The term "knots" originates from an old maritime practice. Sailors used a device called a log line to measure the speed of their ship. The log line was a rope with knots tied at regular intervals. They would throw the rope overboard and count the number of knots that passed through their hands in a specific amount of time, usually measured with a sandglass. This method allowed them to determine the ship's speed in nautical miles per hour, which is why we still use the term "knots" today
Exactly. And it wasn't until sufficiently accurate clocks were invented that they could accurately determine longitude. Neil should've talked about that a bit.
@bestsnow.. You are absolutely correct. A shame that Tyson didn't tie this into his explanation, (no pun intended). As opposed to a sextant, counting the knots in the log line informed the captain or navigator of their PRESENT speed in real time.
It makes perfect sense to me. I am a Navy veteran. We learned about all this and much more. It’s a great system. I mean they used it way back when to navigate the globe. It works. In fact the USN still plots the old school way just in case the GPS goes down. We can still navigate without modern technology. I was a welder but watching the quartermasters and such navigate and plot always fascinated me. I joined in 2002 and served on CV-63, LHA-1, and LCC-19. Shoutout!
It's a vestige of another time. If you're navigating the seas without satellite equipment, it might be a good thing to know. But it's the marine equivalent of, instead timing something with your smart phone, you count, "One Mississippi, two Mississippi, three Mississippi..."
@ it’s not a vestige of another time if it is still used today. As with anything knowing how to do things without a cell phone or the internet is a good thing. I rely on technology as much as the next man but there are many things I know how to do that would be valuable if for some reason we lost it. I’m a rural man and my family would be fine without electricity or any service provided including water. Perhaps a vestige of another time but any time spent on learning/practicing anything is time well spent.
@@jeanaprewitt9658 A standard assumption for all of the U.S. military is that "Murphy" will make an appearance. If you rely on anything then you must have an alternate for it (Redundancy). Satellites can break down or be destroyed, but the Sun and Moon, Stars and Planets are immune to breakage or enemy action. It also blows up the entire plot of Tomorrow Never Dies.
@adriangarcia9626 It's still used today but it carries no actual advantage. The system made sense when it was used and developed because it allowed people to forego accurate measurements (which they couldn't do) by relying on geometry and mathematical principles to subdivide into easier approximations of distance. Since we already have all the measurements, all you need to work without knots is a cheat-sheet with the measurements and a scale-map. If you know the circumference of the earth in kilometers, you can subdivide it by kilometer distances just as easily as by nautical miles. And knots as a speed measurement only make sense when you have a standardized navigation aid that actually uses knots. That used to be a rope with knots, which you could use in conjunction with a standardized time-keeping device to derive your speed and you could then use that speed in conjunction with other navigation methods to derive your change in position from your last measurement. It's a shame he didn't explain this in the video, but that's why a knot is called a knot. But that also means that if you don't have that rope on-board, you get absolutely no benefit from using the system. You could use any other system just as easily, as long as you have a way of measuring or deriving your speed, you're good. And calculation in base 10 is far more intuitive to us as humans than any other system.
I dare to disagree. Knots and nautical miles make total sense navigating with a sextant, a pencil, and a paper chart. OK, everybody has a GPS nowadays, but what if a lightning strike your sailboat? It happened to me. When at sea, depending on where you are, there is nobody around to save you, to sell you a new GPS, or extra batteries. And nautical miles make finding where you are a lot easier. Even more so in stressful situations. Just a feedback from someone who have being living on a sailboat for years, a different perspective maybe, but I love the show. Keep up the good work, guys.
There is also the possibility of satellites disabled and the need to navigate with paper and stars. Also it is a great backup in case of system failure.
I'm surprised it didn't come up, but we do have a name for one arc minute which is nautical miles. So a knot is one nautical mile per hour. These are used because it does make things much easier to calculate in a map, and it's used not only in ships but also in aviation.
Okay, I'm confused though. The distance between arc minutes changes with latitude. So the answer to who's going faster depends on what latitude they are at. I mean if i do a spin around the pole at the north pole i went through 21600 arc minutes in about 3 seconds. So is a knot 1 nautical mile per hour, or is it 1 arc minute per hour?
As you say! I don't understand the angst. With the coordinate system in use today (lat/long) 1 nautical mile (which can be equated to 1 nm = 1 knot) equals 1 minute of latitude. 60 minute of latitude equals 1 degree of latitude. Doing the math, 60 nm x 360 degrees = 21,600 nautical miles. The generally accepted average circumference of the earth is 21,639 nm. That approximates to 99.8% accuracy for that coordinate system.
As someone who still knows how know to use a sextant, knots/nautical miles make sense as they are measurements of angle and it’s all spherical trigonometry.
@@GWNorth-db8vn because of the old machine tools limitations. With current CNC, tool paths can obey to any math. function (OK approximated to series of small vectors... ). Eg. boat propellers, turbine blades, wing profile .....
@@ellsworthm.toohey7657 - That's why I said oldschool. I do a type of precision grinding (jig grinding) where the manual machines are still more precise and give a better finish than the CNC. We use a CNC just to rough things out. I've actually been around since paper drawings and wooden patterns for copying mills, and I was taught to use a slide rule in high school. The thing about CNC is that they operate in steps, not smooth curves. The finish needs to be polished or ground to get rid of the roughness built into the method. Half a tenth sounds pretty fine, but you can see a finish that rough in oblique light, and it's way too coarse for a lot of things.
Actually... The term knot dates from the 17th Century, when sailors measured the speed of their ship by the use of a device called a “common log.” This device was a coil of rope with uniformly spaced knots tied in it, attached to a piece of wood shaped like a slice of pie. The piece of wood was lowered from the back of the ship and allowed to float behind it. The line was allowed to pay out freely from the coil as the piece of wood fell behind the ship for a specific amount of time. When the specified time had passed, the line was pulled in and the number of knots on the rope between the ship and the wood were counted. The speed of the ship was said to be the number of knots counted (Bowditch, 1984). I'm amazed Neil didn't explain this.
It was also inaccurate because it was based on the notion of the water as a stagnant medium. If your ship was travelling with a current flowing in the same direction as the ship was travelling, the speed of the ship would be greater than the measured speed. For example, a ship travelling with a 4 knot current that measured a speed of 8 knots would actually be moving at 8 + 4 = 12 knots between fixed points on the surface of the Earth. If you were travelling at the same apparent speed AGAINST a 4-knot current, your true speed would be 8 - 4 = 4 knots. This was one reason that developing a way to fix Longitude was so important. If there were no currents in the oceans, the combination of a compass, a sand glass, and a ship's log would allow the navigator to fix a ship's position fairly accurately after days or even weeks of travel. For most voyages, combining this with adjusting the position occasionally when known landmarks were spotted would have been adequate. But because of unknown, immeasurable, and variable ocean currents, this "dead reckoning" method could be off by dozens of miles per day, far too much for safe and efficient navigation. Interestingly, even with GPS available, some ships still use a form of dead reckoning known as "inertial navigation systems." These are based on accelerometers that can sense any acceleration in any direction so accurately that it can give an excellent estimate of where a ship is even after weeks of travel. An early and very important application of these systems was on submarines, which, when submerged, could not use many of the navigation tools available to surface ships. Subs also found it helpful to have an independent measure of DEPTH. Measuring water pressure is closely related to depth, but because water density varies with temperature and salinity, it's not perfect. Sensitive accelerometers can measure how far a ship has travelled up and down as well as E-W and N-S across the Earth's surface! These accelerometers used to be very bulky and expensive, but in a very short period of time, they became cheap and compact. This was because compact and reliable accelerometers were needed for Safety Airbags in automobiles. When those were mandated by law in the U.S., tiny, cheap, accurate accelerometers had to be quickly developed. These new accelerometers were also noticed by Shigeru Miyamoto at Nintendo. He realized that a new type of video game console could be developed so that the motion of the console in the player's hands could be easily integrated with the video game, and the Nintendo Wii was born.
@@joeanonimous1105 Knots have always been based on ship speed through the water rather than absolute speed. If you are on a treadmill and running at 10 mph that is your speed. If you set the treadmill to 10 mph on a ship heading West at 10 mph you are still running at 10 mph. If you were on the ISS travelling East [ish] at 17500 mph you would still be running at 10 mph. The advent of aviation was the real eye-opener for relative and absolute speeds, especially for takeoff and landings which are preferentially done into the wind to reduce the ground speed when getting off, or more importantly, back on the ground. Seeing your indicated air speed at 80 ish and ground speed by GPS at over 140 is interesting!
I navigated in the US Navy in the late 70's. We had what we called "SatNav" back then primarily for position locating. We still did all of our course and speed and set and drift calculations by hand. A standard mile is 1760 yards. A nautical mile is 2000 yards. It made the math much easier. We also had to shoot the stars for I guess an emergency back up and to check our equipment to a point. Thanks for the great explanation and thank you for your time.
@@godsbeautifulflatearth You know, there are things called dictionaries where you could look up the meaning of a word such as level. But the fact that you think the UN logo is somehow evidence of something, tells me that reality just isn't in your wheelhouse.
@@godsbeautifulflateartherr ... sea level is measured relative to the geoid which ain't a flat surface. Also there is a tidal bulge on opposite sides of the world. Where do you think all that water runs off to during low tide if its level genius ?
