Book excerpt: 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.