Sextant Tutorial: The Principle of the Sextant
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- Опубліковано 21 вер 2024
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---------ABOUT THE VIDEO---------
This video was originally uploaded to our other channel, Casual Navigation, back in 2018.
The sextant is one of the fundamental navigational instruments. Once you have mastered it, you can navigate the world without the need for a GPS.
This video is the first in a series which will teach you how the sextant works and how you can use it.
This video covers Parts of the Sextant, and the Sextant's Operational Principle.
The next video will cover Sextant Errors and Methods of Corrections.
The final video will cover Taking Sights.
----OTHER TOPICS WE COVER----
Consider subscribing to the channel if you are interested in any other topics we plan to cover:
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✔ Tutorials about creating engaging content for education and training.
---------DISCLAIMER---------
This video should not be considered professional advice or education.
We try to make the content as accurate as possible, but the responsibility rests with the viewer to determine the full accuracy and reliability of the content.
Any action you take as a result of watching this video is strictly at your own risk.
Captain George Vancouver, tutored by Captain Cook, sailed 65,000 miles, never lost a man to scurvy, charted all the west coast of Canada and Hawaii, with only a sextant. Incredible sailors back then.
His first mate was a very young Cap'n Crunch
Both Vancouver and Bligh were proteges of Captain Cook. Unfortunately for them, Captain Cook came from a time when it was possible for an ordinary seaman could rise to the post of Captain, even Admiral. By the time the careers of Vancouver and Bligh got started, the British caste system had pushed it's way into the navy. Bligh had a particularly hard time of it, struggling to gain the respect of his upper class officers. The army officer corp had always been the preserve of the hereditary rulers of Britain. When the prestige of the navy increased, they moved into the navy. The descendents of the Normans who conquered Britain in 1066 and had held their conquered lands and all the positions of power over the centuries, now saw the navy as important as the army.
Clock?
@@ianbruce6515Commissions were bought all along. Not a lot of difference in the 70s either. If you went to the right school (paid) you would have a much higher chance of a commission. I was in with guys who were brilliant (based on IQ tests) and they had to rise up through the ranks, whereas I never met an Eton old boy scrubbing the decks. And yes we actually did that. A very rare beast then was a Commander who had started off as an ordinary able seaman. He was regarded with awe and fear because he was an unstoppable force with total iron discipline.
Who invented the sextant ?
Who made the sextant in production ?
Who thought the first sailor man ?
twenty thousand leagues under the sea brought me here 🤣🤣 i was curious to know how to operate the sextant and once again, thanks to UA-cam, I’ve gained some knowledge that I may never use in real life !
That would be me as well, the Walter James Miller and Frederick Paul Walter's translation, right?
simply buy a sailing yacht for $500,000 and head off to sea. Then you'll be able to test your sextant knowledge. Problem solved - simple!
You never know mate. Weird shit has been going on and it doesn’t appear to be getting any better.
Love this, love this channel, and really appreciate your commitment to this sort of VERY high quality educational programming. 11/10, am binge watching them all. Thank you.
While I'm sure undereducated sailors burning their retinas out contributed, I'd always learned that the eyepatch was a primitive form of underdeck preparedness: sacrifice a little bit of peripheral vision for instant access to low-light vision when moving quickly between decks.
Even militaries teach to keep one eye closed when operating in between the bright sun and indoor locations for extended periods.
Covered eye also works better at night
Excuse my uneducated ass, but considering NVG's are standard issue these days and that they can be regulated so you could use them in broad daylight, if you're willing to sacrifice peripheral vision, isn't it better to use those? lose colours too but on trade you could also adjust to look into dark areas from outside, say a window where someone might be hiding or the opposite, look outside from a dark building into a bright day and such by just changing gain
@@johjoh9270they cost a LOT of money and break in rough conditions easily. Unless you're using state of the art
@@johjoh9270 Are you talking about modern sailors using NVGs? Visibility below deck hasn't been an issue since the invention of the lightbulb, and they would be almost useless for looking at anything outside a warship because _nothing_ that could ever pose a threat is getting that close to a modern warship anyway. Anything that tried would be sent to the abyss expeditiously, probably before it even crested the horizon. Plus even the cheapest reliable NODs are running you 4k at the minimum. Those fancy quad nods are 40 grand.