Originally knots were tied in a rope regular intervals and they would throw the rope over the side of the boat and count the number of knots that would pass in a certain length of time
That's the definition I always heard. I also have wondered if the sea voyage calculations had to compensate for currents when math-ing knots. Because the rope with knots really is only measuring how much water has flown past the ship. It cannot know what speed it's going relative to land by just using the knotted rope. I guess the sextant and other equipment came in to do those calculations. It also makes sense then to use in planes to measure airspeed. Because, for a plane, what the sensor on the fuselage can measure is likewise just the flow of air going past the plane. If it's windy, you can effectively stand still landspeed wise while still doing 50 knots in airspeed. Same thing when climbing or diving. Little landspeed but potentially lots of airspeed. My guess is that the archminute thing was retrofitted to make it more scientifically relevant than knotted ropes and a sailor kind of gut feeling the length of time before portable watches and clocks.
@@utube7930 you tie the knots before you throw it over the overboard. It's a very long rope too so you don't throw the whole rope over just the part that has the knots on
Neil said early on the the video that although degrees were divided into minutes and seconds, there's no connection with time (apologies if I'm misquoting, I'm paraphrasing). It's true that there isn't an obvious relationship between degrees and time, but 360 degrees of longitude equates to a full day of 24 hours. Navigation by latitude and longitude requires an accurate clock. One reason why James Cook's maps were so accurate was because he had a new type of ship's clock, which enabled him to calculate longitude accurately. He was also an excellent navigator and cartographer as well. Observatories in cities like London (well, Greenwich) and Sydney had a ball on a pole on the roof which gave the crews on ships a visual indication of time by which to set their clocks. This was essential in order for them to navigate safely. I'm glad that someone else in the comments also mentioned the origin of "knots" originally being literal knots in a cord attached to a sea anchor fed over the stern. I was really surprised that these things weren't mentioned.
But why do we still use 360 degrees, 60 minutes an hour or degree and 60 seconds a minute. We do use the 10 base number system after all. Both in imperial and metric. Well we sometimes do. They tried to make metric time and degrees. 400 degrees on a circle, 100 minutes an hour and 100 seconds a minute. But it didn't catch on. It is because calculators is only about 50 years old. 60 is much easier to calculate with fractions. 100 is divided by 2, 4, 5, 10, 20, 25, 50. 60 is divided by 2, 3, 4, 5, 6, 10, 12, 15, 20, 30.
@@andvil01 60 isn't easier, it's just what we're used to. Europeans would say the opposite. Imperial can be more convenient for things that need to divide by three, but most things one might divide by five would be easier in metric. Twos and fours come out even, either way, and usually don't even _need_ to be measured, if you can fold a rope, string, or sheet of paper in half. (This also cuts half the work of dividing by 6 and other higher numbers.) It's also not that much work to memorize 0.33333 or 0.16666 for dividing metric by thirds and sixths. We have to memorize cramming 16ths and 32nds into a unit that uses twelfths, which goes into another unit that uses thirds. 10's are easier, lol.
@@andvil01 I think it's also because way back before the invention of zero and the Arabic numerals we now use folks calculated in base 12 using the thumb to traverse the knuckles of one hand.
Fun fact: You can calculate latitude (relatively) easily with an astrolabe, but longitude is almost impossible because the Earth rotates. The guy who cracked the problem by associating longitude with time was John Harrison. He was from Greenwich, England, which is why the Prime Meridian is there.
Nautical mile is also a minute, which is on the scale on the left/right (or east/west) side of most of maps. Therefore it is easy to quickly copy the distance in NM or speed in KTS needed for the navigation from the side of the map.
Well, SORT OF but not really. Harrison created an accurate and more portable time piece that could be carried aboard a ship for the purpose of calculating longitude based on heavenly observations/stars. The French had created a magnificent and ornate chronometer but is was several feet tall and extremely delicate and sensitive, many countries and England had been creating very accurate clocks, but the delicacy of the movements meant that any great jostling and moving about would result in its accuracy being affected. By accuracy I don't mean it kept perfect time, but any gain or loss of time in seconds was exactly predictable and determined and that was accuracy. Navigators had long understood longitude and how to calculate a position east or west of a Prime meridian but had to use different means to arrive at a solution before highly accurate time pieces were available to be carried on ships. Latitude can be determined by using a sextant and making an observation of Polaris, or the Sun when the Sun reaches its Zenith. I won't go into all the details but those are two basic methods to determine Latitude. Before the ability to carry predictably accurate time aboard ship, they would take daily observations to determine latitude while sailing in a northerly or southerly direction. Knowing the latitude of their destination, once they reached that latitude, they would turn either East or West and head for their destination. Gaining the ability to determine Longitude made the shorter diagonal sailing point A to point B possible, to put it as basic as I can. Longitude and determining it requires precise calculations of the movements of stars and celestial bodies, a Prime Meridian for time keeping, and an imaginary Meridian in the "Celestial Sphere" which we call Aries because it runs through the constellation of Aries which gives us a steady baseline to measure the track of navigational stars from. Time needs to be precise when determining for any day and time, exactly where that star should be and where at that exact moment it would be if it fell directly to earth, measuring it's elevation and being able to calculate where it would be on the earthly sphere requires accurate time, and the difference in local time and Prime Meridian time, or GMT "Greenwich Mean Time" or more commonly stated today as UTC or "Universal Time Corrected" This is extremely rudimentary and simple for an explanation, but making several calculated observations of celestial bodies, their height and direction in degrees from you and using accurate time to be able to know exactly where their Azimuth would intersect the surface of the earth, then plotting the intercepts for each and where all cross is your position. And that's all done long hand or using a calculator and it's called "Spherical Trigonometry and ALL the way back to Pythagoras and before and NOT to Harrison a hobbyist clock maker. Longitude by Zenith observation of the Sun. Much easier and only requires a single celestial body, our Sun. Using accurate measurement of time by chronometer set to GMT/UTC, observing the Sun's angle in degrees above the horizon, at it's Zenith, or Actual NOON/MID-DAY and, knowing that for any particular day the Sun will be so many degrees N or S of the equator, the calculation for Latitude is quite easy. Then having an accurate measure of time when the Sun reaches it's Zenith and comparing that to GMT/UTC you can derive Latitude. A Sun Sight at mid-day is the easiest way to determine Lat/Lon. Harrison ONLY made the more portable chronometer; he was not a navigator, nor did he solve the Longitude question!
John Harrison was from a small village in Lincolnshire called Barrow upon Humber The Greenwich Meridian was so called because that was where the observatory was 😅
Well, I don't really want to "yuk" your "yum", but this video is terrible. It has about 45 seconds of useful information wrapped 9 minutes of nonsense. So... pardon your hyperbole but there are hundreds of UA-cam channels that are better than this.
In Australia we are required to carry paper charts in case our electrical means of navigation fails. If we have kept the ships LOG (notebook/diary) up to date, we know where we were at the last entry. From this point to where we are going can be measured with dividers/rule, using the scale on the RIGHT-HAND side of the chart for the area we are sailing we can measure distance to travel. This scale is adjusted by the chart maker to allow for the curvature of the earth so as we go North/South of the equator this scale changes. Hope this explanation makes sense.
A minute of latitude is always very, very, very close to 1 NM and needs no compensation for convergence. There is no scale adjustment needed by the map maker. So measure with your dividers then against the N/S axis in minutes - that is NM to 1/100th of a percent.
Alan, that is not absolutly true, it depends on the chosen method of projection and the scale of the map. For small scale and most usual small area projection the difference is negligable, especialy if you are using right-side scale directly right of the area travelled. On the large scale maps, the difference is huge.
For DCV's in Australia this is no longer true, and the AHO has been rationalising the paper chart index for some time. The NSCV no longer requires PNC back up so long as a second ECS/ENC is available.
@@michalbujna3755 On a mercator projection it does increase with latitude - BUT on charts I use (VFR air navigation) it's negligible as they cover a local area of a two and quarter degrees of latitude and the plane of projection goes through the chart twice - so as to minimize that "stretch" as much as possible. (aka: Lambert Conformal Projection - [secant conic] or [conic projection with two standard parallels].) Measuring a NM as a minute anywhere on the chart has pretty much undetectable difference. (eg: on a handy chart here, 30 minutes of latitude covers 112mm whether at the top, middle or bottom of the chart). And - if I took a chart from 20°S of here (or north), I'd get the same thing, as the intersecting planes would be local to that chart. The meridians on the other hand clearly converge on the chart. See page 29 of "The American Practical Navigator" [aka "the Bowditch"] - which can be freely downloaded from the US Navy site. This is _the_ navigation bible - I keep a copy on my computer, my iPhone, my Macs ...
This is the most sensible thing to teach everyone involved with navigation, regardless of how high is the tech you are equipped with and what backups it has. When the technology fails (and there are too many good reasons and practical scenarios), knowing how to navigate using simple means could be the difference between anything from stuck to life or death. Over-reliance on ever more complex technology ALWAYS being available and working properly is an increasing problem today. I can also compare this to the giving up on knowing morse code.
While we're on the subject of navigation, the story of John Harrison, who created the first chronometer accurate enough to be used when determining longitude on sea voyages, is absolutely fascinating.
If you see his clocks in order it's astounding H1 - Huge bulky complex clock carefully balanced with moving bits sticking out H2 - Huge bulky complex clock carefully balanced with moving bits sticking out H3 - Huge bulky complex clock carefully balanced with less moving bits sticking out H4 - Large Pocket Watch
Do you know about François Joseph Paul de Grasse? That's Neil's ancestor. That's the reason the US isn't using the Metric System today. Do you know the story? Have you ever been Rochambeaued? I thought everybody in France knew about DeGrasse and Rochambeau. Everyone in the USA should know about it but we don't.
