Annex - Unified Interpretation on the Application of COLREG with Respect to the Placement of Sidelights
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Annex - Unified Interpretation on the Application of COLREG with Respect to the Placement of Sidelights

Annex I/9(a)(i) and annex I/10(a)(i) of COLREG 1972, as amended, state:

"9 – Horizontal sectors

(a) (i) In the forward direction, sidelights as fitted on the vessel shall show the minimum required intensities. The intensities must decrease to reach practical cut-off between 1 degree and 3 degrees outside the prescribed sectors."

"10 – Vertical sectors

(a) The vertical sectors of electric lights as fitted, with the exception of lights on sailing vessels underway, shall ensure that:

  • (i) at least the required minimum intensity is maintained at all angles from 5 degrees above to 5 degrees below the horizontal;"

Interpretations with respect to sidelights' horizontal sectors

9(a)(i) – Horizontal sectors (noting MSC.1/Circ.1427 and MSC.1/Circ.1260/Rev.1)

COLREG annex I, section 9(a)(i) would require the full intensity of the sidelights to be maintained in the forward direction of 1° outside the prescribed sector (one-degree toe-in sector) with the practical cut-off between 1° and 3°. This is needed to enable other vessels to determine a "head-on-situation" as per COLREG rule 14.

10(a)(i) – Vertical sectors

Where sidelights, installed in a position at or "near the side",footnote are not fully visible at all angles from 5 degrees above to 5 degrees below the horizontal including the 1° toe-in sector (e.g. see Area A), then that installation is acceptable provided the installed sidelights are visible, with the ship in all normal conditions of trim corresponding to the lightest seagoing draught in the approved Trim and stability booklet, at a minimum distance of 1000 m measured from the stem when viewed from sea level throughout the horizontal plane of 112.5o defined by rule 21(b) including the horizontal 1° toe-in sector in the forward direction prescribed in 9(a)(i).



Parent topic: MSC.1/Circular.1577 - Unified Interpretation on the Application of COLREG with Respect to the Placement of Sidelights – (16 June 2017)
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