Night Navigation by Grog©

Common Navigation Light Patterns of Vessels Moving at Night.



Bow and Stern:


Choose a scene to see:

  1. The Light Pattern
  2. A Picture of the Ship(s)
  3. A Catchy Explanation








Important Light Patterns: The patterns represent critical situations to be memorized by anyone taking the helm at night. More details are to be found on the US Coastguard Website and the US European Code for Inland Waterways.

Presentation: Test your knowledge until each pattern is familiar. For teaching, the other vessels are shown close to your ship, the very situation that these lights are normally intended to prevent.

Primary Focus: Concentrate on which side light is showing and whether there are additional lights on the mast. Place no trust in the vertical alignment of the Mast lights with the Port or Starboard light. The heading of the other vessel varies this.

Additional White light: Moving vessels in excess of 50 feet have an additional white light further aft at a greater elevation.

Major Omissions: Restricted Ability, Towline in Use, Vessel Anchored, Shallow Water, and Vessel not Under Command. Such vessels are stationary or moving slowly and the additional masthead lights should discourage any close approach.

Included: The rare example that has been included is minesweeping. Years ago some friends told me they had been intrigued by all the pretty green lights and had gone close to take a look. They were very unpopular. So would you be.

Personal Experience: In the mid 1950's we were crossing the English Channel in foggy conditions at night in our family ketch, Sonia. Technology then extended only to a direction-finding radio antenna. We had confidently plotted our position and decided we could safely continue away from the strongest signal, the light ship only a mile or two behind us. Our plotting was terrible but our course was dangerously precise because, a short while later, the dazzling light appeared high above us. Collision was only avoided by a very abrupt change of course.

Still Relevant? Today's wonderful technology makes it tempting to place Navigation Lights on the scrapheap with Semaphore Signals, Morse Code, and Signal Lamps. On a small yacht, failure of the navigation system occurs. In the last few years I have had failures due to: loose connection in the charging system, grounding problems, and a faulty wire to the GPS antenna. Quick recognition of lights at night would appear to remain a minimum safety requirement.

Disclaimer: Handling boats, especially at night, is potentially hazardous. Lives may be at risk - possibly your own. These scenes have been prepared to help visualize and memorize light patterns. Apparent proximity and vessel relationship does not represent accepted practice. Recognition and response must occur when both vessels are far apart. No responsibility is accepted for incidents arising from the use of this material.     Copyright. All rights reserved.