Rabbit: tie them together Piglet, can you tie a knot? Piglet: I cannot Rabbit: Uh, so you can knot Piglet: no, I cannot knot Rabbit: not knot? Pooh: who's there? Rabbit: Pooh!? Pooh: Pooh who?
After. dare I say 100's of videos I'd say Chuck is of above average intellect. Seems to understand the majority of dozens (100's) of concepts quickly...and later can discuss coherently. He's got me beat.
Chuck is such a good sport as he plays along as the "student". I do enjoy Neil's channel. It is not only educational but also entertaining. Well done!!
I really appreciate an interviewer who is not only funny and understands humor, but is also knowledgeable enough to understand the science and scientific explanations as well.
When I was in grade school (waaay back in the 60s) my father was stationed at West Ruislip, England. My class took a field trip to Greenwich to see the Prime Meridian. We all took pictures straddling the line painted down the street. The Cutty Sark is also moored there. At one time it was considered the fastest clipper ship on water. It was pretty neat to be able to board it and see how the sailors of that time lived and worked.
Aviation uses a complex mix of metric, imperial, and nautical measurements worldwide. We measure altitude in thousands of feet (imperial), speed in knots (as defined in this video), and temperature in Celsius (because you always want to know how close you are above or below the freezing point, ice on the wings is bad).
One aspect that can be confusing is the use of "mile" as a term. Whenever it is used in an aviation or maritime context, it refers to a nautical mile, not a statute mile.
@@PistonAvatarGuy Why should it al be metric? It works just fine the way it is, just the opposite of insane. No one (no one that matters, that is) gets confused by mix of units. You refuted your own assertion about what it should be with your observation about the horrifically painful tran$sition.
@@blindleader42 I suppose that's mostly true, it's just insane that we ended up with such a ridiculous mix of units in general. Everything should be metric and aircraft were new enough that metric units could have been easily used in aviation from the beginning.
@@blindleader42 The other issue is that we're likely to be stuck with those units in aviation for all of the foreseeable future, unless there's some sort of massive collapse. What happens if flying cars become a thing? Do people use US standard units on the ground and nautical units in the air? What happens if they fly outside of the US? Do they then switch to metric units? I suppose that everything will be automated by then, but do the designers of those flight systems then have to juggle three different measurement systems, or will they just program everything in metric and convert the units displayed to the operator of the aircraft? Seriously, it really is just nuts. Everything should be metric.
The aliens in Close Encounters had possession of several Naval airplanes, and their pilots for many decades. They wouldn’t have had to know anything about French history or anything else to understand latitude and longitude.
A knot is one nautical mile per hour. The SI definition is one arcminute per hour along a line of longitude. The comes out to 2000 yards or 1850 meters and a little change. If you work out distances on a nautical chart, the utility of the nautical mile make distances easy to measure. Aviation uses many of the same terms (port, starboard, knot and even cockpit) because they are useful for navigation. Early aviators used charts in the same way mariners use them. The term has its origins in the age of sail where navigators would use rope with "knots" tied into it. And at the end of it is a weight. The knots are spaced at even intervals and when the rope was dropped into the water, the number of knots going in the water would be counted to get the ship's speed.
THIS! Ordinary "civilians" may find knots and nautical miles per hour unintuitive, but for navigation using basic tools and maps, they are far more convenient then constantly multiplying with some arbitrary coefficient.
@@justinrogers1807 The weight on the end isn't that heavy. Its enough to go into the water at a shallow depth. The line goes off a free spinning reel on the stern and pays out like if you were trawling for fish. The faster the forward motion through the water, the faster is pays out and the faster the knots move out into the water at a shallow angle. They w would count the knots as they left the stern If they had an idea of water current they were traveling through, they would perform a set and drift calculation to estimate speed over ground. and true course.
That was awesome! I have been flying for decades and have randomly wondered why the heck we used Knots. I figured there was some reason like this, but knowing what it is now makes me very happy. As to the question of "why people are holding on to knots"....well, can you imagine the expense of converting every single aircraft and watercraft that uses instrumentation calibrated in Knots, ripping it all out and replacing it, reformulating every single procedure, like the thousands of instrument approaches in the world, re-training millions of people across more disciplines than I can name to do their job, or their hobby, without getting anyone killed... um yeah, knots are fine. Numbers on the dial match the numbers on the chart match the numbers on the instruments match the numbers everybody else is using. I hate all the random Imperial measurements as much as anyone, but changing it all to something new... (head explodes)
Extra reason to use knots in aviation was hydroplanes (amphibious aircraft maybe in English?) were much more common about a 100 years ago. When airfields were still mostly fields and flat runways were nothing but a dream, taking off and touching down on a quiet, still water surface was preferable. Thus cartography and surface operations favoured shifting from nautical to aeronautical work.
@@RadeticDaniel No - it's all about navigation. Either nautical or aeronautical. Early long distance aviation nav was done by stars exactly the same as on water, and because lat/long is bisected by NM, it makes sense to use kts. We use miles and km to measure distance on roads, and mph/kph for speed - would be a mouthful to say 'nautical miles per hour' for measuring aviation and maritime speed, so knots moved from the use of the common log into the calculated vernacular.
The system makes a lot more sense, if you remember that the big, hard, really vital question wasn't "Exactly how fast are we going?" but "Exactly where on the globe are we?"
As an aviation expert, my opinion is that knots is still the best method for long range navigation. It’s not nostalgia - flight instructor, air traffic controller, aviation professor
You might be right, but you fail to say _why_ you have that opinion. Without a stated reason, an opinion really doesn't matter much. We need to be able to estimate the validity of it. It could be that you are just used to it, but that is not a valid reason for an objectively best method. And being a flight instructor, air traffic controller, or aviation professor is certainly not enough to make your opinion matter without a reasoning. So, _why_ do you have that opinion?
one of the reasons may be that it's a different speed. km/h and mph are usually used as relative to the surface of the earth/land. Knots (both in planes and ships) are actually measured relative to the medium (air/water), because that's what is interesting performance-wise. So using this different unit also may help with the mental picture, that it's something else, not your conventional speed relative to the landmass.
@@skyhawk_4526 You are travelling over a large distance of unobstructed travel. You know where you are and that is measured/defined in two angles (N/S and E/W); you know where you want to end up and that location is also defined by the two angles. Do you want to use an arbitrary length or do you want to use a length that is directly related to angles on the globe? Then you realise that the distance isn't that important; it is far more important to know how long it is going to take. The unit that ties a 'measurement system based on the globe' to time is 'nautical miles per hour' (= knots.) Maps have these angles on them already and you can directly copy them with a compass to 'walk' the total distance. You don't need to calculate anything, just compare and count how many times something goes. Makes the life of a navigator much easier. Does this makes sense?
"Knots made sense back in the day"? It still makes sense! Plus, the Nautical Mile is in this regard more logic then the statue mile. (And, a NM is not just a arcminute, it's a arcminute on a greatcircle)
Fun fact: When the Brits and French were arguing over who got to be the prime meridian, the Brits ended up winning it in exchange for changing over to the Metric system (which they didn't for a long time and still haven't *fully* done)
I'm all knotted up now 😂 This is a great channel to watch I've learned a lot from this man. Neil is a humble guy who sees things that others don't and he has a way of explaining complex scenarios in a simpler format for the human mind to grasp... Some of the thoughts that roll around in his mind are probably not as easy for some of us to understand. Through out his life he has focused on things that have interested him and intrigued him until his level of intelligence has become very impressive and gives off serene perceptiveness with reassuring understanding. Something that is very hard to come by today. I would like to read some of his books. They're probably very interesting. Most of the things he talks about will definitely help your understanding of a lot of things and increase your common sense tenfold.
Sailors would tie a rope to a log known as a "chip log" or "common log" shaped like a pie and knots were tied in the rope spaced 14.4 meters apart. They would throw the log overboard, flip an hourglass calibrated for 1 minute, and would count how many knots passed through their hand. Thus giving them the speed of the vessel. That's where knots came from. We use knots because charts are in nautical miles and it's far easier to calculate 1:1 rather than having to convert everything.
The modern international nautical mile has been set at exactly 1,852 meters (about 6,076.1 feet). In the UK, they commonly use a nautical mile equal to 6,080 feet.
I think that the reason knots and nautical miles are used in modern day navigation is because of the Mercator projection (which is very useful in navigation). When you have you basic distance unit same as arch minute of latitude, you have your scale always on the left side of the map and it changes depending on how far north or south is the area on the map. This makes it easy to measure distances on maps even if it's Mercator projection.
As a former navigator I can safely say that the Mercator projection is unbelievably awful for navigation. The distortion increases as you move North or South from the Equator. No navigator would ever use a Mercator projection to navigate across the ocean unless he was staying very close to the Equator at all times.
Many militaries, especially ones with long histories, love to hang on to outdated traditions BECAUSE it's tradition. My father flew an A-6 Intruder in the United States Marine Corps. Long after his retirement he would still used knots in place of miles an hour.
No it’s not an outdated tradition. Nautical charts and aviation charts are marked in Degrees Minutes and Seconds. It’s how you navigate. You take your divisors and measure your distance in minutes at the latitude lines at the edge of the charts and move the divisors along your position to the destination or where you came from to mark the distance. And you measure from the nearest degree down to the nearest second. Which is about 33.7 yards. So you are within 33. Yards on a sea chart of your actual position. Your second of measurement can be broken down into decimal places to an exact position. The GPS does the same thing.
