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Academic Paper
Atsuo Maki, Naoya Umeda, Renilson Martin, Tetsushi Ueta, Analytical methods to predict the surf-riding threshold and the wave-blocking threshold in astern seas, Springer, Journal of Marine Science and Technology, Vol.19, No.4, pp.415-424, Feb. 2014.

Abstract: For the safe design and operation of high-speed craft, it is important to predict the behavior of these craft in following and astern quartering seas as it is well known that serious problems can occur when a vessel is forced by the waves to travel at wave speed. The surf-riding threshold is the lower speed limit above which the vessel will be forced to travel at wave speed (usually on the face of the wave) which is generally accepted to be a prerequisite for broaching. While a vessel travelling below this speed will experience significant changes in its longitudinal speed in the wave, it will not be forced to travel at wave speed. For high-speed craft, the wave-blocking threshold also becomes important. This is the upper speed, below which the vessel will also be forced to travel at wave speed (usually on the back of the wave) and is related to the possibility of bow diving. By the application of a polynomial approximation to the waveinduced surge force, including the nonlinear surge equation, an analytical formula to predict both the surf-riding and the wave-blocking thresholds is proposed. Comparative results of the surf-riding threshold and wave-blocking threshold predicted utilizing the proposed formula and the thresholds predicted using numerical bifurcation analysis indicate fairly good agreement. In addition, previously proposed analytical formulae are examined.

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