33 CFR §83.22

The lights prescribed in these Rules (Subpart C) shall have an intensity as specified in Annex I to these Rules (33 CFR part 84), so as to be visible at the following minimum ranges:

(a) In a vessel of 50 meters or more in length:

(i) A masthead light, 6 miles; (ii) A sidelight, 3 miles; (iii) A sternlight, 3 miles; (iv) A towing light, 3 miles; (v) A white, red, green or yellow all-round light, 3 miles; and (vi) A special flashing light, 2 miles. (b) In a vessel of 12 meters or more in length but less than 50 meters in length: (i) A masthead light, 5 miles; except that where the length of the vessel is less than 20 meters, 3 miles; (ii) A sidelight, 2 miles; (iii) A sternlight, 2 miles; (iv) A towing light, 2 miles; (v) A white, red, green or yellow all-round light, 2 miles; and (vi) A special flashing light, 2 miles. (c) In a vessel of less than 12 meters in length: (i) A masthead light, 2 miles; (ii) A sidelight, 1 mile; (iii) A sternlight, 2 miles; (iv) A towing light, 2 miles; (v) A white, red, green or yellow all-round light, 2 miles; and (vi) A special flashing light, 2 miles. (d) In an inconspicuous, partly submerged vessel or objects being towed: (i) A white all-round light, 3 miles. (ii) [Reserved]