If I didn’t know any better, I’d say a tachymeter was a type of dinosaur. I know this completely disregards the suffix “meter,” but it does sound a little like “pterodactyl,” and for many of us, the purpose of a tachymeter can be as mysterious as those prehistoric creatures.
In this article, I’m going to unveil some tachymeterical mysteries to you.
- It’s not a dinosaur, so really, what is it?
- How do I use it?
- Is it actually useful or just for looks?
At the most basic level, a tachymeter, or tachymeter scale, measures speed. On an analog chronograph (i.e. watch with both timekeeping and stopwatch ability), the tachymeter scale is inscribed along the rim of the watch.
But don’t confuse the tachymeter with the rotating bezel. The rotating bezel is simply a timer labeled in increments 0-60, but the tachymeter is generally labeled in increments from 60 to 400 or 500.
More specifically, a tachymeter can measure speed based on travel time or distance based on speed. It doesn’t matter what unit of distance you use (e.g. miles, kilometers) as long as you maintain the same unit of distance throughout your calculations.
The tachymeter can also be used to measure industrial productivity by converting elapsed time in seconds per unit into units per hour.
You can check out one of Orient’s Automatic Racing collections to see some classy tachymeters at their finest.
However, if you don’t think you’ll ever have the need or desire to calculate the MPH of a race car or how many bolts a machine can churn out in an hour, you can also use a tachymeter to calculate pulse or your car speed if your speedometer’s fried.
That’s the easy part, now here’s where the ‘tachy’ can get a little fuzzy.
The tachymeter can measure either speed or distance based on this formula:
To measure the speed your car is traveling, follow these steps:
- Start your chronograph at a starting marker of a known distance (e.g. mile marker on a highway)
- Stop your chronograph at the next mile marker
- Look to see where your watch’s sweep second hand points
We’ll say the hand is pointing to 11 o’clock, so 55 seconds have passed since starting. The number on the tachymeter bezel adjacent to 11 o’clock is 65. Your car is traveling at an average of 65 MPH (or whatever unit of distance you choose).
You can use this process to calculate the speed of anything traveling faster than 60 units per hour. Measuring slower speeds will require a little mental math, but it can be done by decreasing the unit of measurement.
To measure the distance your car is going, follow these steps:
- Maintain a consistent speed
- Rotate the tachymeter bezel to align with the second sweep hand at the start of the distance to be measured
- Watch the sweep second hand; once it reaches the number equal to the speed your car is going, you’ve traveled 1 unit (e.g. mile, kilometer)
If you’re into gadget-y watches, then a tachymeter is like the icing on your watch cake. It looks pretty cool and confusing enough for people to wonder what it is/assume you’re some sort of speed racer.
Of course, these days, it’s rare you’ll be driving a car without a speedometer or hanging out at a NASCAR race timing cars for fun.
But who knows? As someone’s mom might say, life is full of surprises. And in that case, if you think it’s useful or not, a tachymeter-equipped watch has its place.
And whether your watch has the feature or not, the worst thing you can do is not learn how to use it. But, lucky for you, you just did.
Know of a cool way to use a tachymeter? Comment below.
- Apr 19, 2010: CVZ00002J: A Watch as Tough as You - Reviews & information on Watches - Watches Channel