@@Jerry10939 Right, it's not outdated because it's based in observable, measurable facts about our planet and spherical trigonometry. in that sense it shares more with the metric system than with many Imperial units.
That is the pre-1929 definition. After the definition of the nautical mile in 1929, it is defined as 1 nautical mile per hour. A nautical mile is defined as 1 arcminute of the circumference of Earth at the Equator.
How anout when old wooden ships through a log over the back of the ship. The log had a rope wraprd about it with knots every so many feet. The number of knotd that rooled off the log during a certain amount of time determined the speed in knots per hour,
Aliens absolutely did not have to know French and English history to know Science and Navigations on earth use a longitudal/lat system. They could have observed my 6th grade science class. We certainly were not taught the history of it, only how it works.
That’s the best explanation. I’ve heard. All previous reading on this had to do with knots in a rope and letting the rope out and didn’t make much sense now. I understand that not is tied to an arc minute. Thanks.
Knots simply comes from sailing ships. They had ropes with knots on them and to see how fast they were sailing they toss it overboard and count how many knots pass through your hand in a minute. That would be your speed in knots. How far apart the knots were was possibly the degrees Tyson talks about, but he doesn't mention the rope at all. The rope is where the term comes from. I learned this in primary school as a precursor to algebra.
This is correct. There were no number systems like Metric or Imperial back then, so they tied knots at equal intervals on a rope to measure their ships or boats speed. The airline and marine industries still use this age old system.
Thank you as always for the videos. There is a glaring omission in that a knot is one nautical mile per hour. Also it is not nostalgia or inertia that motivates their continued use (unlike the instance of the US to use imperial units). They are very practical to estimate how many degrees you will travel on a map when sailing or flying, and in the case of sailing, very easy to measure using a piece of wood and a rope with, suprise, knots.
We still use knots as pilots. 5280 feet per statute mile and 6076 feet per nautical mile. Simply put for this video, Latitude is a measure of distance, longitude is a measure of time. Every degree is 4 minutes. So if you use a sun dial during the day and mark the zulu time your position is at noon (shadow lowest on the dial) you can then calculate your longitude. If it is noon where you are and 628 pm zulu (1828Z) your longitude is the number of minutes divided by 4. Since there are 15 degrees an hour you got 6 hours so 90 plus 28\4 is 7 you are at 98degreed west. As an example
I did Sonar with the US Navy. "Sonar" is an acronym for "sounding navigation and ranging." Here's a fun fact: The kilometer was made at the Equator to the north pole, Dividing 10 over and over until you get to a Kilometer. Keep Dividing until you get meters. The Equator is larger than the pole-to-pole used in making a Knot, so the Math is still accessible: 50 Knots=100 Kilometers=80 miles, or your 60 knots = 120 kilometers = 75 miles. This is rough math, but true, very close to accurate. The knot (/nɒt/) is a unit of speed equal to one nautical mile per hour, exactly 1.852 km/h (approximately 1.151 mph or 0.514 m/s). The ISO standard symbol for the knot is kn.
6:14 despite what you've been told (fellow commenters) this is why the Mercator projection was made and so prevalent. Because they stretched the north and south so much so that it was easier to plot courses and such.
I'm a bit confused (not that unusual). I always thought that the Greenwich Meridia went through Spain as well. In fact I'm sure I saw it marked when I visited the Coata Brava (near Barcelona?). But your globe / map at 1:44 shows that it misses Spain by miles.
I want to live on a sailboat someday, so I know plenty about boats. I knew about the origin of the term knots and that eventually it came to mean nautical miles per hour, but I had no idea that a nautical mile was also an arcminute. Thanks for teaching me something. :)
Great system when using a map with Lat/Long graticule. One use springs to mind back when I was an airline pilot on a long haul flight: A passenger requested the time of sunrise - for his morning prayers. It gave us something [extra] to do in the middle of the night, taking into consideration the changing Lat/Long navigation, planned speeds IN KNOTS, Earth rotation rate, Sun seasonal declination and Solar altitude angle. Easy for Mr deGrasse I'm sure, but got our tired old heads churning old Trig and Calculus. We nailed though, probably with a big helping of luck!
Pop Quiz Time! Convert 100 knots into km h? (let's see how the Americans fare)
This is completely unrelated, but do you think that we will, with enough advancements in technology, find that photons have mass?
185.2 kmh
186.7 km/h if considering the 24901 miles of circumference at a conversion rate of 1.62 km per mile. (Didn’t google this)
Maybe, maybe knot.
185.2 km/h because one arcminute is now defined as being exactly 1,852m instead of 1/60th of a degree.
The term "knots" originates from an old maritime practice. Sailors used a device called a log line to measure the speed of their ship. The log line was a rope with knots tied at regular intervals. They would throw the rope overboard and count the number of knots that passed through their hands in a specific amount of time, usually measured with a sandglass. This method allowed them to determine the ship's speed in nautical miles per hour, which is why we still use the term "knots" today
I'm not convinced "knots" (the rate of speed) was ever named for the knots in the log line. It's short for "nautical" (knotical) miles per hour.
Exactly. And it wasn't until sufficiently accurate clocks were invented that they could accurately determine longitude. Neil should've talked about that a bit.
8 fathoms between knots ( 48 feet, fathom is 6ft 6*8 48)
@bestsnow.. You are absolutely correct. A shame that Tyson didn't tie this into his explanation, (no pun intended). As opposed to a sextant, counting the knots in the log line informed the captain or navigator of their PRESENT speed in real time.
Disappointed this wasn't implemented into the video but what do ya do lol
It makes perfect sense to me. I am a Navy veteran. We learned about all this and much more. It’s a great system. I mean they used it way back when to navigate the globe. It works. In fact the USN still plots the old school way just in case the GPS goes down. We can still navigate without modern technology. I was a welder but watching the quartermasters and such navigate and plot always fascinated me. I joined in 2002 and served on CV-63, LHA-1, and LCC-19. Shoutout!
All chronometers have been compared….request permission to strike eight bells on time.
It's a vestige of another time. If you're navigating the seas without satellite equipment, it might be a good thing to know. But it's the marine equivalent of, instead timing something with your smart phone, you count, "One Mississippi, two Mississippi, three Mississippi..."
@ it’s not a vestige of another time if it is still used today. As with anything knowing how to do things without a cell phone or the internet is a good thing. I rely on technology as much as the next man but there are many things I know how to do that would be valuable if for some reason we lost it. I’m a rural man and my family would be fine without electricity or any service provided including water. Perhaps a vestige of another time but any time spent on learning/practicing anything is time well spent.
@@jeanaprewitt9658 A standard assumption for all of the U.S. military is that "Murphy" will make an appearance. If you rely on anything then you must have an alternate for it (Redundancy). Satellites can break down or be destroyed, but the Sun and Moon, Stars and Planets are immune to breakage or enemy action. It also blows up the entire plot of Tomorrow Never Dies.
@adriangarcia9626 It's still used today but it carries no actual advantage. The system made sense when it was used and developed because it allowed people to forego accurate measurements (which they couldn't do) by relying on geometry and mathematical principles to subdivide into easier approximations of distance.
Since we already have all the measurements, all you need to work without knots is a cheat-sheet with the measurements and a scale-map. If you know the circumference of the earth in kilometers, you can subdivide it by kilometer distances just as easily as by nautical miles. And knots as a speed measurement only make sense when you have a standardized navigation aid that actually uses knots. That used to be a rope with knots, which you could use in conjunction with a standardized time-keeping device to derive your speed and you could then use that speed in conjunction with other navigation methods to derive your change in position from your last measurement.
It's a shame he didn't explain this in the video, but that's why a knot is called a knot.
But that also means that if you don't have that rope on-board, you get absolutely no benefit from using the system. You could use any other system just as easily, as long as you have a way of measuring or deriving your speed, you're good. And calculation in base 10 is far more intuitive to us as humans than any other system.
I dare to disagree. Knots and nautical miles make total sense navigating with a sextant, a pencil, and a paper chart. OK, everybody has a GPS nowadays, but what if a lightning strike your sailboat? It happened to me.
When at sea, depending on where you are, there is nobody around to save you, to sell you a new GPS, or extra batteries. And nautical miles make finding where you are a lot easier. Even more so in stressful situations.
Just a feedback from someone who have being living on a sailboat for years, a different perspective maybe, but I love the show. Keep up the good work, guys.
preparing the line is probably beyond the seamanship knowledge of most sailors today, even though it is logical and easy.
Knowing thay stuff is mandatory for a commercial ship's captain even today. @@richardelliott8352
There is also the possibility of satellites disabled and the need to navigate with paper and stars. Also it is a great backup in case of system failure.
@@CaptDrewman I totally agree.
You know what belongs next to your sextant? A backup GPS.
I'm surprised it didn't come up, but we do have a name for one arc minute which is nautical miles. So a knot is one nautical mile per hour.
These are used because it does make things much easier to calculate in a map, and it's used not only in ships but also in aviation.
1.8 km in 3600 seconds, 0.5 m in s
Thanks!
An even 852 meters
Edit missed a 1 before 852
...and space re-entry points
Okay, I'm confused though. The distance between arc minutes changes with latitude. So the answer to who's going faster depends on what latitude they are at. I mean if i do a spin around the pole at the north pole i went through 21600 arc minutes in about 3 seconds.
