This is my Omega Speedmaster, a fancy mechanical chronograph that my wife gave me for my birthday a couple of years back. It is, in fact, a special 50th anniversary edition of this legendary time piece, released back in 2007, when I myself turned 50.
Watch fanatics will at once remember the Speedmaster as the first and only watch ever worn on the moon. NASA conducted extensive tests back in the 1960s to discover which watches could function reliably outside spacecraft during space walks, and the Speedmaster was the only one that passed muster. It was thus duly anointed as NASA's official space watch. Later, when the shit hit the fan on Apollo 13 and the power went down, the crew used their Speedmasters to manually time the rocket burns that brought them safely back to Earth.
But what I really want to discuss is not the watch itself. Instead, please focus on the telemeter bezel ring circumnavigating the watch face.
Like most contemporary chronographs, my Speedmaster came equipped with a tachometer bezel ring. These allow you to measure the speed of a moving object over a fixed distance. I wasn't too interested in this feature, as my car has a reasonably accurate speedometer and my boat has a very accurate GPS unit. Even if they didn't, I wasn't about to go around measuring off fixed distances just so I could usefully punch the buttons on my fancy new watch.
So I had the tachometer ring removed and replaced it with a telemeter ring. These were first developed during World War I so that hapless troops in trenches could accurately calculate distances between them and the artillery bombarding them. You see the flash of the artillery and hit the button that starts your chronograph's stopwatch function. When you hear the boom following the flash, you stop the watch. Then you see where the big sweep second hand has come to rest in relation to the telemeter bezel, and it tells you the distance to whatever it was that made the flash in the first place.
I figured I could use my telemeter chronograph to reckon distances between me and thunderstorms while on the water. Except, of course, I realized later this watch isn't terribly waterproof and is bit too fancy anyway to wear on boats.
No problem. Study the telemeter ring closely and you'll see that the miles rate out roughly at five-second intervals. So now I use this very simple rule whenever I'm caught out in a summer thunderstorm: each five seconds of delay between a flash of lightning and its accompanying thunder clap equals one statute mile (NOT a nautical mile) of distance between me and the thunderstorm in question.
What could be simpler???
BoaterMouth link: here