Meaning of "Ballast"

Any weight carried solely for the purpose of making the vessel more seaworthy. Ballast may be either portable or fixed, depending upn the condition of the ship. Fixed or permanent ballast in the form of sand, concrete, scrap or pig iron is usually fitted to overcome an inherent defect in stability or trim due to faulty design or changed character of service. Potrable ballast, usually in the form of water pumped into or out of the bottom, peak, or wing ballast tanks, is utilized to overcome a temporary defect in stability or trim due to faulty loading, damage, etc.