Simulation and stability of ship towing

Article type: Research Article

Authors: Bernitsas, M.M. | Kekridis, N.S.

Affiliations: Department of Naval Architecture and Marine Engineering, The University of Michigan, Ann Arbor, Michigan, U.S.A.

Abstract: A nonlinear time dependent mathematical model is used to simulate the surge, sway and yaw motions and study the stability of a vessel towed by a nonlinear elastic rope. The five Routh-Hurwitz stability criteria for the corresponding linear time invariant system are studied and it is shown that only two can be critical in ship towing. The sensitivity of the stability surfaces generated by the reduced criteria is studied and the parameters which mostly affect the local stability of towing systems are identified. Global stability characteristics of the towed vessel trajectory are also revealed by finding the critical points of the corresponding autonomous nonlinear system in the phase space. Numerical examples using a barge, a tanker and a mariner which have distinctly different behavior in towing are used to illustrate the simulation and verify the theoretical results. The latter are also used to explain the apparent contradiction between Strandhagen’s theoretical results and Benford’s and Brix’s observations.

DOI: 10.3233/ISP-1985-3236901

Journal: International Shipbuilding Progress, vol. 32, no. 369, pp. 112-123, 1985