PROBABILITY ANALYSIS slamming WISE-8

PROBABILITY ANALYSIS slamming WISE-8 Slamming is something that interacts with the vertical movement of the ship. This occurs due to extreme movement of the waves which cause the bow (bow) ship out of the water, then slamming occurs when the bow of the ship fell on the surface of the water. The determination of the probability of slamming can be described as follows: where d is loaded on the ship's bow, ms0 area under the spectrum of relative motion, relative velocity deviation MS2 bow and VT is the relative speed threshold. The following image shows the slamming pressure. From the results of the analysis showed that the probability of the occurrence probability of slamming on the specified wave conditions are very small or less than 1%. While standard seakeeping performance criteria required frequency of occurrence of slamming no more than 3/100. Following the calculation of the probability of slamming at speeds of 20 and 35 knots. Input: Length between perpendiculars 11.847 m Draught at longitudinal position 0.57 m Running trim (+ve bow up) 0 m Even keel condition Wave profile due to forward speed 0.29 m Bow wave height or aft depression, +ve = above static waterline Swell-up coefficient 1.5 Depends on position, speed and hull form, approx. between 1 and 2 Average period of peaks 3.76 s Approximately Tzero m0 of relative vertical motion spectrum 0.006 m^2 From Seakeeper summary table Critical velocity 1.002 m/s See below m0 of relative vertical velocity spectrum 0.116 m^2/s^2 From Seakeeper summary table Results: Draught including trim 0.57 m Draught including wave due to forward speed 0.57 m Probability of emergence 0.001% Expressed as a percentage probability of occurrence Occurrences per hour 0.006 Probability of slamming 0.000% Occurrences per hour 0.001 Calculation of Critical Velocity Ochi (1964) Method Critical velocity 1.002414824 m/s Input: Length between perpendiculars 11.847 m Draught at longitudinal position 0.57 m Running trim (+ve bow up) 0 m Even keel condition Wave profile due to forward speed 0.29 m Bow wave height or aft depression, +ve = above static waterline Swell-up coefficient 1.5 Depends on position, speed and hull form, approx. between 1 and 2 Average period of peaks 3.76 s Approximately Tzero m0 of relative vertical motion spectrum 0.01 m^2 From Seakeeper summary table Critical velocity 1.002 m/s See below m0 of relative vertical velocity spectrum 0.17 m^2/s^2 From Seakeeper summary table Results: Draught including trim 0.57 m Draught including wave due to forward speed 0.57 m Probability of emergence 0.073% expressed as a percentage probability of occurrence Occurrences per hour 0.701 Probability of slamming 0.020% Occurrences per hour 0.189 Calculation of Critical Velocity Ochi (1964) Method Critical velocity 1.002414824 m/s

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