The boat
Lighthouses
The first French lighthouse was built in Cordouan, at the mouth of the Gironde around 1360. In France today there are 150 lighthouses and 3,577 lights managed by the Lighthouses and Beacons Service
Each light is identified by its colour, phase characteristic, group and period so there is no ambiguity about its position.
Colour
White, green and red, used worldwide.
Phase characteristic
Isophase (light and darkness for equal times), fixed (always on steady), flashing (darkness duration longer than light), occulting (light duration longer than darkness) and quick flashing (fast isophase with frequency more than 40 times a minute).
Group
Determined by the light/darkness pattern (occulting in group of three, five spaced flashes, etc.)
Period
Defines the timing of the complete light/darkness cycle (usually 5 to 30 seconds).
In this way, except for port entrance lighthouses with a range of several kilometers, one light cannot be confused with another.
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