Passing distance and CPA from chart plot

Bowditch Ch. 13 §1303

Bowditch Ch. 13 §1303 — Radar Navigation ARPA (Automatic Radar Plotting Aid) computes target tracks automatically and displays predicted CPA and TCPA. ARPA does not replace bridge watchkeeping; it supplements visual look-out.

Bowditch Ch. 7 §703

Bowditch Ch. 7 §703 — Bearings and Lines of Position Bearings to a single object can produce a running fix when the relative bearing changes substantially. The 'doubling-the-angle' technique uses two relative bearings; the distance run between them equals the distance to the object at the second bearing.

Bowditch Ch. 7 §704

Bowditch Ch. 7 §704 — Bearings and Lines of Position Compass bearings of an approaching vessel are the canonical method of detecting risk of collision. If the bearing remains constant and the range is decreasing (CBDR), risk of collision exists.

33 CFR §164.03

§ 164.03 § 164.03 Incorporation by reference. (a) Certain material is incorporated by reference into this part with the approval of the Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other than that specified in this section, the Coast Guard must publish notice of the change in theand the material must be available to the public. All approved material is available for inspection at the National Archives and Records Administration (NARA). For more information on the availability of this material at NARA, call 202-741-6030, or go to:Also, it is available for inspection at the Commandant (CG-NAV), U.S. Coast Guard Stop 7418, Attn: Office of Navigation Systems, 2703 Martin Luther King Jr. Ave. SE., Washington, DC 20593-7418, telephone 202-372-…

33 CFR §164.38

§ 164.38 § 164.38 Automatic radar plotting aids (ARPA). (a) The following definitions are used in this section— means material in any quantity that is shipped, stored, or handled without benefit of package, label, mark or count and carried in integral or fixed independent tanks. means a stage of construction where— (1) The keel is laid; (2) Construction identifiable with a specific ship begins; or (3) Assembly of that ship has commenced comprising at least 50 tons or 1 percent of the estimated mass of all structural material, whichever is less. means— (1) A flammable liquid as defined in 46 CFR 30.10-22 or a combustible liquid as defined in 46 CFR 30.10-15; (2) A material listed in table 151.05 of 46 CFR 151.05, table 1 of 46 CFR 153, or table 4 of 46 CFR Part 154; or (3) A liqui…

33 CFR §164.40

§ 164.40 § 164.40 Devices to indicate speed and distance. (a) Each vessel required to be fitted with an Automatic Radar Plotting Aid (ARPA) under § 164.38 of this part must be fitted with a device to indicate speed and distance of the vessel either through the water or over the ground. (b) The device must meet the following specifications: (1) The display must be easily readable on the bridge by day or night. (2) Errors in the indicated speed, when the vessel is operating free from shallow water effect, and from the effects of wind, current, and tide, should not exceed 5 percent of the speed of the vessel, or 0.5 knot, whichever is greater. (3) Errors in the indicated distance run, when the vessel is operating free from shallow water effect, and from the effects of wind, current, and …