Before Ships Used GPS, There Was the Fresnel Lens
spectrum.ieee.org
spectrum.ieee.org
The Swedish inventor Gustaf Dalén (1869-1937) invented many revolutionary systems for beacon lightning for lighthouses [1]. In Sweden those lighthouses was called "AGA-fyr" (AGA-lighthouse) after his company AGA and abroad Dalén-lights.
Some of the inventions was the:
- "Dalén Flasher" that made the beacon flash and that conserved 90% of the acetylene gas, and the timing between flashes also made so observers could differentiate between beacons.
- "Dalén Mixer" that gave lighthouses greater luminosity where acetylene and oxygen was mixed in specific proportions.
- "Sun valve" made so the lighthouse only was on during the night to preserve gas. It was a black body rod that was connected to a membrane and tree shiny rods. So when the sun shined, the black expanded and turned off the gas. When the Blockhusudden beacon in Stockholm, the first sun valve beacon in the world, was electrified in 1980, it was discovered that the sun valve had never needed to be repaired!
For this, he also got the Nobel Prize in Physics 1912 “for his invention of automatic regulators for use in conjunction with gas accumulators for illuminating lighthouses and buoys.”
[1] https://www.tekniskamuseet.se/en/learn-more/swedish-inventor...
TIL the AGA cooker was also invented in Sweden. Somehow I have always assumed that it is a British peculiarity.
For me, absent any other facts, I default to trusting the instrument over the human. I think the risk that the is human misidentifying a landmark is greater than the risk that a ship's GPS is malfunctioning. Again, absent any knowledge of hacking/spoofing in the area.
A phone + powerbank should suffice. And most likely there would be additional people on board in case someone's phone stops working (e.g. dropped into the sea).
And if I were to navigate in a foggy/stormy day by myself, I'd at least carry an additional phone.
And if there was so much fog that would affect GPS signals, how can lighthouse lights be seen anyway?
I'm not a sailor or anything, just trying to understand why this can't be done and why lighthouses are still needed.
Speaking more generally it's just very risky to put all your eggs into one basket when it comes to navigation. It's so difficult to impress upon the new generation of navigators that they are guaranteed to be completely screwed at least once in their lives if they don't learn something other than GPS.
How to you know?
Of course one could imagine other scenarios where GPS might become inaccurate or unavailable on a larger scale, such as an attack on the satellites themselves.
[1] https://safety4sea.com/us-marad-gps-interference-incidents-r...
[2] https://www.traficom.fi/en/news/unusual-amount-reports-about...
(my guess is that _moof is a navigator with experience in the eastern med sea)
And not necessarily malicious. Before I ditched Strava (insert separate rant about tech "ecosystems"), one of my bike rides took me near a nuclear power plant. The resulting GPS track had a sudden hundreds-of-feet "climb" near the power plant that didn't exist in the real world, as if I had literally climbed a wall on my bike.
How do you know?
How do you know?
Looking at years of MAIB reports I'd say that the thing which you're guaranteed to be "completely screwed" by sooner or later is negligence: https://www.gov.uk/maib-reports
The technology used pales in comparison, a man comfortably asleep in a nook on the bridge at 0300 is equally oblivious to a lighthouse, urgent radio calls from the coastguard, GPS monitoring or anything short of being shaken awake by the vibration when the ship smashes into something.
Some harbour/river entrances have a sectored light. White if you're sailing in safe water, red if you're to the left of it, green if you're to the right. Makes a fantastic navigation aid for the entrance and I'll take a setup like that over a plotter for pilotage any day.
https://en.wikipedia.org/wiki/Precision_approach_path_indica...
Flashing to indicate how much of a correction needs to be made and turning yellow once on center line.
Incidentally I couldn't find much information on this "Long range laser lineup" outside of DCS where I've heard of this first, a bit odd considering the other landing system for glide slope is fairly well documented.
Perhaps laser is also good to reduce the visible signature of the ship, the fewer lights the better. Or maybe it's just brighter for the pilots.
> maybe that's legacy now
No as far as I'm aware it continues to be a thing, to assist in keeping on glidepath.
