Specialized flotation to enhance oceanographic mooring performance
Abstract
Mooring structures are used in oceanographic research to hold scientific instruments inplace at various depths throughout the wate"r column. While they may be attached to surface buoys,it is often preferable to keep the entire structure below the surface to avoid ship traffic and surfacewaves. In these cases, the mooring wires are shorter than the water depth, and held upright by(submerged) flotation elements. Whenever ambient currents are strong, the moorings will beknocked down to some degree, depending on the amount of flotation and drag inflicted by thestructure itself. In applications where sampling at specific depths, especially in the upper watercolumn, is important, this results in an engineering challenge to minimize mooring knockdown.Here, acquisition of a buoyancy system composed of six specialized flotation elements is soughtthat will enable construction of an array of three moorings with minimal knockdown. These floatshave lower drag for a given amount of buoyancy than conventional floats (multiple 17~ glassspheres in plastic shells). The proposing investigators anticipate using such an improved mooringarray in the CALYPSO program. CALYPSO is an effort funded by ONR to investigate circulationnear a surface-intensified front in the Mediterranean Sea. CALYPSO~s need to make near-surfaceobservations despite strong surface currents is challenging for conventional subsurface mooringdesigns. The use of surface buoys instead is undesirable due to ship traffic and high cost. The lowdrag,high-buoyancy solution sought here provides the capability to make these measurementswith a subsurface mooring knockdown that is expected to be about four times smaller than thatobtained with conventional floats, which is a significant improvement that will benefit data qualityand better meet CALYPSO~s needs. Once these components are in hand, the ongoing operationalexpense for such moorings, already relatively low-cost, is also further reduced. The proposedbuoyancy components also take significantly less space on a research vessel, important for usingthe smaller ship ~SOCIB~ out of Mallorca.Simulating mooring knockdown for different configurations of buoyancy and currents is alreadypart of the class curriculum offered by the investigators at Scripps Institution of Oceanography.This happens in classes that teach observational methods of oceanography, and is open to studentsof oceanography as well as engineering. The flotation elements of this proposal will be integratedinto the mooring simulations done in class to enhance the learning experience for the futurestudents and train" them for more challenging mooring applications.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 13, 2019
- Source ID
- N000141912379
Entities
People
- Uwe Send
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego