Click for animation of tow-yo method.

The CTD is towed behind the ship while being cycled through the bottom 200 meters or so of water where the hydrothermal plumes are located. This is an efficient strategy for mapping and sampling dispersing neutrally buoyant hydrothermal plumes because the amount of time the CTD is passing through unaffected regions of the seawater (i.e. 1000-2000 meters above the plumes) is minimized, resulting in relatively high density data along the tow track of the ship.

The ship can typically travel at a speed of about 1-1.5 knots (or 3-4km per hour).