Why Do Lighthouses Have Red Stripes?

[@-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)

[@narri214]

Adding to that, the fog horn sounding at a specific intervals to help identify in low visibility

[@giantidiot31]

@@narri214 Have you seen that video of the lighthouse man starting up the steam to blow the whistle? It's an incredible amount of work, but it's worth every time

[@gergokerekes4550]

well, you could make them globally unique, patterns, line counts and colors and their order can net you quite a bit of types. but that would not make sense. locally it can be useful. I am lost, but I see a lighthouse, it has 3 red stripes. bam, now I know roughly where I am.

[@derHutschi]

also Lighthouses have different coloured glass plates for different directions, especially for bays so you know if you're on course or not. so you drive to the first lighthouse that has a white beam shining in your direction, if the colour changes to red or green you adjust your heading to stay in the white beam. when the second lighthouse has a white light you turn to that. rinse and repeat until you reach the harbor

[@quillmaurer6563]

@@derHutschi I've heard of that called a "range light." Similar is used by airports for the approach to a runway, show red light if you're low and white light if you're high, you're on the right glidepath if you see two red two white. Another similar, shorter-range design (for use within channels) is moiré lights, which will show arrows pointing towards center if you're off center. Tom Scott did a video on how they work, and I've managed to replicate the effect with two combs.

[@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.

[@BoBandits]

Not exactly true, par and fresnel are still the lens, not the head..ask your local renal/supply guy

[@geigertec5921]

Also the lyme light, from burning a piece of lyme over the stage is still called that despite no lyme being used anymore.

[@joshroolf1966]

I was a stagehand for a few years and was personally amazed by all the nautical carry over, I really felt it coiling cables and holding chain ladders for the riggers.🤔💚 It made every event a worthwhile destination we were ferrying the audience/participants to, or something..:::😂😅🐾

[@johndododoe1411]

​@@joshroolf1966The maritime origin may date back to roman navy sailors operating rigging at Roman arenas like the Colloseum, as well as minor venues throughout the empire. I don't know who did the stage rigging in ancient Athens that invented the term "Deus ex Machina" to refer to a God character being lowered from the stage rigging to solve an impossible plot point .

[@terrylandess6072]

Understanding the design was to lower weight, it sure makes sense for light rigging. I know the Par Lamps are common names and the Alt light was fun for bands as well. Today the LED's seem to be the better choice for weight and heat. Melting color gels gets expensive.

[@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

[@tpobrienjr]

A wise mariner will know where the lights are, and how they flash, etc., because it is possible that the GPS can be spoofed (misled).

[@greed0599]

I got baited! I came to learn about stripes, but ended up learning about lenses!

[@JH-lo9ut]

We have lots of lighthouses here in the Baltic sea too. The archipelagos of Stockholm, the Åland island and the archipelago of Finland is an almost continuous labyrinth of tens of thousands of islands and underground reefs. It is totally navigable, even at night, thanks to an extensive system of lighthouses and marking bouys. Of course, GPS plotters makes it really easy and much safer to navigate these waters but most people still use a combination of GPS and paper charts.

[@geigertec5921]

The lighthouses of Lake Superior are the best lighthouses in North America imo.

[@SioxerNikita]

​@@tpobrienjrSpoofing is an intentional act by someone else to send out signals to trick a GPS ... No one does that, no point... GPS have error rates, and decent GPS software tells you it, so you wont be misled...

[@bru2al1tyusa82]

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

[@goodgame3374]

And it shows how unbelievably clever Fresnel was

[@quillmaurer6563]

I was thinking the same thing - if I were to give a lecture on optics and discuss fresnel lenses, I'd be tempted just to show part of this video as, especially with the graphics, it does a better job than I could ever do on my own.

[@kjamison5951]

While I knew of Fresnel lenses, and their optical characteristics, I did not know the back story of removing chunks of lens and then moving it all back to a common plane to achieve the same result. Outstanding!