Thank you, always wondered how the heck this thing works and you delivered in great way. Also, loved the insight about why pirates wear an eye patch.
Well it's not the only reason. Another reason for an eyepatch is to see better in low light environments such as below deck
Хорошее объяснение. Я пользовался им для определения места корабля в море,когда учился в высшем морском учебном заведении. При походе вокруг Европы. Определял по нижнему краю солнца,луны,звёздам. Важно знать точное время,ведь земля за 1 секунду поворачивается на 400метров. Вычисления занимали 30минут. Много разных нюансов. А изучали работу с ним на случай,если GPS отключат.
This was still used in the US Navy in 1956. Every day, the destroyers in the screen around the aircraft carrier had to send in their positions calculated using a sextant. One day, one was hundreds of yards off from all the others. The officer responsible was told to "do it again". I know, because I sent the message.
Did you send the message with the wrong position or the message telling the officer to do it again? It sounds like a nice story but it is actually quite confusing. It also begs the question whether it was much better the second time and what had gone wrong the first time and, of course, whether there was any punishment or correction and whether you feel you had any responsibility.
@@richardbloemenkamp8532 - The second attempt was "in the group", so acceptable. I don't know if the officer got a slap on the wrist or not. Why should I have had any responsibility? I was just the radioman. both sending and receiving PS. Our destroyer was the command destroyer of the squadron, which is why I was involved at all. Actually, this made my job quite interesting, since all the info back and forth flowed through us. The radio gang was the most "informed" bunch on the ship!
@@fredrichenning1367 Ok, thanks for the information. That makes sense. Of course as are radioman you are not responsible, but I can imagine that with certain messages you know that there can be severe consequences for individuals. Probably not the case here.
@@richardbloemenkamp8532 - The thing that amazed me was that they put their positions reasonably within a hundred yards or so just using a sextant -- in the middle of the whole damned Pacific. Shackleton would have nodded approvingly, I bet. BTW. Where possible, we used LORAN, of course. As a radioman (AND "captain's talker"), I spent a lot of time on the bridge hobnobbing with the officers. Even steered the destroyer once for five minutes, 'cuz the helmsman had to go take a piss (nobody else was on the bridge just then, LOL). Interesting times!
It would be nice if you had mentioned the whole point of a taking a sight with a sextant in the first place, that measuring the height of a celestial body like Polaris or the sun above the horizon can be used to determine your location (latitude and longitude).
Where sextants around before ships clocks?
@@alangreen4156 Yes. Sextants could always be used to measure latitude accurately. The ship’s clock made them very accurate for determining longitude as well.
@@rayopeongo Before ships' clocks it was possible to determine longitude approximately using "lunars" i.e. the angular distance between the Moon and a known star or sometimes the Sun.
@Joël With Polaris, only latitude.
@Joël
Latitude is easy with Polaris, or sighting on the noon day sun. Figuring out longitude is much more difficult, and requires a very precise clock. That is why the British parliament offered prizes for anyone who could invent a chronometer that was precise enough for determining longitude.
en.wikipedia.org/wiki/Longitude_Act
awesome vid. Pirates wore eyepatches to have one eye they can use in the darkness of the hull. there was only one navigator per ship.
I dont think that was really true. Pirates probably wore eye patches for the same reason anyone else did. Not to mention being around explosions involving wooden splinters flying as shrapnel, its even easier to assume an eye patch was worn to protect a wounded eye form the sunlight/dust etc.
True about the eye patch, but the number of navigators on board depends on the ship it was. In the british navy for exemple, there is a master that is responsible but all midshipmen would take sights throughout their watch and all lieutenants and supperior officers were supposed to keep a log with their personnal sights and estimated position.
