Exploring Bezel Functions and the Subcommander's Safety Necessity

At Brigade Watch Company, we believe every component of a true tool watch tells a story and serves a purpose. While the dial, movements, and hands set often grab the spotlight, an unsung hero is doing heavy lifting on your wrist: the bezel. More than just a decorative ring, the bezel is a critical piece of engineering that transforms your timepiece into a precision instrument. Join us as we peel back the layers of this fascinating component, exploring its history, mechanics, and the deliberate choices we make for your Subcommander.

What Exactly is a Watch Bezel?

You've undoubtedly noticed that prominent ring perched atop your watch crystal, framing the dial. This is the bezel. While it's certainly a key aesthetic element, its primary role often goes far beyond mere decoration. At its core, a watch bezel is a functional component designed to extend the utility of your timepiece, transforming it from a simple time-teller into a specialized instrument. Whether it rotates or remains fixed, its purpose is to provide a readily accessible measurement, calculation, or timing mechanism. A true tool watch's bezel adds layers of functionality right on your wrist.

Specialized Bezels: Tools for Every Mission

While many might associate bezels only with diving, they come in a fascinating variety, each designed for a specific purpose. The type of scale and whether the bezel rotates (and in what direction) depends entirely on its intended function. Here are some of the specialized bezels:

GMT Bezels (Bidirectional):

What is it?

A GMT (Greenwich Mean Time) bezel typically features a 24-hour scale. It's designed to track a second, or even third, time zone in conjunction with a dedicated 24-hour hand on the watch's dial (the GMT hand).

Why is the Bezel Bidirectional?

These bezels are almost always bidirectional because their primary purpose is to quickly adjust to different time zones (e.g., forward for a time zone to your east, or backward for one to your west). The ability to rotate in both directions makes setting and adjusting the third time zone much more efficient and convenient without having to spin the bezel all the way around if you overshoot or need to go back.

How to use it?

First, set your watch's main hour hand to your local time. Then, set the GMT hand to Greenwich Mean Time. To track a third time zone, simply set the zero marker (the triangle on the bezel insert) to the 12 o'clock mark on the dial and rotate the 24-hour bezel for x [number of hours counterclockwise if ahead of Greenwich's time or clockwise if behind Greenwich's time] amount of clicks. For example, if you want to know the time in New York (GMT -5) while your GMT hand is set to GMT, you'd rotate the bezel 5 clicks counter-clockwise from the 24 (or 0) mark. A simpler way to understand is to simply rotate the 24-hour bezel until the corresponding hour on the bezel for the third time zone aligns with the GMT hand. From there, the GMT hand will point to the GMT hour time and the hour time of the third time zone indicated on the bezel. Remember, the minute hand is the same for all time zones.

Compass Bezels (Bidirectional):

What is it?

A compass bezel (often found on field or pilot watches) is marked with cardinal directions (N, S, E, W) and degrees (0-360). It works in conjunction with the sun and your watch's hour hand to provide a basic directional reference.

Why is the Bezel Bidirectional?

These bezels are usually bidirectional because you need to align the bezel's South (or North, depending on hemisphere) marker precisely between the 12 o'clock marker and the hour hand. The ability to rotate in both directions allows for fine-tuning this alignment efficiently, ensuring an accurate reading from any starting position.

How to use it?

Point your watch's hour hand directly at the sun. Then, rotate the bezel so that the "South" (S) marker if in the Northern Hemisphere or the "North" (N) marker if in the Southern Hemisphere on the bezel is exactly halfway between the 12 o'clock marker and your hour hand. Once aligned, the other cardinal points on the bezel will indicate approximate directions.

Tachymeter Bezels (Fixed):

What is it?

A tachymeter bezel features a scale that allows you to calculate speed over a known distance (typically one unit of measure, like one mile or one kilometer).

Why is the Bezel Fixed?

Unlike rotating bezels, a tachymeter scale is usually fixed (non-rotating) and printed directly on the bezel ring itself. This is because it's designed to be used in conjunction with a chronograph (stopwatch) function to measure a rate. The scale provides a constant lookup table against the elapsed seconds, so there's no need for it to move or be adjusted.

How to use it?

To measure speed, start your chronograph with the top pusher - located above the crown head - when you begin a measured distance (e.g., passing a mile marker). When you complete that distance, stop the chronograph by pressing the top pusher again. The second hand of your chronograph will then point to a number on the tachymeter scale, which directly indicates your average speed per hour. For example, if it takes you 30 seconds to cover one mile, the second hand will point to "120" on the tachymeter scale, meaning your speed was 120 miles per hour. To reset the second hand for the chronograph press the bottom pusher located below the crown head. This function is useful for tracking average speeds of vehicles or even calculating production rates. The regular function of the second hand on a regular watch is seen on a smaller hand on a subdial — a small circle acting as a mini watch on the main dial.

