A day beacon is an unlighted nautical navigational aid. Typically, day beacons supplement channels whose key points are marked by lighted buoys. Day beacons may also mark smaller navigable routes in their entirety.

Identification

Day beacons, as with other aids, are generally paired. Proceeding from open water towards harbor, odd-numbered beacons are kept to starboard (right facing abow) of the vessel, with even-numbered aids to port. Beacons are numbered in descending order from open water to harbor.

Region A

Region A is comprised of Europe, Africa, Australia, and Asia, with the exception of Japan. Within Region A, day beacons are characterized as follows:

Even-numbered beacons are characterized by:

• Green color
• Conical shape (floating, also known as a nun)
• Triangular shape (signpost)

Odd-numbered beacons are characterized by:

• Red color
• Cylindrical shape (floating, also known as a can)
• Square shape (signpost)

Region B

Region B is comprised of the Americas and Japan. Within Region B, day beacons are characterized as follows:

Even-numbered beacons are characterized by:

• Red color
• Conical shape (floating)
• Triangular shape (signpost)

Odd-numbered beacons are characterized by:

• Green color
• Cylindrical shape (floating)
• Square shape (signpost)

A common mnemonic for remembering the appropriate characteristics (within Region B) is "an odd can of green beans."

General Placement

Navigation around day beacons is the same as with all other navigational aids. When beacons are paired, vessels should pass between the pairing. However, beacons are also commonly placed individually. Generally, single beacons are at the inside corner of a turn. However, single beacons are also occasionally placed outside a turn. Interior or exterior placement can be determined based upon the passing side (port or starboard) dictated by beacon designation. In either case, common practice is to approach the beacon as close as is prudent under the assumption that the beacon itself is in channel-depth water. However, current charting should always be consulted for all but the shallowest-draft vessels, as channel conditions are rarely ideal. This is particularly necessary when encountering non-standard beacons such as those neither red nor green.

Identification on Charts

Because color standards vary internationally, beacon number is the best way to identify beacons on charts. Additionally, charts may be limited in color and not show red and green beacons directly as such. When color is not immediately apparent, a red beacon is typically shaded white with an "R" in its designation. More frequently, green is omitted from charts, and a green beacon is rendered black with a "G" in its designation.