OBSERVATIONS ON 1,000 CUBIC METER EXPERIMENTAL LNG CARRIER AT SEA (1ST REPORT)-MEASUREMENTS AND ANALYSIS ABOUT WAVES

Observations on a ship at sea carried out to verify the usefulness of a method of analysis developed for the safety assessment of LNG carriers. The ship is 60m in length between perpendiculars and has two LNG tanks (spherical and prismatic). In the observations, various kinds of dynamic responses such as ship motions, pressures on tanks, stresses on tanks and their supports etc. totaling about 60 channels are measured simultaneously. In addition, waves are measured using a wave buoy with a pressure transducer. For the first report of the observations, this paper deals with measurements and analyses of wave data, and evaluation of wave spectra from measured ship responses. The wave spectra evaluated from measured ship responses shows better agreement with measured ones in head seas than in following seas. The errors of the evaluated wave heights and wave periods are within 20% mostly.