Accession Number : AD0442601


Title :   SEA TESTS ON A SPREAD-MOORED LANDING CRAFT,


Corporate Author : NAVAL CIVIL ENGINEERING LAB PORT HUENEME CA


Personal Author(s) : O'Brien, J T ; Muga, B J


Report Date : 15 Jun 1964


Pagination or Media Count : 114


Abstract : Sea tests of motion and mooring force were conducted on an LST (Landing Ship Tank) of about 4400 long tons displacement. The LST was spread-moored by six 2-1/16 inch and one 1-1/4 inch (port breast) stud-link chains in about 45 feet of water in the open Gulf of Mexico about 65 air miles south of New Orleans, Louisiana. Water-level variations at a single location, ship rotations and accelerations, mooring force, and wind were measured in sea states of 2 and 5. Three recordings of 38, 62, and 67 minutes duration were analyzed, using time-series techniques to provide apparent amplitude-response operators for all of the ship's motions and the mooring force. Those for longitudinal motion compare well with those obtained by use of theory. The most probable maximum-motion amplitudes in sea state 4 are found to be 1.7, 1.1, and 1.8 feet, respectively, in surge, sway, and heave, and 3.43 and 0.61 degrees, respectively, in pitch and yaw. Roll was measured only in sea state 2, with a corresponding maximum of 2.2 degrees. In sea state 4, the maximum wave-induced tensions measured were 85.1 kips in the port-bow chain (consistently the dominant chain) and 9.9 kips in the stern chain. The initial tensions in these chains were 30.8 and 7.5 kips, respectively. (Author)


Descriptors :   MOORING , LANDING CRAFT , MOTION , ANCHOR CHAINS , WIND , MOTION , FORCE(MECHANICS) , ROLL , YAW , ROTATION , WATER WAVES


Distribution Statement : APPROVED FOR PUBLIC RELEASE