drop keel

Drop keels

A unique feature of the vessel are two drop keels that contain an array of scientific instruments.

an inside view of the drop keel

Drop keel

The keels are about 1.3 metres wide by about 3.6 metres long – the shape of an aircraft wing – and are kept inside a tube in the ship. They can be lowered down to 4 metres below the hull, putting the acoustic equipment inside them well below the bubble zone as the vessel goes through the water.

The drop keels can be raised mid-voyage and sensors added, replaced or checked and then lowered down again.

A seawater inlet on the forward edge of one of the keels  allow scientists to collect uncontaminated seawater samples that can be used in the laboratories and on deck.

Other instruments mounted in, or on, the keels can:

  • measure the speed, direction and depth of currents – understanding current speed and direction is key to understanding the transport of heat in oceans
  • indicate fish abundance and size
  • detect fish schools and individual fish, giving location and depth relative to the vessel as it moves through the water
  • measure the velocity of sound in water – sound velocity affects depth calculations
  • measure the width and height and depth of a scientific trawl net carried behind RV Investigator – the net can be towed down to 4 kilometres deep and 6 kilometres aft of the vessel. Knowing how the size of the net mouth opening changes it moves through the water helps calculate abundance estimates for trawl catches, and improves understanding of the general behaviour of trawl nets
  • provide data on the position of instruments towed by or moored to the ship, increasing the spatial accuracy and precision of measurements.


Updated: 12 May 2016