博士 / 國立海洋大學 / 漁業科學學系 / 88 / Aquaculture not only contributes tremendously to aquatic product industry, but also earns valuable foreign exchange in Taiwan. Following the well-developed aquaculture, of the commensurate natural resources are paid for the lose such as stratums subside, soil salinized, and so on.
In order to reduce the loss and increase the aquatic product, aquaculture using marine net cage seems to be a positive way.
The objective of the project based on the protection of net cages from waves and strong currents by reduction of the swash through adjusting the tension in the mooring ropes. In present study, a 40cm´40cm´32cm traditional net cage model with a new design mooring rope net cage were used in a current — wave water tank. There were 4 kinds of sinker weights fastened to the bottom of net cage. The tension of the mooring rope was adjusted and measured under different flow velocity (V) and wave heights (H). The results are as follows:
Under the controlled condition, it was demonstrated that the maximum tension of the new design mooring rope to the net cage can be reduced to 55%, and the instantaneous tension of the new design mooring rope net cage was reduced to 44%. Due to the design of the elastic characteristics, the new design mooring rope net cage can further reduce the maximum tension and instantaneous tension against strong waves and current. This find was used in the development of an anti-wave mooring rope to protect the net cage.
The second experiment was conducted on the prevention of net cage deformation from waves and strong current by reducing the deformation rate through adding the stable rope to the net cage.
Under the second study, a 40cm´40cm´32cm traditional net cage model with a new design mooring rope net cage and a stable net cage were used as models in a current — wave water tank. There were 4 kinds of sinker weights fastened at the bottom of the net cage. The shape and volume of cage were determined and measured under different flow velocity (V) and wave heights (H). The results are as follows:
In the case of Velocity=15cm/sec and H=0 (waveless condition), it was determined that the relative volume ratio of the traditional net cage (35%) raised to 68% of the stable net cage. The volume deformation ratio of the traditional net cage was 90%, reduced to 50% of a stable net cage when against strong waves and current.
Due to the extra elastic space that a stable net cage provided more inner volume of cage, the fishes reared in such cage should have more moving living space than traditional net cage during strong waves and current condition. All the results will be used in the development of an anti-wave net cage for increasing the fish aquaculture production.
| Identifer | oai:union.ndltd.org:TW/088NTOU0451005 |
| Date | January 2000 |
| Creators | Kei-Chien Yu, 俞克儉 |
| Contributors | Yau-Shou Chow, 周耀烋 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 0 |
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