Abstract—Using observations and model forecasts, warning index system reflecting wave's effects on ships is formed, including indexes of wave-ship resonance, wave shoaling effect index, wave steepness index and swell proportion index. Wave-ship resonance indexes contain rolling resonance index (the rate of encountering wave period to ship's inherent rolling period), pitching resonance index (the rate of encountering wave period to ship's inherent pitching period) and heaving resonance index (the rate of encountering wave period to ship's inherent heaving period). Knowing distributions of the wave-ship resonance indexes which depend on wave period and wave direction, ships can make timely adjustment by changing their speed and direction to avoid being in resonance state. Wave shoaling effect index is the rate of wave height to its original wave height. It always reveals a semi-tidal character and has tight links with the unique topography, water level change and current variation in the Yangtze River estuary. Wave steepness index and swell wave proportion index are both extracted from wave spectra, the former tells the steepness of wave and the latter is useful to judge wave's effect on ship's momentum and cable tension. These indexes describe different aspects of wave's impacts on ships, which can be used efficiently to protect ship's sail and mooring safety.
Index Terms—Yangtze river estuary, wave warning, wave-ship resonance, shoaling effect.
Q. Yang is with Shanghai Ocean University, and with Shanghai mariNe Meteorological Center, Shanghai, China (e-mail: yangqiabuwanju@163.com).
J. J. Ou, and N. L. Huang are with Shanghai Marine Meteorological Center, Shanghai, China (corresponding author: N. L. Huang e-mail: hnl873211@gmail.com). Y. P. Li is with Shanghai Typhoon Institute of China Meteorological Administration, Shanghai, China.
Cite: Q. Yang, J. J. Ou, N. L. Huang, and Y. P. Li, "The Study of Wave Warning Indexes for Ships," International Journal of Engineering and Technology vol. 10, no. 1, pp. 23-28, 2018.