What exactly can this watch do?

May 18, 2006 1:34 AM

I recently received this cool watch as a gift. What I want to do is figure out how to do all the nifty functions, namely the bezel and all numbers running along the rim(s). It's a (partial) calculator I know, and has techy-sounding words like "STAT" and "NAUT" and "Flight Timer", which I deduce will allow pilots to...well, do what? Can someone help me decipher all the geeky goodness so I can impress my fellow nerd friends?

Reason I'm asking is the instructions are in Japanese, which I can't read. I've looked for instructions on the net to no avail.Are these functions pretty standardized among watches, or are they more specific to each watch?

posted by zardoz to sports, hobbies, & recreation (11 comments total)

that's a nice watch. Could you splash out and pay for a translator to translate the instructions for you? I know of at least one on this site, or you could try this translators' portal.
posted by altolinguistic at 3:14 AM on May 18, 2006

In general, this is a rotary slide rule. If you can wait about five days for my father to return from a trip, I can call him up and ask -- he flew light planes for many years, and I know he has the stiff-cardboard version of one of these in his gear bag.

I can tell you that "STAT" and "NAUT" refer to statuate and nautical miles. If you twiddle the dials right, it'll probably convert between the two, and probably kilometers as well, judging by the KM ring.

The rest of it is pretty inscrutable to me -- the outermost ring is obviously a compass, but like you, I have no idea what you can actually do with it relative to the other rings.

I'm unclear on the innermost ring -- it looks like there's some text I can't read from this angle on the upper right portion of the ring, but I doubt that'd clarify much on its own. Some of these have fuel burn rate calculators and such, but it doesn't look like that to me -- maybe part of the distance conversion thing, still?

And I'm sorry this isn't so much a manual as "a few things I know, second hand, about rotary slide rules" but hopefully it will enhance your Google-fu.
posted by Alterscape at 3:15 AM on May 18, 2006

The numbers running around the outside: tachymeter. It looks like there are several, but they all work the same way, just with different units.
posted by Rhomboid at 3:18 AM on May 18, 2006

Working from the outside in...

1) Compass "rose" (I think that's what they call it.) Presumably for taking differential bearing (angle between two landmarks) or some other nav function.

2 & 3) Circular slide rule. You can use this for multiplication and division (Google is your friend here.) A bonus feature here are the naut/stat/km markings allowing you to convert between nautical and statute miles and kilometers. It looks like to convert between km and (I think -- play with it to confirm) statute miles you'd line up the km marker on the outer bezel with the 10 (or 1.0 -- slide rules don't show decimal points) on the inner bezel. Then, for a given statute mile distance on the outer bezel read the number underneath it on the inner bezel and that'll tell you how many km that mileage corresponds to. The other markings would work similarly, but again, without having it in front of me you'll have to play with it a bit to determine which units each marking converts between.

4) Tachymeter (under the crystal). Used to determine speed in units per hour given the time in seconds to cover a distance. You need a measured mile/km/whatever for this to work. Using miles per hour -- reset the chronometer so that the sweep second hand is at "12." Start the chrono when you enter the measured mile. Stop it when you exit. The number opposite the second hand when you stop it is your average speed over the measured mile in mph. Obviously, this only works if you're averaging over 60 mph, but if you're going slower, you can measure the time it takes to cover a shorter distance and convert -- (e.g., if it takes 45 seconds to cover a half-mile the tachymeter'll read 80 -- i.o.w. 80 half-miles per hour or 40 mph)
posted by Opposite George at 3:23 AM on May 18, 2006

On (non-)preview: Rhomboid has the right idea on the tachymeter but the wrong position -- the 2 middle rings are the slide rule part and the innermost one is the tachymeter.

Also, Wikipedia article on slide rules, including instructions, a photo of a Breitling Navitimer (a watch that was probably the inspiration for yours) and lots of good links.
posted by Opposite George at 3:31 AM on May 18, 2006

Great answer, Opposite George! A friend just got a Breitling with the navigation computer on it and we were wondering how to use it.
posted by TedW at 4:31 AM on May 18, 2006

The specific type of slide rule used by pilots is an E6B. More info here, but if you've got a local municipal airport, there's a good chance you can pick up an inexpensive set of directions at their pilot "shop" (often just a bunch of stuff they keep stashed under the counter).
posted by richmondparker at 4:31 AM on May 18, 2006

Re: E6Bs:

You can pick up a paper version here. Instructions here. They're fun to play with.

They do quite a bit more than the circular slide rule in zardoz's watch, but the instructions from page 6 on titled "The Slide Rule Side" have lots of good examples for practice. Ignore the superflous stuff.
posted by Opposite George at 5:50 AM on May 18, 2006

You can also use the outer ring to use your watch as a compass, provided you can see the sun.
posted by plinth at 7:00 AM on May 18, 2006

plinth, as your link says, you can use any analog watch as a compass; no outer ring needed.
posted by Kirth Gerson at 7:16 AM on May 18, 2006

Right, but the outer ring lets him mark the compass points more accurately so that he could actually do some orienteering...
posted by plinth at 9:11 AM on May 18, 2006