Hopper Dredges

Dredging is defined as moving bottom material from one location to another using floating plant. Hopper dredges are seagoing vessels designed to dredge and transport dredged material to open-water relocation areas. The working of a hopper dredge is similar to that of a vacuum cleaner.

Hydrographic survey boats, using sophisticated electronic equipment, survey the river and harbor
bottoms to determine if dredging is required and, after dredging is completed, to ensure that the desired results have been achieved.

Hopper dredges move like ships, maneuvering back and forth and usually have powerful bow thruster propellers that allow them to turn in tight circles. While they are dredging they often cannot make quick course changes and other boats should be aware of this. A working dredge will have distinctive shapes raised on their mast to warn other ships that they have limited maneuverability. The shapes are a ball over a diamond over a ball.

The Corps of Engineers operates 4 hopper dredges; Essayons, Yaquina, McFarland and Wheeler. Essayons and Yaquina operate on the West Coast for the most part, and McFarland and Wheeler operate the East Coast. Annual costs for operating the dredges are:

Some Interesting Links:

US Army Corps of Engineers Minimum Dredge Fleet Study
Dredging Network
Dutch Dredging
International Dredging Review
Coastal Engineering Research Board (CERB)
The International Association of Dredging Companies (IADC)
Dredging Operations Technical Support