THE CONTRIBUTION OF HYDRODYNAMIC DAMPING INDUCED BY MOORING CHAINS ON LOW-FREQUENCY VESSEL MOTIONS

To compute the low-frequency mooring forces of a turret-moored storage/production tanker exposed to survival conditions, the hydrodynamic excitation and reaction forces must be known. The low frequency excitation is assumed to be caused by the velocity- dependent wave drift forces. The hydrodynamic reaction forces consist of the added mass forces; the low-frequency viscous forces and the wave drift damping on the tanker; and the damping forces acting on the chain legs. Although investigations on chain damping have been carried out, data on low-frequency chain damping are scarce. This paper describes oscillation tests and damping computations on chain legs in a current and in still water, where the assumed water depths amounted to 82.5 and 247.5m. The first part of the paper concerns the determination of the chain damping due to the oscillating motions of the low-frequency surge. In the second part, the effect of the combined low-frequency surge and wave frequency heave motions on the chain damping are investigated. Finally, the simulation of the simultaneous occurrence of the low- and high-frequency motions is discussed.

  • Supplemental Notes:
    • Conference paper; Paper OTC-6218
  • Authors:
    • Wichers, J E
    • Huijsmans, R H
  • Conference:
  • Publication Date: 0

Media Info

  • Features: References;
  • Pagination: 12p.

Subject/Index Terms

Filing Info

  • Accession Number: 00660824
  • Record Type: Publication
  • Source Agency: Maritime Technical Information Facility
  • Files: TRIS
  • Created Date: Jul 21 1994 12:00AM