Ballast Banished

8 March 2008 shiptalk

University of Michigan researchers are investigating a radical new design for cargo ships that would eliminate ballast tanks, the water-filled compartments that enable non-native creatures to sneak into the Great Lakes from overseas. The U-M ballast-free ship concept offers a promising alternative that could block hitchhiking organisms while eliminating the need for expensive sterilization equipment, said Michael Parsons, professor of naval architecture and marine engineering and co-leader of the project.

Ships take on ballast water for stability when they're not carrying cargo. They discharge ballast when they load freight, expelling tons of water and anything else---from pathogenic microbes to mollusks and fish---that's in it. The idea is opening part of the hull to the sea, creating a very slow flow through the trunks from bow to stern and continuously sweeping water through the ship and out so the ship is always filled with local sea water, not hauling water from one part of the world to the other The U-M ballast-free ship concept was conceived in 2001 and patented in 2004. It is intended for new-vessel construction only.