U.S. Geological Survey Open-File Report 2007-1194

Figure 4.  Images of several kinds of tripod frame employed in CMGP research programs.

Figure 4.

4A. Large bottom tripod frame being deployed from the U.S. Coast Guard Cutter Marcus Hanna at a site in Massachusetts Bay. These frames were used extensively to collect near-bottom observations along the East Coast of the United States. The tripod frame, made of stainless steel pipe, is 4.6 meters high. The frame and attached instruments are lowered to the seafloor, where they collect and record data unattended for about 4 months. For recovery, an acoustic signal releases the floats on the top of the tripod that pull a recovery line to the surface, allowing the tripod to be raised. The current sensors on this tripod include an Acoustic Doppler Current Profiler (ADCP) and a Benthic Acoustic Stress Sensor (BASS).

4B Three types of bottom frames on the dock just prior to loading aboard ship for deployment as part of an experiment near Myrtle Beach, South Carolina.

4C A small tripod frame, about 1.5 meters high, being deployed at a site in Massachusetts Bay. An ADCP and sediment trap are mounted on this frame. The same recovery mechanism is used on both sizes of tripod.

4D The instrument package used in the Lydonia Canyon experiment on the continental slope near Cape Cod was designed to obtain near-bottom observations in areas of rough topography or where extreme sediment transport might bury the instruments and in water depths were a standard tripod could not be deployed. The package deployed in a subsurface mooring and was supported by a subsurface float about 2 meters above the seafloor. Mounted on the frame were a Vector Averaging Current Meter (VACM) (mounted 180° from normal configuration), transmissometer, sediment trap, and time-lapse camera. A vane oriented the triangular frame so that the current meter faced into the flow.