Why Do Lighthouses Have Red Stripes?

✩ABOUT THIS VIDEO✩
In this video, we investigate how lighthouses work, looking at the Fresnel Lens and asking why they are painted with red stripes.

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[-Jethro-]

Worth mentioning: Lighthouse lenses can be colored, or blocked, such that each lighthouse has a unique pattern of white, colored, and missing flashes. Likewise, the daytime paint schemes can be unique as well. This helps ships positively identify which light they’re seeing.

(Edit: Locally unique, obviously not globally unique)

[tacklebill]

I'm a stagehand by trade, and specialize in stage lighting. In my trade we use ropes and knots that descend from the era of sail for our overhead rigging. But it's wild to me that our lighting tech also shares a maritime origin. Fresnel lenses are still used on stages around the world, to the point that Fresnel is the generic name for a type of stage lighting fixture.

[WootZoot]

Saw this video and wondered why you needed more than five minutes to explain “to make them visually distinct from one another during the day”.

[ThatOneGuyOG]

One of the most extensive networks of lighthouses still in use is on the Great Lakes in the United States. The pilotage for that region requires knowing all of the lights and not only the color/flash pattern of the lights, but the shape of the house and pattern of colors of the house. It's an old system but it still works and is reliable even if gps/ecdis fails

[brualtyusa]

The best explanation of the Fresnel lens I've seen. Great video

[NW-gicp]

To make them look like giant forbidden candy canes

[peregreena]

There's actually even more "high tech" in those rings. Aside from colouring to identify lighthouses, they have uniform width. Marine binoculars often have a scale, which gives distance from apparent width.

[madeofmandrake]

The other crazy thing about fresnel lenses is that they were often placed on a tub of mercury so they could spin slowly and evenly. This, of course, also took an even greater toll on the keeper of the lighthouse, slowly turning them mad from mercury poisoning. Coupled with how isolated some towers get, it's no wonder how lighthouse keepers are sometimes seen as crazy.

[FPVsean]

There's currently a lightship getting restored as a public monument/attraction in Dublin, it was part of Dublin Harbour for decades and was always just sitting around. When I looked it up why it had disappeared altogether it turns out its getting a full restoration and will be used to put on display soon :)

[matthewpeters]

Ham radio has a day called national lighthouse/lightship day where they open to amateur contacts! It's really fun to see who you can get in contact with!

[SRFriso]

Good video. Having grown up practically in the shadow of a red and white lighthouse, it's a nice trip down memory lane. The one thing I feel you left out about the rotating Fresnell lenses is that they can be placed around the light without perfect radial symmetry. Many lighthouses have deliberately unevenly placed lenses to give the beams of light hitting the ships a distinct frequency, so that sailors in the dark could work out which lighthouse they were looking at, and where they were in relation to it.

[edwardgurney]

I worked in an opticians for nearly 8 years and today was the first time I understood how a Fresnel lens works

[acomingextinction]

That explanation of a Fresnel lens succinctly captures what a clever idea it is. Maritime engineering has been the impetus for some really brilliant advancements - Harrison's clocks also come to mind.

[PaulJones-bruv]

The thing I love about lighthouses is that each lighthouse (in the UK) has a different time / flash signature. So just by counting the number of flashes over a period of time you know which light house you are looking at. So not just a warning out danger but also a navigational aid.

[CyberSystemOverload]

What an absolute genius idea the Fresnel lens is, he was amazing to have figured it out! Great video as always!

[Yupppi]

I clicked the video to find out why the lighthouses have red stripes. 70% through the video I had only listened about luminosity and parabola reflection.

[markcarey]

Years ago I was a lighthouse painter assistant. One day when the boss was away I painted I giant pic of Mickey Mouse on one side because I was bored and OMG did that cause a fuss. Ships radioed in in a panic and the head office called us and boy did I get a bollocking. This was in NZ in the 70s.

[АндрейОнищенко-зх]

Most of the video was not about red stripes and I am actually glad for that, got to know way more interesting things than expected, never knew about such lenses surprisingly, thank you dear author!

[sidkemp]

Along the US east coast, and possibly elsewhere, each lighthouse had its own custom horizontal stripe patterns of colors. This way, a ship could not only navigate coastal waters but also identify their own location by recognizing the specific lighthouse.

[elguido]

It is amazing how you can make every topic clear and fascinating. Thank you