Ship Maneuvering Performance with Various Degrees of Dynamic Course Stability.
STEVENS INST OF TECH HOBOKEN N J DAVIDSON LAB
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Results are given of analytical studies to evaluate the effect of inherent dynamic course stability on ship performance in an effort to indicate guidelines to acceptable degrees of instability. Eigenvalue analysis and nonlinear trajectory analysis were applied to examine the performance of three ships having various degrees of stability. To ensure a realistic representation of a ship dynamic system, previously obtained captive model test results were used. A summary chart was made to indicate the directionally stable region for these ships. A ship with a large degree of inherent instability requires a large value of yaw-rate gain to achieve directional stability. This can cause difficulties in ship handling. Motion predictions in zig-zag and spiral maneuvers indicate that a very unstable ship has a tendency to divert from the straight course, having a large overshoot in heading change. Modified author abstract
- Marine Engineering