A Wire-Guided, Free-Fall System to Facilitate Shipborne Hydrographic Profiling

J. M. Toole Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

Search for other papers by J. M. Toole in
Current site
Google Scholar
PubMed
Close
,
K. W. Doherty Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

Search for other papers by K. W. Doherty in
Current site
Google Scholar
PubMed
Close
,
D. E. Frye Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

Search for other papers by D. E. Frye in
Current site
Google Scholar
PubMed
Close
, and
R. C. Millard Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

Search for other papers by R. C. Millard in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

The design and performance of a new style underwater frame for supporting instrumentation and water collection bottles used in hydrographic sampling is presented. Unlike a conventional frame that is fixed to the end of an electromechanical cable, the new frame is free to slide vertically along its tether. Allowing the frame to move relative to the sea cable decouples the underwater instrumentation from ship roll on downcast. Improved data quality from CTD instrumentation and the ability to work in more severe sea states result. Furthermore, the chance of cable damage that occurs when wire speed (lowering rate plus ship roll velocity) exceeds the terminal velocity of conventional underwater packages is greatly reduced. Absence of direct electrical connection to the underwater instrumentation necessitates an alternative scheme for real-time data display and command of water sample collection. These are accomplished with an acoustic telemetry system, implemented using commercially available components.

Corresponding author address: John M. Toole, Dept. of Physical Oceanography, Woods Hole Oceanographic Institution, Mail Stop 21, Woods Hole, MA 02543.

Email: jtoole@whoi.edu

Abstract

The design and performance of a new style underwater frame for supporting instrumentation and water collection bottles used in hydrographic sampling is presented. Unlike a conventional frame that is fixed to the end of an electromechanical cable, the new frame is free to slide vertically along its tether. Allowing the frame to move relative to the sea cable decouples the underwater instrumentation from ship roll on downcast. Improved data quality from CTD instrumentation and the ability to work in more severe sea states result. Furthermore, the chance of cable damage that occurs when wire speed (lowering rate plus ship roll velocity) exceeds the terminal velocity of conventional underwater packages is greatly reduced. Absence of direct electrical connection to the underwater instrumentation necessitates an alternative scheme for real-time data display and command of water sample collection. These are accomplished with an acoustic telemetry system, implemented using commercially available components.

Corresponding author address: John M. Toole, Dept. of Physical Oceanography, Woods Hole Oceanographic Institution, Mail Stop 21, Woods Hole, MA 02543.

Email: jtoole@whoi.edu

Save
  • Baumeister, T., and L. S. Marks, Eds., 1967: Standard Handbook for Mechanical Engineers. 7th ed. McGraw-Hill, 3–69 pp.

  • Berteaux, H. O., R. G. Walden, P. R. Clay, and R. E. McDevitt, 1993: WHOI Tech. Rep. WHOI-83-21, 39 pp. [Available from Woods Hole Oceanographic Institution Document Library, McLean Laboratory MS8, Woods Hole, MA 02543.].

  • Düing, W. O., and D. R. Johnson, 1972: High resolution current profiling in the Straits of Florida. Deep-Sea Res.,19, 259–274.

    • Crossref
    • Export Citation
  • Fofonoff, N. P., E. Levy, A. J. Kettle, and R. C. Navitsky, 1990: Report on R.V. Akademic Vernadsky Cruise 39, Stave IV. June 17–July 17, 1989. Woods Hole Oceanographic Institution Tech. Rep. WHOI-90-12, 87 pp. [Available from Woods Hole Oceanographic Institution Document Library, McLean Laboratory MS8, Woods Hole, MA 02543.].

    • Crossref
    • Export Citation
  • Giles, A. B., and T. J. McDougall, 1986: Two methods for the reduction of salinity spiking of CTDs. Deep-Sea Res.,33, 1253–1274.

    • Crossref
    • Export Citation
  • Gregg, M. C., J. C. Schedvin, W. C. Hess, and T. B. Meagher, 1982: Dynamic response calibration of the Neil Brown conductivity cell. J. Phys. Oceanogr.,12, 720–742.

    • Crossref
    • Export Citation
  • Lueck, R. G., O. Hertzman, and T. R. Osborn, 1977: The spectral response of thermistors. Deep-Sea Res.,24, 951–970.

    • Crossref
    • Export Citation
  • Merriam, J. S., and J. M. Toole, 1991: Application of acoustic telemetry for tethered shipboard oceanographic instrumentation. EOS,51 (Suppl.) 31.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 335 118 0
PDF Downloads 58 19 1