T. Soomere FAST FERRIES AS WAVEMAKERS IN A NATURAL LABORATORY OF ROGUE WAVES

The evolution of solitonic waves traveling in slightly different directions is analysed in the framework of the Kadomtsev-Petviashvili equation. Nonlinear interactions of solitonic waves generally lead to phase shifts of the counterparts. If the amplitudes of the interacting solitons, the angle between their crests and the water depth are specifically balanced, interactions result in particularly high wave humps resembling the phenomena occurring during the Mach reflection of solitary waves. Surface elevation up to four times as high as the amplitude of the counterparts may occur, and the slope of the front of the hump may be eight times as large as the maximum slope of the fronts of the interacting waves. Although such a balance occurs seldom, the resulting structure may persist for a long time until the balance is violated. Solitonic waves occur relatively seldom in natural conditions. However, leading waves of wakes from contemporary large high-speed ships sailing in shallow water frequently have solitonic nature. The described interactions are realistic in areas hosting intense fast ferry traffic.