So is a knot 1 nautical mile per hour, or is it 1 arc minute per hour?
Nobody talks about science in the same pedagogical way Neil and Chuck do it, this podcast is amazing!
Yet the fake science guy doesn't know what a woman is.
These two are wonderfully entertaining.
Neil should have started by saying a minute of latitude is one nautical mile.
i feel the same and about to say this in the comment and saw you already said it.
They should stick to topics they are actually experts on. This was like a half baked conversation you would overhear in a bar.
As you say! I don't understand the angst. With the coordinate system in use today (lat/long) 1 nautical mile (which can be equated to 1 nm = 1 knot) equals 1 minute of latitude. 60 minute of latitude equals 1 degree of latitude. Doing the math, 60 nm x 360 degrees = 21,600 nautical miles. The generally accepted average circumference of the earth is 21,639 nm. That approximates to 99.8% accuracy for that coordinate system.
Not to mention the diagram of latitude had the lines drawn at to wrong places.
@@CyBirr You forgot to mention that this is for measurements at the equator. They don't apply anywhere else in latitude.
As someone who still knows how know to use a sextant, knots/nautical miles make sense as they are measurements of angle and it’s all spherical trigonometry.
I never learned to use a sextant, but to an old-school machinist everything is made of circles and triangles.
That will help you learn how to use one. You should learn it'll help with navigation@@GWNorth-db8vn
@@GWNorth-db8vn because of the old machine tools limitations. With current CNC, tool paths can obey to any math. function (OK approximated to series of small vectors... ). Eg. boat propellers, turbine blades, wing profile .....
Believe it or not, the old B-52‘s had an observatory bubble so the navigator could use a sextant.
@@ellsworthm.toohey7657 - That's why I said oldschool. I do a type of precision grinding (jig grinding) where the manual machines are still more precise and give a better finish than the CNC. We use a CNC just to rough things out. I've actually been around since paper drawings and wooden patterns for copying mills, and I was taught to use a slide rule in high school.
The thing about CNC is that they operate in steps, not smooth curves. The finish needs to be polished or ground to get rid of the roughness built into the method. Half a tenth sounds pretty fine, but you can see a finish that rough in oblique light, and it's way too coarse for a lot of things.
Actually... The term knot dates from the 17th Century, when sailors measured the speed of their ship by the use of a device called a “common log.” This device was a coil of rope with uniformly spaced knots tied in it, attached to a piece of wood shaped like a slice of pie. The piece of wood was lowered from the back of the ship and allowed to float behind it. The line was allowed to pay out freely from the coil as the piece of wood fell behind the ship for a specific amount of time. When the specified time had passed, the line was pulled in and the number of knots on the rope between the ship and the wood were counted. The speed of the ship was said to be the number of knots counted (Bowditch, 1984).
I'm amazed Neil didn't explain this.
I think Neil explained what a knot is, and you explained how it was calculated. I do agree this could have been fleshed out more in his video.
I vaguely remember hearing about that method a while back.
It was also inaccurate because it was based on the notion of the water as a stagnant medium. If your ship was travelling with a current flowing in the same direction as the ship was travelling, the speed of the ship would be greater than the measured speed. For example, a ship travelling with a 4 knot current that measured a speed of 8 knots would actually be moving at 8 + 4 = 12 knots between fixed points on the surface of the Earth. If you were travelling at the same apparent speed AGAINST a 4-knot current, your true speed would be 8 - 4 = 4 knots. This was one reason that developing a way to fix Longitude was so important. If there were no currents in the oceans, the combination of a compass, a sand glass, and a ship's log would allow the navigator to fix a ship's position fairly accurately after days or even weeks of travel. For most voyages, combining this with adjusting the position occasionally when known landmarks were spotted would have been adequate. But because of unknown, immeasurable, and variable ocean currents, this "dead reckoning" method could be off by dozens of miles per day, far too much for safe and efficient navigation.
Interestingly, even with GPS available, some ships still use a form of dead reckoning known as "inertial navigation systems." These are based on accelerometers that can sense any acceleration in any direction so accurately that it can give an excellent estimate of where a ship is even after weeks of travel. An early and very important application of these systems was on submarines, which, when submerged, could not use many of the navigation tools available to surface ships. Subs also found it helpful to have an independent measure of DEPTH. Measuring water pressure is closely related to depth, but because water density varies with temperature and salinity, it's not perfect. Sensitive accelerometers can measure how far a ship has travelled up and down as well as E-W and N-S across the Earth's surface! These accelerometers used to be very bulky and expensive, but in a very short period of time, they became cheap and compact. This was because compact and reliable accelerometers were needed for Safety Airbags in automobiles. When those were mandated by law in the U.S., tiny, cheap, accurate accelerometers had to be quickly developed.
These new accelerometers were also noticed by Shigeru Miyamoto at Nintendo. He realized that a new type of video game console could be developed so that the motion of the console in the player's hands could be easily integrated with the video game, and the Nintendo Wii was born.
Yes! I’m surprised he didn’t mention where the term “knots” actually came from!
@@joeanonimous1105 Knots have always been based on ship speed through the water rather than absolute speed. If you are on a treadmill and running at 10 mph that is your speed. If you set the treadmill to 10 mph on a ship heading West at 10 mph you are still running at 10 mph. If you were on the ISS travelling East [ish] at 17500 mph you would still be running at 10 mph.
The advent of aviation was the real eye-opener for relative and absolute speeds, especially for takeoff and landings which are preferentially done into the wind to reduce the ground speed when getting off, or more importantly, back on the ground. Seeing your indicated air speed at 80 ish and ground speed by GPS at over 140 is interesting!
I navigated in the US Navy in the late 70's. We had what we called "SatNav" back then primarily for position locating. We still did all of our course and speed and set and drift calculations by hand. A standard mile is 1760 yards. A nautical mile is 2000 yards. It made the math much easier. We also had to shoot the stars for I guess an emergency back up and to check our equipment to a point. Thanks for the great explanation and thank you for your time.
If you get off boarded, a swimmer's mile is 1600 yards
Also,
The Oceans are level, which means the Earth is Flat.
@@godsbeautifulflatearth If the earth was round all of the oceans would run to the edges, obviously.
@@godsbeautifulflatearth You know, there are things called dictionaries where you could look up the meaning of a word such as level. But the fact that you think the UN logo is somehow evidence of something, tells me that reality just isn't in your wheelhouse.
@@godsbeautifulflateartherr ... sea level is measured relative to the geoid which ain't a flat surface. Also there is a tidal bulge on opposite sides of the world. Where do you think all that water runs off to during low tide if its level genius ?
Originally knots were tied in a rope regular intervals and they would throw the rope over the side of the boat and count the number of knots that would pass in a certain length of time
Without looking it up right now, this is what I always thought. Surprised Neil and Chuck didn't mention it.
That's the definition I always heard.
I also have wondered if the sea voyage calculations had to compensate for currents when math-ing knots. Because the rope with knots really is only measuring how much water has flown past the ship. It cannot know what speed it's going relative to land by just using the knotted rope. I guess the sextant and other equipment came in to do those calculations.
It also makes sense then to use in planes to measure airspeed. Because, for a plane, what the sensor on the fuselage can measure is likewise just the flow of air going past the plane. If it's windy, you can effectively stand still landspeed wise while still doing 50 knots in airspeed. Same thing when climbing or diving. Little landspeed but potentially lots of airspeed.
My guess is that the archminute thing was retrofitted to make it more scientifically relevant than knotted ropes and a sailor kind of gut feeling the length of time before portable watches and clocks.
I saw this in Black sails 😅
How do you tie a knot in a rope which is being thrown overboard?
@@utube7930 you tie the knots before you throw it over the overboard. It's a very long rope too so you don't throw the whole rope over just the part that has the knots on
As a Chief Mate on an offshore supply vessel… 🚢 i appreciate these topics. ✊🏾💯
Neil said early on the the video that although degrees were divided into minutes and seconds, there's no connection with time (apologies if I'm misquoting, I'm paraphrasing). It's true that there isn't an obvious relationship between degrees and time, but 360 degrees of longitude equates to a full day of 24 hours. Navigation by latitude and longitude requires an accurate clock. One reason why James Cook's maps were so accurate was because he had a new type of ship's clock, which enabled him to calculate longitude accurately. He was also an excellent navigator and cartographer as well. Observatories in cities like London (well, Greenwich) and Sydney had a ball on a pole on the roof which gave the crews on ships a visual indication of time by which to set their clocks. This was essential in order for them to navigate safely. I'm glad that someone else in the comments also mentioned the origin of "knots" originally being literal knots in a cord attached to a sea anchor fed over the stern. I was really surprised that these things weren't mentioned.
But why do we still use 360 degrees, 60 minutes an hour or degree and 60 seconds a minute. We do use the 10 base number system after all. Both in imperial and metric. Well we sometimes do. They tried to make metric time and degrees. 400 degrees on a circle, 100 minutes an hour and 100 seconds a minute. But it didn't catch on. It is because calculators is only about 50 years old. 60 is much easier to calculate with fractions. 100 is divided by 2, 4, 5, 10, 20, 25, 50. 60 is divided by 2, 3, 4, 5, 6, 10, 12, 15, 20, 30.
