Beam Sea Rolling of USCG 120 FT Notional WPB Design Model in Regular Waves.
STEVENS INST OF TECH HOBOKEN NJ DAVIDSON LAB
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A 11 8-scale model of the 120 ft. WPB Notional Design at the half load condition was tested in beam seas having a nominal steepness of 150. The metacentric height was kept constant, but the roll radius of gyration was adjusted to give values of 36, 45, and 52 percent of the crafts maximum chine beam. The roll response was defined for each natural period over a range of wave lengths whose periods spanned the natural roll period of the model. The model was tested with freedom to roll, pitch, heave, and sway. The model was mounted on a self-propelled servo carriage so that it could drift with the waves, and the drift displacement was measured by an ultrasonic transducer. Measurements were also made of the wave height and period, and of the time histories of the roll motion. The results are scaled to full size and tabulated. Graphical presentations include the roll magnification, roll amplitude, roll response operator, and selected time histories. The roll response to the regular waves was significantly nonlinear. The experimental results demonstrate that the roll response of a boat decreases significantly with decreasing rotational moment of inertia. Roll motion will be minimized by minimizing the roll moment of inertia of a boat having a given displacement and metacentric height. Planing boats, Roll motion, Servo apparatus, Drift velocity, Harmonic analysis.
- Marine Engineering
- Fluid Mechanics