The assesment of the safety of ship's transit in a curved narrow channel consists of the maneuvering safety determined by the chance of running aground, the maneuvering difficulty determined by ship's workload, and shiphandler's subjective evaluation. In this study, to examine the correlation between shiphandler's subjective evaluation and the maneuvering safety, the real-time and full-mission shiphandling simulator in the Korea Marine Training & Research Institute(KMTRI) was utilized. On the conning bridge of the shiphandling simulator, 50 experienced masters have conducted the modeled vessel of 60, 000 deadweight tonnage along the designed channel under 3 different environmental conditions. It was possible to assess and analyze theoretically the correlation between the shiphandler's subjective evaluation and maneuvering difficulty under each environmental condition by quantifying the data obtained from the tests. The results are as follows: ① As the degree of maneuvering difficulty increases, the shiphandler's subjective evaluation increases in the designed channel under the designed environmental condition. ② In the straight area, not the bend of the designed channel, maneuvering difficulty increases sharply under the environmental condition of current and wind coming from the stern.