@@andvil01 60 isn't easier, it's just what we're used to. Europeans would say the opposite. Imperial can be more convenient for things that need to divide by three, but most things one might divide by five would be easier in metric. Twos and fours come out even, either way, and usually don't even _need_ to be measured, if you can fold a rope, string, or sheet of paper in half. (This also cuts half the work of dividing by 6 and other higher numbers.) It's also not that much work to memorize 0.33333 or 0.16666 for dividing metric by thirds and sixths. We have to memorize cramming 16ths and 32nds into a unit that uses twelfths, which goes into another unit that uses thirds. 10's are easier, lol.
@@andvil01 At this point, the more sensible thing would be to switch to base12 system for general arithmetic.
@@andvil01 I think it's also because way back before the invention of zero and the Arabic numerals we now use folks calculated in base 12 using the thumb to traverse the knuckles of one hand.
There is still an existing and working clock tower at Williamstown in Melbourne that has been restored to working order
Fun fact: You can calculate latitude (relatively) easily with an astrolabe, but longitude is almost impossible because the Earth rotates. The guy who cracked the problem by associating longitude with time was John Harrison. He was from Greenwich, England, which is why the Prime Meridian is there.
There's a *great* book (and PBS show?) about John Harrison, appropriately titled "Longitude" (Dava Sobel)
Nautical mile is also a minute, which is on the scale on the left/right (or east/west) side of most of maps. Therefore it is easy to quickly copy the distance in NM or speed in KTS needed for the navigation from the side of the map.
Well, SORT OF but not really. Harrison created an accurate and more portable time piece that could be carried aboard a ship for the purpose of calculating longitude based on heavenly observations/stars. The French had created a magnificent and ornate chronometer but is was several feet tall and extremely delicate and sensitive, many countries and England had been creating very accurate clocks, but the delicacy of the movements meant that any great jostling and moving about would result in its accuracy being affected. By accuracy I don't mean it kept perfect time, but any gain or loss of time in seconds was exactly predictable and determined and that was accuracy. Navigators had long understood longitude and how to calculate a position east or west of a Prime meridian but had to use different means to arrive at a solution before highly accurate time pieces were available to be carried on ships.
Latitude can be determined by using a sextant and making an observation of Polaris, or the Sun when the Sun reaches its Zenith. I won't go into all the details but those are two basic methods to determine Latitude. Before the ability to carry predictably accurate time aboard ship, they would take daily observations to determine latitude while sailing in a northerly or southerly direction. Knowing the latitude of their destination, once they reached that latitude, they would turn either East or West and head for their destination. Gaining the ability to determine Longitude made the shorter diagonal sailing point A to point B possible, to put it as basic as I can.
Longitude and determining it requires precise calculations of the movements of stars and celestial bodies, a Prime Meridian for time keeping, and an imaginary Meridian in the "Celestial Sphere" which we call Aries because it runs through the constellation of Aries which gives us a steady baseline to measure the track of navigational stars from. Time needs to be precise when determining for any day and time, exactly where that star should be and where at that exact moment it would be if it fell directly to earth, measuring it's elevation and being able to calculate where it would be on the earthly sphere requires accurate time, and the difference in local time and Prime Meridian time, or GMT "Greenwich Mean Time" or more commonly stated today as UTC or "Universal Time Corrected" This is extremely rudimentary and simple for an explanation, but making several calculated observations of celestial bodies, their height and direction in degrees from you and using accurate time to be able to know exactly where their Azimuth would intersect the surface of the earth, then plotting the intercepts for each and where all cross is your position. And that's all done long hand or using a calculator and it's called "Spherical Trigonometry and ALL the way back to Pythagoras and before and NOT to Harrison a hobbyist clock maker.
Longitude by Zenith observation of the Sun. Much easier and only requires a single celestial body, our Sun. Using accurate measurement of time by chronometer set to GMT/UTC, observing the Sun's angle in degrees above the horizon, at it's Zenith, or Actual NOON/MID-DAY and, knowing that for any particular day the Sun will be so many degrees N or S of the equator, the calculation for Latitude is quite easy. Then having an accurate measure of time when the Sun reaches it's Zenith and comparing that to GMT/UTC you can derive Latitude. A Sun Sight at mid-day is the easiest way to determine Lat/Lon.
Harrison ONLY made the more portable chronometer; he was not a navigator, nor did he solve the Longitude question!
He wasn't from Greenwich
John Harrison was from a small village in Lincolnshire called Barrow upon Humber The Greenwich Meridian was so called because that was where the observatory was 😅
The French part at 3:00 is what TV was like in the 90s and we should cherish it.
This is the best youtube channel in the history of UA-cam channels
Except for Neil constantly interrupting and talking over everyone
@@reeceguy3949 I adore Neil enough to overlook that..
Well, I don't really want to "yuk" your "yum", but this video is terrible. It has about 45 seconds of useful information wrapped 9 minutes of nonsense. So... pardon your hyperbole but there are hundreds of UA-cam channels that are better than this.
@@tuckertucker1 Your politics is disturbing you
Yesssss fascinating
I know I’ve said this a whole bunch, but the editing on these 10 minute lessons makes the videos 10 times funnier than they already are on their own.
In Australia we are required to carry paper charts in case our electrical means of navigation fails. If we have kept the ships LOG (notebook/diary) up to date, we know where we were at the last entry. From this point to where we are going can be measured with dividers/rule, using the scale on the RIGHT-HAND side of the chart for the area we are sailing we can measure distance to travel. This scale is adjusted by the chart maker to allow for the curvature of the earth so as we go North/South of the equator this scale changes. Hope this explanation makes sense.
A minute of latitude is always very, very, very close to 1 NM and needs no compensation for convergence. There is no scale adjustment needed by the map maker.
So measure with your dividers then against the N/S axis in minutes - that is NM to 1/100th of a percent.
Alan, that is not absolutly true, it depends on the chosen method of projection and the scale of the map. For small scale and most usual small area projection the difference is negligable, especialy if you are using right-side scale directly right of the area travelled. On the large scale maps, the difference is huge.
For DCV's in Australia this is no longer true, and the AHO has been rationalising the paper chart index for some time. The NSCV no longer requires PNC back up so long as a second ECS/ENC is available.
@@michalbujna3755 On a mercator projection it does increase with latitude - BUT on charts I use (VFR air navigation) it's negligible as they cover a local area of a two and quarter degrees of latitude and the plane of projection goes through the chart twice - so as to minimize that "stretch" as much as possible. (aka: Lambert Conformal Projection - [secant conic] or [conic projection with two standard parallels].) Measuring a NM as a minute anywhere on the chart has pretty much undetectable difference. (eg: on a handy chart here, 30 minutes of latitude covers 112mm whether at the top, middle or bottom of the chart).
And - if I took a chart from 20°S of here (or north), I'd get the same thing, as the intersecting planes would be local to that chart.
The meridians on the other hand clearly converge on the chart.
See page 29 of "The American Practical Navigator" [aka "the Bowditch"] - which can be freely downloaded from the US Navy site. This is _the_ navigation bible - I keep a copy on my computer, my iPhone, my Macs ...
This is the most sensible thing to teach everyone involved with navigation, regardless of how high is the tech you are equipped with and what backups it has. When the technology fails (and there are too many good reasons and practical scenarios), knowing how to navigate using simple means could be the difference between anything from stuck to life or death. Over-reliance on ever more complex technology ALWAYS being available and working properly is an increasing problem today.
I can also compare this to the giving up on knowing morse code.
I love hearing neil talk about stuff hes so passionate about things so it makes me passionate to learn new stuff aswell
“One at a time”
I fricken love Chuck.
Me too absolutely love chuck 😂
Lord Nice is just spectacular and grounding in these episodes. Love his participation!
While we're on the subject of navigation, the story of John Harrison, who created the first chronometer accurate enough to be used when determining longitude on sea voyages, is absolutely fascinating.
I'm surprised Neil didn't mention this and the chip log. That would've tied it all together.
@@bigredracingdog466
If you see his clocks in order it's astounding
H1 - Huge bulky complex clock carefully balanced with moving bits sticking out
H2 - Huge bulky complex clock carefully balanced with moving bits sticking out
H3 - Huge bulky complex clock carefully balanced with less moving bits sticking out
H4 - Large Pocket Watch
agreed! the book titled “Longitude “ is a great read for those interested. As is a trip to Greenwich England.
@@davidioanhedges Was H4 back-engineered from alien tech, seems like a massive leap. Joking of course.
Knotted up right now is crazyyy
ayo
So casually while he looks up at the sky
WILD 😂😂😂
What that mean
@@lhrmusic1It just sounds nasty 😂 super sus
They forgot to mention that a nautical mile is 6076 feet, and an American mile is 5280 feet.
🇫🇷 here, I love you too guys.
Do you know about François Joseph Paul de Grasse?
That's Neil's ancestor. That's the reason the US isn't using the Metric System today.
Do you know the story? Have you ever been Rochambeaued?
I thought everybody in France knew about DeGrasse and Rochambeau. Everyone in the USA should know about it but we don't.
Chuck Nice is hilarious and it's great how much he makes Neil chuckle
Chuck's the straight man but he's pretty smart himself.
Don’t you notice how exaggerated the laughter is? While you sit in silence…..
@@metricdeep8856Nope because he's genuinely funny. Have fun with that stick your sitting on
@@towlie9428 Easily entertained is a simple way to go through life. Scary for others……but appropriate for most.
@@towlie9428 you're
I am always smarter for hanging out with my guy Neil. Thank you for sharing. I believe that is the true blessing of life sharing usable information.
Rabbit: tie them together Piglet, can you tie a knot?
Piglet: I cannot
Rabbit: Uh, so you can knot
Piglet: no, I cannot knot
Rabbit: not knot?
