33 CFR § 84.14
Intensity of lights
August 2, 2023
§ 84.14 Intensity of lights.
(a) The minimum luminous intensity of lights shall be calculated by using the formula:
I = 3.43 × 106 × T × D2 × 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 |
---|---|
1 | 0.9 |
2 | 4.3 |
3 | 12 |
4 | 27 |
5 | 52 |
6 | 94 |