Acquisition of Ocean Wave Surface by X-band Ship Radar and Very-short-term Wave Surface Prediction

The fact that the crest-line-like lines can be seen in the PPI image of ship radars was known from relatively old days. Many trials obtaining wave information as wave directional spectrum, significant wave height and wave mean directions were also done. Recently, products giving such information and supporting navigation are also developed and becoming in use. Considering such a situation, wave radar will become a necessary item as a standard equipment for ships, in not a so long future. On the other hands, Hirayama et al. Showed, that by the PPI image, individual waves are recognized and very short term predictions, for example, a few minutes after, will be possible. If the prediction of individual waves is possible, then ship motion on them become possible, including dangerous conditions, and finally contribute to the safety navigation of ships. This paper reports about the results of the demonstrative examination of individual waves done in the actual sea and this will be the first in the world.