The Seacat sensors are mounted on an oblong wire frame a water bottle can be attached to the wire above the frame to sample water. The frame is attached to a wire and lowered from the ship to depth and then brought back aboard. The data is downloaded to a computer after the Seacat is brought back aboard. The Seacat is smaller and easier to launch and retrieve but one of the disadvantages of using the Seacat is the data cannot be viewed until after the instrument has been brought back aboard ship. Temperature and conductivity is measured from water that is drawn into the system through an opening in the hull of the ship.
Salinity is derived from the temperature and conductivty variables.
A graphic readout is displayed in the Oceanographic lab on the ship so that scientists always have this information available.