Hopper dredges are designed to vacuum material from the sea floor through drag arms that load the material into the hold of the vessel. The cargo of mud, or sand, can then be transported to either an ocean disposal site, where the material is dropped to the bottom through openings in the bottom of the hull, or at an upland site such as a beach, or reclamation, where the material is pumped ashore by the ship. This method is most suited when excavating loose material from open areas for delivery to a distant disposal location. These vessels are generally certified to sail in coastal or ocean waters and are suited for working in rougher sea conditions beyond those suitable for other dredging plants.

Reprint of the original, first published in 1841.

Are the nation's ports adequate for our present and future needs? This volume points out that no significant new deep-water construction has occurred for a decade, and provides the information and analysis needed to goad the ports and the federal government into action. The book asks three questions: Is additional port construction and maintenance dredging needed now or over the next 20 years? What would prevent dredging if it is needed? What alternatives could make additional dredging possible? The book identifies several problems in dredging ports, including the long interval between a decision to deepen a port and the time the alterations are complete. The United States needs to speed port construction to meet changing needs, and the committee recommends that we prepare for future needs by dredging now.