WATERMARK Sounding Reel & Sounding Weight : The bridge board was designed for use in making discharge measurements and obtaining water quality samples from off of bridges. It is a free-standing support, accommodating A-Pack, A- 55 or B-56 sounding reels. It comes with an adjustable foot rest which makes it easily adaptable to bridge railings of different heights and walkways of various widths. In use, the Bridge Board is set to the approximate height of the bridge rail at the measurement site. With the sounding reel secured to the mounting plate, the boom is positioned so the sheave extends out past the bridge rail. The suspension cable is now stretched out over the sheave at the end of the 4 foot long boom. The current meter or sampler is then suspended from the cable and is in position to be lowered into the water below. The maximum sounding weight to be used with the bridge board is 50 pounds ( 23 kg) .

The A-Pack Reel is used to position stream gaging and sample collection equipment. The reel is small and compact and was designed for use at remote sites where it is necessary for the hydrologist to backpack or  hand carry the stream gaging equipment for some distance. It is for use with weights up to 50 pounds ( 23 kg) . The USGS bridge board mount plate and the cable car reel mount plate are drilled to accommodate this reel. The reel is equipped with a removable handle, and is equipped with a counter to measure water depth in feet. The drum has 45 feet ( 13.7m) of 0.10 in. Ellsworth cable. The A-Pack reel comes in a steel carrying case as shown with the reel. See the Technical Data page for more information on sounding reel selection.

The A-55 Sounding Reel is used to position stream gaging and sample collection equipment. The reel is used with weights up to 100 pounds ( 45 kg) and holds 75 feet ( 22.9 m) of 0.10-inch ( 0.25cm) cable. The reel can be mounted on Type A and Type E cranes, the bridge board, the sit-down or stand-up cable car, and the boat boom assembly. The A-55 reel is equipped with a USGS-type computing depth indicator and can be furnished to read in either English or metric ( A-55M) units.