Regulations last checked for updates: Nov 22, 2024

Title 33 - Navigation and Navigable Waters last revised: Nov 20, 2024
§ 84.14 - Intensity of lights.

(a) The minimum luminous intensity of lights shall be calculated by using the formula:

I = 3.43 × 10 6 × T × D 2 × K−D Where: I is luminous intensity in candelas under service conditions, T is threshold factor 2 × 10−7lux, D is range of visibility (luminous range) of the light in nautical miles, K is atmospheric transmissivity. For prescribed lights the value of K shall be 0.8, corresponding to a meteorological visibility of approximately 13 nautical miles.

(b) A selection of figures derived from the formula is given in the following table (Table 84.14(b)):

Table 84.14(b)

Range of visibility
(luminous range) of light
in nautical miles D
Minimum luminous intensity of light in candelas for K = 0.8 I
10.9
24.3
312
427
552
694
authority: Sec. 303, Pub. L. 108-293, 118 Stat. 1042 (33 U.S.C. 2071); Department of Homeland Security Delegation No. 0170.1
source: 79 FR 37921, July 2, 2014, unless otherwise noted.
cite as: 33 CFR 84.14