[@olivierrevert8165]

100% agree, this is the best short and simple explanation ever 👍

[@Marqan]

Nah, it didn't explain it at all. Like why would lower density of air have an effect on the light's direction? And that doesn't have much to do with the solution anyways. I think the proper explanation is that the light breaks when it enters and exits the lens, but not while it's moving inside it. So it doesn't matter how thick the lens is, only its curvature, and that's why you can get rid of those chunks, ending up with what looks like many smaller lenses joined together.

[@peregreena9046]

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.

[@RobertCraft-re5sf]

That's very interesting and a simple solution.

[@NW-gi1cp]

To make them look like giant forbidden candy canes

[@HesJustSteven]

Shoot, that should be a rule. If you go to the candy cane, it won’t be sweet

[@Xetta_Mode]

@@HesJustSteven YOU MENACE! ...I LIKE IT!

[@USS_Grey_Ghost]

Orange and white then Forbidden candy corn

[@AsterGB]

​@@USS_Grey_Ghost traffic cones

[@BetaTester704]

Nothing is stopping you from licking them.

[@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 :)

[@PutitinDaramen]

thats super cool. do you know what museum it will be at?

[@elenatissari1866]

there's also one at the maritime museum in den helder u can have a look on street view

[@sierr4echo805]

And another one in Hull (Light Vessel No. 12 Spurn) that has just been restored and is berthed in the marina while a permanent wet berth is being built a short distance away.

[@stoutyyyy]

There’s one in Baltimore in the US as well

[@oscarosullivan4513]

That the Gannet

[@madeofmandrake1748]

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.

[@BCLighthouseKeeper]

Langara Lighthouse in BC still uses a bed of mercury for its first order lens. An amazing sight to behold. Last one in BC to use this.

[@DKNguyen3.1415]

@@gregoryford2532 No it is isnt. Mercury produces vapors at room temperature.

[@CX103]

I was on Rottnest Island a few weeks ago and visited the Wadjemup lighthouse. It, too, has a mercury floating base for the rotating lantern. The liquid is, of course, enclosed and the guide claimed that it was still the stuff they poured in when they installed the mechanism in 1929.

[@stupitdog9686]

In the past you couldn't be a lighthouse keeper unless you had a hump and a gimpy eye, & liked stuffing dead animals. Shame they switched to unmanned tho !!

[@SRFriso94]

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.

[@redshankyman4181]

That's really cool

[@edwardgurney1694]

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

[@danieldipalma704]

One is never too old to learn!

[@dukebaloof2540]

@@danieldipalma704 Yeah, but you can easily be too old to render that learning useless. Education is for developing minds, not adults.

[@musicenthusiast9801]

​@@dukebaloof2540 what? "Education is for developping minds, not adults" why do you think university exists? Learning is ageless. And should always be ageless. We have 50 year olds learning how to wire a circuit, or learn a language. Please don't gatekeep yourself or others by saying you're or they're "too old"

[@RiversJ]

The notion that only kids or adults learn effectively is bunk, there is certainly some biological differences but those are utterly dwarfed by effective learning techniques and motivation.

[@onions1183]

What 'tosh'. Learning is for all minds. You sound elderly and embittered. Enjoy the pleasure of finding out new things..😊

[@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.

[@lpc9929]

I am infertile from eating scented candles

[@PaulJones-br6uv]

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.

[@dougcook7507]

Its the same here in the US. Also, I haven't seen many light houses here in the US that have red strips. mostly black. The stripes also are distinctive to the light houses, usually. Which like the blinking lights at night, help identify where you may be at.

[@CyberSystemOverload]

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

[@martijn3015]

Yeah.. You can pretty much say that he saw the light.

[@diazinth]

@@martijn3015 angry updoot......

[@markcarey8426]

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.

[@oscarosullivan4513]

Brendan Behan was sent by his painter father to paint St John’s point lighthouse but he made a mess of it

[@beardedchimp]

That's because there is a Mickey Mouse lighthouse up in Scotland. The sailors were terrified they were back in Glasgow all over again. :P Your story is amazing, thanks for sharing.

