The purpose of this paper is to study the dynamic motion and mooring line tension of an in-situ single-point-mooring (SPM) net cage system, and then the field tension data were utilized to validate the numerical model for cages. This prototype SPM cage system was installed at water depth about 30 m in the north of Hsiao-Liu-Chiu Island. On the mooring line, a load cell was fixed so that the environmental loading on the net cage were sensed and recorded in the data log. In addition, an ADCP was bottom mounted near the concrete anchor to measure the sea states simultaneous. All of these data were analyzed and used as input for the numerical model of cage. This numerical model was based on the lump mass method to form a set of motion equations and adopted the Runge-Kutta fourth order method to simulate the cage¡¦s dynamic motion.
The results shows that the sea surface is quite calm and the current speeds are usually less than a half knot at the tested site. If waves occurred, then its direction is always around 270¢X~360¢X which means the wave direction is usually normal to the shore line. During study period, a strong typhoon TALIM attacked the site on September 1st , 2005. The maximum mooring line tension of net cage 530 kg was recorded by the data log. However, it was much smaller than the breaking strength of mooring line which means that the cage system is quite safe for this typhoon event. The developed numerical model has been validated by good agreements between the numerical results and the field tension data. One more thing worthy to mention is the final position of net cage may drift to the on-shore direction just as the same direction of the incident waves.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0828107-201448 |
| Date | 28 August 2007 |
| Creators | Wang, Bo-seng |
| Contributors | John R.C. Hsu, Chai-cheng Huang, Mao-seng Su |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0828107-201448 |
| Rights | off_campus_withheld, Copyright information available at source archive |
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