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Annex I (8) - Intensity of Lights

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Overview

Annex I (8) details the intensity of the lights required by the COLREGs.

Annex I (8) - Intensity of Lights

  1. The minimum luminous intensity of lights shall be calculated by using:

    I = 3.43 × 106 × T × D2 × K-D

    where I is luminous intensity in candelas under service conditions,
    T is threshold factor 2 × 10-7 lux,
    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.

  2. A selection of figures derived from the formula is given in the following table:

    Range of visibility (luminous range) of light in nautical miles Luminous intensity of light in candelas for K=0.8
    D I
    1 0.9
    2 4.3
    3 12
    4 27
    5 52
    6 94

    Note: The maximum luminous intensity of navigation lights should be limited to avoid undue glare. This shall not be achieved by a variable control of the luminous intensity.

Convention on the International Regulations for Preventing Collisions at Sea, 1972 (COLREGs)

About This Work

No visual explanation of this rule was produced within the original series, but the text is included here for completeness within the COLREGs in Depth collection.

A dedicated visual explanation can be produced for this rule upon request.

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