[@markcarey8426]

@@beardedchimp cheers

[@unitrader403]

probably because they were afraid Disney would sue them..

[@markcarey8426]

@@unitrader403 Haha. Hadn't thought of that. :)

[@sidkemp4672]

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.

[@gdoof1728]

Thank you for the great article describing lighthouses and the Fresnel lenses!! I was in the USCG as a young 18 year old boy fresh out of boot camp and stationed at the Montauk Point Long Island, US Coast Guard lighthouse from 1971 to 1972. That lighthouse was built in the late 1700s!!!! There were five of us stationed there and our job was not only to maintain the the lighthouse and surrounding property and backup generators for the Montauk lighthouse-which had one of the largest and most beautiful Fresnel lens light -but also one of the largest foghorns at any lighthouse. We also maintained and monitored a very special radio homing beacon that the airliners coming from Europe across the Atlantic from Europe could home in on when they were flying to the airports of New York and New Jersey!! To service and get to the top of the lighthouse we had to climb almost 140 steps and once we arrived there the view literally took your breath away, looking across Long Island Sound towards Block Island, then east to the Atlantic. Seeing the sun coming up over the Atlantic on a beautiful spring or summer day was perfect!! The local radio station in New York used to play “Morning Has Broken” by Cat Stevens and the words fit perfectly!! In the summer, the rich folks from Rhode Island, Connecticut and New York City would Vacation in their summer homes on eastern Long Island, and come to the lighthouse for tours. We got a chance to meet many nice girls when we were just young men of 18 years old - 😂- so it was great-we each had our own room, a dayroom with TV and all that and a full kitchen, in which we prepared all our own meals!! The officer in charge was a wonderful man, bless him, named Ralph Conant - - he was a Bosun’s Mate First Class and was a great boss!! His wife and family had quarters there also, as did our engineering officer, who went by the name of “Smitty”- he taught us a lot about diesel engines, electricity hydraulics, mechanical stuff and all those kind of things and had a wonderful wife for baked us all sorts of cookies and things like that and was very nice to us. My two friends were Bill Eberline from Poughkeepsie, NY and William Appleby, Jr. from Boston, Massachusetts!! I probably would’ve stayed there my whole four year tour, but I put on for and received orders to go to flight school and flying USCG helicopters doing search, rescue and medevac missions for the US Coast Guard for the rest of my career which I thoroughly enjoyed. I hope to get back to Montauk and take a tour one day the place I was at over 53 years ago!!!! Great memories and great shipmates of a different time and place😌😌

[@americanfreedomlogistics9984]

it has always been my understanding that they each do their own striping style to not only make themselves more conspicuous but also to set themselves apart from other to make them easily identified from a geographical standpoint.

[@katherynedarrah4245]

"The earliest ones were simply open fires burning on top of hills" But they found this was too dangerous so they made a safer version.

[@Quasihamster]

Also, the Riders of Rohan kept speeding to the scene every damn time and started complaining why they were being summoned all the time for no particular reason.

[@samuelfellows6923]

@@Quasihamster🙃

[@stanislavkostarnov2157]

@@Quasihamster funnily enough, the most likely inspiration is an actual set of fire beacons along the channel/Devon coast, used to warn of French, and somewhat later, Spanish invasion fleets approaching

[@justasandvich7168]

​@@Quasihamstercause Gondor keeps calling obviously

[@Quasihamster]

@@justasandvich7168 Yeah but they assume it's to fight back a fleet of corsairs! Not guarding a shipment of pipeweed or malt beer against... well, nothing!

[@elguido]

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

[@АндрейОнищенко-з8х]

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!

[@guywiththebottle]

Once you search up such a lense, you quickly realize that they look very familiar.

[@HeisenbergFam]

Props to lighthouse keepers, the loneliest job in the world

[@toahero5925]

What about firewatch rangers?

[@Gebri3l]

I wish for a job like this to be honest. If any available hit me with it

[@PutitinDaramen]

so said the lighthouse keeper

[@unvergebeneid]

So you're saying maximum odds of not having shitty coworkers?

