BARGE TRAINS IN A COASTAL SEAWAY, PART 1: MODEL TESTS IN OBLIQUE SEAS

Tests of a 1/50-scale model of push-tow barge trains were carried out under various wave conditions, including wave-to-heading angle change, to obtain forces on tow connections and motions of the train. Test results are presented for lateral bending moment, longitudinal and vertical forces on tow connections and for oscillatory motions such as roll, pitch and heave, with variations in wave conditions (wave length, wave height and wave-to-heading angle), number of barges, types of connections (hinge, short and long linkage), loading conditions and speeds. Test results of forces and moments indicate that the lateral bending moment is the most critical component in the resultant force generated on connections of barge trains in waves. For example, the maximum magnitude of measured moment coefficient (moment/(beam x one barge displacement)) was approximately 0.25 at the middle connection of the three-barges and tug train in moderate waves (wave height/wave length = 1/100) at wave-to-heading angles of 120 degrees and 60 degrees. The maximum longitudinal force coefficient (force/one barge displacement) obtained in tests was approximately 0.05 in moderate head seas (wave height/wave length = 1/100). Lateral bending moment and longitudinal and vertical forces were roughly doubled when the wave height relative to the wave length was increased from 1/100 to 1/50.