Sea trials were conducted featuring measurement of wave impact loads and hull response for a patrol boat with displacement about 1, 300 ton, while the boat ran in severe waves with angle of wave encounters and speeds changed. Some results of the analysis of the trial data were reported in the first¹⁵⁾ paper, in which bow flare slamming, impact pressure on the bow flare and very high logarithmic decrement of whipping vibration were discussed. This paper presents some results of the further analysis of the data, as follows : 1. Bow flare slamming induced very high bending stresses on the deck, whose distribution on it was given, and relation between local stress and deck stress are also discussed. 2. Bow flare slamming induced whipping vibration. Careful observation of measured data led to understanding how whipping vibration was initiated by bow flare slamming, which also implied the mechanism of high decay of whipping vibration at its initial stage. 3. Whipping stresses have so high peak values and high frequencies compared with ordinary wave bending stresses that they may cause severe fatigue problems. Based on the measured data, fatigue strength of the hull was diseussed.