[@Elitaria]

​@Penny Lane but also max odds of not having good co workers.

[@Spinexus]

As a non-sailing gamer i learned to love lighthouses because of the game Dredge. In which thick fog (cthulu shit) covers the sea and land at night, the only thing punching through being the lighthouse!

[@dragonace119]

The spookiest part of the game is when your sanity is low, giant ass fins freak me out.

[@goodgame3374]

That's no game lad. When you achieve the required level you'll receive a knock on the door & a pair of sea boots. The great old ones cannot be allowed to..... urgh...uh...gah...☠

[@davidschwartz8125]

As a small entertainment lighting history note: if you look at the shape at 2:50 this was another lens type used called a stepped lens. It also reduces the weight of the plano convex lens but those flat planes on the inside face caused more diffraction than desired and they fell out of favor compared to fresnel lenses since the 1940's/50's. But if you dig through old theaters that haven't dumped their old gear you may find an ellipsoidal fixture with a stepped lens hiding in a corner. Or being used still.

[@evlkenevl2721]

This is the first in-depth explanation I've ever seen for Fresnel lenses. Thanks!

[@randydewees7338]

Very nice simple description of the optical system. I do have a technical niggle - at 2:00 and 3:24, the parallel light rays coming from the parabolic reflector would be refracted inwards by the lens, not outwards as shown. However, the practical effect of being not usefully directed would be the same in either case.

[@IncognitoAtreides]

Fantastic video! The title was intriguing. You kept us waiting for the answer while educating us in an amusing manner and the pay-off was great. Great intonation and cadence of speech, you earned yourself a sub!

[@thomastaylor6699]

The invention of the Fernell lens was a remarkable achievement considering all the time and energy it took to work out the parabolic geometry of the lens! I just love history like this!😊

[@nathangamble125]

"This revolution by Fresnel" Ah, a *literal* revolution, because it revolves.

[@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”.

[@quillmaurer6563]

Very well done video on fresnel lenses and lighthouses in general - the red/white stripes was only a brief tidbit compared with the rest. I might even use this if I am substitute teaching a physics class and they're discussing optics. I understand fresnel lenses pretty well, but this explanation and graphics are far better than anything I could do on a whiteboard. I've seen an interesting historic lighthouse, the one in Hope Town, Abaco, Bahamas. If I remember right it is the only still-operational kerosene lighthouse in the world. Clearly kept that way just for the historic value and novelty, not the most effective or practical solution now available. But it was fascinating seeing everything, including climbing up to see the lens system and burner. Airports commonly use fresnel lens beacons as well. I once tried to use a large plastic fresnel lens from an overhead projector (insert Pepperidge Farm meme) to set things on fire, but only succeeded in blinding myself.

[@oscarosullivan4513]

Last clockwork mechanism and paraffin lamp lighthouse in the world

[@Syclone0044]

@@oscarosullivan4513 the 200 year old Point Reyes, California lighthouse still has a magnificent 1860’s brass mechanism made by a Paris, France jeweler and a giant First Order fresnel lens

[@oscarosullivan4513]

@@Syclone0044 Lovely

[@quillmaurer6563]

@@oscarosullivan4513 I'm guessing there are others preserved (or even abandoned in good condition), but Hope Town is the only still operating one.

[@oscarosullivan4513]

@@quillmaurer6563 I don’t think so

[@shake307]

I am positively chuffed I watched this video. Very well done

[@raideveloper]

This randomly appeared in my feed, really cool channel, when I was a kid I was fascinated by lighthouses because they're such isolated towers visually appealing

[@Nikioko]

The pattern of the stripes is also very distinctive for each lighthouse. And there are even lighthouse in yellow and red.

[@jst7714]

I was lucky enough to be a volunteer at the second tallest lighthouse in the USA several years ago. One gets a great view up there!

[@SeaDog337]

Back in the days before GPS, lighthouses were especially useful as fixing points and the distinct colour patterns could help you determine which one you were looking at. Lighthouses are charted, so once you knew which one you were looking at, you could roll off the bearing and figure out where you were.

