Stability of autopiloted ships in a following sea.
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Authors
Folsom, David Lindley.
Subjects
Advisors
Mandel, Phillip A.
Date of Issue
1967-06
Date
June 1967
Publisher
Massachusetts Institute of Technology
Language
en_US
Abstract
The object of this thesis was to investigate the stability of a ship with automatic steering in a following sea using the nonlinear equations of motion and to compare these results with the results of linear approximations. The solution of the nonlinear equations was obtained by a technique of treating nonlinear terms as linear terms with non-constant coefficients. Results showed that when drift angles become 0.1 radians or greater the nonlinear solution differs substantially from the linear solution. But the nonlinear solution has a greater range of stability in the wave profile than the linear solution. This leads to the conclusion than a system designed using linear theory provides sufficient stability for the ship in a following sea. The most important effect which this approach neglected was the coupling effect of the roll or heel motion on the yaw motion. Before a complete and accurate solution to the steering problem can be found the coupling effect must be investigated and some method of expressing it analytically must be produced.
Type
Thesis
Description
This thesis document was issued under the authority of another institution, not NPS. At the time it was written, a copy was added to the NPS Library collection for reasons not now known. It has been included in the digital archive for its historical value to NPS. Not believed to be a CIVINS (Civilian Institutions) title.
Series/Report No
Department
Naval Architecture and Marine Engineering
Organization
Massachusetts Institute of Technology