Pulsometer Bezels (Fixed):

What is it?

A pulsometer bezel is a specialized scale used to quickly measure a patient's heart rate. It's often found on chronographs intended for medical professionals.

Why is the Bezel Fixed?

Like the tachymeter, a pulsometer bezel is typically fixed. Its scale is calibrated to instantly convert elapsed time over a fixed number of heartbeats (e.g., 15 or 30) into beats per minute. Since it's a direct readout based on the chronograph's timing, the scale itself doesn't need to rotate.

How to use it?

Start the chronograph by pressing the top pusher when you begin counting a set number of heartbeats (e.g., 15 or 30 beats, depending on the bezel's specific calibration). Once you've counted the required number of beats, stop the chronograph by pressing the top pusher again. The second hand will point to a number on the pulsometer scale, which directly gives you the patient's heart rate in beats per minute. This allows for rapid assessment without complex calculations. To reset the second hand for the chronograph press the bottom pusher - located below the crown head. The regular function of the second hand on a regular watch is seen on a smaller hand on a subdial — a small circle acting as a mini watch on the main dial.

Telemeter Bezels (Fixed):

What is it?

A telemeter bezel features a chronograph scale used to measure the distance to an event that can be both seen and heard (like lightning or artillery fire). It works by calculating the time difference between seeing an event and hearing it.

What is the Bezel Fixed?

Similar to tachymeter and pulsometer scales, telemeter bezels are usually fixed. The scale is a direct conversion of time (the difference between seeing and hearing) into distance, based on the constant speed of sound. Thus, it's a static reference scale that doesn't require rotation.

How to use it?

Start your chronograph on the telemeter at the exact moment you see the event (e.g., a lightning flash or muzzle flash from a distant cannon) by pressing the top pusher - located above the crown head. Stop the chronograph the moment you hear the sound by pressing the top pusher again. The chronograph's second hand will then point to a number on the telemeter scale, indicating the approximate distance to the event in kilometers or miles (depending on the scale's calibration). To reset the second hand for the chronograph, press the bottom pusher - located below the crown head. The regular function of the second hand on a regular watch is seen on a smaller hand on a subdial — a small circle acting as a mini watch on the main dial.

Historical Importance in Wars:

Telemeter scales were particularly significant during military conflicts, especially in the era before advanced range finding technology. Artillery spotters and forward observers could use telemeter-equipped watches to estimate the distance to enemy positions or shell impacts quickly. By observing the muzzle flash of enemy artillery and then listening for the sound, they could swiftly calculate the approximate distance, providing crucial targeting information for their own forces. This simple, reliable, and entirely mechanical function proved invaluable on the battlefield.

Dive Bezels (Unidirectional):

What is it?

Think of this as a miniature stopwatch built directly onto your watch. For a "diver's watch," the bezel is typically marked with a 60-minute scale. It acts as a countdown timer or an elapsed time indicator. Its robust design is meant to be easily gripped and turned, even with wet hands or gloves, underscoring its utility in demanding environments. Dive bezels can be designed to rotate in one direction (unidirectional) or both directions (bidirectional), depending on the watch's intended use and safety standards.

How to use it?

To use it, you align the bezel's zero marker (often a luminous triangle or "pip") with your watch's minute hand. As time passes, the minute hand moves, indicating the elapsed time against the number on the bezel's scale.

Why Our Dive Watch Subcommander is Unidirectional

For any dive watch truly built for the depths, a unidirectional bezel isn't just a feature-it's a non-negotiable safety requirement. At Brigade Watch Company, our flagship Subcommander embodies this principle with a bezel meticulously engineered to rotate only counter-clockwise. This crucial 'fail-safe' mechanism is paramount for diver safety and precisely what sets a professional dive instrument apart from watches not designed for underwater reliability.

Imagine the critical task of timing remaining air or decompression stops underwater. If a bezel could accidentally be nudged clockwise, it would falsely indicate more available time than truly remains, leading to potentially fatal miscalculations. This danger is profoundly amplified by conditions like Nitrogen Narcosis, a very real threat divers face at depth.

Nitrogen Narcosis: Divers breathe compressed air from their tanks, which contains about 78% nitrogen-the same proportion found in atmospheric air. As they descend and water pressure increases, nitrogen dissolves more readily into the bloodstream and tissues. In the brain, it acts like a mild anesthetic, producing effects similar to alcohol intoxication, such as euphoria, confusion, and impaired judgment. Symptoms usually begin around 100 feet (30 meters) and intensify with both increased depth and prolonged exposure-staying deep for 25-30 minutes can significantly worsen the effects.