Here you will find some of the interesting information a boat's Captain uses as part of navigation and understanding lighted buoys, lights, and... not least... those magnificent lighthouses we admire.
Three sources of information are the USCG Light List, NOAA nautical Charts, and Coastal Pilot volumes
  An overview of parts of the 3 documents follow:

The USCG Light List

The US Coast Guard publishes a list every year of every active Aid to Navigation (ATONs) including those which are privately owned and maintained.

The list includes lighthouses, lighted buoys, unlighted buoys, radio beacons, and fixed "daybeacons" which are small specially shaped and colored signs.

see: ATON Identification      
USCG Aux website

The NOAA Nautical Chart 

The Nautical Chart shows the the Spring Point Light and some of the same information which appears in the "Light List".

  A graphic representation of the light's sectors is helpful to the vessel's captain. 

This is a view of the INSIDE of the lens at Spring Point Light.  The red panels creating the "red sectors"  are shown permanently fastened in place.

The narrow white slot results in the safe "white sector" used by the captain to line up the ship in the channel when approaching Portland Harbor.

Lights can be red, white, green or yellow... and a great variety of flashing and blinking patterns.

Some are "fixed".....that is: always "on"...
but each lighthouse has it's own distinct flashing or blinking pattern. 

 The terminology describing the patterns is explained in a page copied from the USCG Light List immediately below. 

The United States Coast Pilot_tm
 consists of a series of nautical books that cover a variety of information important to navigators of coastal and intracoastal waters and the Great Lakes. 

Issued in nine volumes, they contain supplemental information that is difficult to portray on a nautical chart.

( All 9 Coast Pilot  volumes are  updated
 and released in July of each year)

Topics in the Coast Pilot include applicable NOAA charts by number, channel descriptions, anchorages, bridge and cable clearances, currents, tide and water levels, prominent features, pilotage, towage, weather, ice conditions, wharf descriptions, dangers, routes, traffic separation schemes, small-craft facilities, customs requirements, security requirements, and Federal regulations applicable to navigation.

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Specific details of harbor navigational lights are listed.

   Lighthouse description, latitude-longitude and  light characteristics are updated at each version release.

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An aerial photograph and description of harbor entrance hazards is given for the more difficult harbors, or those with a great deal of vessel traffic.

This is a welcome supplement to the nautical charts and GPS chartplotter the vessel may have on board. 

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   These reference volumes can be downloaded in PDF format FREE: