The SeaSoar, manufactured by Chelsea Instruments, Ltd., is a towed vehicle equipped with
impeller-forced wings that can be rotated to allow the vehicle to undulate in the upper ocean. The
wings are controlled through the multi-conductor tow cable by sending current signals generated
by a PC-based controller onboard ship to a hydraulic unit inside the vehicle. Typical
instrumentation includes a
SeaBird 911+ CTD with pressure and dual conductivity and
temperature sensors, and optical instrumentation such as fluorometer, transmissometer, PAR
sensor, an experimental bioluminescence sensor and others.
Under the original open-ocean configuration, SeaSoar undulates between the surface and about 400 meters depth while being towed on faired cable at about eight knots. A typical dive cycle takes about 12 minutes to complete, providing an up- and down profile every 3 km. We obtained more frequent sampling during our shallow water experiments (PRIMER, GLOBEC), where a complete dive cycle down to 100 meters takes on average three minutes, providing a horizontal resolution of about 400 meters at mid-depth.
Since late 1996 we have used a glass fiber tow cable instead of the traditional copper-conductor cable to allow the transfer of video signals. As of 1998, new bio-optical sensors such as the HiStar by WetLabs with high output rates prompted the further development of fiber optic data transfer to include serial data as well.