Mooring developments and design philosophy at the national data buoy center

Buoy moorings used by the National Data Buoy Center (NDBC) have varied from all-synthetic to all-chain moorings. In each case, the mooring is custom designed for each site, but uses off-the-shelf components and a "standard" design philosophy. The NDBC numerical models are used to size the mooring components and segments, given a general design. The NDBC mooring design philosophy has evolved over the past decade by adapting to the various hazards and failures encountered by NDBC, the U.S. Coast Guard, and other users of moored buoys. Hazards such as fishing longlines and fishbite in the Gulf of Mexico have resulted in the use of more chain in the upper mooring. The resulting accelerated mooring staple wear caused NDBC to reevaluate the mooring designs to decrease the tension at the buoy. This paper discusses some of NDBC\´s mooring experiences and the resulting mooring design philosophy.