Full Content is available to subscribers

Subscribe/Learn More  >

Viscous Damping Effects on Heading Stability of Turret-Moored Ships

[+] Author Affiliations
Razieh Zangeneh, Krish P. Thiagarajan, Raul Urbina

University of Maine, Orono, ME

Zhigang Tian

Exmar Offshore Company, Houston, TX

Paper No. OMAE2014-23638, pp. V08AT06A054; 7 pages
  • ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering
  • Volume 8A: Ocean Engineering
  • San Francisco, California, USA, June 8–13, 2014
  • Conference Sponsors: Ocean, Offshore and Arctic Engineering Division
  • ISBN: 978-0-7918-4550-9
  • Copyright © 2014 by ASME


Tankers used for offshore oil production and storage are kept in station by turret mooring systems, enabling the vessels to weathervane in the direction of the dominant environmental loads. These passive weathervaning systems have been observed in model experiments to be ineffective in swell-dominated long wave conditions. Over a range of wavelengths from 0.6 < λ/L < 2 (L – ship length), the vessel was observed to lose heading control in head sea condition, due to a pitchfork bifurcation that is initiated at a critical wavelength of 0.73L. A notable feature of poor heading stability is the existence of a stable equilibrium at a large heading angle (50–60°) with respect to the direction of oncoming waves. With lack of heading control, the ship motions, principally roll, can increase thus affecting onboard operations.

Time domain analysis conducted with no added viscous damping shows reasonable agreement with experimental data for the final heading angle. Further numerical tests reported in a previous paper by the authors showed that small to moderate viscous damping in sway and yaw did not alter the final heading, while the role played by viscous damping in other modes (heave, roll and pitch) needed further investigation. This paper reports on a parametric study on the heading stability of a turret moored tanker using time domain tools. Viscous damping is systematically varied in different modes of motion and its effect on final heading equilibrium is assessed. It is shown that effects of pitch damping are stronger than heave or roll, and can eliminate heading instability altogether.

Copyright © 2014 by ASME
Topics: Stability , Damping , Mooring , Ships



Interactive Graphics


Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In