[@hawksights]

The explanation of the fresnel lens was way more interesting, than the topic of the videotitle

[@Nylak-Otter]

I experienced the opposite. I came here to confirm the answer to the question to see if my supposition was correct, and already had plenty of familiarity with the fresnel lens. Even my old supposition was wrong. My old lighthouse had stripes that were to be counted to see how many were visible; in bad storms, the water levels would surge and you could only see two or so colored stripes when there were a total of five in calm waters.

[@hawksights]

@@Nylak-Otter Well something like this weren't mentioned in the video ;)

[@rphb5870]

This reminds me of an old joke, it took place doing a foggy night. I see you there, the first one said over the radio: MOVE I'm not moving, you move. No, you move, I am the larger ship I have precedent. I don't care you move. I happen to be a supertanker one of the biggest ships in the world so you need to move. okay but see I'm a lighthouse.

[@edi9892]

That was a beautiful explanation of how Fresnel lenses work!

[@matthewpeters2062]

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!

[@davidpawson7393]

Fun fact, the Cape Hatteras lighthouse paint scheme was mixed up with another lighthouse which was supposed to be black and white diamonds for Diamond Shoals instead of the black and white spiral. Another fun fact, I was the first person to climb the steps to the light during a hurricane while it was sitting on the temporary shoring towers at its new location. Tallest masonry lighthouse in the US and I highly recommend visiting.

[@LogicalNiko]

I used to love seeing WLV-612 (the last light ship commissioned in the US) and LV-112 the predecessor to WLV-612. Both used to be the primary light for Nantucket but now sit docked at Boston Harbor

[@bertbaker7067]

In optometry we use fresnel lens stickers to temporarily induce prism in a patient's glasses to treat diplopia (double vision). Pretty rare to use them tho.

[@RaindropsBleeding]

the striping is so that you can see it against any background. they do this for buildlings that could be struck by aircraft as well. Fantastic explanation of the fresnel lense though.

[@robbabcock_]

Great video! You answer so many questions I'd never even thought to ask but find fascinating.

[@D-B-Cooper]

The lighthouses on the high cliffs were abandoned because there is a lot of fog on the coasts and they weren’t visible most of the time. They moved the lights down to the coast for this reason. Even when the lighthouse was below the horizon the light would reflect off the bottom of the cloud cover.

[@TheDuckofDoom.]

If you replace the parabolic mirror with a hemisphere mirror it will work in cooperation with a lense. The hemisphere simply reverses the light back through the source. Alternatively the parabolic mirror can be extended well beyond the light source to capture more stray light, although with diminishing returns.

[@RobSchofield]

Another classy little nugget of Maritime wisdom. Great!

[@jamesjellis]

Yea but I have never seen a lighthouse painted with red. Every single lighthouse I have ever seen is white and black or a solid white.

[@crabby7668]

I was once told by a work colleague that he often went up to the light house in Den Helder in the Netherlands, to smoke some dope and watch the lighthouse. He advised me to go and see it, which I did. It was a tall tower with a wide grass green around it. The light was like the biggest disco mirror ball you have ever seen! The blobs of light scintillating across the flat grass was really trippy. I can see why a smoke would have enhanced the experience. It was awesome.

[@simonspacek3670]

Frensel lens is amazing thing. You can see it in many places, like on back windows of cars to give you bigger field of view. And it can be made from cheap and light plastic, so you can have one for hiking. To check details on flowers or to start a fire.

[@InternetDarkLord]

I manned the Cape Hatteras Lighthouse for the National Park Service several summers. The lighthouses on the coast each had a different paint pattern for coastal navigation. Lookout=Black and White Diamonds Ocracoke=Solid White Hatteras=Black and White Spiral Stripes Bodie= Black and White Horizontal Stripes Corolla=Solid Brick Red

[@ProjectAtlasmodling]

Better to keep lighthouse around than to get rid of them. If your navigational systems fail a lighthouse will be your only warning

[@oscarosullivan4513]

As a sailor I agree

[@charliescott7764]

One of my favourite lighthouses is Rathlin Island West which is upside down. Thanks for explaining Fresnel lens.

