Glossary of navigational warning terms

Navigational warnings are written as telegrams, for a watch officer who already knows the code: upper case, no articles, positions in degrees and minutes, times in UTC date-time groups, and stock phrases repeated thousands of times. This glossary explains the terms that do most of the work — what each means, why it is there, and, from the archive, how often and where it has been used.

Reading one warning, line by line

  1. HYDROLANT 1159/12The series and number: the 1,159th HYDROLANT of 2012, issued by the U.S. National Geospatial-Intelligence Agency for Atlantic waters. more →
  2. ENGLISH CHANNEL.The general area. NGA headings narrow from ocean region to sea or country, so the heading alone tells you where to look.
  3. CHART 36050The chart the danger falls on, so a navigator can find and mark it. more →
  4. 1. SUBMERGED OBSTRUCTIONThe danger itself. Something on or near the seabed — the warning does not say what, because often nobody knows yet. more →
  5. VICINITY 49-40.8N 003-43.8W.Where: 49° 40.8′ N, 3° 43.8′ W. "Vicinity" says the position is approximate. more →
  6. WIDE BERTH REQUESTED.The instruction to the reader: keep well clear. more →
  7. 2. CANCEL HYDROLANT 1085/12.This message replaces an earlier one. Warnings about an unresolved danger are often reissued this way, each cancelling the last, until the danger is charted or removed. more →

The full record: HYDROLANT 1159/12.

The term list is temporarily unavailable.

Archive counts appear after the nightly count. The explanations are written by seahazards; the quoted warning text is the issuing service's. Not for navigation.