Lateral Marker System

U.S. Aids to Navigation – Lateral Marker System

The lateral marker system is a set of markers used in boating to show which way is safe to navigate. These markers are like signs on the water. They help boaters know where the safe, deep water is so they don’t run aground or hit anything. The system uses different colored buoys and signs.

How to Use the Lateral System

Using the lateral marker system to navigate is like following traffic signs on the road. Here’s how to do it:

• Stay Between the Markers: Think of the red and green markers as boundaries. Your safest route is to stay in the middle of them, just like driving between the lines on a road. Just as leaving your lane on the road can be dangerous, going outside these markers can lead you into unsafe waters. Shallow areas, rocks, or other hazards might be outside the marked channel.
• Red Right Returning: Keep the red markers on your right side when coming back from the sea or heading upstream.
• Green on the Left: As you return from the sea, the green markers should be on your left.

Types of Markers

Green Markers

• Purpose: Green markers indicate a channel’s port (left) side when a boater is returning from open water or heading upstream.
• Appearance:
  • Buoys: Floating markers, often cylindrical, known as “can buoys.”
  • Beacons and Daymarks: Fixed land or shallow water structures showing green signs or lights.
• Location: Positioned on the left side of channels and waterways when heading upstream.

Red Markers

• Purpose: Red markers signal a channel’s starboard (right) side for boaters coming from the sea or going upstream.
• Appearance:
  • Buoys: Often conical or nun-shaped, these are floating red markers.
  • Beacons and Daymarks: Like green markers, these are fixed aids with red colors or lights.
• Location: Found on the right side of navigable channels when heading upstream.

Junction Buoys

• Purpose: Junction buoys, or bifurcation markers, indicate where a channel splits and help boaters decide where to go.
• Appearance:
  • These buoys combine both red and green colors.
  • The top color indicates the preferred (primary) channel.
• Location: Placed at the junction of channels, they guide boaters through splits in the waterway.