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Navigation Light Switching for Vessels Under 20 Meters

January, 25 2005

The possible switch configurations for navigation lights vary greatly depending on the vessel size, type, and purpose. This article addresses the most common configurations for smaller vessels.

ABYC standards state that one switch, or position of a switch, will turn on all of the navigation lights required for the vessel while underway. Another switch, or position of a switch, will turn on the anchor light. This allows the use of either 2 switches or a 3 position switch with one off position.

The most common configurations of lights are:

  1. A bicolor light with an all-round (360°) white light
  2. A bicolor light with a 135° stern light and a 225° masthead light and a 360° anchor light
  3. Two sidelights with an all-round (360°) white light
  4. Two sidelights with a 135° stern light and a 225° masthead light and a 360° anchor light
  5. A masthead tri-color light with a 225° masthead light and a 360° anchor light

these can be broken down into 3 combinations:

    1. A bicolor or two sidelights and an all-round white light
    2. A bicolor or two sidelights with a 135° stern light and a 225° masthead light and a 360° anchor light
    3. A masthead tri-color light, a bicolor or two sidelights, a 135° stern light, a 225° masthead light, and a 360° anchor light

    CombinationNavigation LightsAnchor LightSteaming LightFigure #
    ADPSTSPST*1
    ADPDT**2
    B (Power Boat)SPSTSPST*3
    B (Power Boat)SPDT**4
    B (Sailboat)SPSTSPSTSPST5
    B (Sailboat)DPDTSPST*6
    CSPSTSPSTSPST7
    CSPDTSPST*8

    *included in navigation lights switch
    **includes navigation lights excluding masthead tri-color


    SPST – Single Pole Single Throw
    SPDT – Single Pole Double Throw (Center Off)
    DPST – Double Pole Single Throw
    DPDT – Double Pole Double Throw (Center Off)

    The following illustrations use a bicolor, but two sidelights can be substituted for it in the diagram. All of the double throw switches are "Center Off".















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