There are some evaluation methods of operation efficiency of cargo handling from the view of moored ship motions. Basically, they are derived from comparison of the calculation results of numerical simulation with allowable ship motions for the operation of cargo handlings. In this paper, the evaluation method proposed by KLTBO5) is used. And we use the allowable ship motions proposed by UEDA6).
Calculation results of operation efficiency for 696GT and 15,000DWT ships are estimated as 99.9% and 100%, respectively.
3. INVESTIGATION OF ACTUAL CARGO HANDLING REPORT AND WEATHER CONDITIONS
3.1 EVALUATION OF INTERRIJITION RATIO BY THE ACTUAL CARGO HANDLING REPORT
The ship arrival and departure times, situations of the wharf operations, weather conditions (wave and wind data) for the berth and hearings from the pilots and operators of cargo handlings are investigated and summarized. According to the cargo handling report and the weather conditions, we made a time table of the berth usage. Then various cases of the interruptions are distinguished and the interruption times and the ratio are estimated respectively as shown in Table-3.
Table-3 Causes and ratio of the interruptions
Ship standing off' means a case which ships stand off a berth when a typhoon approaches to the harbor. "Ship nonentering" means that a pilot doesnt go on board the ship and the ship didnt enter the berth.
3.2 SITUATION OF WAVE, WIND AND MOORED SHIP MOTIONS AT THE INTERRUPTIONS
There are four interruptions caused by wave and wind conditions during the tern as shown in Table-4. Two sample cases are investigated in detail as below.
Table-4 Interruptions caused by wave and wind
Case1: August 2 UN maru by standing off
Typhoon No.1 hits the center of the main land and then it becomes to be a tropical depression in the Sea of Japan. The weather is cloudy. The maximum average speed of the wind is U10=l3.9 m/s at 7:00 and maximum instantaneous one is Umax=2 1.6 m/s at 350 Almost 13s period waves are coming in proportion to closing the typhoon and the maximum offshore wave on August 2 attains as Hmax=4.0m, Tmax=1O.8s. The wharf operations aren't held in August 1 on holiday. However on July 31, the interruptions are already occurred in several berths. All berths are knocked off the operation from the early morning. From the above mentions and according to the weather conditions, the cause of this interruption is judged as the standing off by the typhoon.
Case2: September 1 AC maru(499GT) by swell
The weather charts in September 1-3 are shown in Fig.-3. Though typhoon No.15 passes through the East on the Pacific Ocean, it doesn't hit the main land. So it is a fine andcloudy day. The maximum instantaneous speed of the wind is Umax=5.8 m/s. The offshore waves of T1/3=17s, H1/3=3.5m are observed from the end of August. The interruptions of wharf operations and berthings are occurred in many berths by swells. After knocking off the operation, AC maru shifts to another berth. However the interruption happens again at the berth on September 2. The cargo handling iscarried out on September 3 at the other berth. From the above, the cause of the interruption is estimated by swell in spite of the fine weather and weak winds.
