Red buoys have even numbers and red lights; green buoys have odd numbers and green lights.
Nuns are red.
The main purpose of the lateral system of red and green buoys and markers is to indicate the sides of a navigable waterway or the location of hazards. Red buoys/markers should be kept on the right or starboard side of the boat when traveling upstream, while green buoys/markers should be kept on the left or port side. This system helps to ensure safe navigation and prevent collisions.
When heading downstream (away from harbor) leave the red buoys to port and the green buoys to starboard.When heading upstream (back in to harbor) it's the opposite: leave the green buoys to port and the red buoys to starboard.
In the United States, when you are outbound for sea you would have red buoys (even numbered) on your port side(left) and green buoys on your starboard side (right). When returning fromsea you would have red buoys on your starboard (right) side (Remember " Red right return") and green buoys on your port side (left).
Preferred channel markers are buoys showing red and green bands.
When going into a port or harbor, you should keep green buoys on your left. When leaving a port or harbor, you should keep green buoys to your right. A good way to remember this is the phrase "Red, Right, Return." This phrase means that you should keep Red buoys on your Right (thus keeping green buoys on your left) when coming into a port/harbor (Returning).
Nun buoys are typically marked with a single red mark, while can buoys are marked with a single green mark. These marks help to indicate the direction in which boats should pass the buoy in order to navigate safely through the waterway.
Some red buoys are known as "nun" buoys.(Ref: SB-4)some red buoys are known as nun buoys
They indicate the two sides of a navigation channel. In different countries the buoys are found on different sides of the channel (for example, in the U.S. the rule is red on the right when returning from the sea) but the water in between the buoys is always meant for navigation. Be careful, it may only be 3 feet deep, though - check your chart, always!
Swim area not!! It is the navigable channel
Red and Green Colors and/or Lights: These are placed at the junction of two channels to indicate the preferred (primary) channel when a channel splits. If green is on top, the preferred channel is to the right. If red is on top, the preferred channel is to the left. These also are sometimes referred to as "junction buoys."