Table of Contents:

U.S. ATON System

Private Aids to Navigation

Safety Tips

Lateral System

Non-Lateral Aids to Navigation

Uniform State Waterway Marking System

Western Rivers Marking System

Visual Buoyage Guide

Nautical Chart

Bridge Lighting & Other Signals

ATON Abbreviations

USCG District ATON Offices

Report ATON Defects

Aids to Navigation — Road Signs of the Waterway

Non-Lateral Aids to Navigation

Dayboards — May Be Lettered

White Square White Light Only

White Square. Chart mark for dayboard, which appears as a white square. The first caption reads RW and the second caption reads Bn.
RW
Bn

Illustration of dayboard, which appears as a diamond with a white border, with two red diamonds vertically and two white diamonds horizontally in the middle. A dark red letter A appears in the upper red diamond. White Square. Chart mark for dayboard, which appears as a white square. The first caption reads GW and the second caption reads Bn.
GW
Bn 		Illustration of dayboard, which appears as diamond with a white border, with two green diamonds vertically and two white diamonds horizontally in the middle. A dark green letter A appears in the upper green diamond. White Square. Chart mark for dayboard, which appears as a white square. The first caption reads BW and the second caption reads Bn.
BW
Bn		 Illustration of dayboard, which appears as a diamond with a white border, with two black vertical diamonds vertically and two white diamonds horizontally in the middle. A white letter A appears in the upper black diamond.

The sole purpose of these diamond shaped dayboards is to help the vessel operator determine his/her location. They are like the "X's" on shopping mall maps "You Are Here." Appropriate nautical chart must be consulted to determine location.

 

Safe Water
No Numbers — May Be Lettered

White Square White Light Only   Morse Code
Mo(A)  Illustration of Morse code, which shows a sequence of a short flash of white light, a short pause, a medium flash of light and a long pause.
Illustration of lighted and/or sound buoy, which has a platform that is white on the left and red on the right. The cylindrical structure is white on the left and red on the white, with a white square on the upper left and a white letter N on the upper right. A white light and a red circle are affixed to the top. Chart mark for lighted and/or sound buoy, which appears as a magenta circle with a clear diamond affixed to the upper right side. A line bisects the diamond vertically and a small clear circle is affixed to the top of the diamond. The first caption reads RW "N" and the second caption reads Mo (A).
RW N"
Mo(A)		 Illustration of MR daymark, which appears as an octagon that is white on the left half, red on the right half, and has a white border all around. A white letter A appears in the center of the red half. Chart mark for MR, which appears as a clear square. The first caption reads RW and the second caption reads "A".
RW
"A" 		Illustration of a Can buoy, which appears as a narrow cylinder, which is white on the left side and red on the right side. A white square appears in the upper left and a white letter N appears in the upper right.
Can 		Chart mark for can buoy, which appears as a clear circle with a clear diamond affixed to the upper right side. A vertical line bisects the diamond. The caption reads RW "N". Illustration of an unlighted and/or sound buoy, which has a platform that is white on the left and red on the right. The rectangular structure is white on the left and red on the right, with a white square on the upper left and a white letter on the upper right. A red circle is affixed to the top. Chart mark for unlighted and/or sound buoy, which appears as a clear circle with a clear diamond affixed to the upper right side. A vertical line bisects the diamond and has a small clear circle affixed to the top. The caption reads RW "N"
RW "N"
These aids are used to mark fairways, mid-channels, and offshore approach points, and have unobstructed water on all sides. They can also be used by the vessel operator transiting offshore waters to identify the proximity of intended landfall. Lighted/unlighted buoy may show a red topmark.

Isolated Danger
No Numbers — May Be Lettered
White Square White Light Only
FI(2) 5s  Illustration of flashing white light sequence, which consists of one short flash, a medium pause, a second short flash and a long pause.
    Chart mark for lighted buoy, which consists of a magenta circle with a diamond affixed to the upper right side. The lower half of the diamond is magenta and the upper half is black. Two small black circles appear above the diamond, extending upward diagonally to the right. The first caption reads BR "A" and the second caption reads FI (2) 5s.
BR"A"
FI(2) 5s		 Illustration of a lighted buoy, which has a black base, a rectangular structure that is red on the bottom and black on top. A white light and two black circles, stacked vertically, are attached to the top. A white letter A appears on the upper right side of the structure.
Lighted		   Illustration of an unlighted buoy, which has a black base, and a rectangular structure that is red on the bottom and black on top. Two black circles, stacked vertically, are attached to the top. A white letter C appears on the upper right side of the structure.
Unlighted 		Chart mark for unlighted buoy, which appears as a clear circle with a diamond affixed to the upper right side. The lower half of the diamond is magetna and the upper half is black. Two small black circles appear above the diamond, extending upward diagonally to the right. The caption reads BR "C".
BR "C"		  
These aids indicate an isolated danger which may be passed on all sides. They are erected on or moored on or near dangers, they should not be approached closely without special caution.

Range Dayboards — May Be Lettered
KGW
Illustration of KGW range dayboard, which is a rectangle with a white vertical stripe in the middle and a green vertical stripe on either side.		 KWG
Illustration of KWG range dayboard, which is a rectangle with a green vertical stripe in the middle and a white vertical stripe on either side.		 KWB
Illustration of KWB range dayboard, which is a rectangle with a black vertical stripe in the middle and a white vertical stripe on either side.		 KBW
Illustration of KBW range dayboard, which is a rectangle with a white vertical stripe in the middle and a black vertical stripe on either side.		 KWR
Illustration of a KWR range dayboard, which is a rectangle with a red vertical stripe in the middle and a white vertical stripe on either side.		 KRW
Illustration of a KRW range dayboard, which is a rectangle with a white vertical stripe in the middle and a red vertical stripe on either side.		 KRB
Illustration of a KRB range dayboard, which is a rectangle with a black vertical stripe in the middle and a red vertical stripe on either side.		 KBR
Illustration of KBR range dayboard, which is a rectangle with a red vertical strip in the middle and a black vertical stripe on either side.		 KGB
Illustration of a KGB range dayboard, which is a rectangle with a black vertical stripe in the middle and a green vertical stripe on either side.		 KBG
Illustration of a KBG range dayboard, which is a rectangle with a green vertical stripe in the middle and a black vertical stripe on either side.		 KGR
Illustration of a KGR range dayboard, which is a rectangle with a red vertical stripe in the middle and a green vertical stripe on either side.		 KRG
Illustration of a KRG range dayboard, which is a rectangle with a green vertical stripe in the middle and a red vertical stripe on either side.
Ranges are a PAIR of aids to navigation. When the dayboards and/or lights appear to be in line with each other (Figure "A"), it assists the vessel operator in maintaining a safe course within the navigable channel. The appropriate nautical chart must be consulted when using ranges to determine whether the range marks the centerline of the navigable channel and also what section of the range may be safety traversed. Ranges are generally, but not always, lighted, and display rectangular dayboards of various colors. Ranges which are lit 24 hours a day may not have dayboards. Illustration of a pair of range markers aligned vertically. Each range appears as a rectangle with a green stripe in the middle and a red stripe on either side. A red light appears at the top center of each range. Exclamation
Exclamation

Typical Information and Regulatory Marks
When lighted, may display any light
rhythm except quick flashing
and flashing (2)
NW  White Square White Light Only  
Illustration of a daymark that appears as a white diamond with an orange border. The word "DANGER" appears in the center. Illustration of an exclusion area daymark, which appears as a white square outlined in orange. A white diamond outlined in orange appears in the center. An orange line bisects the diamond vertically and horizontally.
Exclusion
Area		 Illustration of a restricted operations daymark, which appears as a white square outlined in orange. A white circle outlined in orange appears in the center.
Restricted
Operations 		Illustration of a danger daymark, which appears as a white square outlined in orange. A white diamond outlined in orange appears in the center.
Danger
Information and Regulatory Marks are used to alert vessel operators to various warnings or regulatory matters. Examples:
Boat Exclusion
Area
Illustration of a boat exclusion area daymark, which appears as a white square outlined in orange. A white diamond outlined in orange appears in the center. An orange line bisects the diamond vertically and horizontally. The words "SWIM AREA" appear at the bottom of the square.		 Danger
Illustration of a danger daymark, which appears as a white square outlined in orange. A white diamond outlined in orange appears in the center. The word "ROCK" appears in the center of the diamond.		 Controlled
Area
Illustration of a controlled area daymark, which appears as a white square outlined in orange. A white circle outlined in orange appears in the middle, with the word "SLOW" inside the circle. The words "NO WAKE" appear at the bottom of the square.
Explanation may be placed outside the crossed diamond shape, such as dam, rapids, swim area, ect.. The nature of danger may be indicated inside the diamond shape, such as rock, wreck, shoal, dam,ect. Type of control is indicated in the circle, such as slow, no wake, anchoring, ect.
Information
Illustration of an information daymark, which appears as a white rectangle outlined in orange. The words "MULLET LAKE" appear inside the rectangle, with a long arrow beneath it pointing to the right. The words "BLACK RIVER" appear below the arrow, with a long arrow underneath them pointing to the left. 		Illustration of buoy used to display regulatory markers, which appears as a white cylinder with an orange horizontal stripe on the top and bottom. A white diamond outlined in orange appears at the center. Illustration of buoy used to display regulatory markers, which appears as a white cylinder with an orange horizontal stripe on the top and bottom. A white circle outlined in orange appears in the center. The legend "5 MPH" appears inside the circle.
For displaying information such as directions, distances, locations, ect. Buoy used to display regulatory markers May show white light
may be lettered

Intracoastal Waterway (ICW) Marks
The ICW runs parallel to the Atlantic and gulf coasts from Manasquan Inlet, New Jersey to the Mexican border. Aids to navigation marking the ICW display unique yellow symbols to distinguish them from aids marking other waters. Yellow triangles [yellow triangle] indicate aids should be passed by keeping them on the starboard (right) side of the vessel. Yellow squares [yellow square] indicate aids should be passed by keeping them on the port (left) side of the vessel. A yellow horizontal [yellow rectangle] band provides no lateral information, but simply identifies aids to navigation as marking the ICW.

