The United States Coast Guard is evaluating the use of automatic Loran-C user equipment aboard a commercial iron ore carrier transiting the Great Lakes and the St. Marys River. The St. Marys River, located in northern Michigan near the city of Sault Ste. Marie, serves as the only water shipping route connecting Lake Superior with the rest of the Great Lakes and the St. Lawrence Seaway. The 65-mile river, which is traversed by iron ore carriers up to 1000 feet long and 105 feet wide, has channels as narrow as 300 feet. An experimental Loran-C mini-chain with two stations in Canada and two in Michigan was established by the Coast Guard in 1976 to investigate the feasibility of providing an all-weather, year-round navigation capability. Shipboard user equipment has been developed to process the mini-chain signals and provide continuous position fixes on the river. Initial tests were performed on U.S. Coast Guard vessels to determine the feasibility of using Loran-C as a navigation aid on the St. Marys River. Further tests were performed in the summer of 1977 on the Arthur M. Anderson, a 767-foot Great Lakes iron ore carrier. This paper describes the operational environment, Loran-C mini-chain, shipboard user equipment and results of the feasibility tests and ore carrier installation. The ore carrier installation has shown the ability of the mini-chain and user equipment to provide useful, timely guidance information in restricted waters. However, further investigation of apparent temporal instabilities in the Loran-C time difference grid is needed.

  • Supplemental Notes:
    • Symposium Papers presented at RTCM Assembly Meeting April 17-20, 1978, Detroit, Michigan and Windsor, Canada. With participation of International Association of Great Lakes Ports. Volume 2, Navigation.
  • Corporate Authors:

    Radio Technical Commission for Marine Services

    /Federal Communications Commission
    Washington, DC  United States  20554
  • Authors:
    • Olsen, D L
  • Publication Date: 1978

Media Info

  • Features: References;
  • Pagination: 12 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00184781
  • Record Type: Publication
  • Source Agency: Radio Technical Commission for Marine Services
  • Report/Paper Numbers: Paper No. 2.B
  • Files: TRIS
  • Created Date: Jan 13 1979 12:00AM