pipework systems are completely and continuously protected against bio-fouling and corrosion.

The size of the anodes is determined by the flow rate of the seawater and the desired anode life, which is usually calculated to coincide with scheduled dry docking intervals. However, if the anodes are fitted in the strainer they can be changed when the ship is alongside. Indeed, complete systems have been fitted in this way within a matter of 48 hours. “I was recently onboard a bulk carrier at Immingham where they changed the anodes when the Greek vessel came into unload coal,” says Woolley.

Anodes for ship sizes

In operation, the system is automatic and requires very little attention from the crew. Woolley told The Motor Ship: “We have developed large systems for cruise vessels consisting of more than one control panel and more than one set of anodes for the very big cruise ships. However, over the years we have come down in size and can now do them for craft as small as fishing vessels, tugs and workboats.” As well as miniaturisation, the system has also become modular so that if one module failed in the electrical control panel another one can be sent out quickly to replace it.

He says: “The other thing we have been able to do is computerise the electronics and provide the crew with more information with regards to the output to the anodes ?showing system failing were that to occur. As a result, some of the larger operators are having that information taken right up to the bridge and put into bridge information systems.”

Many of Cathelco?s anti-fouling and ICCP systems are destined for the booming Chinese shipbuilding market and the company has seen a steady stream of orders going to the China Shipbuilding Corporation in Taiwan.

One of the latest is for equipment for installation on eight container ships that are being built for the Yang Ming Line.