Ballast water management is to become a major consideration in the design of new vessels following the approval by IMO of a series of measures aimed at reducing the harmful effects of marine organisms transported in ballast water and the risks involved in some ballast water management techniques. As a fundamental principle, the recently approved IMO Circular states that ballast water management and the processes chosen to achieve it should be considered as a basic component of a ship’s design and that ballast tank design should facilitate all aspects of ballast water management.
The ballast water system designs should take special account of the increased need for content sampling, with an aim to enhancing the quality and ease of sampling of ballast water and sediments, without the need to enter potentially dangerous spaces or to partially fill ballast tanks. Installation of recording equipment should be considered for all ballast water operations and treatment actions and it should be possible for these records to be readily available to appropriate authorities that may request copies. The design of the ship should include consideration of the consequences of ballast water exchange at sea including: stability, hull girder strength, shear forces, resonance, sloshing, stemming, propeller immersion, limitations brought about by insufficient strength in various parts of the ship when the tanks are sequentially emptied and appropriate strengthening incorporated to allow this operation to be conducted safely.