Abstract
ISO (the International Organization for Standardization) suggested guidelines for the assessment of speed and power performance in 2002. And recently ISO revised the guidelines in 2015. Thus, there needs to adopt newest guidelines for estimating the performance of ships. However, it is not suitable for estimating the performance in actual ships which operate in the ocean. Because ISO 15016:2015 was focused on assessment of ideal performance using sea trial data. Therefore, modified procedure of ISO 15016:2015 was proposed in this study. the modified procedure is mainly composed of four steps. First, additional resistance according to sea state is estimated. Second, speed correction due to current and shallow water effect is calculated. Third,