NEW DEVELOPMENTS IN PREDICTION OF MOORING SYSTEM DAMPING

Drag forces on the mooring lines can represent the dominating contribution of the surge damping of moored vessels. In order to calculate this damping effect correctly one normally has to take into account the effect of the wave-frequency motions of the vessel, superposed on the low-frequency, resonant motions, whose damping we wish to predict. This paper suggests a simple and practical procedure for this purpose. It applies the concept of "apparent drag coefficient" in combination with an iterative use of a catenary equations to obtain the low-frequency damping. The range of applicability of this procedure covers most practical mooring configurations. Only in cases of very deep water, heavy lines, and suspended clump weights it may be necessary to use a complete FEM procedure to get the effect of wave-frequency motions and line dynamics accurately described. The paper also publishes for the first time results from investigations of the possible heave damping effect of the mooring system. It turns out to be normally negligible for moored ships, moderate but significant for semisubmersibles, and can be dominating the heave damping of spar buoys.

• Supplemental Notes:
  • OTC 91, 23rd Annual Offshore Technology Conf; 6-9 May 1991; Houston, Tx, USA. Procs. Vol 2, Ppr OTC 6593, p 291 [8 p, 6 ref, 4 fig]
• Authors:
  • Huse, E
• Publication Date: 1991

Language

• English

Subject/Index Terms

• TRT Terms: Damping (Physics); Mooring; Moorings; Motion; Surging
• Subject Areas: Marine Transportation; Terminals and Facilities;

Filing Info

• Accession Number: 00701259
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Aug 14 1995 12:00AM