Chart symbols and abbreviations (Chart No. 1)

Bowditch Ch. 4 §404

Nautical Charts Chart No. 1 (US) — "Symbols, Abbreviations and Terms used on Paper and Electronic Navigational Charts" — is the authoritative key to every symbol and abbreviation on a nautical chart: aids to navigation, bottom characteristics, depth contours, hazards, and the meaning of chart colours. A mariner reads a chart by decoding its symbols and abbreviations against Chart No. 1 before plotting.

33 CFR §62.21

General. (a) The navigable waters of the United States and non-navigable State waters after December 31, 2003, are marked to assist navigation using the U.S. Aids to Navigation System, a system consistent with the International Association of Lighthouse Authorities (IALA) Maritime Buoyage System. The IALA Maritime Buoyage System is followed by most of the world's maritime nations and will improve maritime safety by encouraging conformity in buoyage systems worldwide. IALA buoyage is divided into two regions made up of Region A and Region B. All navigable waters of the United States follow IALA Region B, except U.S. possessions west of the International Date Line and south of 10 degrees north latitude, which follow IALA Region A. Lateral aids to navigation in Region A vary from those descr…

33 CFR §62.23

Beacons and buoys. (a) Aids to navigation are placed on shore or on marine sites to assist a navigator to determine his position or safe course. They may mark limits of navigable channels, or warn of dangers or obstructions to navigation. The primary components of the U.S. Aids to Navigation System are beacons and buoys. (b) Beacons are aids to navigation structures which are permanently fixed to the earth's surface. They range from large lighthouses to small, single-pile structures and may be located on land or in the water. Lighted beacons are called lights; unlighted beacons are called daybeacons. (1) Beacons exhibit a daymark. For small structures these are colored geometric shapes which make an aid to navigation readily visible and easily identifiable against background conditions.…

33 CFR §62.25

Lateral marks. (a) Lateral marks define the port and starboard sides of a route to be followed. They may be either beacons or buoys. (b) Sidemarks are lateral marks which advise the mariner to stay to one side of the mark. Their most frequent use is to mark the sides of channels; however, they may be used individually to mark obstructions outside of clearly defined channels. Sidemarks are not always placed directly on a channel edge and may be positioned outside the channel as indicated on charts and nautical publications. (1) Port hand marks indicate the left side of channels when proceeding in the Conventional Direction of Buoyage. Beacons have green square daymarks, while buoys are green can or pillar buoys. (2) Starboard hand marks indicate the right side of channels when proceedin…

33 CFR §62.27

Safe water marks. Safe water marks indicate that there is navigable water all around the mark. They are often used to indicate fairways or midchannels, or the seaward end of channels. Safe water marks are colored with red and white vertical stripes. Beacons have an octagonal daymark; red and white buoys are spherical or display a red spherical topmark. [CGD 86-031, 52 FR 42640, Nov. 6, 1987, as amended by CGD 88-018, 54 FR 48608, Nov. 24, 1989]

33 CFR §62.51

Western Rivers Marking System. (a) A variation of the standard U.S. aids to navigation system described above is employed on the Mississippi River and tributaries above Baton Rouge, LA and on certain other rivers which flow toward the Gulf of Mexico. (b) The Western Rivers System varies from the standard U.S. system as follows: (1) Buoys are not numbered. (2) Numbers on beacons do not have odd/even lateral significance but, rather, indicate mileage from a fixed point (normally the river mouth). (3) Diamond-shaped non-lateral dayboards, checkered red-and-white or green-and-white, similar to those used in the U.S. Aids to Navigation System, as appropriate, are used as crossing dayboards where the river channel crosses from one bank to the other. (4) Lights on green buoys and on beacons…