Impact Of Climatology On Ship Design Discussed At Chesapeake SNAME
The first meeting of the 1980- 81 season was held by the Chesapeake Section of The Society of Naval Architects and Marine Engineers at the National Naval Medical Center Officers' Club. The technical session featured a paper titled Potential Impact of Twenty Year Hindcast Wind and Wave Climatology on Ship Design, by Susan L. Bales and William E. Cummins of the David W. Taylor Naval Ship R&D Center, and Edward N. Comstock of the Naval Sea Systems Command.
Lester Rosenblatt, president of the Society, was present at the meeting and in a short speech called for a greater degree of communication between the naval and commercial ship design communities. He cited the evening's technical session as a good example of how this interchange of ideas could occur, and expressed a desire that it continue.
The major focus of the paper was the specification of the natural ocean environment to serve as an input to ship sea-keeping analyses. In her presentation Mrs. Bales stated that significant advances in the development of ship motion response operators have occured in the past 15 years; however, the expected operating environment must be accurately defined to insure that ship performance in a realistic seaway can be determined. A good description of anticipated seaways coupled with ship response prediction techniques and missionlimiting response criteria should enable the designer to better develop hull forms that meet mission requirements.
The sensitivity of ship motions to the description of the sea state was evaluated using five naval ship types — FFG, DD, LHA, AOE, and CVA. The roll, pitch, and heave motions resulting from three different sea spectra, i.e., B r e t s c h n e i d e r , Station India (empirical), and hindcast, were compared with the hindcast spectra providing good correlation with the observed spectra of Station India and B r e t s c h n e i d er Spectra depending upon model period. This leads the authors to believe that the hindcast methodology has potential for more realistically determining sea spectra for design purposes; however, a significant amount of effort remains in its development.
Prepared discussions were presented by Seth Hawkins and Prof.
Philip Mandel of DTNSRDC.