This paper deals with the effects of wind and tidal current on the weather routing for a small vessel in coastal sea area. The measurements of sailing time by tidal currents and leeway by wind effects of a small running vessel were carried out in real sea area. The sailing time were measured based on computer simulation for the weather routing. Also, the qualitative leeway was measured under the conditions of variable relative wind direction against a course of a small vessel. As for the results, it was considered that the effects of wind and tidal currents were very important for considering the optimum current sailing.
