46 CFR 7.5 - Rules for establishing boundary lines.
(a) For application of the Vessel Bridge-to-Bridge Radiotelephone Act, 33 U.S.C. 1201 et seq., the line is 12 nautical miles seaward of the baseline from which the territorial sea is measured.
(b) Barges of 100 gross tons and over operating on the sheltered waters of British Columbia as defined in the United States-Canada treaty of 1933 (49 Stat. 2685, TS 869) are not required to be inspected as seagoing barges under 46 U.S.C. 3301.
(c) Except as otherwise described in this part, Boundary Lines are lines drawn following the general trend of the seaward, highwater shorelines and lines continuing the general trend of the seaward, highwater shorelines across entrances to small bays, inlets and rivers.