How to use a Slide Rule Bezel on your Watch. Watch and Learn #11
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- เผยแพร่เมื่อ 9 ก.พ. 2025
- In today's episode of Watch and Learn, we show you how to use the rotary slide rule on a watch. Often referred to as an aviation slide rule, this indispensable tool is the pre-cursor to modern calculators. From dividing up a dinner tab among friends, then adding a tip, to calculating fuel consumption on a weekend flight, these little machines can do it all.
The rotary version of the slide rule uses the same principles of the linear slide rule that some engineers still use today. Employing the Logarithm function, they make easy addition out of complex multiplication problems. With just a little know-how, and a few minutes watching this video, you will find out how to unlock the potential of this awesome tool strapped to your wrist, like converting kilograms to pounds, miles to kilometers, etc.
This video uses the Seiko Flightmaster SNA411P watch, but the principles apply to any slide rule watch, from the Breitling Navitimer to the Citizen Blue Angel watch.
To see some of the watches we offer with the rotary slide rule, please visit: longislandwatc...
I can honestly say that your decision to make informational videos has been one of the greatest contributions in recent times to horology from a non-manufacturer that I can recall. Seriously, keep this coming. Even if it is information I already feel I am familiar with, I still watch to possibly learn more. All the best, Mike
Thank you for watching along. I do enjoy making them, though they are a time cruncher. Glad they are serving a good purpose.
I swear I am about to trash all my my watches and starting new .. that’s crazy how I didn’t nothing about watches til last weekend
Alarm please how does it work it's been 7 years and haven't heard a beep from it 😔
Seiko should thank you for this video.
Unless Seiko has hosted paid tutorial(s) for using such bezel lol
The slide rule is an awesome tool. I learned how to use the slide rule in flight school. Bought a Citizen Nighthawk and used it all the time. While in sales, I would use it on the fly when figuring rough numbers quickly for the customer. Customers would ask when seeing me slide bezel and I would explain what it was and how I was using it. I'm sure it helped me in closing a few sales. Its still practical for everyday use. Multiplication and division, time and distance, miles per gallon, fuel flow, average speed, time to destination, miles to kilometers, distance to empty, and other handy calculations. Very cool, handy and practical tool.
If you're interested in the slide rule, you can order the E6B slide rule from any pilot shop or even Amazon. They come with a lil book for using it and it will help you learn it inside out and practice on a larger model.
For the private pilot license they expect you to do a divertion with one slide rule calculator or E6B how we call it and execute the diversion in around 2 minutes. You have to find approx. Distance to the alternate airport then calculate with this rule the time it will take with your ground speed, the amount of fuel you will burn and how much you will have when you arrive. All without losing your altitude or heading without autopilot. This slide rules are very useful.
Thanks for sharing.
I have my private pilot license with 250+ hrs. In the cockpit of small piston-powered aircraft, it's next to impossible to use a slide rule this small on your wrist. The normal E6B most of us use is around 115mm in diameter and it's still a challenge to use with engine vibrations and anything other than smooth air. If you want a useful pilot watch, buy a Casio G-Shock with dual-time (UTC) and use a normal-size E6B. Better yet, get a tablet and enjoy all the benefits.
@@markthibault8579 Yeah. I've written about this on another channel but nobody should have the idea that this watch is useful for a pilot flying. Even traditional pilot's watches with large, highly legible, and simple dials are no longer very useful on most aircraft except as a pretty crappy backup to the much more ergonomic clocks and timers on the panel and EFB. Which paradoxically is exactly the reason why I think this is an excellent pilot's watch. If a wristwatch is going to be almost useless to the pilot flying no matter what, we may as well forget about legibility and just make it into the mother of all backups, and as useful as possible for the pilot when they're not flying. This thing backs up three instruments/functions on the panel, plus a bag item: local time, zulu time, chronograph, and E6B. It's convenient enough to use for flight planning calculations. And of course once you put it on in the morning, you're pretty unlikely to forget it somewhere or leave it out of reach of the cockpit!
The watches only have two scales, the standard multiply and divide scales, and they're tiny. A real aviation slide rule has extra scales for time distance and a back for wind effects.
