Navigation Center
United States Coast Guard
U.S. Department of Homeland Security

LNM Frequently Asked Questions

What is a Local Notice To Mariners (LNM)?

The LNM is the primary means for disseminating information concerning aids to navigation, hazards to navigation, and other items of marine information of interest to mariners on the waters of the United States, it's territories, and possessions. These notices are essential to all navigators for the purpose of keeping their charts. Light Lists, Coast Pilots and other nautical publications up-to-date. These notices are published weekly. The LNM's are available on the World Wide Web. Vessels operating in ports and waterways in several districts will need to obtain the LNM's from each district in order to be fully informed.

How does the Coast Guard develop an LNM?

Each Coast Guard District is responsible for developing and issuing LNMs. LNMs are developed from information received from Coast Guard field units, the general public, the Army Corps of Engineers, U.S. Merchant Fleet, National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), and other sources, concerning the establishment of, changes to, and deficiencies in aids to navigation and any other information pertaining to the safety of the waterways within each Coast Guard District. This information includes: Reports of channel conditions, obstructions, hazards to navigation, dangers, anchorage's, restricted areas, regattas, information on bridges such as proposed construction or modification, the establishment or removal of drill rigs and vessels, and similar items.

What are LNM enclosures?

Enclosures contain NOS chartletts of a local area of tabulations of controlling depths, excerpts from Code of Fed regulations regarding marine laws or regulations, marine events, Corps of Engineer report of channel condition survey sheets, Coast Pilot corrections, and more.

What is a Coast Guard Light List?

The Coast Guard Light Lists are published in seven volumes covering the U.S. Coasts, the Great Lakes, and the Mississippi River System. These are complete listings of all lights, buoys, daybeacons, ranges, fog signals, radiobeacons, and radar beacons (RACONS); detailed information is given on each aid including position (where necessary), shape, color, and characteristics. In addition, each Light List volume contains introductory pages with general information on aids to navigation and their use, and the GPS, DGPS, and LORAN- C radionavigation systems. Each volume is republished annually, but during the year should be kept continuously corrected from the Local Notice to Mariners.

You may download weekly updates to the Light List corrected through each LNM week (displayed on the header of each page). The weekly Light Lists are provided in two formats: PDF and XML.

What is a Light List Number (LLNR)?

Light List numbers are assigned to all aids to navigation in order to facilitate reference in the Light List and to resolve ambiguity when referencing aids. Aids are tabulated in the same sequence as lights are numbered - basically, clockwise around the U.S. Coasts from Maine to Florida to Texas, California to Washington, east to west on the Great Lakes, and upriver in the Mississippi River System; seacoast aids are listed first in the applicable volumes, followed by harbor and river aids, and then Intracoastal Waterways aids, if applicable.

What is a Coast Pilot?

Just as for aids to navigation, charts are limited in what can be shown by symbols and abbreviations regarding channels, hazards, winds and currents, restricted areas, port facilities, pilotage service, and many other types of information needed by a navigator for safe and efficient navigation. These deficiencies are remedied by the Coast Pilots published by National Ocean Service (NOS). U.S. Coast Pilots are published in nine volumes to cover the waters of the U.S. and it's possessions. They are of great value to a navigator when used with charts of an area both during the planning stage of a voyage and in the actual transit of the area.

Where do I obtain nautical charts?

The principal U.S. Agencies involved with nautical charts are the National Ocean Service (NOS) and the National Geospatial-Intelligence Agency (NGA). Both of these agencies have branch or regional offices, plus a network of local sales agents from whom charts and other publications can be obtained. Charts or "navigational maps" of some inland rivers, primarily the Mississippi, Ohio, Tennessee, and their tributaries, are prepared by the Army Corps of Engineers. Such charts or maps are normally purchased from District Engineer Offices. The FAA also maintains their own list of aeronautical and nautical authorized chart sales agents.

How do I know what chart to use ?

Charts are published with an edition number and the date to which the information it contains has been corrected. The NOS and the NGA publish chart catalogs consisting of various pages or panels showing the area covered by each chart.

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