The Navitimer’s bezel is a hand-operated circular slide rule: align its rotating scale with the fixed scale on the dial, then read the corresponding value. A tachymetric scale, when present, is a separate tool; the chronograph hands and registers record elapsed time. The exact layout and functions vary by reference, so check the manual for your watch.
What the three dial systems do
“Three scales” is a useful way to make sense of a busy Navitimer, but it does not mean every model has three identical rings. The dial brings together distinct systems: a pair of logarithmic scales that work together as a circular slide rule, a tachymetric scale on models fitted with one, and chronograph displays that record elapsed time. The chronograph displays are registers and hands, not calculator scales.
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The fixed and rotating slide-rule scales
One scale is printed around the dial; its partner is on the rotating, bidirectional bezel. Turning the bezel aligns values on the two scales. Breitling describes it this way: “The slide rule is used by rotating the bezel to align the moving scale with the fixed scale on the dial.” The result must be read and interpreted by the wearer; the watch does not calculate automatically.
Breitling says the slide rule can support calculations involving speed, distance, fuel consumption, climb or descent rate, and unit conversions. The scales work as an analog calculation aid, and the user must interpret the decimal place and units for the problem.
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The tachymetric scale
A tachymetric scale, where fitted, is separate from the slide rule. It is associated with measuring rate over a known distance using elapsed time. Do not confuse its markings with either of the slide-rule scales. Check the markings on your dial and the manual for your reference: not every Navitimer has the same scale arrangement or labeling.
The chronograph hands and registers
The chronograph records elapsed time. The central chronograph seconds hand and the minute and hour totalizers are distinct from the ordinary hour and minute hands, which continue to show the time. Breitling’s manual identifies these components, but register ranges and layouts vary by model.
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How to use the circular slide rule
- Identify the scales. Locate the fixed scale around the dial and the matching scale on the rotating bezel.
- Turn the bezel. Align the two values relevant to the calculation, as Breitling’s instructions describe.
- Read the result. Find the corresponding value on the other scale, then interpret its decimal place and units for your calculation.
- Check important results. Treat the slide rule as an analog aid and verify the arithmetic independently when precision matters.
Breitling names the types of calculation the slide rule can support, but its cited product guidance does not provide a worked numerical example. The scales require manual alignment and interpretation.
How to operate the chronograph
- Start: Press the upper pusher to begin timing.
- Stop: Press the upper pusher again to stop the chronograph.
- Reset: Once timing has stopped, press the lower pusher to return the chronograph display to zero.
Breitling advises stopping the chronograph before resetting it. The precise sequence should be checked against the manual for your watch’s reference, especially for vintage or unusual variants.
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Why the reference matters
Navitimer layouts, movements, scale labels, and chronograph functions differ across references and generations. For example, Breitling specifies the B01 Chronograph 46 with a bidirectional slide-rule bezel and a chronograph capacity of 1/4th second, 30 minutes, and 12 hours. Those figures describe that cited model, not every Navitimer. The official instructions-for-use manual labels the slide rule, tachymetric scale, chronograph seconds hand, minute and hour totalizers, and start/stop and reset pushpieces; consult the manual matching your reference for its exact arrangement and operation.
A brief history of the design
According to Breitling’s account, Willy Breitling developed the wrist-worn chronograph with a circular slide rule in 1952. Breitling says the Aircraft Owners and Pilots Association (AOPA) announced the design as its official timepiece in 1954, and that astronaut Scott Carpenter wore a Navitimer in space in 1962. These are historical dates as recounted by the manufacturer.
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