Down-wire Net Monitor

The down-wire net monitoring system was purpose-built for BAS to enable live two-way communication with our pelagic net systems via a single conductive towing cable. It feeds back live information such as depth, temperature and light penetration from net-mounted sensors and allows researchers control of their nets during deployment.

The deck unit consists of a standard PC that is connected to the towing cable via a coaxial cable. The underwater unit consists of an underwater housing rated to a depth of 1,000m, which holds the electronics and a back-up battery. All sensors The housing has six connectors for a range of sensors (depth, conductivity/salinity, temperature, light intensity, flow/current and an altimeter), with two outputs ports for two-way control, e.g. to control net release mechanisms.

The system’s graphical user interface is divided into four parts:

  • Information from the underwater sensors;
  • A depth display showing the distance of the net from the seafloor, as well as any events such as net opening or closing;
  • A net control display;
  • A winch information display providing data including the amount of wire out and tension on the wire.

The system is very reliable as high levels of redundancy are built in and BAS have several replacement sensor units. All underwater units and the sensors are mounted on the same holder, facilitating fault-finding and cross-swapping.

Peter Enderlein

NERC BAS Head of AME Mechanical Engineering

Science and Technology team