Pooh: who's there?
Rabbit: Pooh!?
Pooh: Pooh who?
"no, i am Yu. he is Mi." 🤣
Who's on first, What's on second, I Don't Know's on third....
I'm french and I love it when Chuck does its french impersonation!
ButOfCoouurrsee'
C’était parfait !
@@alexisnaranjo Bien sûr
After. dare I say 100's of videos I'd say Chuck is of above average intellect. Seems to understand the majority of dozens (100's) of concepts quickly...and later can discuss coherently. He's got me beat.
Chuck is such a good sport as he plays along as the "student". I do enjoy Neil's channel. It is not only educational but also entertaining. Well done!!
I really appreciate an interviewer who is not only funny and understands humor, but is also knowledgeable enough to understand the science and scientific explanations as well.
When I was in grade school (waaay back in the 60s) my father was stationed at West Ruislip, England. My class took a field trip to Greenwich to see the Prime Meridian. We all took pictures straddling the line painted down the street. The Cutty Sark is also moored there. At one time it was considered the fastest clipper ship on water. It was pretty neat to be able to board it and see how the sailors of that time lived and worked.
Aviation uses a complex mix of metric, imperial, and nautical measurements worldwide. We measure altitude in thousands of feet (imperial), speed in knots (as defined in this video), and temperature in Celsius (because you always want to know how close you are above or below the freezing point, ice on the wings is bad).
It's absolutely insane. It should all be metric, but that would be a horrifically painful transition.
One aspect that can be confusing is the use of "mile" as a term. Whenever it is used in an aviation or maritime context, it refers to a nautical mile, not a statute mile.
@@PistonAvatarGuy Why should it al be metric? It works just fine the way it is, just the opposite of insane. No one (no one that matters, that is) gets confused by mix of units.
You refuted your own assertion about what it should be with your observation about the horrifically painful tran$sition.
@@blindleader42 I suppose that's mostly true, it's just insane that we ended up with such a ridiculous mix of units in general. Everything should be metric and aircraft were new enough that metric units could have been easily used in aviation from the beginning.
@@blindleader42 The other issue is that we're likely to be stuck with those units in aviation for all of the foreseeable future, unless there's some sort of massive collapse. What happens if flying cars become a thing? Do people use US standard units on the ground and nautical units in the air? What happens if they fly outside of the US? Do they then switch to metric units? I suppose that everything will be automated by then, but do the designers of those flight systems then have to juggle three different measurement systems, or will they just program everything in metric and convert the units displayed to the operator of the aircraft? Seriously, it really is just nuts. Everything should be metric.
Chuck is simply the coolest man out there. Smart, humble, hilarious.
The way the story was told was beautifully done
Knot what I expected! :D
Nooooooooo!
LOL. Good pun!
The aliens in Close Encounters had possession of several Naval airplanes, and their pilots for many decades. They wouldn’t have had to know anything about French history or anything else to understand latitude and longitude.
What a complex way to measure, and hopefully I’m using the right term, travel speed in today’s day and age. Also keep it up NDT!
A knot is one nautical mile per hour. The SI definition is one arcminute per hour along a line of longitude. The comes out to 2000 yards or 1850 meters and a little change.
If you work out distances on a nautical chart, the utility of the nautical mile make distances easy to measure. Aviation uses many of the same terms (port, starboard, knot and even cockpit) because they are useful for navigation. Early aviators used charts in the same way mariners use them.
The term has its origins in the age of sail where navigators would use rope with "knots" tied into it. And at the end of it is a weight. The knots are spaced at even intervals and when the rope was dropped into the water, the number of knots going in the water would be counted to get the ship's speed.
"Arcminute per hour along a line of longitude" 👍
@@Ciubaruahh, that was not well described. I was thinking it changed depending on your latitude.
Why do they talk about fathoms as depth and not knots?? Knots are speed not depth and connot be both
THIS! Ordinary "civilians" may find knots and nautical miles per hour unintuitive, but for navigation using basic tools and maps, they are far more convenient then constantly multiplying with some arbitrary coefficient.
@@justinrogers1807 The weight on the end isn't that heavy. Its enough to go into the water at a shallow depth. The line goes off a free spinning reel on the stern and pays out like if you were trawling for fish. The faster the forward motion through the water, the faster is pays out and the faster the knots move out into the water at a shallow angle. They w would count the knots as they left the stern If they had an idea of water current they were traveling through, they would perform a set and drift calculation to estimate speed over ground. and true course.
That was awesome! I have been flying for decades and have randomly wondered why the heck we used Knots. I figured there was some reason like this, but knowing what it is now makes me very happy. As to the question of "why people are holding on to knots"....well, can you imagine the expense of converting every single aircraft and watercraft that uses instrumentation calibrated in Knots, ripping it all out and replacing it, reformulating every single procedure, like the thousands of instrument approaches in the world, re-training millions of people across more disciplines than I can name to do their job, or their hobby, without getting anyone killed... um yeah, knots are fine. Numbers on the dial match the numbers on the chart match the numbers on the instruments match the numbers everybody else is using. I hate all the random Imperial measurements as much as anyone, but changing it all to something new... (head explodes)
Extra reason to use knots in aviation was hydroplanes (amphibious aircraft maybe in English?) were much more common about a 100 years ago.
When airfields were still mostly fields and flat runways were nothing but a dream, taking off and touching down on a quiet, still water surface was preferable.
Thus cartography and surface operations favoured shifting from nautical to aeronautical work.
surely if you've been flying for decades you know that the 1:60 rule is the whole basis of a Knot? How could you *not*?
@@RadeticDaniel No - it's all about navigation. Either nautical or aeronautical. Early long distance aviation nav was done by stars exactly the same as on water, and because lat/long is bisected by NM, it makes sense to use kts. We use miles and km to measure distance on roads, and mph/kph for speed - would be a mouthful to say 'nautical miles per hour' for measuring aviation and maritime speed, so knots moved from the use of the common log into the calculated vernacular.
The system makes a lot more sense, if you remember that the big, hard, really vital question wasn't "Exactly how fast are we going?" but "Exactly where on the globe are we?"
7:20... It's not Imperial or Metric... it's Knot-ical. 😏😆
😂😂😂😂
As an aviation expert, my opinion is that knots is still the best method for long range navigation. It’s not nostalgia
- flight instructor, air traffic controller, aviation professor
That's nice sir
You might be right, but you fail to say _why_ you have that opinion. Without a stated reason, an opinion really doesn't matter much. We need to be able to estimate the validity of it. It could be that you are just used to it, but that is not a valid reason for an objectively best method. And being a flight instructor, air traffic controller, or aviation professor is certainly not enough to make your opinion matter without a reasoning.
So, _why_ do you have that opinion?
But why?
one of the reasons may be that it's a different speed.
km/h and mph are usually used as relative to the surface of the earth/land.
Knots (both in planes and ships) are actually measured relative to the medium (air/water), because that's what is interesting performance-wise.
So using this different unit also may help with the mental picture, that it's something else, not your conventional speed relative to the landmass.
@@skyhawk_4526 You are travelling over a large distance of unobstructed travel. You know where you are and that is measured/defined in two angles (N/S and E/W); you know where you want to end up and that location is also defined by the two angles.
Do you want to use an arbitrary length or do you want to use a length that is directly related to angles on the globe?
Then you realise that the distance isn't that important; it is far more important to know how long it is going to take.
The unit that ties a 'measurement system based on the globe' to time is 'nautical miles per hour' (= knots.)
Maps have these angles on them already and you can directly copy them with a compass to 'walk' the total distance. You don't need to calculate anything, just compare and count how many times something goes. Makes the life of a navigator much easier.
Does this makes sense?
"Knots made sense back in the day"?
It still makes sense!
Plus, the Nautical Mile is in this regard more logic then the statue mile.
(And, a NM is not just a arcminute, it's a arcminute on a greatcircle)
Fun fact: When the Brits and French were arguing over who got to be the prime meridian, the Brits ended up winning it in exchange for changing over to the Metric system (which they didn't for a long time and still haven't *fully* done)
Both Canada and Australia converted to metric currency to be compatible with metric USA.
Next question: wth is a stone? 😂
Meanwhile the US is happy to measure distances in football fields.
@@Vtarngpb Fourteen pounds.
@@Xero_Wolf and bananas. do not forget bananas. Oh and height by statue of liberty.
To Neil's point at 7:00: us metric people would just call it 2kmh and we'd be off by about 150m, or 0.1 mile. What's a tenth between friends?
I love how Tyson cracks up at "how do you divide a degree?" "One at a time" xD
😂
finally, a video right up my alley: its all about knots!! 😭🤣🤣🤣
If a bald eagle is flying 60 knots, how many units of freedom can be delivered in 1 hour?
What do you mean, African or European?
10 freedom fries?
@@MrDshack that sounds like metric to me.
How many AR15’s is the eagle holding with his bulging biceps?
1.88 gigiafreedom +\- with # of freedom squalls
This is the reason I watch StarTalk is Neil deGrasse Tyson teach us, thank you
As a metric person, I was always estimating with 1 kn ~ 2 km/h, which is just about 10% off - less the error than with 1 kn ~ 1 mph.
km/hr isn't metric. It's a customary derived measurement. The metric unit of velocity is m/s. Incidentally, 1kn is ~0.5m/s
@@meanmutton Yes, with an error of around 1%
@@meanmuttonIt is metric. It's part of the SI system, which is literally the modern form of the metric system.
