Characteristics Analysis of Weather Routing by Practical Navigators

In the weather routing, it is very important to take account of encountered weather and sea states, which are major factors of the function in a weather routing simulation model. To clarify the criteria for the safety navigation of practical navigators quantitatively, the weather routing simulation and the interview were carried out to the navigators. According to the interview, the upper limit of wind force for the navigators is the Gale rank in the Beaufort scale. For the upper limit of the wave height, the navigators had two criteria, 5 to 8 m and 10 to 12 m. From the results of the weather routing simulation, the criteria for wind speed are 40 knots in the following wind case, 30 knots in the side wind case, and 30 to 40 knots in the head wind case. The criteria for the wave height are 5 m in the case of wave from right ahead, 5 to 6 m in the beam wave case, and 7 m in the case of wave from the right astern. Moreover the criteria for the wave height in the head wave case is 7 m, in the side wave case is 8 m, and in the following wave case is 11 m.