Abstract

A design methodology is formulated to reveal the dependence of nonlinear slowmotion dynamics of spread mooring systems (SMS) on mooring line arrangement. For a given SMS configuration, catastrophe sets are developed in the parametric design space showing the dependence of stability boundaries and singularities of bifurcations on design variables. This approach eliminates the need for nonlinear simulations. For general SMS design, however, the designer relies on experience rather than scientific understanding of SMS nonlinear dynamics, due to the high number of design variables. Several numerical applications are used to demonstrate counterintuitive ways of improving SMS dynamics. The SMS design methodology formulated in this paper aims at providing fundamental understanding of the effects of mooring line arrangement and pretension on SMS horizontal plane dynamics. Thus, the first guidelines are developed to reduce trial and error in SMS design. The methodology is illustrated by comparing catastrophe sets for various SMS configurations with up to three mooring lines. Numerous examples for a barge and a tanker SMS which exhibit qualitatively different nonlinear dynamic behavior are provided.

Issue Section:
Research Papers
Topics:
Dynamics (Mechanics), Mooring, Design, Design methodology, Bifurcation, Errors, Nonlinear dynamics, Parametric design, Simulation, Stability, Tankers
1.
Abkowitz, M. A., 1972, Stability and Motion Control of Ocean Vehicles, MIT Press, Cambridge, MA.
2.
API, 1994, “Draft Recommended Practice for Design and Analysis of Stationkeeping Systems for Floating Structures,” API Recommended Practice, May.
3.
Bernitsas
M. M.
, and
Chung
J. S.
,
1990
, “
Nonlinear Stability and Simulation of Two-Line Ship Towing and Mooring
,”
Journal of Applied Ocean Research
, Vol.
12
, No.
2
, Apr., pp.
77
–
92
.
4.
Bernitsas
M. M.
, and
Kekridis
N. S.
,
1986
, “
Simulation and Stability of Ship Towing
,”
International Shipbuilding Progress
, Vol.
32
, No.
369
, pp.
112
–
123
.
5.
Bernitsas
M. M.
, and
Papoulias
F. A.
,
1986
, “
Stability of Single Point Mooring Systems
,”
Journal of Applied Ocean Research
, Vol.
8
, No.
1
, Jan., pp.
49
–
58
.
6.
Bernitsas, M. M., and Papoulias, F. A., 1990, “Nonlinear Stability and Maneuvering Simulation of Single Point Mooring Systems,” Proceedings of Offshore Station Keeping Symposium, SNAME, Houston, TX, February 1-2, pp. 1–19.
7.
Bernitsas, M. M., Papoulias, F. A., and Chung, J. S., 1988, “SPMSIM: A Program for SIMulation of Single Point Mooring Systems,” Report to The University of Michigan/Sea Grant Industry Consortium in Offshore Engineering, and Department of Naval Architecture and Marine Engineering, The University of Michigan, Ann Arbor, MI, Publication No. 308.
8.
Brown, K. M., and Conte, S. D., 1967, “The Solution of Simultaneous Nonlinear Equations,” Proceedings of the 22nd National Conference of the ACM, Thompson Book Co., Washington DC, pp. 111–114.
9.
Chung
J. S.
, and
Bernitsas
M. M.
,
1992
, “
Dynamics of Two-Line Ship Towing/Mooring Systems: Bifurcation, Singularities of Stability Boundaries, Chaos
,”
Journal of Ship Research
, SNAME, Vol.
36
, No,
2
, June, pp.
93
–
105
.
10.
Cox, J. V., 1982, “Statmoor- A Single Point Mooring Static Analysis Program,” Naval Civil Engineering Laboratory, Report No. AD-A119 979, June.
11.
Guckenheimer, J., and Holmes, P., 1983, Nonlinear Oscillations, Dynamical Systems, and Bifurcations of Vector Fields, Springer-Verlag, Inc., New York, NY.
12.
Jiang, T., and Schellin, T. E., 1987, “Maneuvering Simulation of a Tanker Moored in a Steady Current Including Hydrodynamic Memory Effects and Stability Analysis,” Proceedings, RINA International Conference on Ship Maneuverability, London, U.K., Apr., pp. 1–12.
13.
Jiang, T., and Schellin, T. E., 1988, “Motion Prediction of a Single Point Moored Tanker Subjected to Current, Wind and Waves,” Proceedings of the ASME 7th International Conference on Offshore Mechanics and Arctic Engineering (OMAE), Vol. II, Houston, TX, Feb., pp. 317–326.
14.
Kwan
C. T.
,
1991
, “
Design Practice for Mooring of Floating Production Systems
,”
Marine Technology
, Vol.
28
, No.
1
, Jan., pp.
30
–
38
.
15.
Martin
L. L.
,
1980
, “
Ship Maneuvering and Control in Wind
,”
Transactions SNAME
, Vol.
88
, pp.
257
–
281
.
16.
Mc Kenna
H. A.
, and
Wong
R. K.
,
1979
, “
Synthetic Fiber Rope, Properties and Calculations Relating to Mooring Systems
,”
Deepwater Mooring and Drilling
, ASME Ocean Engineering Vol.
7
, Dec., pp.
189
–
203
.
17.
Papoulias, F. A., and Bernitsas, M. M., 1988a, “MOORLINE: A Program for Static Analysis of MOORing LINEs,” Report to the University of Michigan/Sea Grant/Industry Consortium in Offshore Engineering, and Department of Naval Architecture and Marine Engineering, The University of Michigan, Ann Arbor, MI, Publication No. 309, May.
18.
Papoulias
F. A.
, and
Bernitsas
M. M.
,
1988
b, “
Autonomous Oscillations, Bifurcations and Chaotic Response of Moored Vessels
,”
Journal of Ship Research
, SNAME, Vol.
32
, No.
3
, Sept., pp.
220
–
228
.
19.
Seydel, R., 1988, From Equilibrium to Chaos, Elsevier Science Publishing Co., Inc., New York, NY.
20.
Sharma, S. D., Jiang, T., and Schellin, T. E., 1988, “Dynamic Instability and Chaotic Motions of a Single Point Moored Tanker,” Proceedings of the 17th ONR Symposium on Naval Hydrodynamics, The Hague, Holland, Aug., pp. 543–562.
21.
Wiggins, S., 1990, Introduction to Applied Nonlinear Dynamical Systems and Chaos, Springer-Verlag, Inc., New York, NY.
This content is only available via PDF.
Copyright © 1996
 by The American Society of Mechanical Engineers
You do not currently have access to this content.