The running lights on a Liberty ship have two modes, regular navigation and convoy blackout conditions. The mode that was used varied depending on the perceived threats in the area the ship was operating. If a ship was operating independently in a blackout zone, then the lights would simply be left off instead of using the convoy blackout mode. The running lights are on a dimmer switch, and when used they would typically be turned down to reduce visibility.
The running lights are typical of any large powered vessel. There is a white stern light, red and green side lights located on the bridge wings, and two white masthead lights. The forward masthead light is located on the foremast, on a platform extending from the top of the crows nest. The second light is mounted on the top of the telescoping upper section of the mainmast. There are additional lights that are required by special situations, but these were not permanently rigged. For more information on the requirements governing these lights, including the arcs of visibility, check out the International Rules of the Road.
The convoy mode only has a single formation light, a blue light mounted directly below the stern light. This light is shielded to present a narrow arc, just enough to be visible from a ship directly astern.
There were two types of signal lights used during the war. Two Morse signal lights were carried, and these can be mounted on the bridge or flying bridge wings. In addition, there were lights used to signal in convoy. Initially these consisted of three pairs of red and green lights hung one on top of the other, which could be run up the signal halyards. The reds were to port and the greens to starboard, just like the side lights. Later on more permanent light towers constructed from steel pipe were used. These had an additional pair of white blinker lights added above the red and green lights.
There were other exterior lights that were not typically used during wartime. Spotlights are located on each bridge wing and on either side of the boat deck between the lifeboats. There are mast lights for illuminating the cargo hatches, and smaller lights are spread around the main house, after house and forward gun deck.
Regards,
Chris Friedenbach
Crewmember, SS Jeremiah O’Brien