| Summary: | This work is focused on determination of roll damping of warped hull form at low relative speed for which little data are available. The effect of hard chine and round bilge on roll damping has been investigated for two models of same characteristics and same inertial properties in displacement and semi-displacement regime. It was expected to experience the difference between two forms in nonlinear roll damping only, which is amplitude dependent and therefore roll decay tests were performed for angles from 10 to 30 degrees at zero speed up to Fn = 0.48. Roll decays have been analyzed considering logarithmic and linear decrements. Obtained results are natural roll frequencies and periods, equivalent linear damping αEQ and linear α and quadratic β damping coefficients as functions of ship speed.
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