This article details the replacement of conventional determination for sea vessel clearances, which uses the location of the sea floor or height of overhead structure and the location of the ship’s keel and mainmast, by renegotiating these data points toward a time-invariable ellipsoidal model. To acquire ellipsoidal depths and overheads, researchers used a combination of Global Positioning System (GPS) surveys and acoustic soundings. For low waters, coast lines, and inside harbors, the sensitivity of the ellipsoid can be established using differential GPS (DGPS), which measures accurately within five to ten centimeters. The article concludes that the necessity of finding a ship’s squat, draft, and settlement during bathymetric surveying will be mitigated by determining the ship’s invariant zero reference surface, or vertical datum, and that, consequentially, the older time-variant method, which requires complex calculations with regard to tide, will be eliminated.

  • Availability:
  • Supplemental Notes:
    • Page range: pp 16-17,20-21
  • Corporate Authors:

    Advanstar Communications, Incorporated

    131 West First Street
    Duluth, MN  United States  55802-2065
  • Authors:
    • Kumar, M
    • Maul, G A
  • Publication Date: 2005-9


  • English

Media Info

  • Features: Figures; Photos;
  • Pagination: 4p
  • Serial:
    • GPS World
    • Volume: 16
    • Issue Number: 9
    • Publisher: Advanstar Communications, Incorporated
    • ISSN: 1048-5104

Subject/Index Terms

Filing Info

  • Accession Number: 01005602
  • Record Type: Publication
  • Source Agency: UC Berkeley Transportation Library
  • Files: BTRIS, TRIS
  • Created Date: Oct 19 2005 2:04PM