(a) The minimum luminous intensity of lights shall be calculated by using the formula: I = 3.43 x 10\6\ x T x D\2\ x K-D Where: I is luminous intensity in candelas under service conditions,T is threshold factor 2 x 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)------------------------------------------------------------------------
Minimum luminous
Range of visibility (luminous range) of light in intensity of
nautical miles D light in candelas
for K = 0.8 I------------------------------------------------------------------------1.................................................... 0.92.................................................... 4.33.................................................... 124.................................................... 275.................................................... 526.................................................... 94------------------------------------------------------------------------