As a CFII, I prefer a divers watch with the minute bezel. I use that all the time. I agree that the E6B on a watch is not practicable in a single pilot situation.
The overall most simple and useful Watch I’ve had, is the old Casio amw360. UniDirectional bezel, dual time (for Zulu time) and a timer.
That’s really all you need in a watch for a pilot.
A watch slide rule will not do wind calculations, so it’s not going to suffice for a diversion anyway.
That said, I do like the Flighty and really want one, just because it’s a beautiful watch.
Practically speaking, a Vostok will be my next mainstay as it’s built like a tank and does what I really need in a simple to read manner.
iPad has replaced paper charts, and does all the complex functions one could need.
A thousand videos on slide rule watches and only Mark tackles actually using one. Thumbs up.
7:23 Face description and markings
11:33 Multiplication
13:53 Division
16:13 Unit conversions:
16:30 mi (NAUT)/mi (STAT)
17:20 Km/mi
18:49 ft/mi
20:12 Kg/lbs
Need to add, speed, dist, time.....fuel burn....endurance.
I study physics and mathemarics, slide rules have always fascinated me. Mathematically, they are an excellent way to think about linear transformations, everything scales uniformly.
Pilots do not likely use watch slide rules in the air, even in smaller aircraft, pilots usually carry a number of slide ruleesque instruments for particular parts of their flight (like crab angles to adjust for wind, fuel burn, and so forth). But they do offer pilots a backup and are excellent survival tools. Let's say you go down and lose all your special tools. You remember your airspeed as you came down in the wilderness and the indicated heading on your compass, you can use some trig and math (slide rule is excellent to assist in that) to determine an approximate grid location. Also, using a watch, you can identify north by the time and sun location. The compass headings on the dial help you adjust the position of north every 30mins or so and give you an accurate indication of your direction simply by reorienting your dial to to maintain true north indication while you turn your body. A few key pieces of information (wind direction, indicated airspeed, and time from last known position) can easily allow a pilot to know how far he is away from his/her last known position. If the pilot can make it back to that position, the likelihood of rescue increases, as search zones are based off of that last known radar position.
Military pilots would likely find much more utility from the watch in survival situations, as they can use it to identify direction and distance to friendly territory is downed behind enemy lines. Rationing water and supplies based on distance and progress also can help increase survival. I'm not sure if these dial slide rules do trig, but if they do, some fixed reference can give the pilot an accurate approximation of ground speed by comparing the ground distance from cos at two stopping points by dividing the distance by the elapsed time. If we ever have a nuclear war, a slide rule that sits on your hand, even if the chronograph no longer works, is an invaluable tool which most people would be without if their phones and calculators were fried by emp.
They are awesome tools. And yes they are difficult to use in a small bumpy plane bouncing around on thermals haha. But I have used my watch E6B for many everyday calculations. Awesome tool.
This is the best slide rule instruction I can find in TH-cam. I am a happy owner of Navitimer now. Thank you.
I'm a professional pilot and I have 8 slide rule watches. I never use them for any practical purpose, but I do love the aesthetics of the functional instrument. Great video.
I'm a glider pilot old enough to have learned navigation before the GPS era. But after many years I had forgotten how to use a slide rule, thanks!
I remember using a slide rule in school and college in some advanced classes, and now I don't remember anything. I have a Nighthawk, I tried to use it to no avail. But as soon as I finished watching your video I was automatically able to use it again, thank you so much for the video, I love the entire series so much, keep it coming. Cheers.
