Chart symbols and abbreviations (Chart No. 1)

Bowditch Ch. 4 §401

Bowditch Ch. 4 §401 — Nautical Charts A nautical chart is a graphic representation of the navigable waters and adjacent coast. It is the most fundamental tool of marine navigation; modern ECDIS systems use vector ENC files but paper or raster equivalents remain the back-up.

Bowditch Ch. 4 §403

Bowditch Ch. 4 §403 — Nautical Charts US charts show soundings in feet, fathoms, or metres referenced to Mean Lower Low Water (MLLW). The unit is stated in the chart title; always verify before plotting.

46 CFR §25.25-3

§ 25.25-3 § 25.25-3 Definitions. As used in this subpart: (a)means the first six digits of a number assigned by the Coast Guard to approved equipment. Where approval is based on a subpart of subchapter Q of this chapter, the approval series corresponds to the number of the subpart. A listing of current and formerly approved equipment and materials may be found on the Internet at:Each OCMI may be contacted for information concerning approved equipment. (b)means approved under subchapter Q of this chapter. (c)means operate, navigate, or employ. [USCG-2012-0919, 79 FR 53630, Sept. 10, 2014]

Light List — Bottom Type Codes

Light List — Bottom Type Codes Bottom Type Codes Charts annotate bottom characteristics with letter codes — e.g. M (mud), S (sand), R (rock), Cl (clay), Co (coral), Sh (shells), G (gravel). Used to assess holding ground for anchoring.

Light List — Italicised Aid Names

Light List — Italicised Aid Names Italicised Aid Names Aid-to-navigation names are shown in italics on US charts; non-aid placenames are shown in upright lettering. This convention helps identify aids quickly under chart-light conditions.

Light List — light-characteristic (Iso)

Light List — light-characteristic (Iso) Isophase (Iso) A light with equal periods of light and darkness. Charted "Iso <colour> <period>s".