U.S. Department of Defense


Date of this Version



Published in Hydraulic Engineering: Saving a Threatened Resource—In Search of Solutions: Proceedings of the Hydraulic Engineering sessions at Water Forum ’92. Baltimore, Maryland, August 2–6, 1992. Published by American Society of Civil Engineers.


A towable sled was developed at the Hydraulics Laboratory of the Waterways Experiment station in conjunction with SIRAD, Inc. to survey navigation channels with "fluff" or fluid mud. Fluid mud layers on the bottom of navigation channels can result in a false bottom record when surveyed with conventional acoustic fathometers. The WES gage was designed to tow along channel bottoms at a specific gravity of about 1.15- 1.20 g/cc and coincide with nautical depth. To monitor this towed density value, a nuclear density gage was installed in the original prototype. Field trials have been completed at the Gulfport, MS, Calcasieu, LA, and Sabine Pass, TX navigation channels. Data are presented that show the sled tracks a fairly constant density level at a given site, and that its depth is situated between the high and low frequency acoustic depths in channels with a significant layer of fluid mud.