Split-Hull Hopper Dredge Launched At Avondale Yard

Avondale Shipyards recently launched the Eagle I, one of the largest split-hull hopper dredges in the world, for Eagle Dredging Corporation of New Orleans. The unique vessel is being constructed at a cost of more than $30 million, according to J.W. Bean, president of Eagle Dredging.

The Eagle I has an overall length of 340 feet, beam of 68 feet, and depth of 24 feet. Hopper capacity is 6,300 cubic yards.

A crew of 24 will operate the 7,500-bhp ship at a service speed of 14 knots.

"Hopper dredges are designed specifically for operations at sea, and they are used primarily to maintain water depths at channel entrances such as Southwest Pass at the mouth of the Mississippi River," Mr. Bean said. "This dredge will allow further participation in that portion of work presently handled primarily by the U.S. Army Corps of Engineers." Mr. Bean added that Eagle I will make a significant contribution to private industry's capability for construction of new deepwater ports.

"Further," said Mr. Bean, "such a vessel will be able to help solve many of the present environmental demands associated with inland disposal areas, given the vessel's ability to load dredged material from inland and coastal waters and transport and dump these materials in acceptable offshore disposal areas." A split-hull hopper dredge is a ship whose hull is divided and hinged at the deck so that it can open at the bottom to dump a load of dredged material. Only six split-hull hopper dredges exist in the world, according to Mr. Bean.

Dredging is carried out in the closed position. Once over the site to be dredged, the vessel lowers two drag arms, one on each side, to the bottom of the body of water.

These drag arms are pipes with specially designed heads that dig into the bottom material like bulldozer blades.

The arms are dragged alongside the ship with the heads on the bottom, breaking up the material, loosening it, mixing it with water, and pumping it into the vessel's hopper for storage. The hopper resembles the hold of a bulk carrier.

Once full, the arms are lifted and the ship sails to the disposal site with its cargo of dredged material and water. When over the disposal area, two huge hydraulic cylinders force the ship open in less than two minutes, allowing the dredged material to drop into the sea. The ship then closes and returns to the dredging site to repeat the process.

The Eagle I will be powered by two 3,750-bhp, 16-cylinder Alco diesel engines, and Propulsion Systems Inc. bow thrusters will enhance maneuverability. The ship was designed by Dredge Technology Corporation of New York, and will be commissioned in December this year. She will be classed by the American Bureau of Shipping, and meets all the latest rules of the U.S. Coast Guard and other regulatory bodies.

Eagle Dredging is a U.S. company formed as a joint venture by C.F. Bean Corporation, an international dredging firm headquartered in New Orleans, and Royal Volker Stevin of the Netherlands, the world's largest dredging company.

Maritime Reporter Magazine, page 13,  Sep 1980

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First published in 1881 Maritime Reporter is the world's largest audited circulation publication serving the global maritime industry.