For the exact text concerning arcs of visibility, please see Rule 21. This guide is intended to give a graphical representation of Rule 21 (with the exception of an all-round light and flashing light).

 
Lighting DiagramMasthead Light Starboard SideLight Port SideLight Stern Light Towing Light Special Flasing
 
imagemapstbdarc towingarc mastheadarc portarc sternarc
 
   
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