In the merchant navy, before precise chronometer, they would only be able to know lattitude so they would sail to the lattitude of their destination and then head west or east. The captain, first officer and master would all take sights at noon. It wildly depends on type, size, and purpose of the ship and on the period.
I see, whereas the everyone else used fluorescent lighting in their vessels to remove the need for eyepatches?
I totally regret watching this while hammered..at some point in my life I'll totally need this info
I hear you can make a makeshift one with paper and string? Something like that. Better get on it! You gatta know where you WHERE in order to find out where you ARE, so when you're lost, you know where you ARE, because you know where you were!
@@avatar1867 We're not in the Nautilus, captain. Use a GPS or smt
Harbor freight, $22
Also, yeah, i get afraid when things randomlt come up, like, why am i going to need to know this., i don't want to be in that situation
@@kaan_isiksatellites could fail
*Very nicely explained and most elaborate information...... Thanks a lot, Brother 🙏*
European ingenuity never ceases to amaze me.
better than the how to calculus vids. I understand this
Not sure why I ended up here, but I truly feel like these methods of understanding how to navigate our blue planet in relation to celestial bodies shouldn’t be a lost art
I'm watching this because yesterday I watched the Sylvester Stallone's movie titled: "Escape Plan" and a sextant was used there.
EDIT:
Thanks for the likes and the comments. 😽
Lol same here
Same here
Same!!
And I found one on Amazon!
me to😂
Thank You......never knew the details of this device .....This is how they mapped the old world ......
Devices that aren’t nearly as fun as the name would suggest.
Very intersting as a former mariner.
Not sure about the sailors eye patch theory. They covered one eye to get acustomed to dark light and one for daylight. So you got acustomed to it, before going on watch at night.
At time stamp 03:45, many old sailors wore eye-patches because of splinters from cannonades. Other than that, good video!
Thank you for that ,Just learning. My Father said to many times at sea Captain cook Didnt use Radar GPS
Me@ midnight: Think I'll turn UA-cam off and go to bed.
UA-cam: But do you know how to use a sextant?
Me:........ Go on....
Planning on using one of these for night vfr these monts,lets see how itll go
fantastic presentation with visualization.
Excellent presentation and much appreciated ... Thanks. God bless the British. You sound like Professor Brian Cox. Sure beats the cocksure, can-do alternative. Greetings from OZ.
Plastic sextants are also much lighter than metallic ones.
If you ever used a sextant in heavy or rolling seas you know what advantage this is 😊
Despite the flat earther's claim that a sextant can only work on a pancake, no flat earther has ever shown how it "works".
It can't work as all the calculations are made using astronomical determinations of Sun, Moon, planets and star positions which derive from a rotating spherical Earth.
@@karhukivi Is there any evidence to this, or is it just a theory?
@@EternaL1fe The evidence comes from astronomical observatories, astronomers, and hundreds of thousands of navigators who use and have used celestial navigation for the last three hundred years. Every space agency in the world use this data, as well as topographers and geophysicists and geographers who study the planet. By the way, a "theory" is science is not some notion from a magazine, it is a well-tested set of observations and predictions backed up by mathematical reasoning and widely-accepted by knowledgeable people.
@@karhukivi
Very well said.
Basic navigation doesn’t work on a flat earth.
I was in the US NAVY a good friend of mine was in the department that handled navigation on the ship we were on. He showed me how to use a sextant. We wrote the math out both ways and it does not work if the earth is flat. So in short, we know the earth is round because we can navigate around it with the stars.
Your animations extra ordinary
Aren't the eye patches for when sailors go below the deck? Since it's pretty dark below, they wear an eye patch so they don't have issues with visibility both outside the deck and inside.
Yes that's what I was taught.
I thought it was the other way around - so that at night, they can take a peak at some charts in the cabin with candle light and go back on deck, lift the eye patch and see in the night without waiting for the other eye to adjust ;)
@@hernerweisenberg7052 maybe both?