[@oscarosullivan4513]

It is one of the last built in Ireland

[@st.charlesstreet9876]

Absolutely fascinating! Thank You for the post.

[@jamesfernick3741]

for those of you wondering why lighthouses sometimes have green stripes this is to indicate the position of the channel, the way i was taught to remember it is Red, Right, Return, if your coming in from the ocean and the lighthouse is red you want it to be on your right hand side as you are returning, if you see a green lighthouse you want it to be on your left as you are returning into harbour, Side note: did you ever wonder why the signs going into most marinas and harbours by boat have a point or notch in the top of them? its because there is usually a post with a light somewhere in front of the sign you can line up with the notch and that allows a boat to know if they are in an unmarked channel, if the post in front drifts out of the notch on the sign your out of the channel and might scrape,

[@mhoover]

Excellent explanation of the Fresnel lens.

[@smarts53]

Thank you for pronouncing Fresnel correctly!

[@ryhol5417]

The lense explanation is insanely helpful (to me). Thanks

[@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.

[@sarcasmo57]

I always thought being a lighthouse keeper would be a cool job.

[@ScaleAutoGarage]

It is the greatest job in the world. I love it.

[@redsable6119]

The Fresnel lens also made rear projection tvs possible back in the day.

[@pauulthefair]

I love this channel, it gives me answers to questions I never would've had.

[@tsbjelland]

Many of the more famous lighthouses in the United States are painted in black & white for the high contrast to improve visibility from the sea. The different patterns are for easy identification of the specific lighthouse, in the days before radio, radar or any other electronic aids.

[@stevekight1955]

Light houses aren't all striped the same color. They generally have a unique color pattern so you can tell which one you are seeing in the daytime when the light isn't on, thereby telling you your location.

[@mitchellslate1249]

Brilliant breakdown! Truly! And short and quick and tight and full information 😊

[@darylcheshire1618]

At Queenscliff in Victoria, there are two lighthouses a white one and a black one. The two have to line up so a ship can sail in a straight line to navigate around this huge rock at the heads of Port Phillip Bay. I understand the lighthouses were funded by this association of ship owners who were always looking for cheaper ways and replaced them with navigational markers.

[@BitwiseMobile]

The lighthouse at Cape Hatteras, North Carolina has a somewhat distinctive pattern using a diagonal pattern similar to a barbershop pole. It's black and white. In Michigan there is one that has diagonal red and white stripes which makes it look exactly like a barbershop pole. There might be a few others using the diagonal pattern, but it's fairly unique.

[@jamesjellis]

NC has some amazing patterns on their lighthouses from stripes to diamonds though most of them are black and white not red.

[@HugeRademaker]

I used Varne and Sandettie lightships to plot the helm over point on radar.

[@mikenco]

I had a literal lightbulb moment. I have known 'Phrenel' lenses my whole life, just never knew they had a name, nor quite how they worked.

[@stanislavkostarnov2157]

one thing you missed is the color coding of lighthouses that widely exists certainly, a green lighthouse on the right side of the channel (as heading towards the harbor) would be seen as unusual in the Americas, whilst the opposite is generally true in the UK... black and white lighthouses meanwhile, are generally at the center of a shoal in the middle of (relatively) blue water edit* as pointed out by @David Cowie I forgot to mention the 3R rule... yes, when right side, I meant right side incoming.

[@DavidCowie2022]

"On the right side of the channel." Heading upstream or downstream?

[@stanislavkostarnov2157]

​@@DavidCowie2022 right as you head into the port return red right... sorry, forgot to mention that (obviously opposite for the UK & some of Canada) correcting with an edit.

