Water Ballast Tank Specifications for Ships

Ship Water Tank Ballast
Sea ships allow widespread trade and travel that would never been possible without them. Among the ship’s components, the ballast keeps it afloat. Ballast systems today comprise a tank filled with water to hold down the ship. Ballast water can contribute to oceanic environmental problems if the water is not disposed properly.

In the past, ballasts were composed of wood or steel, which would act as something heavy to hold the ship down for travel. Now, water tanks have been favored. It is essential that these be well maintained so that they can support the entire ship. ISO 16145-1:2012 – Ships and marine technology – Protective coatings and inspection method – Part 1: Dedicated seawater ballast tanks specifies a procedure in which the components of the ship ballast are cleaned and given a protective coating to protect them from seawater damage.

A major advantage of a ballast of water is that it does not need to be filled all the time, making it lighter when it is not in use. Filling it with water is very simple, since it simply needs to take some from the ocean or body of water in which it is traveling. Additionally, releasing it is a basic reverse of the same process, letting it become part of the body of water in which the ship finishes its journey. Unfortunately, this can transfer water and bio-life that should not be spread.

Oceanic pollution can be detrimental to both marine life and the atmosphere. Chemicals and harmful materials could be concentrated to a particular area of water, and could be picked up and transferred somewhere else, where they can spread and damage other areas. In addition, the parts of the ship that make contact with the water other than the ballast can spread harmful chemicals. ISO 13073-1:2012 – Ships and marine technology – Risk assessment on anti-fouling systems on ships – Part 1: Marine environmental risk assessment method of biocidally active substances used for anti-fouling systems on ships provides a testing method to determine whether the treatment to the surface of the ship to prevent the attachment of fouling organisms can be detrimental to a marine ecosystem.

Barnacles Fouling Organism
Barnacles are an example of fouling organisms

The primary fouling organisms that can attach to ships as addressed in ISO 13073-1:2012, such as algae and barnacles, can cause different problems, not only with the ships, but also with any ecosystem where the ship travels. Sea voyages throughout history have benefited humans by letting them reach all parts of the world, but in this long range, we have given certain plant and animal species new environments to thrive. This introduces nonnative species into a new ecosystem, which threatens a delicate balance. Some nonnatives can become invasive species, which diminish the population of native species by outperforming them.

Even if a ship is completely clean of plant species as it is placed in the water, its ballast can actually pick up species that are located in the water that the ship is using to fill its ballast. Marine animal species can be picked up as well and live in the ballast water until they are released at the ship’s destination. For example, the invasive Green Crab, which now has established populations in North America, southern South America, Australia, South Africa, and Japan, originated in Europe, where ships continuously picked it up in ballast water from the North Sea’s ports. In its new widespread habitat, this crab has flourished due to its all-encompassing diet consisting of the shore life in different ecosystems.

Green Crab Ballast Invasive Species
Green Crab (Carcinus maenas) is an invasive species

It is very difficult to manage invasive species, especially once they have established a significant population. However, we can prevent the spread of more invasive species that could add to the damage that has been done. In the case of ballasts, this requires checking the water so that it does not contain any animal or plant life. ISO 11711-1:2019- Piping and machinery – Ballast water sampling and analysis – Part 1: Discharge sampling port does just this, with guidelines that ensure any water released by ballast is free of any marine life that would be harmful to the ecosystem in which it is released. By taking a representative sample of the ballast water, adhering to these guidelines can “verify that the ballast water management system (BWMS) is working as designed, i.e. the treatment is reducing the concentration of living organisms to levels established in discharge standards”.

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