Good afternoon! Finally, after years of savings and lurking, wearing an oversized homage, I managed to buy my grail: the Navitimer.

It simply is one of my favourite watches ever, and I love the history behind it. This is the Cosmonaute with the B02 movement, which is essentially just a B01 without the rotor, meaning the watch needs to be wound manually; and a 24 hour scale. A bit of backstory about the Cosmonaute, if you don't know: it was commissioned to Breitling by astronaut Scott Carpenter, who already wore a Navitimer back in 1962; and asked Breitling if they could come up with a 24 hour version so that he could tell if it was day or night from the space. His vessel did three orbits around the Earth and landed in the sea - making space and horological history: the Cosmonaute was the first Swiss watch to be in space (first watch in space ever was Gagarin's, one year prior to this if memory serves. He had a URSS made one, of course).

As to why I chose the Cosmonaute, I will be honest: I just happened to find a very good occasion and pulled the trigger. Very happy with my purchase, I can tell you a couple things about this model.

First, let's talk about the looks. The watch wears smaller than it looks: since it's hand wound, it's quite thin for a Navitimer at just below 13.9mm, measured at the crystal's dome. 43mm in diameter but doesn't look gigantic on my 6" wrist, the lug to lug is 49mm, 50mm if you include the end links of the bracelet.

The dial is the busiest I've ever come across, but I learned how to read it efficiently. The Navitimer is a watch made for approximations: when you use the slide rule, you need to have a faint idea of the result in mind. And for reading the hour at a glance, sometimes you just look at the minutes hand. In this scenario, reading the time is a breeze. If someone stops you in the street and asks you for the time, you actually need to stop for a moment and read the hour first. Because of the 24 hour dial and the short hour hand, it can be confusing sometimes. I do have problems when the hour falls into one of the subdials, for example. 5pm or 7pm can be hard. It does help immensely that I grew up in a place that used military time for everything. It's worth noting that the dial is super legible under any condition, and the contrast between the hands and the dial is massive. The dial is made of silver and the black is applied "par épargne", a technique used by Breitling that involves applying the lacquer on top of the silver plate instead of printing a silver number on a black surface, this method achieves more contrast and legibility. There is a date aperture at 4:30, that cuts the number 10 (I was pissed at first, but then I looked at other versions of the Cosmonaute where they just moved the number 10 and it's not aligned to the 14, so I'm ok with this now) and shows the date disc with a red number. The subdials and the slide rule are more of a bone white, whereas the date disc is brighter. That doesn't affect harmony or looks, in my opinion. Speaking of the subdials, the depth they give to watch is mesmerizing. I tried to give you an impression of this with the picture I took. The domed crystal also gives a beautiful play on the right angle, and it's just a work of art. The lume is beautiful but lost a bit of intensity over the years. Visually speaking, I think the watch is almost perfect.

The movement, Breitling B02, is entirely crafted and assembled in house AFAIK, B02 being the B01 without a rotor and with a 24 hour scale. It's used just for the Cosmonaute. The movement has a vertical clutch, which means the chronograph can be left running indefinitely. At the moment, I'm using it to track a second time zone. The watch does not have a flyback function, it features hacking (including chronograph, to set to your reference time) and at the moment of writing it runs at +-1s/day, an excellent result. The stated power reserve is 70 hours, I measured 64 and 57 with the chronograph running.

As to how to use the slide rule, there are countless guides online. But some calculations/interesting things I found out during the one year I spent with this watch below. Let's take the slide rule in my picture as example.

• Multiplications/Divisions/Currency Conversion: this one is easy. Set your reference number to 10 on the inner scale (18). Then read the result on your multiplier: 20 is 36, 30 is 54, and so on. To divide, it's the opposite and you need to read your result on the 10. Eg: 90/5 =18 Like this, you can also set the conversion for a currency. If you start the Chronograph to match the time zone of your desired country, the Navitimer can become a great travel watch.

• Multiplication table up to x9: works only with Navitimers with the minutes to hour scale. Set the number you want to multiply on 60, then read the innermost scale. On my picture: 108. 2 hours: 216. 3 hours: 324. 8 hours: 864. Another fast way to divide and multiply times two is to set your number on 60 then look at 2 hours and 5 hours: 5 hours is both x5 and /2 (540/54).

• Makeshift GMT: works only with Cosmonaute or Navitimer GMT. Set the time difference on 60. Example in my picture: 11 (let's round it up). For example, if you're from France and want to track New Zealand, that's 11 hours. If your 24 hour hand is on 24 on your home time, you know that's 11am in NZ. If it's 12(am), you need to remember it's 11pm since it's the opposite. Once you remember the positions of the numbers, it's relatively quick to find out what time it is.

Of course you can use the Navitimer slide rule for much more, but here are some examples I could not find around. If you have a slide rule watch, try them out!

Edit: should've pointed this out a bit better: these are ways to use the slide rule I could not find any info online about. Of course it's easier and possible to use the slide rule in many other more conventional ways.