The lineup system is for aligning to center line (horizontally relative to carrier's deck) from a distance. I did find it odd that there is barely any mention of it outside some internet forums, the closest to an authoritative source I found was this https://www.cnatra.navy.mil/local/docs/pat-pubs/P-816.pdf (see Page 24)
my elderly father sails.
he has a fairly modern android smart phone, but he has absolutely no ability to use the phone outside the large 'make a phone call' button that was setup for him by family in the middle of his locked-down homescreen. He requested his phone be setup this way because he
1) has no interest to learn a how a smartphone works outside the small paradigm that he believes a phone should work and
2) he has trouble with the dexterity required to use a touch-screen and not press every button on the screen inadvertently during normal use.
so , tl;dr : don't assume that having a smart phone means having the ability or know-how to use even half of the things that it's capable of. Some people have smart phones simply because they were carried into the decision by the tides of time; many would probably still be using rotary land-lines if they got their preference.
https://skysedge.com/unsmartphones/RUSP/index.html https://news.ycombinator.com/item?id=31166026
At this point it becomes more of a business/hobby/profession-related thing to learn that would help a lot, rather than a trend or a luxury.
It is always amusing to listen old sea dogs after they run aground and they tell you that they have always sailed there and never had any problems.
Even after that they still claim that iPads are toys and only dumb youngsters use them.
Navigational errors that could result in grounding or collisions may endanger life (and be very expensive), so it is unsafe to rely solely on GPS, even if you have redundant receivers and power supplies.
[1]: https://en.wikipedia.org/wiki/Global_Positioning_System#Mili...
[2]: https://en.wikipedia.org/wiki/Spoofing_attack#Global_navigat...
Jamming and to a lesser degree spoofing are obviously still problems
All of which use the same very small, very narrow, band of frequencies—sometimes the exact same frequency of GPS:
* https://gssc.esa.int/navipedia/index.php/GNSS_signal
You jam L1 (1575.42 MHz) and you take out a whole bunch of services out.
It's one of the reasons why there's L2, L5/E5, and E6. But everything is in the Aeronautical Radio Navigation Service and Radio Navigation Satellite System bands.
Sure, but coverage can suck off the coast for a variety of reasons. Also, saltwater and chaotic environments (rocking boats, loose grips, lack of places to set them down securely, annoying unlock procedures, wet touch screens, etc) mean They’re pretty annoying to use especially when things get exciting.
> But doesn't virtually anyone have a smartphone now?
Perhaps one tool amongst the others, but they have several disadvantages
* You have to hold them -> one hand less available to anything useful
* Even if you can figure out a way to mount a phone so that you can read it (remember to somehow accommodate charging!), the screen is still quite small -> can't be viewed at a distance
Even if you somehow get all of the physical problems sorted, software problems still persist:
* Where are you going to get your charts from? Certainly do not expect to not have to pay for them (a couple of hundred of dollars is not uncommon)
* How are you going to view them? The solutions of the big players are quite expensive (couple hundred quid per season). Sure, the play store and such are full of some random dude's chart viewers, but are you going to trust that some random ass guy got the projection and datum conversions right? Even if they mostly did, even an error of ten meters or so could be critical.
tl;dr: a good phone-based solution costs at least as much as a basic chartplotter. In addition, you have to make multiple compromises.
It is really cheap and improves safety a lot on board. Even without any navigational experience they can use this app, same can't be said about most nav systems.
I am not saying you should only rely on it, but it is great addition where even passangers can use when main navigator gets injured/is sleeping/...
Granted, I sail in Finland which has one of the rockiest waters in the world but in my situation, their products are simply inadequate for any serious use.
But yeah, I could see a use case for it in some situations
According to my experience (off road motorbiking including a rally with weather going from really hot to bad downpours and everything in between) using a cheap (120€) rugged phone works just fine. There can be some lag sometimes (100+ km/h on a motorbike is way faster than what most boats can manage though) but in this case you rely on Mark 1 Eyeball and spatial awareness anyway. During rally we were required to carry an old school map of the area so if your GPS device failed you could find your way back to bivouac. I carried a spare phone, because it's cheap enough anyway. Can't speak for nautical charts but for general navigation I guess OSMAnd should work just fine. I'd still recommend against going out without basic navigation experience, relying on a smartphone only.
