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ABSTRACT
An open ocean aquaculture net pen system was developed for offshore deployment south of the Isles of Shoals, New Hampshire, USA in 55 meters of water. Two cages were specified for the growout of summer,flounder as part of an interdisciplinary effort at the University of New Hampshire involving engineers, biologists, economists, and commercial fishermen. This effort included the design of mooring system suitable for the offshore environment. Assembly and deployment of these cages and associated moorings occurred in the summer of 1999. An overview of the procedures and techniques used during these efforts are presented here.
INTRODUCTION
The decline of fish stocks in the Northeast United States has been a motivating factor for expanding the role of aquaculture in the fishing industry. While there are many facilities that have been successfully raising salmon in near shore, protected sites, little has been done to move aquaculture offshore, where competition from shore based activities is eliminated. The need for grow-out space is a primary factor for moving offshore. The Open Ocean Aquaculture Demonstration Project has as its engineering goal the development of design, testing, modeling and monitoring tools for offshore, open ocean cages for grow-out space.
Ocean Spar Technologies manufactured the cages chosen for this project. The design of these cages uses tension lines to hold their shape when exposed to environmental loading. These cages require a mooring system to maintain their position on site and allow their survival at inclement weather and seastate. The design of the mooring system for this offshore installation is a critical element to the long-term success of the installation. Escape from destructive storm wave forcing is accomplished by lowering the cage from the surface position to a location below the grid line.
To meet the objective of designing a robust system a series of activities were performed by the faculty, staff, and students at the Jere A. Chase Ocean Engineering Laboratory (JACOEL). These activities include physical model testing and the development of numerical models to predict dynamic behavior. The physical modeling testing was accomplished using a 1/22.5 scale model, and the wave making and towing capabilities in the wave basin at JACOEL. A series of monochromatic wave tests were run to estimate the maximum dynamic loads and the...