Hey Mark, thanks you for putting together this series of videos, I have learned a lot thanks to you, and since you asked for a pilot's perspective, I thought I'd add my 2 cents to repay you for your excellent effort. Having been a pilot for the past 35 years (civilian, military, and airlines) as well as having been formally trained as a navigator in the Air Force, I used to live by, and get tested on slide rule computers, but the ones we used were of the CR-5 and E6B variety, and of course much bigger in size. Although I love slide rules (they are almost magical), I always felt that these type of watches were more of a gimmick than anything really useful, because they forced the movement of the watch to be much smaller (ergo less readable) than it could have been, while still having a nearly unreadable slide rule section (at least to an older pilot's eyes). I remember back in the '80s when some of my colleagues purchased expensive slide rule Brietling as reward for finishing the Air Force Academy and heading off to pilot school, I always thought that was more of a status symbol statement than anything useful a pilot could actually make use of. Of course individual preference is what counts on this subject, and personally I'd much rather have a Laco 45mm pilot watch with a sterile B face than a small movement watch crowded with useless features. When I fly I want a watch that "talks to me" (if this makes any sense), and not one I have to spend any amount of time trying to read. As a matter of fact, all the Navigators I knew would used cheap LCD watches rather than anything with dials because they were quick and fool proof to read. Once back on terra firma I'd switch back into a diver's watch, or something else with dials, because I liked the look, and didn't care if it took slightly longer to read. Great job as always Mark.
Thanks for the awesome feedback!
You are most welcome Mark, and I just subscribed to your channel. Ciao, Marco.
This happens to me with sailing watches. Most are unusable, if you want to take times in a regatta better use a stopwatch, a tactical watch or a full sized gps.
Quite educative. Thanks all!
I regret watching this video. I went into this video not liking the Seiko Flightmaster; after watching, I love the slide rule bezel and want a Seiko Flightmaster. In all seriousness, great video!
Your the best intellectual/layman's discussion out here on any of this!!!
Great character and an even better job explained
I have now used my slide rule bezel correctly for the first time. Thank you! This is the easiest to understand instructional I've come across on the subject in any medium.
Thank you!
As a former mechanical engineering student, I find this video, and owning a Nighthawk very entertaining and interesting. Especially when hanging out with engineers.
Super cool! Thank you for this very clear explanation of the slide rule. I had no idea what one was, and am happy to know what it is for. Just excellent!
Thanks for taking the time to watch
I just started to think about adding a Flightmaster to my collection last night, and you upload a video today explaining it lol
The time is now then, isn't it? : )
Long Island Watch Indeed. I just can't choose between this version, which is obviously more rugged, and the SNAB71 white dial version, which is much more relaxed and elegant.
I still have two of my slide rules... This brought back Memories. Hewlett-Packard and Texas Instruments with their Scientific Calculators Amadeus Slide Rules almost Obsolete.
However, we were taught to keep them our slide rules around in case of Power failure, batteries ran down, etc. On my Iphone I have An AP that does conversions but it is still fun to see if I can do calculations with my slide rules. Also, using the slide rule bezels on several of my watches. I love technology and love to fly. If I had Catastrophic failure of all instruments on my plane I could possibly Navigate, and calculate with this Watch Bezel. If Flying in Turbulence - would be nearly impossible to use this but I would try! Thank You so much for your instructional Videos. I have this watch and several others in my collection with this type Bezel and enjoy them!
I don't skip the TH-cam commercials that play in order to support your channel.
Keep up the good work.
alex delgado Thank you!
Superb Marc ! Now I can finally use the simple slide rule of the Orient Multi Calendar.
Great, enjoy!
This guy does the BEST watch reviews without doubt.
love the video very informative....... its like being back in school............... thank you sir.....!
Just picked up a Flighty and was interested to learn more about the bezel and dial markings before the watch arrives. This was absolutely great Marc. All the Log scale explanation took me back a few years, but the practical demonstration with the watch was superb. I can’t wait to get the watch now.
Wow! i had no idea there was a watch made to do math/ slide rule. thank you for posting this. Really appreciate it.
Just got this watch a week ago - I'm still to figure out but this made some things a little clearer. Thank you!
This is a truly great video. It may be hard to believe, but even at my age I have never used a slide rule and I am not even sure I have seen one in person. You explain it so well in this video. Because of this I went from knowing nothing about slide rules to understanding the basics in just this one video and I really like how this watch has the different unit conversions too. Thank you very much for making this video and this whole series. You are a major asset to the watch community. Have a great day and cheers.
I always wondered how to use a watch like that and you have answered it. Thank you for the tutorial it was very helpful and now you even make me like math more.
Great, thank you!
I have never 'ever' binged this much of videos on TH-cam, Good stuff Marc
I am not a numberphile by any means but I am a watch guy. Once asked a sales lady at a jewelry store how to use the slide rule function. She had no clue. LOL. Loved this tutorial.
