33 CFR § 84.14 - Intensity of lights.

§ 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
1 0.9
2 4.3
3 12
4 27
5 52
6 94

The following state regulations pages link to this page.