Accession Number:

ADA088340

Title:

Horizontal Datums for Nautical Charts,

Descriptive Note:

Corporate Author:

DEFENSE MAPPING AGENCY HYDROGRAPHIC/ TOPOGRAPHIC CENTER WASHINGTON DC

Personal Author(s):

Report Date:

1980-07-01

Pagination or Media Count:

23.0

Abstract:

Marine navigation charts are based on many and varied geodetic datums in use throughout the world. These datums range from local datums to the DoD World Geodetic System WGS 1972. In many cases, the datums for adjoining charts will differ, although this difference will usually introduce only minor errors into the solution of navigational problems. There are times, however, when even small errors can be very disconcerting, if not dangerous, and it is under these conditions that it is advantageous for the navigator to possess some knowledge of the factors in datum selection and chart construction which lead to apparent discrepancies in position plotting. It is equally important for the chart compiler or cartographer to understand the basic principles of navigation and, therefore, the need for establishing clearly definable horizontal datums on charts. For this reason, the author has aimed at tracing the evolution of datums on Defense Mapping Agency DMA nautical charts, mainly for the benefit of cartographers who must realize how the product they produce impacts on the safety of navigation in ways other than the portrayal of up-to-date information such as navigation aids, depths, etc. This paper discusses the differences between chart datums and coordinates determined by using various navigation systems, accuracy requirements for nautical charts, navigation system accuracy requirements as related to datums, and datum transformation methods. Author

Subject Categories:

  • Cartography and Aerial Photography
  • Geodesy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE