​Aids To Navigation (ATON)

Similar to road signs for on land, the Aids to Navigation (ATON) help boaters avoid problems on the water and navigate when used in combination with a nautical chart. 

ATON includes buoys and daymarks (or dayboards).

About the Buoys

Information and regulatory markers - Have orange symbols and black lettering.

  • Alerting boaters of various warnings and regulatory matters.
  • They are white can buoys with orange shapes and black lettering.
Diagram of buoy instructions. Diamond with cross through it is boats keep out. Diamond means danger. Circle means controlled area. Square with arrows and words inside show information.
Red elongated trapezoid shape with a number.

Red markers (Nun bouys) - Mark the edge of a channel.Navigate with the markers on your starboard (right) side when traveling upstream. (Remember “Red, Right Return,” to find your way home to port.)

Green rectangular buoy with numbers on it.

Green markers (Can buoys) - Mark the edge of a channel. Navigate with the markers on your port (left) side when traveling upstream. 

  • Have odd numbers.  
  • Can buoys: cylindrical-shaped and mark the edge of the channel on the port (left) side when entering from the open sea or heading upstream.
A red and white striped mid channel buoy looks like a red rectangle with two vertical white lines inside of it.

Red and White Striped Markers (Mid-channel) - Mark the center of a channel. Pass close on either side. 

Red and white flag with diagonal stripe down center. Blue and white flag with half vertical white and half vertical blue with triangle cut out on end.

Signs for Diving 

  • Diver down - red flag with white diagonal stripe to indicate diver down 
  • Code Flag Alpha - a blue and white flag displayed during dive operations signaling the boat's limited ability to maneuver
  • Boat should remain at least 100 feet from areas displaying these signs.

Private Aids To Navigation

Private aids to navigation are buoys for individuals or organizations to place permanently or temporarily on Commonwealth waters for private use. These buoys may include slow, no-wake buoys near private docks or temporary markings for approved regattas or races. Purchasing, positioning, setting, and maintaining private buoys is the responsibility of the applicant. Permanent private buoys must be marked with the PFBC permit number. Private aid permits are valid for a calendar year and must be renewed before the start of the following year to remain valid.  Applications must be submitted to the address on the form along with the established application fee.

ATON Plans

An ATON plan is required whenever there are impacts to safe navigation on a Commonwealth waterway. The PFBC's Guidelines for ATON Plans is designed to assist consultants, engineering firms, or others with  determining when an ATON plan is necessary. ATON plans must meet the outlined submission requirements.

For questions regarding ATON requirements for projects on federal waterways, please contact the appropriate US Coast Guard Unit:

ATON Manual

The PFBC's Aids to Navigation Policy Manual provides guidance to individuals as well as engineering and consulting firms for the planning and placement of navigational aides to ensure safe boating and the protection of property and natural resources.  

If you have any questions about Aids to Navigation (ATON), please email us at RA-FB-ATONPLANS@pa.gov.