You really think a ship that cost with hundreds of millions dollars can't provide a simple oil lamp? I mean really? :|
just amazing....in hope to see video on ECDIS. love from INDIA
Do you have a source for me regarding the "eyepatch because sextant burns" topic? Don't get me wrong, I'm not trying to "um, actually ..." you, but I only ever heard they were for adjusting to the darkness below deck more quickly. I'd like to educate myself a bit further if there were multiple reasons for eyepatches :) anyway, great video, thanks!
It's a great and very informative video. I never thought that sextants are used in that way.
Do sailors still use sextants nowadays or you rely on gps more often?
REAL navigators know how to use a sextant, whether they use it or not.
Most probably rely on GPS, or atleast the ones I know and me myself do. However, you must always be prepared for it to fail, so you generally know how to navigate without any electronics and such
@@harbourdogNL Damn, calm down man
A good sailor, even with the very useful GPS, has his sextant, the HO249 tables, and a few little items to be able to navigate old way in case of.
Absolutely LOVED this video. Amazing. Thanks.
Never heard any explanation but this is exactly what I thought the first time I saw one.
Awesome animation as well as explanation. Thanx man for the effort.
Thank you so much for this very usefall explaination
One of the best channel on youtube!
Narrator: Luckily it's a LOT simpler than it looks..
Also Narrator: we're gonna have to break it up into 3 tutorials.
.... fuck.
Time to prepare for the Apocalpyse ! Navigation won't be a problem now
Thank! Really found your explanation very helpful. No one else explained it so completely as you did from what I’ve found. Just one question. Why is it (I+I) + 2x and not 2I+2x? Thanks
In math it doesn't really a matter, so you can also call it 2 I if you'd like to call
Now I'm ready to jump in my sail boat and sail across the Pacific. Very interesting.
I took a geography class to learn the datelines,
and maybe use a sextant.
this is the part where i shut up and let you infest my brain
Don't worry, i'm a master of the Sex Tent.
Oh. You said _sextant?_ Never heard of it.
I just watch this video to listen to the guy talk.... It's relaxing.
EDD: Yes, well, it's all fun and games but merrymaking nearly cost us this sextant.
(Eddy snickers)
EDDY: You catch that, Ed? Uh... the what? I missed that! What's it called?
EDD: It's called a sextant, an astronomical instrument used to...
(Ed and Eddy snicker)
EDDY: Again? Sorry, I missed it... what's it called?
EDD: It's commonly known as a sextant, Eddy...
(Ed and Eddy burst into laughter)
ED: SAY IT AGAIN, DOUBLE D!
(Edd realizes what’s Ed and Eddy are getting at and blushes.)
EDD: Oh my!
Clever.
I miss that show. Some of the last of the great cartoons.
Beavis: You said Sextant Huh, huh huh huh huh.
Huh huh huh huh
Butthead: Shut up, Beavis
The explanation was splendid😊 I love it❤.
Brilliant series. Thank you!
Excellent video, thank you.
I was watching Doctor stone and Senku made the sextant. I was wondering how it worked!!!
omg i love doctor stone and am here for the same reason lmfao
Same lol
we gathered here for the same reason
sameeeeee
Same
appreciate the explanation, but in 06:15, I did not get the idea. You said "the angle between the incoming and outgoing ray of light [(I+x)+(I+x)] is twice the angle between the mirrors [(x)*2=2x]", which makes 2*(I+x)=2x, and apparently its not right. It should be the angle of the ray of deflection equals to twice the angle between the mirror. The degree of deflection is 2x.
Love this video, however I always heard that sailors and pirates used the eye patch to be able to go in dark rooms and below deck without having to wait for their eyes to catch up.
except that your eyes have reflex where the pupils dilate and contract symmetrically in response to light.
I think they implied that they had their eyes burned from constantly looking at the sun
@@georgegilkey8751 nope
...wasn't the eyepatch mainly so you retain low-light vision in your other eye when going below deck in combat situations?
