Webb Research Slocum Glider
The Slocum Glider is a 1.8 m long, 21.3 cm diameter, 52 kg, autonomous underwater gliding vehicle, manufactured by Webb Research Corporation (USA). Designed to operate in water depths of 4 � 200 m the glider travels through the water column in a sawtooth pattern using a �buoyancy engine�. By drawing in or expelling water the glider can change its density making it more (less) buoyant than the surrounding water causing it to ascend (descend).
This momentum is converted to forward motion by its wings. Pitch adjustments are made by moving an internal mass (battery pack) and steering done using a rudder. Moving at an average forward velocity of 25 - 40 cm/s the glider navigates its way to a series of pre-programmed waypoints using GPS, internal dead reckoning and altimeter measurements. Operating on C cell alkaline batteries, the typical range of operation is 1500 km with duration of around 30 days.
Communications with the glider is undertaken through line of sight high bandwidth radio frequency modem or by iridium satellite modem allowing near real-time data transmission and remote updating of mission instructions. An ARGOS transmitter is installed to aid in recovery. All communication and GPS antennas are all located within the glider�s tail fin which is positioned out of the water during surfacing.
