The prediction of the dynamic behavior of moored tankers like FPSO system is very important to the mooring systems design. There are several types of mooring systems, such as Turret, Spread Mooring System (SMS) and Single Point Mooring (SPM), for which the specification of number and dimensions of the lines depends on the dynamic of the entire system composed by tanker and mooring and riser lines. Although several moored systems were already installed as a positioning system of FPSO, there are still some unknowns that should be investigated to provide more safety and lower cost systems. The drag/damping terms on the ship hull and the mooring and riser lines damping are one of the most important terms in the dynamics of the moored tanker that should be investigated. The hydrodynamic model due to the interaction between hull and fluid has been very studied due to the complexity of the phenomenon. The authors have studied the models of several researchers and three of them were picked up and implemented in the DYNASIM, a moored ship dynamic simulator. These models will be discussed and compared. In deep water, the total length of the mooring lines and risers becomes large and consequently the forces acting on these elements become more important. However, in many cases these important forces acting on the lines have not been considered. There are some works that point out the magnitude of the damping forces of the lines. Recently, a full scale decay test using a 30kDWT moored tanker was realized in Brazil offshore. The results showed the significance of the line damping, in particular on surge motion. Another important phenomenon that has been discussed is the wave drift damping term. There are several research studies concern’s this force resulting in several estimation methodologies. However, only surge direction has been considered important and there is little research about the damping in others directions. The time simulation methodology will be used to analyze and compare the effects of each term in the dynamics of the system. Finally, the comparison between simulated results and model test data will be performed in order to validate the model proposed. In this study, the experimental data of DICAS system (Differentiated Compliant Anchoring System) will be used.

Issue Section:
Technical Papers
Keywords:
ships, simulation, dynamics, engineering, FPSO, Ship Dynamics, Numerical Simulation
Topics:
Damping, FPSO, Mooring, Ships, Wave drift, Dynamics (Mechanics), Water, Fluid-dynamic forces
1.
Wichers, J. E. W., 1988, “A Simulation Model For A Single Point Moored Tanker,” Publication No. 797, Maritime Research Institute, Netherlands.
2.
Molin, B., and Bureau, G., 1980, “A Simulation Model for the Dynamic Behavior of Tankers Moored to SPM,” International Symposium on Ocean Engineering and Ship Handling, Gothenburg.
3.
Obokata
,
J.
,
1987
, “
On the Basic Design of Single Point Mooring Systems (1st report)
,”
Journal of the Society of Naval Architects of Japan
,
161
,
June
June
.
4.
Abkowitz, M. A., 1969, Stability and Motion Control of Ocean Vehicles, M.I.T. Press.
5.
Takashina
,
J.
,
1986
, “
Ship Maneuvering Motion due to Tug boats and its Mathematical Model
,”
Journal of the Society of Naval Architects of Japan
,
160
,
December
December
.
6.
Takashina, J., and Hirano, M., 1990, “Ship Maneuvering Motion by Tugs in Deep and Shallow Water,” MARIN&ICSM90.
7.
Leite, A. J. P., Aranha, J. A. P., Umeda, C., and Conti, M. B., 1998, “Current Forces in Tankers and Bifurcation of Equilibrium of Turret Systems: Hydrodynamic Model and Experiments,” Appl. Ocean. Res.
8.
Simos
,
A. N.
,
Tannuri
,
E. A.
,
Pesce
,
C. P.
, and
Aranha
,
J. A. P.
, 2001, “A Quasi-Explicit Hydrodynamic Model for the Dynamic Analysis of a Moored EPSO Under Current Action,” J. Ship Res., 45.
9.
Grue
,
J.
, and
Palm
,
E.
,
1993
, “
The Mean Drift Forces and Yaw Moment on Marine Structure in Waves and Current
,”
J. Fluid Mech.
,
150
, pp.
121
–
142
.
10.
Aranha
,
J. A. P.
,
1994
, “
A Formula for ‘Wave Damping’ in the Drift of a Floating Body
,”
J. Fluid Mech.
,
275
, pp.
147
–
155
.
11.
Aranha
,
J. A. P.
,
1996
, “
Second-Order Horizontal Steady Forces and Moment on a Floating Body with a Small Forward Speed
,”
J. Fluid Mech.
,
313
, pp.
39
–
54
.
12.
Huse, E., and Matsumoto, K., 1989, “Mooring Line Damping due to First and Second Order Vessel Motion,” OTC 6137, 21th Annual OTC, Houston, Texas, May 1–4.
13.
Le Boulluec, M., Le Buhan, Ph., Chen, X.-B., Deleuil, G., Foulhoux, L., Molin, B., and Villeger, F., 1994, “Recent Advances on the Slow-Drift Damping of the Slow-Drift Damping of Offshore Structure,” Behaviour of Offshore Structures (BOSS), Vol. 1.
14.
Nishimoto, K., Aranha, J. A. P., Matsuura, J. P. J., Kaster, F., Namba, H., and Masetti, I. Q., 1997, “Full Scale Decay Test of Moored Tanker: Measurement Procedure of Surge Damping,” OMAE 1997.
15.
Nakamura
,
N.
,
Koterayama
,
W.
, and
Kyozuca
,
Y.
,
1991
, “
Slow Drift Damping due to Drag Forces Acting on Mooring Lines
,”
Ocean Eng.
,
18
(
4
), pp.
283
–
296
.
16.
Nishimoto, K., Brinati, H. L., and Fucatu, C. H., 1995, “Analysis of Single Point Moored Tanker Using Maneuvering Hydrodynamic Model,” OMAE 1995.
17.
Nishimoto, K., Brinati, H. L., and Fucatu, C. H., 1996, “Dynamics of Moored Tankers-SPM and Turret,” ISOPE 1996.
18.
Nishimoto, K., Brinati, H. L., and Fucatu, C. H., 1996, “Dynamic Analysis of FPSO with a Tandem Offloading System,” OMAE 1996.
19.
Nishimoto, K., Brinati, H. L., and Fucatu, C. H., 1995, “Analysis of Single Point Moored Tanker Using Maneuvering Hydrodynamic Model,” Offshore Mechanics and Arctic Engineering OMAE–1995.
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