is used to describe any buoy that is smaller than a lighthouse buoy and has a tall, central structure on a broad base. Lighted buoys in the United States are referred to as pillar buoys. Topmarks The IALA Maritime Buoyage System makes use of can, nun, spherical, and X-shaped topmarks only. Topmarks on pillar and spar buoys are particularly important to indicate the side on which they will be passed and will be used, whenever practical. Lights Where marks are lighted, red and green lights are reserved for port and starboard or starboard and port lateral marks. Yellow lights are for special marks, and white lights are used for other types that will be discussed later in this chapter. Buoy Color Under region B of the IALA system, red buoys mark the starboard side of the channels, or the location of wrecks or obstructions that must be passed by keeping the buoy on the starboard (right) hand when returning from sea. Green buoys mark the port side of the channels, or the location of wrecks or obstructions that must be passed by keeping the buoy to port (left) hand when returning from sea. Red and green horizontally banded buoys are used to mark obstructions and channel junctions. They may be passed on either side, but sometimes the channel on one side is preferable. If the top band on the buoy is red, the preferred channel will be followed by keeping the buoy to starboard. If the top band is green, the preferred channel will be followed by keeping the buoy on the port. However, in some instances it may not be feasible for larger vessels to pass on either side of such a buoy, and the chart should always be consulted. The colors indicated above would be reversed for the region A buoy system. Red and white vertically striped buoys are “safe-water marks,” used to indicate the mid-channel, a fairway, or a landfall. These buoys are also used at the beginning of some vessel Traffic Separation Schemes at the entrances to busy ports, or in narrow passages congested with heavy traffic. Solid yellow buoys are special-purpose buoys typically marking anchorage, fishnet areas, and dredging sites. These buoys have no lateral system significance; but as most are shown on charts, they can often serve to assist in determining one's position. Solid yellow buoys can be any shape. Buoy Numbering Most buoys are given numbers, letters, or combinations of numbers and letters, which are painted conspicuously on them or applied in white retroreflective material. These markings facilitate identification and location of the buoys on the chart. Solid red or green buoys are given numbers or combinations of numbers and letters. Other colored buoys are given letters. Odd numbers are used only on solid green buoys; even numbers, on solid red. Numbers increase sequentially from seaward; numbers are sometimes omitted when there are more buoys of one type than another. DAYBEACONS/DAYMARKS Where daybeacons are substituted for unlighted buoys, the color of the daymark will be the same and the shape similar. Red daymarks will be triangular, approximating the shape of the top of a nun buoy. Square daymarks, corresponding to can buoys, will be green. Daymarks equivalent to spherical buoys are octagonal. The daymarks on a daybeacon replacing a yellow special-purpose buoy are diamond-shape. Daybeacons will be numbered or lettered with retroreflective material in the same manner as a buoy and will have a border of that material. Many have panels of red and green reflective material. Some channels may be marked with a combination of buoys, daybeacons, and lights. LATERAL MARKS Lateral marks are generally used for well-defined channels. They indicate the route to be followed and are used in conjunction with a conventional direction of buoyage. This direction is defined in two ways, as follows: Local direction of buoyage—The direction taken by a mariner when approaching a harbor, river estuary, or other waterway from seaward General direction of buoyage—In other areas, a direction determined by the buoyage authorities, following a clockwise direction around continental 9-15