Ships have to traverse the sea, so it’s only logical that there are many parts of the ship that are exposed to sea water. Additionally, water is taken into the ships cooling system and pumped out all the time. As a result, many marine organisms pass through the ship’s cooling systems as well as other parts of the ship exposed to water for extended periods. These organisms often latch onto the surface of the ship and grow there.
The growth and accumulation of marine life on a ship is called biofouling, and if left alone, can cause many problems. For example, they could clog up the channels of the cooling system, impair the heat transfer system, cause the rust and thinning of metal pipes and add to the weight of a ship, causing loss of efficiency.
There are several marine growth prevention systems that have been developed, including:
The Electrolytic System
This method uses iron or copper and aluminum anodes which are attached to the main sea chest in pairs. A DC current is then passed through these anodes which causes them to produce ions that will be carried by the flowing seawater throughout the whole piping system. The ions prevent the attachment and proliferation of sea life on the pipes. Additionally, the iron anodes also help prevent the corrosion of these pipes due to seawater.
Non Toxic Chemical Coating
There are several types of non-toxic coatings that are used to protect the various parts of the ship. The main principle in these coatings is to form an ultra smooth surface texture on the ship to deprive marine life any texture to attach and grow. These inert and biologically stable coatings consists of polymers that have low surface energy and low friction. They usually come in two classes: hydrophobic or hydrophilic, depending on the ship’s requirements.
Another method of marine life growth regulation on ships is the use of high frequency sound waves. These ultrasonic waves discourage the growth of organisms as it renders the pipes and systems unsuitable as habitats. The ultrasonic waves also help mechanically dislodge small creatures who have already anchored and prevents the solidification of bio-adhesives secreted by some organisms to help attachment. These waves are above the human hearing range and is therefore harmless to crew members.
Biocides and chemicals incorporated into the coating of ship parts to deter the growth of marine life. These biocides target the small microorganisms and prevent them from forming a biofilm, which can lead to the attachment of larger and larger organisms, culminating with barnacles.
These marine growth prevention systems are designed to minimize harm to sea life, and ensure that ships do not interfere with, or damage the local ecosystems, ensuring the best scenarios for all.