Abstract
Ship needs a long time to sail across the ocean and often falls in with severe rough weather. And ship pitches and rolls violently on the way in rough sea. In the past and the present, winds, waves and ship's motion have been described by crew every 4 hours. Authours developed a voyage recorder which automatically measures and recoreds the data of encounter winds, waves and ship's motion. The results of such measured data are reported in the previous paper. In this paper, some characteristics of fluctuation of engine output and propeller revolution in rough sea which data are newly measured and recorded are reported. That are (1) ship's motion becomes violent in response to rough sea, (2) consumption of fuel oil are proportion to engine output, (3) engine output increases in order to prevent a reduction of propeller revolution, (4) propeller revolution decreases slightly in response to rough sea in spite of setting to be constant, (5) propeller revolution is commonly forced to decrease in order to reduce violent ship's motion, (6) ship's speed decreases in more than certain rough sea even if propeller revolution is kept to be constant.
