2007_04_submersboat.jpgThere are some very observant drivers on the Verrazano-Narrows Bridge and BQE. WCBS 2 reports that a number of drivers called 911 to report that a freighter ship was sinking in the New York Harbor. But it turns out the freighter, Dockwise Swan, is actually supposed to sink a little bit!

The ship is a "semi-submersible," and can submerge to allow cargo to be taken on or off using the "float-on/float-off," "roll-on/roll-off," "skid-on/skid-off, or "lift-on/lift-off" procedures. And the freighter can submerge because there are 50 ballast tanks.

See video here. And you can really nerd out on semi-submersibles and other Dockwise ships with this PDF.

Update: It's likely that the semi-submersible ship was launching a specialized dredging or drilling craft. The U.S. Army Corps of Engineers is overseeing several contractors involved in improving multiple areas in New York Harbor, or more generally the Port of New York-New Jersey. The deepening of the Ambrose Channel, which stretches from south of the Verrazano Bridge to deep water outside of the Lower Bay, is scheduled to be completed by August of this year. Deepening of the Anchorage Channel, which extendes northward from the Verrazano to where it meets the Port Jersey Channel is scheduled for completion in January 2008. All sections of the harbor-deepening project will cost an estimated $2.5 billion, with the federal government picking up $1.3 billion of that cost.