This should be MADITORY learning for flat earthers!!!
They will still say nuh-uh.
This video is great, but there is a low frequency hum that is very distracting.
And i thought pirates wore eye patches to cover a missing eye that was wounded in a sword fight.
thought the same LOL
That information is actually wrong, below deck in old ships you would generally not see very much in the middle of the day because its really dark down there so they would use an eyepatch to cover one of their eyes so they don't have to wait for their eyes to adjust
@@evilskills That's very interesting! Thanks for sharing!
Pontus Eriksson Yep you got it. I was gonna say the same thing!
@@evilskills mythbusters
No old sailor wearing a eyepatch is because older sailboats was harder to light below deck you don’t would like to use a candle next to a barrel of Blackpowder and to refracting sun light below the deck was hard and someone maybe working on deck a block the lens and port hole was not used as much because of the price of glass and the fragile if it. And yes sometimes they use eyepatches because of damage to the eye but just because they looked at the sun with a magnifying glass it should look the same as the other endless they was too stupid to feel the pain of the sun trying to eat their eye on fire and that is most likely impossible. But in battle flying pieces of wood could hit the eye but a sextant damaging the eye so bad that the man had to cover it I think not. But to keep one of the eyes adopted to the dark for going below the deck ok. Now if you cover one eye it maybe easier to handle the movement of the rolling sea without getting sea sick. If you want to get sick fast on a boot use a pair of binoculars with two eyes and look at the horizon to long you will be feeding the fish.
Great presentation, nice an clear
Eye patch was used to maintain night vision in one eye so that they could acclimate to darkness faster than those that didn’t wear one
Thank you. I am here because I was just curious.
Not quite true. The eye patch was used to adjust the eye below the decks.
Gerard.
Major nerd-gasm! I love this kind of content!
Thank's to sharing
Good job
I'm definitely too dumb for this.
Ig thats true for a lot of us
No friend you just have to learn some basic principles and by basic its math.. the US has made people hate math because it is the humans universal language and they don’t want us to have that knowledge
@@1unawesome644 could well be true...
Bro no one wants anything from you @@1unawesome644
😂😂😂... Me too.
very informative
Awsm vedio
Instructions unclear. Was aiming for the virgin islands but ended up on the island full of minecraft youtubers in their 30s.
...which actually means I reached my target. Jokes aside, nice video!
That was excellent!
Oh yeah, Sam Witwicky brought that to class.
thanks you for your nice video
Why am I watching this at two in the morning?
Well im watching at 4 in the morning
I don't know are you lost at sea?
@@mattsupertramp6506 no, i was sleeping on my bed
@Fermentum Mobile if lost at the sea you mean lost at the ocean of dreams, well yes 🤣
God damn I love this video.
Was also sold as 'The eyepatch-making machine!'
perfect
That is incredible
Thank You ! !
Excellent
Thanks for the topo
Is the sexant that Harbor Freight sells for $20 usable or just for decoration?
Mike Kennedy Just decorative. Many similar on Amazon and eBay. They also are very small, but look nice on a desk. A navigational sextant has to be made very precisely.
I still can't figure out what are you trying to read with the sextant?
You read the angle between the horizon and an astronomical body.
Sailors would wear an eye patch on one eye so that if they had to go below during battle, they didn't have to wait for the eye to adjust to the darkness. Unfortunately, the reflection of the sun burning the eye had nothing to do with the patch.
That's an urban legend. Ships were lit with lanterns below decks.
Don't ever say battle amond the sailors or here and there, even you can't pee with one eye because of the depth mechanism of eye
The Apollo astronauts also used an eye patch. Whoever was going to take the sextant reading would wear the patch so their eye would be able to see the stars. If the astronaut's eye wasn't acclimated to the dark, space would look ink black.
la naza probo uno expasial en progama lansadera de trasvordadores
se usa para orientarse los navegantes
Isnt (I+I)+2x just 2I +2x?