That was fantastic. Thank you for going over this. I always thought these dials were too busy, but now I want one!
Thanks.
I would have never known this scale does all of this and more, and now I feel I can understand it. Thank you!!!
This by far one of coolest watch videos you've made!
This is as close to being called my favorite watch as any of my watches can be called my favorite lol , not many people really care about the functionality of this bezel we all just think this watch looks awesome lol you are just showing off a engineering degree ( a LOT of hard work) I get it mark your highly intelligent! You’re such a good dude man , thanks for an awesome educational video!!
Great, half an hour ago I placed an order for a chrono with tachymeter and now I want one with a sliderule! Why, thank you, Marc!
Mark, great video. I own the Flightmaster and have read the manual but your video helped me to understand logs and conversions more deeply. Keep up the great work and thanks!
Mike Mantho Great, thank you!
Easy to understand, incredibly informative and very, very cool! Thank you!
Glad you enjoyed, and understood.
It's at least the second time I watch this video. The first time it was for pleasure, now it is because I finally got this watch. Thanks, Mark, and I say it again: you do the best tech videos of the watch youtube world.
Very informative. Now I can show off my flight master like a pro
Hi Marc - great video! Subscribed! I have a SNA411 and am looking forward to putting this info into practice! Longislandwatch is a great store, have bought from you several times. Keep up the good work! All the best, Rob
Thanks!
My granddad always used a slide rule, and taught me how to use it. Great video!
Oh my God. This is one of the best watches in the world. Everyone should have one. I'm glad I just ordered mine. Thanks for the amazing information, Mark.
Excellent. Thank you very much for doing this watch and learn. You got me using my bezel slide rule! So far you showed me how to change straps adjust bracelets etc etc.
Thank You. This takes me back (oh, I don't have my slide rule) to 1963 high school. This will be a very useful tool as long as my eyes hold out. Ordered SNA414P1 today and may get one for my nephew who is a pilot. Shopping for a leather strap (21mm odd size) probably a 22mm Hirsch brown buffalo trimmed to fit. The Seiko looks like an incredible instrument. Very useful as well.
Thank you for the incredibly instructive video. I would have never truly read through the book you showed in the video. I learned a lot and saved it to my favorites.
Thanks so much.
I haven’t used a slide rule in a long time! Your instructions were fantastic and easy to understand! I still have my slide rule I used and Thank God for Texas Instruments and Hewlett-Packard Calculators making calculations so much quicker and accurate! Thanks o much!
Just bought the flightmaster - thanks for the tutorial of how I can use it to it's fullest potential! :D
I have the Flightmaster! This video was easily the most helpful I've seen, by far!!!
Great to hear! I appreciate that.
Amazing, Marc. Congrats from Brazil.
Thanks for watching!
I'm literally amazed at how useful this thing is, tbh this could be used for exams. I'm not sure if people are going to realize this can do math 😂
No cheating ... Lol
Not really, most serious tests require precise calculations, this watch and slide rule in general can only give you "rough" approximate results. This is only useful in real life, not for test.
I cheated my way through high school math using a cheap Casio pilots watch. Teachers had no idea what it was. they would just see me staring at my watch. lol. This was back in the 90's. I wonder if they have a better idea of it these days. (Probably not; as most kids these days don;t even use a watch anymore)
@@nightwinddemon True, they're not super precise, but get you close enough, to figure out the rest in your head.
Thanks for this video! I just placed an order on your website for this exact watch! I found you via The Urban Gentry channel as you were highly suggested. Thanks again!
Hi Mark, what you have is an aviation circular slide rule called an E6B. These were what every pilot used until recently for navigation problems. That’s why the two big indexes are at 60. I have several of these in drawers but don’t use them because there’s an iPhone app that does all those calculations. Today even little airplanes have Flight Management Systems that makes navigation easy without any thinking required. Thanks for the memories.
Excellent job with these Ed videos. Thank you.
You're a very good teach Marc! Thanks for taking the time to make these informational videos, they're really awesome and I always learn a lot.
Thank you.
This presentation is useful and that's what a watch must do.
