Typical vessel types and their ballast needs can be broadly classified as shown in Table 2-1. In this report cubic meters is used as the unit of measurement conversion factors are given in the glossary. There is no international standard unit of measurement for ballast quantities of ballast are variously recorded in metric tons, long tons, cubic meters, U.S. Piping is sized so that flow velocities do not exceed about 2.6 to 3m/s, with ballast pump capacities ranging up to 5,000 m 3/h. Ballasting rates can be as high as 15,000 to 20,000 m 3/h (see Table 2-1). Large tankers can carry in excess of 200,000 m 3 of ballast. Ballast capacity can range from several cubic meters in sailing boats and fishing boats to hundreds of thousands of cubic meters in large cargo carriers. For the purposes of this study, the term ballast includes the sediment that accumulates in ballast tanks, which may be discharged with ballast water.Ĭonfiguration, and requirements of the ship and on the complexity of its pumping and piping systems. Mechanisms for the introduction of nonindigenous species into ballast tanks are addressed in Chapter 1.īOX 2-1 Ballast Defined Ballast is any solid or liquid placed in a ship to increase the draft, to change the trim, to regulate the stability, or to maintain stress loads within acceptable limits. A brief summary of ship types and ballast systems is followed by an overview of safety issues relating to ballast operations and typical ballast conditions at sea and in port. This chapter, which provides information on the role of ballast in ship operations, is a necessary prerequisite to the committee's assessment of proposed strategies for managing ballast water and controlling the introduction of nonindigenous aquatic species without compromising ship safety. The etymology of the word "ballast," meaning "useless load" in Middle Dutch, reflects the fact that since time immemorial ship owners have endeavored to avoid using ballast. Unfortunately, in many instances half of a given voyage must be undertaken in ballast to compensate for the absence of cargo.
Thus, global shipping is the underpinning of the majority of world trade. Today, vessels carry ballast that may be fresh, brackish, or salt water (see Box 2-1).Ībout 80 percent of the world's trade volume is transported by ship (Peters, 1993). From the 1880s onward, ships increasingly used water for ballast, thereby avoiding time-consuming loading of solid materials and dangerous vessel instabilities resulting from the shifting of solid ballast during a voyage. For millennia, ships carried solid ballast in the form of rocks, sand, roof tiles, and many other heavy materials.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.Ships have always required ballast to operate successfully and safely. to give steadiness to keep steady: parental responsibilities that ballast a person.
to furnish with ballast: to ballast a ship.carrying only ballast carrying no cargo.a device that maintains the current through a fluorescent or mercury lamp at the desired constant value, sometimes also providing the necessary starting voltage and current.Also calledballast resistor.a device, often a resistor, that maintains the current in a circuit at a constant value by varying its resistance in order to counteract changes in voltage.gravel, broken stone, slag, etc., placed between and under the ties of a railroad to give stability, provide drainage, and distribute loads.anything that gives mental, moral, or political stability or steadiness: the ballast of a steady income.something heavy, as bags of sand, placed in the car of a balloon for control of altitude and, less often, of attitude, or placed in an aircraft to control the position of the center of gravity.any heavy material carried temporarily or permanently in a vessel to provide desired draft and stability.
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