recognized visually even if both were quite obscure. Both analyzed and visual results, that is the wavelength and die propagating direction, are reasonably consistent to each other. On the 14th. wind waves and swell were analyzed but swell was not recognized visually. Analyzed results of wind waves are quite consistent with those visual results. On the 15th, only swell was analyzed as a prevailing wave but only wind waves observed visually.
Table 5 Results of wave observation and analysis
On the 16th and the 17th of November. wind waves and swell were obscure and not distinguished clearly. On the 16th, wind waves were analyzed and observed although swell was not. Analyzed results of wind waves are almost consistent with visual ones but slightly different from them. On the 17th, only swell was analyzed and only wind waves were recognized visually.
On the 16th, die 19th, and the 21st of December, the seasonal northerly wind blew strongly and waves grew up large enough for the wave observation. On the 16th, wind waves and swell were analyzed but only wind waves were recognized visually. The analyzed results of wind waves are reasonably consistent with visual ones. On the 19th, both waves are analyzed, but swell was not recognized visually same as the 16th. The analyzed results of wind waves are quite consistent with visual ones. On the 2 1st, both waves were analyzed and both results seem to be reasonably good although visual observations were not made unfortunately.
6. CONCLUSION
It is quite important for die safety navigation, planning, and management of ships and marine structures to have accurate wave information, the wave height, period, wavelength, and wave propagating direction. Especially, it is very difficult to measure the propagating direction and wavelength of prevailing waves. Mainly they are still observed visually. The marine radar sea echo data include useful 2-dimensional wave information, the wavelength and the wave propagating direction of prevailing waves. The on-board experiment of the marine radar wave observation system was carried out for 8 days in total in 1994, for 5 days in October and November near around Izu-Oshima Island and for 3 days in December near around Goto Island, to examine its analytical and observational abilitiy.
Waves did not grew large enough for the wave observation in the experiments in October and November even if winds blew relatively strong because of the fetch. In the experiment in December the seasonal northely wind blew relatively strong and waves grew up large enough for the wave observation.
Based on 49 data sets of the radar sea echo, it is shown that the system could analyze reasonably wind waves and swell separately even when it was impossible to observe separately diem visually. But when waves are not large and clear enough, the system can analyze only one wave and can not distinguish both waves, wind waves and swell. On board high speed
