Date of Award

Fall 2001

Project Type

Dissertation

Program or Major

Engineering: Systems Design

Degree Name

Doctor of Philosophy

First Advisor

M Robinson Swift

Abstract

To satisfy the global need for seafood, marine aquaculture is expected to play an increasing role as wild fish stocks decline. The expansion of near-shore aquaculture is becoming more difficult because of multi-use issues and environmental impact concerns. As a result, a national objective has been initiated to establish an open ocean aquaculture industry. To design and evaluate fish cages and moorings for the energetic open ocean requires a systematic approach utilizing physical and numerical modeling techniques. Using these methods, two robust fish cage and mooring systems were designed, deployed and have survived two New England winters. Prior to the second winter, the north system was refurbished and deployed with nine, 89 kN capacity load cells on the mooring and a six degree of freedom accelerometer motion package inside the fish cage. During the redeployment of the cage, open ocean drag tests were performed. A buoy was also deployed to measure the surface wave forcing. Assuming a linear system, a stochastic approach was used to analyze the load response of critical mooring lines and the motion response characteristics of the fish cage in heave, surge and pitch. Transfer functions were calculated for northeast storms. These normalized functions were compared with results of multiple physical and numerical model tests. The comparisons were used to validate the methods and to understand the dynamics of the deployed system so that future fish cage and moorings are designed and evaluated accurately to assist a new aquaculture industry to become economically feasible.

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