FISH FARMING TECHNOLOGY
A moving performance: Quiet, efficient thrusters make a big splash in aquaculture by Vaughn Entwistle, Managing Editor, International Aquafeed
A few years back, I was attending an aquaculture show when I first saw the Electric Subsea Thruster as produced by Danish company Copenhagen Subsea A/S. Unlike typical propellers, this clever design used a ducted, rim-driven impeller. The design has many advantages. The thruster contains only one moving part: the durable composite rotor. No mechanical parts touch, which reduces the risk of entanglement. The thrusters are very compact and use no internal gearbox, dramatically reducing the need for maintenance. The thrusters use seawater for both lubrication and cooling and are very powerful, while their design makes them very quiet in operation, which is a huge bonus for aquaculture operations where noise greatly stresses fish. The revolutionary thrusters are currently being used in Remotely Operated Vehicles (ROVs), Autonomous Underwater Vehicles (AUVs) and in manned submersible vehicles.
Pushing cold water to the surface
Now, the company’s thrusters are being used in novel new way for aquaculture applications. Instead of propelling a vehicle through the water, the thrusters are being used as highly efficient pumps, which remain fixed in position while propelling a high volume of water. By creating a flow of water from 30-40 metres of water 36 | November 2019 - International Aquafeed
By only creating flow in one part of the fish cage, it enables the fish to freely choose when to play in the stream and when to take a break in still water