Session: 01-06-01 CFD Modeling and Offshore Applications

Submission Number: 181581

Heading Behavior of Weathervaning Ship Units in Cyclonic Conditions: Field Measurement vs. Analysis 

A global performance study of a weathervaning ship unit requires the prediction of its heading behavior prior to any response analysis. This is fundamental to both mooring and hull design and for operational analyses. The standard approach calculates the mean heading when the yaw moments acting about the vessel’s turret axis reaches static equilibrium. These yaw moments arise from wave drift forces, wind loads, and current forces acting on the vessel. This method, known as a quasi-static heading analysis, is computationally efficient and widely used in practice.

Given the vital role of heading prediction in accurately calculating vessel responses, particularly during extreme events such as a tropical cyclone, validation against full-scale measurements is essential. However, such validations are rarely documented in the literature, especially for permanently moored ship units that have experienced cyclonic events during operation. This scarcity is attributed to the limited number of such units designed to remain on station during cyclonic events, and the infrequent occurrence of such phenomena, which together restrict opportunities for gathering relevant field data to conduct a validation.

This work validates a quasi-static heading analysis approach by comparing predictions with measured headings from two permanently weathervaning moored ship units during the passage of an historic cyclone that occurred in the Northwest Shelf of Australia. Cyclone tracks from the Australian Bureau of Meteorology (BoM) for 2017-2022 were analyzed to identify suitable events, and a strong cyclone that passed near the two adjacent facilities was selected. Heading records from both facilities were obtained, along with concurrent directional wave, wind, and current field measurements. Additionally, wind field data from the ERA5 satellite reanalysis database provided supplementary information. Following data examination and consolidation, vessel headings for each facility were calculated and compared well with the measured values. Key features of the heading behavior are identified and explained, including each vessel’s heading direction and its rate of change, encounter angles, metocean effects and their relative contributions to each vessel’s heading behavior through the cyclone’s passage.

Presenting Author: Michael Binsar Lubis The University of Western Australia

Presenting Author Biography: Michael Binsar Lubis, commonly known as Binsar, is a postdoctoral research fellow at The University of Western Australia. He earned his bachelor’s degree from Institut Teknologi Bandung (ITB), Indonesia, followed by a master’s degree from the Norwegian University of Science and Technology (NTNU), Norway. He subsequently completed his doctoral studies at The University of Western Australia, where he integrated numerical simulation, machine learning, and wave flume experimentation to enhance the operational capabilities of ultra-deep-water remotely operated vehicles (ROVs).
In addition to his academic pursuits, Binsar has contributed to several government and industry projects. His professional experience includes roles as a structural engineer at ENI Indonesia, a hydrodynamic expert for the Indonesian Ministry of Public Works on a large-scale seawall project aimed at mitigating flood risks, and as a deputy project manager at Tractebel Indonesia, where he was instrumental in the design and construction of a 192 MWp floating solar power system.
Currently, as a member of the TIDE Research Hub at The University of Western Australia, Binsar is conducting research focused on the performance of weathervaning facilities in cyclonic environments. He is also actively involved in several academic projects related to floating solar systems.

Authors:

Michael Binsar Lubis The University of Western Australia
Yuriy Drobyshevski NavTec Pty Ltd
Mehrdad Kimiaei The University of Western Australia
Michael Morris-Thomas The University of Western Australia