That's not what a watch must do. A watch must show the time and be precise. Everything else are useful features.
By far the best description video I've seen on this flight watch. I have a Navihawk AT and if I could see the bezel I could do these calcs because you've done a great job!
Thanks!
This is really fascinating stuff. Your Watch and Learn series is a gold mine of knowledge!
Thanks for patiently explaining how the slide rule works.
Hope you got something out of it.
Most definitely. I also wanted to let you know that I was considering buying one of your watches with a slide rule (Seiko Flightmaster), but then decided to give Invicta a chance and ordered one from them. I just got intrigued by a controversial nature of their brand and thought I should experience it for myself. Will see how it goes and when I receive it, I intend to publish an unbiased review here on my channel.
Thank you for making this. I love my Flighty and I have every intention to learn how to use some of the features but I don’t have a science background at all. This is a great introduction!
Can’t wait to get mine in the mail. On point lesson my dude. Traded my Apple Watch series 4 for this and I’m super happy!
Thanks for this video. It is verry helpful :) I've got CASSIO WR 50 M with logarythmic bezel. I bought it, so now I can learn to count PROPERLY, and train my mind.
The best watch and learn yet!
I appreciate that! Took a while to do.
Great tutorial!! It just so happens that I'll be getting that very watch soon. Loved them ever since I was a kid.
Thanks for this. Got a seiko with slide rule and have no clue how to use it which kinda is embarrassing to rock it without a clue how to use it aside from the clock lol. Amazing stuff man. Binge watching your watch and learn videos. cheers
Fascinating. I failed math at school, but even I could understand most of this. Thank you so much, for a great video.
Mark,
This 'slide rule' is a version of the E6B flight computer used by pilots for ages (and it's still mandatory learning for the FAA private pilot exam). The real difference from the old school slide rule is apparent if you look at the 60 MPH index marker. Pilots read speed in miles per hour and fuel consumption in lbs or gallons per hour. The issue is that when we deal with time intervals of just a few hours or less than an hour, it's much easier to use minutes rather than hours for time. By using the index at 60 rather than 10, the computer is actually converting the hours into minutes by just multiplying by 60! You can also see on the inter chapter ring under the 90 for instance, 1:30 which further converts minutes into hours and minutes which is much more intuitive when you are trying to navigate and fly at the same time. Much easer than working with decimal fractions of hours and having to know that .3 hours is twenty minutes. (Working on my private pilots license down the road from you at Republic Airport as we speak, btw)
Excellent presentation. Very informative.
Great video. I learnt how to use a slide rule at school and still own one. I never really had to use one as calculators came out and now you can do everything on your phone so I had forgotten how easy they are to use. I will practice on my watch now.
Your videos are amazing ... I would not consider a watch like this .... Until now. Very informative. Thank you very much.
Excellent video! I may have to look for a sliderule bezel watch now.
Great!!!
I just got this watch several weeks ago and this was very helpful!
Great! Now you can unlock the potential.
I've got two of these, the first one I left near the tv set for a long period and the magnetic field from it damaged the quartz movement needless to say I've taken better care of the second one it's a really cool looking watch.
Actually, Canadians would find a LOT of use to convert between Imperial gallons and US gallons. All cars in Canada are usually listed in both L/100km and mpg, but if you're car shopping in the US, or reading the fuel efficiency of a car on a US website, the mpg is always lower as there's 4.54 L vs 3.79 L in Imperial and US gallons respectively. Living close to the US border ( as most Canadians do ) we're always converting back and forth and we've internalized most of the conversions. Without looking them up I can tell you 1lb = 454g or 1kg = 2.2 lbs. 1 gallon = 4.54 L, 1 US gallon = 3.79. There are 20 fl oz in a pint of beer ( the fl. oz are slightly different as well). 1 tsp = 5mL, 1 cup = 250 mL, 1L ~= 1 pint. 1 mi = 1.61 km. 1' = 30cm, 1" = 2.54 cm. An 8' 2x4 is just under 2.5m etc.
