Autonomous variable buoyancy system for marine farming.
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This thesis details the design build and testing of a variable buoyancy marine float for use in the Open Ocean Aquaculture sector. The aim of the design was to produce a float that could vary its buoyancy to account for a constantly increasing downward load. The emphasis was to maintain the same water depth through a marine farm growing season.
A literature review showed a wide range of variable buoyancy devices. There was a lack of emphasis on variable buoyancy devices for use in open ocean marine farms. Few designs were developed for long term autonomy or harsh conditions, leaving a gap for a new design to fulfil the needs of the New Zealand Aquaculture Industry.
A float using compressed air to displace water in the float to increase buoyancy was developed with off the shelf parts. A testing tank was constructed with appropriate anchor points for submersion testing. The float was tested at depths of up to 400mm using a load cell to determine if it was functioning correctly by measuring increasing load due to buoyancy. It was observed that the float operated as expected, with the results of the testing showing that the design is feasible. The design requires improvements before open water testing, but the proof of concept was demonstrated.