The human sickness of the ship’s crews and passengers is considered as main requirements to be fulfilled in ship design stages which is related to the performance of ship motion when operating in seaway. This paper describe review some seakeeping criteria which are published by several institutions for the purpose of ship safety and comfort. Since these criteria were initially issued based on extreme sea conditions, it is necessary to study if they are applied to relatively moderate sea conditions in Indonesian. For this reason, a new approach is proposed to deal with a new criteria by measuring motions directly on the ship in operation. Briefly method is described as first, the ship motion in 6 degrees of freedom is measured by sensors which is installed in a particular place on the ship’s board, for which the data generated include an angular velocity, a vertical and a tranversal accelerations of motions. Second, Fast Fourier Transform (FFT) algorithm is adopted to process the measured data which are presented in the form of time series and spectrum diagrams, and the Power Spectral Density (PSD) method is also used to eliminate nois data. Third, the ship motion criteria for the case of the passenger ship is determined and it compare to the existing criteria.

This paper describes a new identification method for the fast ferry motions by using the direct measurements on the ship’s board. The inertial sensor type of the Analog Devices (ADIS) 16364 is selected as a as suitable instrument to measure accelerations and velocity of the ship motions namely heave, pitch, and roll in time domain. Furthermore, the ship motion responses are transferred as the energy spectral density in frequency domain which are identified using the Fast Fourier Transform (FFT) method. For the case study, the measurement equipment was placed on the navigation room of MV. Dumai Line 12 recording in 15 minutes within ship voyage from Bengkalis to Batam in September 2021. Finally, the natural frequencies of heave, pitch, and roll motions are identified about 0.568 rad/s, 0.117 rad/s, and 0.227 rad/s, respectively.

The ship operator needs passenger feedback on the comfort of inter-island speed ferries as information on improving passenger comfort services. This paper analyzes the comfort of passengers on fast passenger ferries operating in the Malacca Straits directly.  The survey focuses on directly assessing the level of passenger comfort and evaluating the leading causes of passenger discontentment. The strategy adopted is the dissemination of a questionnaire to onboard passengers, with a response rate of around 30 out of a minimum of 24 referring to the SLOVIN formula. The comfort score in the questionnaire is divided into five points, namely: uncomfortable or queasy, dizzy and slightly queasy, dizzy, slightly dizzy, and comfortable. The measured data were validated using Analysis of Variance (ANOVA) and the Dunnett Simultaneous Tests for Differences in Means, which gave a P-value of 0.000 and a degree of confidence of 98.97%. The findings of the study indicated that respondents, on average, rated this ship as slightly uncomfortable to comfortable, giving it a comfort rating of 4.10 out of a possible 5. Moreover, three aspects, namely the ship's motion, the accommodation facilities, and the ship's vibration, significantly contribute to discomfort, as indicated by ratings of 3.8, 4.2, and 4.2, respectively, out of 5 (comfortable), indicating the severity of the effect. Furthermore, by knowing that the main source of passenger discomfort is ship motion, it can be input for ship operators in managing the comfort of ship passengers.