When situation is "near shored, small boat and navigate using lighthouses" then I would say smartphone would be better choice than relaying on lighthouses (light range 10+ nautical miles).
There are a lot of other navigational aids usually close to shore (floating or on ground). Even tall mobile antenna towers or wind generators are more common than classical lighthouses.
GPS isn't provided by God, it might be down or hacked, &c. You'd have to get phones certified for this usage for liability issues, and probably tons of other things I can't think about right now.
I don't imagine a cruise ship transporting thousands of people relying on an iphone to avoid hitting a rock/the shore
It's just a super convenient way to navigate around, not for mission-critical tasks (even for those it would probably work but of course not worth the risk without redundence).
I mean anyone who is in a small vessel and a boat would use iPhone maps in daily life, (while keeping other ways as a backup) why not?
Say you're in the middle of an ocean, nothing but water everywhere around you. You're rocking on pretty good waves, going a nice 8 knots. You look at your GPS. You can see where you are right now. You can see a bit further away there's a dangerous rock which you should avoid. How do you interpret from looking at the map whether or not you're going to hit it?
Your GPS might show you your bearing, but because of the waves it's oscillating 10 degrees every 5 seconds. You don't know your leeway (drift because of the wind) nor if any current might still push you into the rock. This is, of course, all calculable.
But still, according to the map it's not that far away. It's hard to interpret on a feature-less ocean, and on a GPS map, whether something is 5 or 10 or 20 meters away. You're getting closer, but according to your calculations you shouldn't hit it. Hmm, did you calculate it correctly? Has the wind changed? Have the currents shifted? You look at your GPS again, the rock looks a bit closer now, but you're not sure whether that's to be expected or whether that's indicative that you might hit it.
Either way, this hypothetical situation might give you a bit more of a sense on what it's like to be on a boat. Things are pretty vague, and even if your phone could say "that rock is 30 meters away", it probably won't be able to say whether you're going to hit it or not with a degree of certainty that you want to risk your life on until you're well away from it. It's hard to explain how it feels like to navigate "by instrument" on a featureless plane like this.
But if there's a buoy floating, marking that rock, you can see it right there. Your human brain can easily interpret whether you're going to hit it or not, and it gives you confidence that you won't if you can see it really clearly. It's also a mark that you can use to navigate to, e.g. "I need to keep bearing X, that's approx in the direction of that lighthouse on the horizon right there" (or "I need to keep it 20 degrees off the bow"). That is much less fatiguing than steering based on a compass that is continually shifting due to the waves.
I guess it's a bit similar to the difference of flying planes through clouds on instruments versus using sight. Using visuals is much easier, and much less prone to errors, which is important because if you do make a mistake it can be very dangerous indeed. Not like with a car where you can just stop or you see when you're going to run into a wall or a pond.
I can see everything easily on the GPS map, and see where I've been going, and I can steer to go wherever I like. Currents and wind and stuff don't affect me much, because I don't look at which way the boat is pointing, but which way its heading on the map (which includes the effects of currents and wind).
The only annoying thing is anything that doesn't show on the map. Like floating logs, men overboard, etc. Those are a pain because I have to look out of the window and try to figure out where they are on the map! And sometimes if it's foggy I can't see those things at all!
If you think that some random rock in middle of open sea, which was probably charted in 1953, is measured with that kind of accuracy that you can pass it by 5 meters then you have more problems than GPS accuracy.
And nobody said buoys are obsolete. Article is about lighthouses (https://en.wikipedia.org/wiki/Lighthouse)
The GPS satellites themselves are a single point of failure. E.g. in northern Norway, GPS becomes unreliable or unusable whenever the Russians decide to jam it for an "exercise".
Then it's whatever software you're using. Does your GPS software give you coordinates if there's some internet outage that kills your maps? Do you have backup paper maps to use those coordinates for? Do you have a compass to determine which way you're going between readings?
I'll often use nothing but a GPS receiver with a map for navigating when flying or sailing. They're pretty reliable. But you bet your ass I'm not trusting my life to that single system, and will know where I am at all times and have a compass and paper map as backup in case they failed.
Lightvessels, classical big lighthouses are obsolescence.
There are a lot of other physical navigation aids which are improved.
Old unlit marks are replaced with lit and AIS capable ones. New safe waterways and danger areas are marked every year.
Nobody said these are obsolete.
Nope. To see something in daylight it needs to be big. That big white pole is visible for miles and identifies the location in exactly the same way as the light does at night. Towers guided ships long before anyone started putting lights on them.
Clover Island Light (2010) is the first lighthouse to be built in the United States since 1962. [2]
If they are not obsolescence why they have built only one lighthouse in last 50 years in USA?
Indeed.
For all the millennial kids on here, there's a famous American Airlines lecture called "Children of the Magenta Line", it's doing the rounds on YouTube[1]. Boaters should adopt the same mentality.
Maybe 15 years ago. Today, GPS is the primary and charting comes slower/later to confirm positions. GPS isn't done intermittently. It is just on 24/7. Then occasionally (on the order of minutes to hours) a ship's position is confirmed by other means if possible. Near land the crew will sight landmarks to confirm the GPS track is accurate. But go onboard a ship in bad weather at night. You won't see the captain out there with a sextant trying to track stars. The GPS is basically it until there is good reason to second guess or confirm its accuracy. If the GPS fails, the ship's insurer might just tell the ship to hold position until it gets fixed. Ships are not planes. They can actually stay away from land/danger for days/weeks while repairs happen.
Mercury had to be used because the lenses were very heavy, so the way to support them was to float them on a heavy liquid. Wheels or bearings would have been too much friction for clockwork.
Mercury vapour is poisonous, especially over time, which is why lighthouse keepers were said to go crazy. At the time people thought it was from being isolated for long periods, but it was probably the mercury in the Fresnel lens support that made them crazy.
The Fresnel re-orients these light rays so they are parallel to each other, pointing towards the photographer's eye [0]
[0] Some example images here: https://www.onlandscape.co.uk/2017/08/large-format-camera-ac...
Also, the Spanish equivalent of academie francais is at least talking about ending gender for inanimate objects I believe. In english, lack of a definitional body makes this very hard (actor/actress chairman &c, not having gendered inanimate objects makes it hard to find a direct equivalent)
> I think this is ironic writing this in English.
Dearest creature in creation, Study English pronunciation. I will teach you in my verse Sounds like corpse, corps, horse, and worse. I will keep you, Suzy, busy, Make your head with heat grow dizzy. Tear in eye, your dress will tear. So shall I! Oh hear my prayer.
Just compare heart, beard, and heard, Dies and diet, lord and word, Sword and sward, retain and Britain. (Mind the latter, how it’s written.) Now I surely will not plague you With such words as plaque and ague. But be careful how you speak: Say break and steak, but bleak and streak; Cloven, oven, how and low, Script, receipt, show, poem, and toe.
Hear me say, devoid of trickery, Daughter, laughter, and Terpsichore, Typhoid, measles, topsails, aisles, Exiles, similes, and reviles; Scholar, vicar, and cigar, Solar, mica, war and far; One, anemone, Balmoral, Kitchen, lichen, laundry, laurel; Gertrude, German, wind and mind, Scene, Melpomene, mankind.
Billet does not rhyme with ballet, Bouquet, wallet, mallet, chalet. Blood and flood are not like food, Nor is mould like should and would. Viscous, viscount, load and broad, Toward, to forward, to reward. And your pronunciation’s OK When you correctly say croquet, Rounded, wounded, grieve and sieve, Friend and fiend, alive and live.