Thank You so much for the review. I actually have my very old slide rule that I used in college. My first Calculator was a Hewlett-Packard Then Texas Instruments came out with a more “user friendly” Scientific Calculator. Along came Casio with a more affordable calculator. I loved the Navitimer Breitling and have always wanted one. I loved the idea of having a calculator on my arm. With Computers we came a long ways and plugged in numbers to formulas and so much easier to let the computer do the work. I’m going to download the Seiko Manual just to see if I can retain the ability to use this on a time piece in case of instrument failure or “blackout!” Thanks so much for your review!
I sat through the whole video and understood most of it. Enjoyed very much.
Would I purchase one? No, but still enjoyed it. I like your blue dial watch video.
I sat through some of it and understood NONE of it. Simply put....I suck a maths. Always have, and 44 years later it looks like I always will. This video was well above higher grade for me.
Mark, this is a great video of how to use this type of watch. I have one.
I'm currently studying to refresh my math skills. I got stumped on logarithms (for the millionth time). That led me to learning about slide rules, and that led me to your channel. Very cool stuff and it is very helpful.
So often with math it helps to view the problem from a different angle. So I guess what I'm saying is that I will be forcing my children to learn math with a slide rule...
Great explanation Mark - made sense even to me!!
I think you're in the minority.
Came in to buy a watch, walked out as a mathematician. Time well spent indeed.
Thank you for this easy to understand guide
Thank you Marc for this most interesting video, really enjoyed how to understand how these work. I really find these watch and learn videos of yours enjoyable and I am learning a lot from them, keep up the good work and will look forward to more.
Thanks!
Oh boy...that's my day taken up :) very helpful thanks
Wow I have been wandering all my life figuring out tachymeters and finally got here! Thanks!!! Im 48 Y/O my first tachymeter aviation watch was a cheap Lorus from the 80s i was 18 never understood how it works but it looked good!! Hehehe
Awesome video. Now i can geek out with my flight master. thanks for making it
That's what its all about. . . geeking out! Have fun!
Very well and nicely explained! Enjoyed it , I will buy it .Thank you very much .
Hah! All of a sudden (now) I want a slide rule watch.... very interesting 🤔 Thx
One day I am going to be smart enough to understand this! My Math teacher growing up would be mad that Watches finally got me interested in Math! I wear my Orient explorer enough that I should learn it lol. Great video man!
LOL! Thanks!
You seem to really love your YachtMaster, as I have seen it in several of your (excellent) videos. Cool !
these informational videos are great; now I want one of these Seikos!
that's the idea, isn't it? : )
Thanks for explaining logarithms!
What? Just kidding lol, you did a fantastic job conveying the functions.
Mind blown!
Great video though and thanks for uploading.. though i'm sure I may need to watch this a few times to get it! :)
Haha, thank you!
Excellent, Marc! I am a new ‘Flighty’ owner and love this piece. Your tutorial is very informative. Much appreciated.👍😃
Great series! How about anti reflective coating/Crystal type pro and con, watch size choice for wrist size
Great ideas, thanks!
Thank you so much for your effort. Really appreciated, from Australia.
I used a slide rule in college before the first scientific calcualtors came out mostly from H-P and Texas Instruments. Nice to learn the old school method. I heard that the U.S. Naval Academy are now teaching midshipmen to start learning how to use the sextant before depending on high tech GPS.
A very important point. When all else fails, we still have the stars and chronometer to navigate by!
The military always teaches dead reckoning and how to do things without modern computers and technology. Atleast that’s what I thought
Thank you for this Mark! Just bought a SRPB61K1. hope you can review one soon.
If I can get my hands on one.
Great video, the watch is inspired by the flight computer I think, and it is used primarily for pre-flight planning. Flying in visual flight rules you are not needed to file a flight plan so you can basically jump in a plane and plan your route 10-30 (maybe somewhere 60) minutes before flight. Assuming it is a non-controlled airspace you are flying in. Love this watch, going to get me one just because of your informational video. thanks!
Thanks. I learned alot today from your video. Thanks for sharing and teaching this info. God bless my friend
Thanks, it was really helpful 👍🏻great work, keep it up
shame on you...now I have to buy another watch. I haven't used a slide rule in 35 years but now I gots to have one :)
LOL
And me .
I bought one today
@@joachimrydelius2125 Me too i love this watch!@!