Platforms
Each monitoring platform is 6 feet-9 inches by 11 feet and is anchored by a two point mooring. The mooring lines, which are ½ inch diameter nylon rope, connect to 3/8 inch diameter chain bridles that are bolted to the frame of the platform. The anchors are 400 pound concrete blocks.
Buoyancy is achieved with eight 24 inch by 36 inch by 16 inch dock floats, which combined provide 3,520 pounds gross buoyancy. Based on water displacement, each platform weighs about 1,700 pounds (excluding counterweights). Because the platforms are rectangular and have a relatively high center of mass in relation to the water surface (i.e., they are top heavy), 100 pound counterweights were added to the ends of each platform. The counterweights were placed 6 feet below the water surface and are attached to galvanized angle-iron sections that are bolted to the frame of the platform. The counterweights lower the center of mass, which stabilize the platforms when people work on them and during storms.
Two flashing beacons are mounted to each platform to ensure high visibility in dark conditions. The water quality profiling system and meteorological instruments are mounted to a steel "T" frame in the center of the platform. The profiling system is protected by two yellow fiberglass covers.
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Constructing the Overton Arm Basin and Virgin Basin platforms (left) and the completed Overton Arm Basin platform (right). |
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