Researchers Design New Towing Carriage

Researchers at the U.S. Naval Academy are designing a towing carriage to be fitted to the existing ESTEX (Estuarine Experimental) facility located at the Engineer Research and Development Center (ERDC) Coastal and Hydraulic Laboratory in Vicksburg, MS.  The carriage is to span the 60-ft width of the ESTEX facility’s main basin and be able travel the 480-ft length of the basin at programmed speeds up to 10 ft/s.  The water depth in the basin is variable up to a maximum of approximately 4ft; induced currents may also be included.  The towing carriage is being designed to tow large-scale physical deep-draft vessel models maneuvering through non-distorted, scaled engineered channels.  This work and capability is to support the Vessel Motion in Confined Waterways/ Enhancements to ERDC-WES Channel Analysis and Design Evaluation Tool (CADET) work unit of NETS.

Additional capabilities of the towing system design, including the ability to test two or more different captured vessels in a passing scenario are also being explored.  A modular horizontal planar motion mechanism design is also being investigated.  The researchers are studying towing carriage designs from many domestic and international existing and retired hydrodynamic facilities, and are consulting and collaborating with colleagues from the Naval Surface Warfare Center and MARIN, among others.  Specific challenges to the ESTEX carriage design include overhead clearance limitations of the existing facility, potential for excessive flexibility and modes of vibration due to the large required span, and questionable foundation and surrounding geotechnical environment.

The design of the towing carriage will be modeled using static and dynamic finite element analysis (FEA).  Once installed, the carriage will be used to experimentally test the behavior of physical model vessels within varying model channel configurations and at varying speeds. Data and information collected from this new and unique capability will be analyzed to refine engineering guidance for waterway design, economic analysis, and algorithms for virtual simulation of vessel operations.  Improved methods and numerical relationships for prediction of dynamic squat or hull sinkage under varying channel conditions can be applied to both economic and engineering analysis of waterway planning and design, as well as improvement of computerized or virtual simulation of vessel response within confined waterways.

revised 8/22/06