An Assessment of Transportable Breakwaters with Reference to the Container Off-Loading and Transfer System (COTS).

摘要

A study covering three specific designs for a tethered float breakwater and simple and legged versions of the sloping float (inclined pontoon) breakwater has resulted in improved definition of certain aspects of the logistic burden connected with transportable breakwaters in military operations. Performance data reported for the two types were analyzed in order to determine the transverse cross-section dimensions required for 50% reduction of the significant wave height associated with the Pierson-Moskowitz wave spectrum with 7-second peak period. Specific designs with this capability were then examined to assess requirements for overseas transportation, installation, and cost. The state performance requirement was drawn from an analysis of the Container Off-Loading and Transfer System (COTS). This analysis concluded that wave-induced motions of moored lighters, barges, and floating platforms (with natural periods between 2 and 7 seconds) could adversely affect cargo flow rates. Thus, a breakwater effective for 7-second waves could decrease the frequency and duration of occasions when the system is degraded by wave action. Bargeships, ships with well decks, or large ocean-going barges would be required to transport the modules of the various designs for a 7-second breakwater. A LASH bargeship is the most likely carrier for COTS breakwaters. LASH capacity varies from 750 to 3,600 lineal feet of breakwater, depending upon the particular vessel and the breakwater design. For the various points in the COTS where a breakwater would be beneficial, the length of breakwater required varies from 650 to 4,000 feet. (Author)