[@SilverGear_]

I've spent many a day visiting various light stations around the UK, even having the pleasure of staying on Lizard's station grounds in the former keepers' cottages. While I understand the economies and practicality of replacing the old Frenel lens installations with modern LED arrays, it seems to remove the soul from the things, those sentries of the sea that have withstood tide, time and toll. Though for technology knocking on the door of three hundred years old, it's had a good innings! I think it is also worth mentioning that the different patterns of the flashes, the colours of the towers and stations, and the fog signal blasts (for those that are left) helps with identification both day and night and during poor visibility. This was to assist mariners in positioning and reckoning when at sea or along a coast, particularly in the days before GPS and modern electronics. FYI for those that dot know, these characteristics are called the "character" of a given light. Depending on local conditions you might also have sectors or pairs of leading lights to mark safe channels, danger areas and so on. An example local to me being the Burnham on Sea High and Low lights, the High light now being just a day mark and lining the two vertical lines up indicates a clear channel towards the anchorage and slip there.

[@JP_TaVeryMuch]

Now there's a lighthouse extraordinaire!

[@SilverGear_]

@@JP_TaVeryMuch if you say so! I just like lighthouses. Have done for perhaps most of my life by now.

[@JP_TaVeryMuch]

@@SilverGear_ The shed on stilts at Highbridge (and Burnham by extension) beach, to which I thought you were referring.

[@andreasarnoalthofsobottka2928]

In the German Beight there used to be light vessels (Feuerschiffe) in the astuaries of Ems, Weser, and Elbe. After they were replaced by high, powerfull Lighthouses on land one was converted into a Schooner- Bark named Alexander v. Humboldt. It's the green one you probably have seen in a Beck's commercial. She is now (since 2001) a floating Restaurant after being used as a training vessel. Anyone can book a trip on her successor. She is the only cultural world heritage you can participate in.

[@HibernoRasputin]

Am i incorrect in my understanding that the stripes and colours were different and with different widths to easily identify the lighthouse? Hook in ireland has 2 thick black stripes identifying it as hook head. I did the tour there and i think i recall the guide saying that?

[@JarrodFrates]

Mostly, yes. They're not entirely unique, but they are (or should be) within a certain geographical distance to help with navigation. On a side note, there are people whose hobby is traveling to spot lighthouses because of their uniqueness. I once met a couple who were spending their vacation going along the East Coast of North America doing just that.

[@ImieNazwiskoOK]

Also a guess but with stripes if you are very far you may even roughly approximate distance by the amount visible

[@The88Cheat]

Video suggestion: I would love a serious where you talk about different ship emergencies where the captain and crew did a good job and then instances when the captain and crew did a poor job at managing the situations.

[@nickmaclachlan5178]

You didn't mention that those lenses float and turn on "bearings" formed from large amounts of Mercury making them virtually maintenance free and extremely energy efficient to rotate. It's another great consideration when you may have a lighthouse stuck out in the middle of the sea and weather so bad you can't get any supplies to it. People take Lighthouses for granted, but they were the proving grounds for some groundbreaking technological advances in a world that was rapidly industrialising.

[@Camptonweat]

I think when you say "focal plane" you mean the "optic axis", which denotes the principal direction of light propagation. The focal plane lies perpendicular to the optic axis.

[@tjb99yt]

Great video! One small point: the light ship should also display an anchor light in addition to the main signal light.

[@semipenguin]

I would think the stripes would give ships some idea how far away you were from the lighthouse. As the top comes into view, the closer you get, the lower stripes would become visible.

[@toddkes5890]

The width of the top part can help as well. Make all the top parts the same width, and when looking at it during the day with a labeled set of binoculars you can get a good estimate of your distance.

[@ruthpage2297]

Omg, the shipping forecast now makes more sense, because they name the ‘light vessel’s. it was just words/names in my head but it relates to the light ships in the channel. Thank you

[@cyrilio]

A friend of mine lives in a decommissioned light ship in Amsterdam. It looks just like the one displayed in the video.

[@mikefochtman7164]

I remember sailing into one port on Lake Ontario that had typical red and green lights to mark the breakwater entrance. Unfortunately, the town just beyond had a traffic light that was right 'behind' the pier markers. Staring for several seconds, you could figure out which was which because the pier lights were 'occulting' and of course the traffic light would change from red to green and back again. But look away at something and then back, you had to pick out the correct lights again and again. Seemed like a terrible situation but the locals just said, "been like that fer years..." sigh.

