How does lighthouses works, why is it so important?
In: Technology
A lighthouse is a tall building with a light on top of it. It is tall so that you can see it from further away as it does not become hidden behind the horizon. In order for the light to be visible from further, especially at the time when it was a small gas lantern, there is a lens mounted over the light which focuses its light in one direction. This makes it visible for further but only in that direction. So the lens is turned around so the light shines in different directions. From a ship it is visible as a blinking light. The main purpuse is to make sure ships who are not quite sure exactly where they are to at least not run aground by just keeping away from any lights. This does not only include lighthouses but also street lights, buildings and other ships. However because the lighthouses are visible from so far away and can usually be identified by difference in the pattern of light they shine lighthouses themselves were used as landmarks for navigation.
They keep ships away from rocky coasts, they’re just big lights that are warnings, usually on top of rocky isles that show a potential hazard.
Big light is placed high in the air and on rocks near the coast so ships don’t smash into rocks. They avoid the light and don’t crash.
In addition to the other replies lighthouses rotate a specific number of times per minute so by counting the rotation ships not only know that there are dangerous rocks around, but also the specific location of the lighthouse and the nature of the danger.
Before GPS was invented, ships often navigated using maps with landmarks if they were near the coast: If you see two or more landmarks with a known location, you can triangulate the exact position of the ship by measuring the angle between the two. Their color and blinking pattern can be used to identify them: Lighthouse A might blink two times and have two stripes, lighthouse B blinks three times and has three stripes.
In addition to just signalling their location, lighthouses also often shine different colors and patterns in different directions, so you don’t need to whip out a compass to measure the angle between two lighthouses. So a map will show you exactly in which sectors the lighthouse signals which color, and multiple overlapping sectors mark safe and dangerous waters.
It allows ship to estimate where the coast is, even very far away, with the curvature of the earth hiding everything, in the dark, when it’s smoggy.
They are important for showing position.
Mainly the position of the land they’re on, but by knowing how tall the lighthouse is, you can know how far away it can be seen. That gives an arc on the chart *(water map)* where you have to be inside there somewhere because you can see that particular lighthouse. Combined with water depth, the location is narrowed more.
And by knowing the characteristics of that lighthouse *(color & design during the day, light color, flashing speed & pattern at night)* you can know that you are definitely near a certain place.
If you can see 2 or more lighthouses, you have a really good idea where you are, based on angle & distance to each.
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