This depends what kinda of cans you are talking about? Are you referring to IALA-B, International Association of Lighthouse Authorities Region B Buoyage system (United States) ?
Can buoys for navigation in this region are almost always green & numbered odd. There maybe yellow cans or white, which are special purpose buoys. These either mark a danger area, no wake or special instructions. Yellow buoys may have a unique special purpose.
The opposite of green cans is red nun buoys, which are even numbered. Also you may find Cans or nuns marked with both red and green bands which makes them preferred channel markers.
Buoys are marked with their location, owner, serial number, and depth. This helps to quickly identify individual buoys and keep track of them.
Red with even numbers
The plural of buoy is buoys.The plural possessive is buoys'.Example: The buoys' positions are marked on this map.
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.
The waterway will be marked with channel buoys.
Can buoys are marked with a green color and typically have a cylindrical shape. They are often numbered or labeled with a specific symbol to indicate their position in a waterway. Additionally, they may have reflective tape or lights for visibility at night. Can buoys are used to mark the left side of a channel when entering from the sea, following the IALA maritime buoyage system.
Lateral red and green buoys and markers are used in maritime navigation to indicate safe channels for vessels. Red buoys, typically marked with an even number, indicate the port side of a channel when entering from the sea, while green buoys, marked with an odd number, indicate the starboard side. This system helps mariners safely navigate through waterways by providing clear visual guidance on channel boundaries. Together, they form part of the IALA (International Association of Lighthouse Authorities) buoyage system.
Some red buoys are known as "nun" buoys.(Ref: SB-4)some red buoys are known as nun buoys
Oh, dude, nun buoys are marked with a letter "N" for "nun." It's like labeling your stuff so you don't lose it at a party. So, if you see an "N" out at sea, you know you're near a nun buoy. Just don't ask them to sing any hymns or anything.
Mooring buoys
Some red buoys are known as "nun" buoys.(Ref: SB-4)some red buoys are known as nun buoys
Mid channel buoys