In Italy, we consider this the main symbol of sailing: the rules applied to lighthouses are very strict and every sailor should know them, to get a sailing license.
Marine signaling is very important within the topic of lighthouses. It helps a lot during the first phase of landing, but also because lighthouses are considered conspicuous points.
Conspicuous points: natural or man-made features (as in this case) that are visible from a distance and provide a physical visual reference while sailing.
How can we find information about lighthouses?
To get detailed descriptions of all lighthouses lights and sound signals in the Italian and neighboring seas, you can consult the Directory of Lighthouses and Fog Signals in IMM editions.
Just search for the name of your location of interest. Then, look up information related to the lighthouses in the area (e.g., phase, color of light, and other items we will see below).
Are you studying for your sailing license? Then, you should take this handbook and start using the 8 columns, captions, and abbreviations.
This way, you will be prepared for when there is a need to inquire about a specific point on the coast.
Now, let’s get back to the lighthouses.
What is a lighthouse?
A lighthouse is a light signal that allows those coming from the sea to see a coastline or location from a distance, during the day but especially at night.
When visibility is poor, such as if there is fog, the beacon also beeps.
A lighthouse is a fixed point and it is highly useful for orientation at sea.
It often emits a beam of light that rotates 360° or flashes, with a much longer range than many other types of light.
Type of light
Unlike lanterns, a beacon equipped with a white light can be seen up to 15 miles.
However, there are not only white-light beacons: the light can have a different meaning according to its color.
You should know about color differences to consult the nautical chart or the Directory of Lighthouses and Fog Signals in IMM editions.
Also, in this booklet, which is updated every two years, any blind spots in the lighthouse are indicated. Those blind spots may be intended by the manufacturer or may be generated by natural obstacles, such as a cliff, a built-up area, or other.
Please note: don’t confuse the lighthouse blind spot and the eclipse!
The eclipse is the period of time of darkness when the lighthouse beam is extinguished. Remember that lighthouse light signaling includes a definite time interval. Within this time lapse, flashes of light alternate with eclipses, repeatedly.
Types of light
Lighthouses vary their light signaling first of all according to phase. We denote by “phase” the duration of each light and eclipse (and thus by period we mean the interval of time in which the phases are repeated cyclically).
Below are the different types of light and their symbols:
- steady (F): continuous light of the same color
- alternating (Alt or AI): light of different colors
- rhythmic: with flashing lights and groups of short or long flashes or constant sparks
- in flashes: Lam or FL on English cards
- intermittent: Int or Oc. The number of eclipses is given in parentheses after these symbols
- scintillating: Sc, Q on English charts
- ISO: in this case light and eclipse of equal duration.
The ranges of a lighthouse
The ranges of a lighthouse are: luminous, nominal and geographical ranges. Then, we will talk about glare.
1) Geographic range
Geographic range is the maximum distance from which a lighthouse can be spotted, and is calculated with this formula:
D=2.04x(√h+√e)
Where D is the distance, h is the height of the lighthouse above sea level, and e is the height of the observer’s eye. 2.04 is a convenient value for converting values entered in meters to miles. The tidal consideration should be added to this formula. Since the geographic range varies with the observer’s height, the tide raises that height, and it is therefore necessary to consult the tide tables before making any other assessment regarding the geographic range.
2) Nominal range
Nominal range, on the other hand, is the distance from which the light from a lighthouse is observed with visibility of not less than 10 miles. It is usually indicated on French, Italian and Maltese nautical charts, while on others only the next luminous range is indicated.
3) Luminous range
Luminous range is the maximum distance from which a lighthouse can be sighted. It depends on the power of the light, the weather, and the sensitivity of the observer’s eye. With atmospheric visibility of 10 miles, the light range corresponds to the rated range.
4) Glare
Finally, glow is a bright aura visible in the sky, over clouds or haze, usually even before the sighting of the lighthouse itself.