I realized that without Google or predawn maps I basically have no idea where I am on this planet.
I watched intently all of your videos on operating a sextant.
I just have one question !
How do I use a sextant to locate position ?
😢
A sextant doesn't determine what your position is. It measures an angle.
Great
I didn t understand shit but I loved the video.
How in the hell did someone ever figure out how to make a sextant in the first place when I cant even understand it after watching a video?
Thanks. Great animation and you are well spoken. Why do you need two mirrors to demonstrate this? Imagine the sun directly above your head and you holding a mirror flat, 45 degrees above your line of vision. Then rotating that mirror 45 degrees from the horizontal towards you. The light would hit the mirror at an angle of 45 degrees from the normal and of course reflect off at the same angle. Through shades you would see the sun. Thus with one mirror only, you would see an object which is 90 degrees above the horizon. It’s not a sextant, but it still halves the degrees of rotation compared to the angular height of the celestial object.
You do realise that with only one mirror the image of the sun would be upside down, right?
I don't know what's wrong with me. No matter how much the explanation is slowed down, I just can't conceptualize it all and make it make sense in my head.
Like, the mirror on the arm is at a slight angle itself. What is that angle and why?
The mirror on the arm is at a slight angle as is the other one on the frame below it, so that the observer will see both the direct image and the reflected one coming from the upper mirror..
Imagine the unnamed genius who invented this centuries ago
couldn't they have thought of a better name for the instrument like anglesighter or latlongerator or even youfindigator.
how does the altitude reading help in navigation. so you fix on a star with altitude of 12.51 degrees , how does that reading tell me my position
Let’s say you take a sextant reading on a star with a height observed of 12.51 degrees, Ho = 12.51 at some unknown location A.
You carefully noted in a logbook for how many hours you sailed, your speed and direction.
You deduct from your logbook that you should be at location B.
Location B could be the same as location A where you took a sextant sighting but you can’t be sure because currents could have pushed you out of your way, your speed was not exact, etc.
You calculate what the sextant reading of that same star would be if you really are at location B.
Let’s say the height calculated is 12.0 degrees, Hc = 12.0
You then compare Ho = 12.51 degrees with Hc = 12.0 degrees.
Since Ho is larger it means location A is closer to the GP, geographic position of the star, that’s the point the star is right over on Earth than location B. The star looks higher so you’re closer to it.
If Ho is smaller than Hc then location A is farther away from the GP of the star than location B. The star looks lower so you’re farther away from it.
This gives you a line of position perpendicular to the azimuth of the star that you can cross with a sextant sighting to another star, another calculation and another line of position perpendicular to the azimuth of that other star.
That is the general idea taking sextant sights for celestial navigation.
3:43 This part was the most surprising thing to me...
PERFECT
Not the easiest of tasks on a pitching and rolling deck! Tricky stuff in a storm. Not often used on a submarine.
Thank you.
Which kind of sextant did you refer to in your video?
I'd like to buy one, but the prices are all over the scale.
Is the mirror on the arm supossed to be straight with the arm, in the animation, it seem to be at an angle
It is at an angle so that when the index arm is on zero degree the two mirrors are parallel. The animation reflects how real sextants are made.
@robertlafleur5179 can you show the mechanism of how the adjustment screws take actually work in the context of the frame?
@@ryanbeard1119 There are screws on the back of the mirrors for slight adjustments.
ua-cam.com/video/PCcq1nHYPS0/v-deo.htmlsi=85A9mC0E3e25oalc
The 2x angle is the feature of every reflection. Delta angle is two times the rotation angle. Nothing to do with the second fixed mirror, used to shape the fixed optical path. Still, nicely done.
You've forgotten to highlight who invented it first !! it was Abu-Mahmud al-Khujandi, an Iranian Muslim scientist in 994 AD.
Because that doesn't really matter for this video since it's on how to use it.
@@LisaAnn777I'm glad they've shared