These are channel markers. The green buoy marks the port (left) side of the channel when entering a smaller body of water.
Keep green buoys on your left when heading upstream.
Red buoys have even numbers and red lights; green buoys have odd numbers and green lights.
You basically have to keep that type of buoy to your right if you are traveling up stream.
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).
Sequential numbers appear sometimes on channel buoys
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.
Regulatory buoys can sometimes have white lights. This type of buoy alert operators of vessels of warnings and regulations in the area.
No, red buoys are not known as can buoys. Red buoys are typically referred to as "nun buoys," which are conical in shape, while "can buoys" are green and cylindrical. These terms are part of the U.S. Aids to Navigation System, which uses color and shape to indicate safe passage in waterways.
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).
Nuns are red.
Buoys are colored red and green to indicate navigational channels and help mariners determine their position relative to safe passage. In the U.S. and many other countries, red buoys typically mark the right side of the channel when entering from the sea, while green buoys mark the left side. This color coding is part of the IALA (International Association of Lighthouse Authorities) buoyage system, which ensures consistency and safety in maritime navigation.
The left edge of a navigation channel as you are heading in.