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Donít Flush -- Ballast, That Is

Docked Cargo Ship



Don't flush! At least not your ship's ballast tanks.

In port, cargo ships load tons of seawater into ballast tanks that add weight to balance the ship and maintain stability at sea. Trouble is, that water contains all manner of local marine flora and fauna.

One study found that most ships carry more than 200 species of sea life in their ballast. When those ships reach their next destination, they flush the tanks, spewing the stowaways into new locales where they've been known to take over whole ecosystems.

For this reason the International Maritime Organization is considering a regulatory change that requires cargo ships to install complex, expensive, sterilization systems in their ballast tanks.

Enter naval architect Michael Parsons of the University of Michigan with an ingenious solution: A ballast-free cargo ship.

Parsons' model uses broad pipes along the ship's hull, sealed at each end with hatches. Need ballast? Open the hatches. Water runs through the pipes during transit -- changing every hour, and stabilizing the ship. When the ship docks, nothing's left in the pipes but local water.

New cargo ships built with Parson's ballast-free system would cost more, but save ecosystems around the globe. And that's priceless.

Script by Bob Rhein