Lateral Aids to Navigation
Aids to navigation consist of a standardized system of light stations, buoys, and day beacons to assist vessels in determining their position or course, mark channels, to alert a vessel of dangers or hazards, and to indicate the preferred route where channels intersect.
Channel Buoys – Port and Starboard are Red and Green lights or buoys mark the sides of channels. It is important to know whether you are going upstream, into or out of harbor and which way the tide comes in (flood). This will determine on which side you should pass Red or Green channel markers.
When entering a harbor or bay, proceeding in the same direction as the tidal flood or going upstream, red channels markers are to be passed on your starboard side (red right returning). green channel markers are to be passed on your port side.
If leaving a harbor or bay, proceeding against the direction of the tidal flood or going downstream, Green channel markers are to be passed on your starboard side. Red channel markers are to be passed on your port side.
Aside from color, the shape, number and appearance of a buoy is very important in identifying the type of buoy. All green lights or buoys are numbered with an odd number and all red lights or buoys are numbered with an even number.
The shape of a buoy can be cylindrical (called a ‘can’ because of its shape), conical (cone), spar and pillar.
Green lights or buoys will have a flat top – can, spar or top mark. Red lights or buoys will have a pointed top – cone, spar or top mark.
Bifurcation Buoys can be found where one channel branches off into two channels or where one channel meets another. The bifurcation buoy marks the preferred channel (typically deeper and wider).
All bifurcation buoys will show markings of either ‘green over red’ or ‘red over green’. The top color is the dominant color.
A red over green bifurcation buoy indicates that the preferred channel can be taken by leaving the bifurcation buoy to the starboard side of your boat. To keep the buoy to the starboard side of the boat, you must take the channel to the left (port).
A green over red bifurcation buoy indicates that the preferred channel can be taken by leaving the buoy to the port side of the boat. To keep the buoy to the port side of the boat, you take the channel to the right (starboard).
Isolated Danger Buoys mark areas of isolated danger. Steer well clear of isolated danger buoys and always consult your chart (preferably in advance) to determine the nature of the isolated danger, its depth and dimensions.
Isolated danger buoys are characterized by flashing white lights (if lighted) and black, red, black (BRB) horizontal lines. The top mark on an isolated danger buoy consist of two balls or discs, one over the other.
Safewater or Mid-Channel Buoys indicate that there is safe water in all directions around the buoy. They are typically used to mark the entrance to channels or the centerline of channels.
Fairway buoys, when marking the centerline of channels, should always be kept to port.
Fairway Buoys are identified by their red and white (RW) vertical lines. The top mark consists of one single ball or disc. If lighted, the light will be a white light flashing either the letter ‘A’ in Morse Code or a single flashing spaced 10 seconds apart.
Special Buoys include cautionary, anchorage, mooring, scientific, swimming and general information. Special buoys vary in color, size and shape.
A Cautionary Buoy is yellow and is used to mark areas of danger such as firing ranges, underwater pipelines, exposed cables, race courses, seaplane bases or areas where no through channel exists.
Always check your chart to determine the particular usage of a yellow cautionary buoy and the nature of the danger being marked.
Mooring Buoys are white with an orange top and are used for securing vessels. Never pass between a boat and the mooring it is secured to.
Anchorage Buoys are yellow and are clearly identified by the shape of an anchor on the side. Anchorage buoys mark the outside perimeter of designated anchorage areas.
Regulatory Buoys are white with orange markings and are used to identify exclusion areas (keep out), speed limits or boat wash restrictions and general information (name of area or marina, marker for campsites, etc.).
Cardinal Buoys indicate the location of a hazard and the direction of safest or deepest water in relation to the named cardinal buoy using the four cardinal points of the compass (North, South, East, West). Accordingly, a North cardinal buoy indicates that the safest water lies to the North of the buoy. It is always important to keep a cardinal buoy between yourself and the area of danger.
Cardinal buoys are identified by their yellow and black horizontal bands and conical topmarks. Each buoy is marked differently to distinguish it from the others.
North cardinal buoys have black over yellow with both topmarks pointing up. South cardinal buoys have yellow over black with both topmarks pointing down. East cardinal buoys have black over yellow, over black with the topmarks pointing away from each other. West cardinal buoys have yellow over black, over yellow with the topmarks pointing towards each other.