[@rereleader]

This Lens is a genius design! It’s inventor allowed the technology to be used far and wide by its simple but effective design. Made me tear up a bit at its brilliance!

[@YossiRafelson]

The lighthouses in California tend not to be painted red and white. Also they tend to be built on cliffs but without a tower. This is to prevent the light getting lost in low clouds.

[@TheGrejp]

Yeah, this definitely isn't always the case. In my country, which has a massive coastline for its size and over a thousand islands and rocks, there are almost 50 lighthouses and none have red stripes. They're usually painted white or not painted at all (and are thus a light grayish color of the stone they're built from)

[@vladislavkalina2039]

Same here in Europe. I don't remember seeing any red-white-striped lighthouse in "my" Adriatic Sea.

[@Mekkiceh]

​@@vladislavkalina2039 The stripes and the colors have a specific meaning. Color is either black, red, white and yellow and it says where the obstacle is and where the chenal is compare to the building.

[@uberunter7457]

When I took theatre in college, we used tiny Fresnel lens in some of our lights. It’s amazing all the uses this invention still has.

[@jannepeltonen2036]

That was a great explanation about the Fresnel lens, thanks!

[@gabrielgarcia7554]

I just want to say thank you for making these videos. I learn so much about the maritime world that I was completely oblivious to.

[@Ebolson1019]

on the great lakes is common for light houses to have black/white stripes, sometimes spirling like a candy cane

[@ukar69]

If I recall, the rotating lenses used to float on a pool of mercury!

[@oscarosullivan4513]

They used the lighthouses retaining their fresnels in these islands will replace the Mercury with spirit alcohol

[@ScaleAutoGarage]

The really large lenses did and still do. Langara point lighthouse in BC still uses a first order lens in a bed of mercury. Last one in BC.

[@Bonzman]

I used to live in Dovercourt in Essex and a couple of miles away is Harwich where Trintity House has its UK operations HQ, for repairing light ships and also two ships that would put to sea maintaining lighthouses and light ships. There is a lightship you can go on and explore, it was used as a pirate radio station! It's well worth a visit if your up that way.

[@danielbond9755]

Lighthouses are not always, or even mostly, red striped. Black is more common. The issue is that different lighthouses have different color patterns, so that it is possible to easily identify which one you are looking at.

[@oscarosullivan4513]

Black striped and white and plain white is more common in Ireland than red and white. The only red and white banded light houses are Kish and Mulligans

[@Zebsterr]

If you just wanto know why the lighthouses have red stripes you can skip to 3:57

[@Anti_Woke]

Haven Ports Yacht Club uses a decommissioned lightship as their clubhouse.

[@josephlai9759]

Thank you so much. I never knew how Fresnel design evolved.

[@paulmiddleton8699]

Scilly Automatic is a great name for a light ship it made me smile while listening to the shipping forecast on BBC Radio 4.

[@mthiffau]

Huh, I had my money on something clever like "you can calculate your distance to the lighthouse by counting the rings you can see above the horizon".

[@terjebe7317]

You can. Atleast for some light houses the distance at which you see the various strips is noted in the charts. You have to be carefull though, as the temperature and humidity may change the light diffraction.

[@mercut10]

There's enchantment in the Fresnel Lens

[@ginnyjollykidd]

"Lo-tech" is not to be dismissed entirely. It still works.

[@BullDeerAryu_]

Long story short: There’s stripes for visibility during the day. The lighhouse’s light doesn’t work during the day

[@steve-marsh]

Fantastic! Thank you!

[@oldmech619]

There is a light house south of Los Angeles. I once put in the wrong waypoints for the peninsula while sailing back from Catalina in a hazy night. Tech is good, errors are made but light houses don’t move.

[@oscarosullivan4513]

More reliable and in the past sometimes the only conversation to be had was with a keeper

[@wobblysauce]

First time hearing about light ships.