MOORING LINE DAMPING FOR SLOW DRIFT OSCILLATION OF SEMISUBMERSIBLES

Dynamic tensions of mooring lines may be ignored in the estimation of wave frequency motions of a floating structure, but for slow drift oscillations hydrodynamic forces acting on mooring lines are important, because drag forces acting on mooring lines act as the damping force and have a great effect on the slow drift oscillation. When dynamic tension of mooring lines are calculated in full consideration of added mass forces and drag forces acting on mooring lines, a numerical calculation such as Lumped Mass Method is usually used. The numerical calculation needs prohibitively long computer time and it is not practical in the early stage of the design of a floating structure. The authors have developed an Approximate Method for calculating the dynamic tension taking the added mass force and drag force into consideration. The method has a short computation time and the accuracy has been confirmed by comparing calculated results with experiments. In this paper a Modified Approximate Method extended to the time domain problem is presented. The calculated results are compared with the experimental ones and they are found to be in good agreement.

• Supplemental Notes:
  • J. Soc. Naval Architects Japan 166 (1989) p.163 (Dec.) [10 p., 20 ref., 21 fig.]
• Authors:
  • Nakamura, M
  • Kyozuka, Y
  • Koterayama, W
• Publication Date: 1989

Language

• Japanese

Subject/Index Terms

• TRT Terms: Mooring; Semisubmersibles; Tractive forces
• Old TRIS Terms: Drift forces
• Subject Areas: Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 00697520
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Aug 14 1995 12:00AM