Please longer conversations we need it
I'm all knotted up now 😂
This is a great channel to watch
I've learned a lot from this man.
Neil is a humble guy who sees things that others don't and he has a way of explaining complex scenarios in a simpler format for the human mind to grasp... Some of the thoughts that roll around in his mind are probably not as easy for some of us to understand. Through out his life he has focused on things that have interested him and intrigued him until his level of intelligence has become very impressive and gives off serene perceptiveness with reassuring understanding. Something that is very hard to come by today.
I would like to read some of his books. They're probably very interesting. Most of the things he talks about will definitely help your understanding of a lot of things and increase your common sense tenfold.
Sailors would tie a rope to a log known as a "chip log" or "common log" shaped like a pie and knots were tied in the rope spaced 14.4 meters apart. They would throw the log overboard, flip an hourglass calibrated for 1 minute, and would count how many knots passed through their hand. Thus giving them the speed of the vessel. That's where knots came from. We use knots because charts are in nautical miles and it's far easier to calculate 1:1 rather than having to convert everything.
Almost correct, except sailors wouldn't have used meters.
and also where the term 'log' or 'logbook' comes from, to refer to a series of records
Sounds like you may be studying some celestial navigation. I'm nearing the end of a course and its really interesting and engaging.
The modern international nautical mile has been set at exactly 1,852 meters (about 6,076.1 feet). In the UK, they commonly use a nautical mile equal to 6,080 feet.
This is therefore 2025 yards, not 2000 as was stated in an earlier comment which compared it to 1760 yards in a statue mile.
Chuck makes these so fun! Thanks guys!
Sorry, buy they look like a couple of caricatures from the 1940's "Song of the South" Disney movie.
I think that the reason knots and nautical miles are used in modern day navigation is because of the Mercator projection (which is very useful in navigation). When you have you basic distance unit same as arch minute of latitude, you have your scale always on the left side of the map and it changes depending on how far north or south is the area on the map. This makes it easy to measure distances on maps even if it's Mercator projection.
As a former navigator I can safely say that the Mercator projection is unbelievably awful for navigation. The distortion increases as you move North or South from the Equator. No navigator would ever use a Mercator projection to navigate across the ocean unless he was staying very close to the Equator at all times.
Once again superb
That was very interesting and really well presented 👍🏼
Many militaries, especially ones with long histories, love to hang on to outdated traditions BECAUSE it's tradition. My father flew an A-6 Intruder in the United States Marine Corps. Long after his retirement he would still used knots in place of miles an hour.
No it’s not an outdated tradition. Nautical charts and aviation charts are marked in Degrees Minutes and Seconds. It’s how you navigate. You take your divisors and measure your distance in minutes at the latitude lines at the edge of the charts and move the divisors along your position to the destination or where you came from to mark the distance. And you measure from the nearest degree down to the nearest second. Which is about 33.7 yards. So you are within 33. Yards on a sea chart of your actual position. Your second of measurement can be broken down into decimal places to an exact position. The GPS does the same thing.
@@Jerry10939 Right, it's not outdated because it's based in observable, measurable facts about our planet and spherical trigonometry. in that sense it shares more with the metric system than with many Imperial units.
That is the pre-1929 definition.
After the definition of the nautical mile in 1929, it is defined as 1 nautical mile per hour.
A nautical mile is defined as 1 arcminute of the circumference of Earth at the Equator.
This is so much more enjoyable when you know you do t have an exam about it on Friday.
8:44 no. 😂
How anout when old wooden ships through a log over the back of the ship. The log had a rope wraprd about it with knots every so many feet. The number of knotd that rooled off the log during a certain amount of time determined the speed in knots per hour,
That was always my understanding. If that is knot correct, where did...KNOT... come from as a unit.
Excellent explanation. Thanks
4:45 Someone in the animation department botched those latitude lines, looks like some flatearther snuck among you.
Those lines that are labeled "latitude"?
@@blindleader42 Yes, the latitude ones. Thanks to you, I've noticed that I wrote longitude instead of the correct word: latitude.
The international date line was between australia and New Zealand
Okay…so what’s an Astro-knot?
Guessing because it's astro- nauts, and naut means zero as in zero gravity?
@ so, maybe something like a lite-year?
@keithjohnsonYT That one I know, but I looked it up and astronaut means "star sailor". Guess the naut part is related to nautical.
I've been asking this question for yrs with not clear definition from anywhere. Gr8 show ❤
Aliens absolutely did not have to know French and English history to know Science and Navigations on earth use a longitudal/lat system. They could have observed my 6th grade science class. We certainly were not taught the history of it, only how it works.
or the aliens took a quick glance at the aerial charts onboard the TBMs they abducted. :)
I don't use knots, i use Dumplings. Far superior.
And tasty too!
That’s the best explanation. I’ve heard. All previous reading on this had to do with knots in a rope and letting the rope out and didn’t make much sense now. I understand that not is tied to an arc minute. Thanks.
Yeah, but the counting of the knots on the rope is why the unit for nautical miles per hour is called "knots".
Knots simply comes from sailing ships. They had ropes with knots on them and to see how fast they were sailing they toss it overboard and count how many knots pass through your hand in a minute. That would be your speed in knots. How far apart the knots were was possibly the degrees Tyson talks about, but he doesn't mention the rope at all. The rope is where the term comes from. I learned this in primary school as a precursor to algebra.
This is correct. There were no number systems like Metric or Imperial back then, so they tied knots at equal intervals on a rope to measure their ships or boats speed. The airline and marine industries still use this age old system.
I’ve known about Lat / Long since I was a kid but I always wanted to understand how the minutes and seconds worked. Thanks Neil & Chuck!
I love this explanation! Thanks guys!!
Thank you as always for the videos. There is a glaring omission in that a knot is one nautical mile per hour. Also it is not nostalgia or inertia that motivates their continued use (unlike the instance of the US to use imperial units). They are very practical to estimate how many degrees you will travel on a map when sailing or flying, and in the case of sailing, very easy to measure using a piece of wood and a rope with, suprise, knots.
Great explanation...👍
What a load on nonsense. These dudes are clueless about the history and use. I thought these people were "scientists"? What an embarrassment.
This was a really worth subject. Mouth watering. This is what America does with its intellect
Cool Best explanation I ever heard.
We still use knots as pilots. 5280 feet per statute mile and 6076 feet per nautical mile. Simply put for this video, Latitude is a measure of distance, longitude is a measure of time. Every degree is 4 minutes. So if you use a sun dial during the day and mark the zulu time your position is at noon (shadow lowest on the dial) you can then calculate your longitude.
If it is noon where you are and 628 pm zulu (1828Z) your longitude is the number of minutes divided by 4. Since there are 15 degrees an hour you got 6 hours so 90 plus 28\4 is 7 you are at 98degreed west. As an example
I would love to be there, sitting and listening in awe all day. My mouth wide open 😮. You are the best!
Great, as always. Thanks!
I did Sonar with the US Navy. "Sonar" is an acronym for "sounding navigation and ranging." Here's a fun fact: The kilometer was made at the Equator to the north pole, Dividing 10 over and over until you get to a Kilometer. Keep Dividing until you get meters. The Equator is larger than the pole-to-pole used in making a Knot, so the Math is still accessible: 50 Knots=100 Kilometers=80 miles, or your 60 knots = 120 kilometers = 75 miles. This is rough math, but true, very close to accurate. The knot (/nɒt/) is a unit of speed equal to one nautical mile per hour, exactly 1.852 km/h (approximately 1.151 mph or 0.514 m/s). The ISO standard symbol for the knot is kn.
You two gentlemen, are a hoot! Thank you for making my day!
I was never even taught that in the Navy. 🤯
you guys are awesome, very intuitive, and still funny
Thank you again for the education.
Ty guy's
Learning something new every day is a blessed 🙏 day
TY
I truly enjoy a mind filled with so much knowledge that can laugh. And give information with such fun. I’m impressed.
You guys are awesome!
Guys, you're genius.
Thanks for this amusng cerebral message.
Regards from Córdoba, Veracruz, México.
Just got my autographed copy of NDT’s book. I’m so excited to read it.
6:14 despite what you've been told (fellow commenters) this is why the Mercator projection was made and so prevalent. Because they stretched the north and south so much so that it was easier to plot courses and such.
I'm a bit confused (not that unusual). I always thought that the Greenwich Meridia went through Spain as well. In fact I'm sure I saw it marked when I visited the Coata Brava (near Barcelona?). But your globe / map at 1:44 shows that it misses Spain by miles.
Don't understand why people go after Nile !! He makes trivia so interesting and important. I love the show and enjoy every bit of Chuck Nice's comedy!
Thanks Tyson sir, I learned it and will never forget it
I want to live on a sailboat someday, so I know plenty about boats. I knew about the origin of the term knots and that eventually it came to mean nautical miles per hour, but I had no idea that a nautical mile was also an arcminute. Thanks for teaching me something. :)
Because it still works.
Great system when using a map with Lat/Long graticule.
One use springs to mind back when I was an airline pilot on a long haul flight: A passenger requested the time of sunrise - for his morning prayers. It gave us something [extra] to do in the middle of the night, taking into consideration the changing Lat/Long navigation, planned speeds IN KNOTS, Earth rotation rate, Sun seasonal declination and Solar altitude angle. Easy for Mr deGrasse I'm sure, but got our tired old heads churning old Trig and Calculus. We nailed though, probably with a big helping of luck!