With GPS systems and other geographical technology being as sophisticated as it now is, do lighthouses still serve an integral purpose? Are they more now just in case the captain/crew lapses on the monitoring of navigation systems? Obviously lighthouses are more immediate and I guess tangible, but do they still fulfil a purpose beyond mitigating basic human error?
In: 5120
Ok, this is one I can answer. When you are navigating a ship, the more methods you have of fixing your position the better.
With modern GPS and electronic chart systems, there are rarely huge faults, but as you may have an oil tanker with 22 men on board and 150,000 tonnes of crude oil, a rare fault could lead to absolute disaster.
So, when driving a ship, you also use other methods which could be:
A) Celestial navigation — using the stars/planets to work out where you are – only accurate enough for deep sea work really. The best celestial fix I ever got at sea matched the GPS by around a tenth of a mile, but that was with practicing almost every day for weeks.
B) Compass directions (bearings) — take the direction (bearing) of three objects at the same time using the ship’s comapss, then draw the lines on the chart, and where they all cross (if you got a good fix) that’s where you are.
C) Soundings (depth of water) — really only good for knowing your progress along a line if you know the depths.
D) Radar — either you can use the same method as b, but use radar bearing, or you just match the lad on your radar screen to the chart.
There are some others, but mainly you use GPS, and B and D as back ups. Which now means if you want to take a visual bearing of something at night, you need it to have a light. So basically a lighthouse gives a very defined and identifiable point from which to take a compass bearing.
As an aside, every light house in a certain section of shore will have a different rhythm and tempo, which the chart will tell you, so that you know which light house you are looking at. Some will also have light sectors, which will show different colours depending on the direction you are looking at them.
There are some more complex uses, but I’ll keep it as that for an (admittedly complex) ELI5 answer.
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