Captain’s License Part 27
As you see from the diagram below now we are going to discuss the VISIBILITY OF LIGHTS. As you will note everything is in NAUTICAL MILES (NM).
The arrow you see at the top of the diagram refers to the usual length of most sailing vessels which in feet would be under 39 FEET. My personal one will be 36 feet.
So therefore my MASTLIGHT would have to be seen for 2 nautical miles. My port and starboard SIDELIGHTS would need to be seen for 1 nautical mile. My STERN LIGHT would need to be seen for 2 nautical miles. If I was TOWING a sailboat my TOWING LIGHT would have to be seen for 2 nautical miles. If I was using an ALL-ROUND LIGHT it would have to be seen for 2 nautical miles.