Note: When following the ICW from New Jersey thru Texas, keep yellow triangles [yellow triangle] on your starboard, yellow squares [yellow square] on your port, regardless of the color navigation aid they appear on. Examples:
Illustration of intercoastal waterway lighted buoy, which has a green platform and green rectangular structure. A green square appears at the top left, a white numeral 5 appears at top right, and a yellow square appears at bottom right. A green light is affixed to the top. Illustration of intercoastal waterway lighted buoy, which has a red platform and red rectangular structure. A red square appears at the top left, a white numeral 6 appears at top right, and a yellow square appears at bottom right. A red light is affixed to the top. Illustration of intercoastal waterway lighted buoy, which has a green platform and green rectangular structure. A green square appears at the top left, a white numeral 7 appears at top right, and a yellow triangle appears at bottom right. A green light is affixed to the top. Illustration of intercoastal waterway lighted buoy, which has a red platform and red rectangular structure. A red square appears at the top left, a white numeral 8 appears at top right, and a yellow triangle appears at bottom right. A red light is affixed to the top. Illustration of an intercoastal waterway can buoy, which is a green rectangular structure with a green square at top left, a white numeral 9 at top right, and a yellow square centered just below the midpoint of the can. Illustration of an intercoastal waterway nun buoy, which is a red rectangle with tapered top. A red square appears at top left, a white numeral 6 appears at top right, and a yellow triangle appears in the center of the nun. Illustration of an intercoastal waterway daybeacon that appears as a green square with a dark green border, mounted on a pole. A yellow triangle is centered in the top of the green square, with a green numeral 3 beneath it. Illustration of an intercoastal waterway daybeacon that appears as a red triangle with a dark red border, mounted on a pole. A yellow triangle is centered at the top of the red triangle and a red numeral 2 appears beneath it.

 

Mooring Buoy
May Show White or Reflector Light

Illustration of a mooring buoy, which appears as a white cylinder with a blue horizontal stripe across the middle.
Mooring Buoys are white with a blue horizontal band. This distinctive color scheme is used to facilitate identification and to avoid confusion with aids to navigation.

Special Marks — May Be Lettered

yellow square Yellow Light Only
      Fixed  Illustration of fixed yellow light, which appears as a continuous beam.  
Flashing  Illustration of yellow flashing lights, which appears as a sequence of a short flash followed by a short pause.
Illustration of an unlighted can buoy, which appears as a yellow cylinder with a yellow square at top left and a black letter A at top right. Chart mark of an unlighted can buoy, which appears as a clear circle with a clear diamond attached at top right. The first caption reads Y and the second caption reads C "A".
 Illustration for unlighted nun buoy, which appears as a yellow cylinder with a taped top, with a yellow square at upper left and a black letter C at middle right. Chart mark for unlighted nun buoy, which appears as a clear circle with a clear diamond attached at top right. The first caption reads Y and the second caption reads N "A".
 Illustration of a daybeacon, which appears as a yellow diamond with a dark yellow border. A black letter A appears in the center.
 Chart mark fordaybeacon, which appears as a white square. The first caption reads Y "A" and the second caption reads Bn. Illustration of a lighted buoy, which has a yellow platform and a yellow rectangular structure with a yellow square at upper left and a black letter B at upper right. A yellow light is attached to the top.
 Chart mark for lighted buoy, which appears as a magenta circle with a clear diamond attached at the upper right. The first caption reads Y "B" and the second caption reads F1.
Unlighted       Lighted  
These aids are not intended to assist in navigation, but rather to alert the vessel operator to a special feature or area (anchoring, traffic separation, fish net area, cable or pipeline, military exercise areas, jetties, ect.)

 

Inland (State) Waters Obstruction Mark
May Show White
Reflector Or Quick Flashing White Light

Illustration of a state waters obstruction mark, which appears as a cylinder with black and white vertical stripes.
State Water Obstruction Mark is a black/white vertically striped buoy used to indicate to a vessel operator that an obstruction to navigation extends from the nearest shore to the buoy. This means "do not pass between the buoy and the shore." This aid is replacing Cardinal System (buoys) within the USWMS.

USCG red rod
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