U.S. Navy Activities In Ocean Wave Measurement And Prediction

The natural environment plays an increasingly important role in U.S. Navy ship design trade-off studies and in at-sea tactical decisions. The performance of ships, weapons, and personnel is strongly dependent on the prevailing winds and state of the seaway. Millions of dollars are expended each year in repairing fleet damage due to wind and wave loadings. Even the largest of vessels is not immune to these degradations where aircraft on deck are constantly faced with the threat of salt spray corrosion. In order to build more sea-kindly ships, the Navy has initiated a program to provide new technology for ship design. A major focus of the program is to develop procedures for better quantification of the wind/wave environment. Central to this effort are directional wave hindcasts developed at Fleet Numerical Oceanography Center (FNOC) in Monterey, California. Analysis of these hindcasts has recently produced new sea state occurrence charts for the North Atlantic and North Pacific Oceans. While the characteristics of wave directionally remain elusive, quantification of spectral spreading has been undertaken. Stratified sampling techniques are being used to develop a new wave spectral family and may permit, for the first time, the probabilistic calculation of ship response in representative moderate to heavy, swell corrupted, wind generated seas. Validation of these data are accomplished, among other ways, by deployment of a directional (roll-pitch) wave buoy and subsequent comparison to FNOC forecasts, and also by postmortem analysis of ship casualty reports with corresponding wave hindcasts or forecasts. Importantly, the hindcast data base also permits the development of wave statistics heretofore unavailable in any quantity. While the primary focus of the hindcasting effort to date has been on the North Atlantic and North Pacific, efforts to expand the work to the Indian Ocean and Mediterranean Sea are planned.