What is indicated by red and green horizontal bands on a lateral marker?

The presence of red and green horizontal bands on a lateral marker signifies a Preferred Channel. This type of marker is specifically designed to indicate that the channel is the recommended route for vessels to navigate safely, often indicating a more favorable depth or width.

In the IALA buoyage system, the marker's color coding helps mariners quickly identify the conditions and intended use of the channel. The red and green combination emphasizes that there is an alternative route available, and it is up to the mariner to choose between following the preferred channel or another method of navigation. This system is vital for safe maritime navigation, particularly in areas where there may be obstacles or shallow waters.

Other options, such as a Danger Area or Restricted Zone, typically use different color patterns to convey their meanings. Conversely, Safe Water markers usually display vertical stripes or spherical shapes to signify clear passages or safe routes devoid of hazards. Understanding these indicators enhances mariner safety and ensures effective communication of navigational implications.