(military; in Russian, bony), floating obstructions used to protect the moorage area of a fleet or the site of important structures (such as bridges and dams) from penetration by enemy ships and floating mines. For the passage of friendly vessels, booms have an adjustable part called boom gates. At entrances to sea harbors and ports, booms in the form of rows of logs are situated along the line or perpendicular to the line of obstructions; they are connected by chains or ropes and held down by anchors. On rivers an iron cable stretched from one bank to the other on floats is used. In order to block access to submarines, torpedoes and underwater mines, combined booms of logs with suspended nets are used. Obstructive booms of logs floating on the surface of the sea serve to ensure fire safety around the water area near warehouses of petroleum products. Booms used in logging, usually in the form of clusters of logs, are established in the riverbed to direct the lumber being floated.