# What the hell is a tachymeter? And why did I wait this long to ask?
**URL:** https://boards.straightdope.com/t/what-the-hell-is-a-tachymeter-and-why-did-i-wait-this-long-to-ask/345891
**Category:** Factual Questions
**Created:** [February 24, 2006, 4:59am UTC](https://boards.straightdope.com/t/what-the-hell-is-a-tachymeter-and-why-did-i-wait-this-long-to-ask/345891 "2006-02-24T04:59:07Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@duffer](https://boards.straightdope.com/u/duffer)
#### Post date: [February 24, 2006, 4:59am UTC](https://boards.straightdope.com/t/what-the-hell-is-a-tachymeter-and-why-did-i-wait-this-long-to-ask/345891/1 "2006-02-24T04:59:07Z")
I’ve had this watch for over 3 years now. It’s a very nice stainless steel analog, water-resistant watch with date, chronograph, and a mess of dials. Polished bevel and numbers inlaid in the face. It’s rugged, it’s handsome, it’s heavy, and I get compliments often on it.
I love it, and it’s starting to piss me off.
Inside the “face area” (or whatever the hell it’s called) is the word “tachymeter” at the one o’clock position followed by numbers that seem both logical and completely illogical at the same time surrounding the entire dial.
I won’t bother detailing it, as those who know what it is and what it’s used for will know what I’m talking about. I’ve seen it presented exactly the same way on many brands from Timex to Bulova.
I always thought it was some sort of tool for divers, but have never been sure. The bevel itself has 01 - 12 marked at the hour positions of the dial and turns, but only counter-clockwise. It can’t be turned clockwise, making my curiosity even more pressing.
Do the two somehow work together? If so, how?
If not, just tell me what the hell the tachymeter is for other than driving me batshit insane in wonderment.
Please help. I’m about 2 months away from crawling in the closet with clinical insanity singing odes to my watch praying it will speak to me and reveal its dark secret. ☹
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### Author:  [@treis](https://boards.straightdope.com/u/treis)
#### Post date: [February 24, 2006, 5:06am UTC](https://boards.straightdope.com/t/what-the-hell-is-a-tachymeter-and-why-did-i-wait-this-long-to-ask/345891/2 "2006-02-24T05:06:23Z")
[http://en.wikipedia.org/wiki/Tachymeter](http://en.wikipedia.org/wiki/Tachymeter)
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### Author:  [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)
#### Post date: [February 24, 2006, 5:07am UTC](https://boards.straightdope.com/t/what-the-hell-is-a-tachymeter-and-why-did-i-wait-this-long-to-ask/345891/3 "2006-02-24T05:07:10Z")
[url-[http://en.wikipedia.org/wiki/Tachymeter](http://en.wikipedia.org/wiki/Tachymeter)]Tachymeter. No, it doesn’t measure tackiness. 😉
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### Author:  [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)
#### Post date: [February 24, 2006, 5:08am UTC](https://boards.straightdope.com/t/what-the-hell-is-a-tachymeter-and-why-did-i-wait-this-long-to-ask/345891/4 "2006-02-24T05:08:26Z")
Damn you and your fancy-schmancy coding skills!
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### Author:  [@duffer](https://boards.straightdope.com/u/duffer)
#### Post date: [February 24, 2006, 6:09am UTC](https://boards.straightdope.com/t/what-the-hell-is-a-tachymeter-and-why-did-i-wait-this-long-to-ask/345891/5 "2006-02-24T06:09:57Z")
Looking at it as a way to measure speed in MPH, it makes much more sense now. At least now I don’t need to worry about tickets while driving on a highway in a car without a speedometer. Such a useful feature. (How did I not just trust my instinct that it was superfluous and basically a decoration?)
This is so disappointing. Here I thought I had a tool that would help in my quest of world domination where the lap dances were free and the beer never had a price. Oh well, another dream torn asunder.
BTW, there is no limit to my tackiness. It cannot be measured by your substandard scientific instruments. After all, you mortals still use these worthless “tachymeters” in this day and age. 😛
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### Author:  [@Rick](https://boards.straightdope.com/u/Rick)
#### Post date: [February 24, 2006, 6:47am UTC](https://boards.straightdope.com/t/what-the-hell-is-a-tachymeter-and-why-did-i-wait-this-long-to-ask/345891/6 "2006-02-24T06:47:03Z")
> [@duffer](#):
>
> I always thought it was some sort of tool for divers, but have never been sure. The bevel itself has 01 - 12 marked at the hour positions of the dial and turns, but only counter-clockwise. It can’t be turned clockwise, making my curiosity even more pressing.
The CCW rotating bezel is for scuba divers, and other to measure elapased time. Let’ say you enter the water at :45 after the hour (the minute hand is at the 9 O’clock position) You rotate the bezel around until the start (12) position is adjacent to the minute hand. As the dive progresses you can keep track of your elapsed by refering to the bezel. Should the bezel move, it will make you think that you have been down longer than you actually have. If the bezel were to be able to rotate clockwise it could make you think that you had extra bottom time available. This could be deadly, and is considered a bad thing.
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### Author:  [@duffer](https://boards.straightdope.com/u/duffer)
#### Post date: [February 24, 2006, 6:54am UTC](https://boards.straightdope.com/t/what-the-hell-is-a-tachymeter-and-why-did-i-wait-this-long-to-ask/345891/7 "2006-02-24T06:54:14Z")
Good God. The answer was that simple. See, I guess I just melded the tachymeter and the bezel deal into the same thing. That’s what you get when you don’t know what either is for. :smack:
Give me credit, though. At least I knew diving was _somehow_ involved.
Thanks for the info. 🙂
Maybe now I can measure how fast I have to drive to [sings]Take My Breath Away[/sings]
😃
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### Author:  [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)
#### Post date: [February 24, 2006, 7:25am UTC](https://boards.straightdope.com/t/what-the-hell-is-a-tachymeter-and-why-did-i-wait-this-long-to-ask/345891/8 "2006-02-24T07:25:47Z")
Dang…I first read it as a Tachyonmeter. I thought this was going to be some cool info on measuring faster than light particles.
Never mind me…carry on.
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### Author:  [@duffer](https://boards.straightdope.com/u/duffer)
#### Post date: [February 24, 2006, 7:31am UTC](https://boards.straightdope.com/t/what-the-hell-is-a-tachymeter-and-why-did-i-wait-this-long-to-ask/345891/9 "2006-02-24T07:31:55Z")
> [@Whack-a-Mole](#):
>
> Dang…I first read it as a Tachyonmeter. I thought this was going to be some cool info on measuring faster than light particles.
>
> Never mind me…carry on.
I’m making GQ posts about using Photoshop for Og’s sake. Do learn to keep up with my ignorance. 😛