571—37.5(462A) Lights on vessels.

1. 37.5(1)  Vessels at anchor.

   1. a. A vessel at anchor shall exhibit between the hours of sunset and sunrise:

      1. (1) In the forepart, a white light to show 360 degrees around the horizon or one ball.
      2. (2) At or near the stern and at a lower level than the light prescribed in 37.5(1)“a”(1) a white light to show 360 degrees around the horizon.
   2. b. A vessel of less than 50 meters in length may exhibit a white light to show 360 degrees around the horizon instead of the lights prescribed in this subrule.
2. 37.5(2)  Vessels not powered by motor or sail. All vessels not powered by motor or sail and not at anchor shall exhibit a white light to show 360 degrees around the horizon that is visible from at least one mile under clear conditions between the hours of sunset and sunrise when operated on natural lakes, Corps of Engineers impoundments, border rivers excluding border portions of the Big Sioux and Des Moines rivers, and impoundments on inland rivers. If the white light is partially obscured due to the nature of the craft, an additional white light must be shown in sufficient time to prevent collision. When operated on bodies of water other than those listed in subrule, all vessels not powered by motor or sail and not at anchor shall have in possession a white light to be used when necessary between the hours of sunset and sunrise.

3. 37.5(3)  Sailing vessels.

   1. a. Vessels of all classes when propelled by sail alone shall exhibit one of the following lighting systems between sunset and sunrise and at all other times required by applicable laws:

      1. (1) While underway, one of the following lighting systems is acceptable:

         1. 1. The international lighting system for the applicable class of vessel.
         2. 2. The combined lantern or separate side lights required for the applicable class of vessel plus a white light so placed as to illuminate the sail so the sail is visible at a distance of at least one-half mile.

      2. (2) While at anchor, one of the following lighting systems is acceptable:

         1. 1. A white light that shows all around the horizon (360 degrees).
         2. 2. An illuminated sail, to be visible all around the horizon (360 degrees) at a distance of one-half mile.
   2. b. A sailing vessel means any vessel whose sole source of propulsion is the natural element (i.e., wind). A sailing vessel using any auxiliary source of mechanical propulsion is a motorboat and must exhibit the lights required for the applicable class of motorboat.

The following lights shall be required on all vessels:

[ARC 9219C, IAB 5/14/25, effective 6/18/25]