Drawing
One drawing that shows how a U.S. Lake Survey vessel and crew are using a "Wire Sweep" in order to locate submerged obstructions. The drawing consists of ink and watercolor paint on heavy white cardboard. Adhesive paper labels and arrows provide brief descriptions of the equipment and the work operation. The typical sweep consisted of a line of about 15 flag buoys, spaced at 100-foot intervals, that supported an underwater wire at a set depth. The line of buoys would then be dragged across an area of water by launches at each end of the buoy line. If the wire encountered any submerged obstructions, it would cause one or more buoy flags to tip and thereby give an approximate location of an obstruction that could be investigated further. Such obstructions could then be plotted on the navigational charts that were produced by the Lake Survey Office.
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Drawing, Technical
Wire Sweep
Blueprint
U. S. Lake Survey, Detail of Intermediate Sweep Float
