Date of Award

Winter 2007

Project Type


Program or Major

Electrical Engineering

Degree Name

Master of Science


The University of New Hampshire's Open Ocean Aquaculture Project operates offshore fish cages in the exposed ocean near the Isle of Shoals. A need exists for improved vertical control of their cages that would permit continuous depth control, communication with operators, and logging of data. This thesis investigates the feasibility and practicality of applying a computer controlled lifting system to an experimental fish cage.

The submersible fish cage investigated has a diameter of 15.54 meters, and in internal volume of approximately 1500 cubic meters. The cage is moved through the water column via an airlift located beneath the cage. Air is supplied from the surface. A series of valves controls the inlet and outlet of air. The project included investigation of lifting systems, design and selection of components, software design, and computer simulation. The computer control system was implemented on a physical scale model for verification of the system's operation. The analysis, simulation, and physical testing showed the system operated and can be applied to a full scale cage.