Ivy, privy, famous; clamour And enamour rhyme with hammer. River, rival, tomb, bomb, comb, Doll and roll and some and home. Stranger does not rhyme with anger, Neither does devour with clangour. Souls but foul, haunt but aunt, Font, front, wont, want, grand, and grant, Shoes, goes, does. Now first say finger, And then singer, ginger, linger, Real, zeal, mauve, gauze, gouge and gauge, Marriage, foliage, mirage, and age.
Query does not rhyme with very, Nor does fury sound like bury. Dost, lost, post and doth, cloth, loth. Job, nob, bosom, transom, oath. Though the differences seem little, We say actual but victual. Refer does not rhyme with deafer. Foeffer does, and zephyr, heifer. Mint, pint, senate and sedate; Dull, bull, and George ate late. Scenic, Arabic, Pacific, Science, conscience, scientific.
Liberty, library, heave and heaven, Rachel, ache, moustache, eleven. We say hallowed, but allowed, People, leopard, towed, but vowed. Mark the differences, moreover, Between mover, cover, clover; Leeches, breeches, wise, precise, Chalice, but police and lice; Camel, constable, unstable, Principle, disciple, label.
Petal, panel, and canal, Wait, surprise, plait, promise, pal. Worm and storm, chaise, chaos, chair, Senator, spectator, mayor. Tour, but our and succour, four. Gas, alas, and Arkansas. Sea, idea, Korea, area, Psalm, Maria, but malaria. Youth, south, southern, cleanse and clean. Doctrine, turpentine, marine.
Compare alien with Italian, Dandelion and battalion. Sally with ally, yea, ye, Eye, I, ay, aye, whey, and key. Say aver, but ever, fever, Neither, leisure, skein, deceiver. Heron, granary, canary. Crevice and device and aerie.
Face, but preface, not efface. Phlegm, phlegmatic, ass, glass, bass. Large, but target, gin, give, verging, Ought, out, joust and scour, scourging. Ear, but earn and wear and tear Do not rhyme with here but ere. Seven is right, but so is even, Hyphen, roughen, nephew Stephen, Monkey, donkey, Turk and jerk, Ask, grasp, wasp, and cork and work.
Pronunciation — think of Psyche! Is a paling stout and spikey? Won’t it make you lose your wits, Writing groats and saying grits? It’s a dark abyss or tunnel: Strewn with stones, stowed, solace, gunwale, Islington and Isle of Wight, Housewife, verdict and indict.
Finally, which rhymes with enough — Though, through, plough, or dough, or cough? Hiccough has the sound of cup. My advice is to give up!!!
> Yes, or a little superscript like ™ but fr for French
Here's an example in English: "cough" and "bough", or "wood" and "food".
Source: spent a ton of time researching adding a freh-nell lens to my large format camera’s ground glass.
Biggest pronunciation difference I've run into even within the same communities is foyer. I've always pronounced it the French way (foy-ey) but seems like 80% of people pronounce it foy-er.
About 250,000 people work in media-arts in the UK out of 24 million full time workers: you are the 1% here!
This is a bit like telling you to say "De Bruijn" and not "De Brown". De Brown is a kind of exonym that's well established, much like the Van Gogh situation: https://en.wiktionary.org/wiki/Van_Gogh
I've never heard a british person call is a Fres-nell.
A fresnel is a commonly used form of light in theatres and studios and everyone I've ever worked with in the theatre has pronounced it the French way.
I assume it's that we are simply exposed to French much more (and learn it badly in school).
I've not had 'Fresnel' as a French name and I'm guessing the pronunciation I have in my head comes from reading it and, more likely, just watching too many American-made YouTube videos with people playing with huge Fresnel lenses for fun and profit.
I wonder if it's a context thing. Thinking about it, other than science lessons, the theatre is the only place I've heard the word on a regular basis. Perhaps it's that.
No. Just no. GPS has serious limitations. Lights of various sizes, lighthouses being the biggest, are still essential. A light not only provides a bearing to a known/fixed point but also gives you weather and visibility information. And since they do not rely on any on-ship equipment, they keep working during onboard power failures. Go tell a pilot that runway lights are irrelevant now that they can follow GPS down to a runway at night.