Dive Watch Safety: Essential Tips for Underwater Use
A dive watch is more than a stylish accessory; it's a piece of safety equipment designed to help you manage time underwater where running out of air has fatal consequences. While modern dive computers have largely replaced watches as primary dive instruments, understanding how to use your dive watch properly remains essential knowledge for any diver who wears one.
This guide covers the safe operation of dive watches, from pre-dive checks to proper bezel use, helping you use your timepiece as the reliable backup tool it's designed to be.
Understanding Your Dive Watch
True dive watches meeting ISO 6425 standards include specific features for underwater use. Understanding these features is the first step to safe operation.
The Unidirectional Bezel
The rotating bezel is the dive watch's most important feature. It only rotates counterclockwise (unidirectional) as a critical safety measure. If you accidentally bump the bezel during a dive, it can only rotate in the direction that would indicate you've been underwater longer than you have, never shorter. This fail-safe could save your life by ensuring you always surface with a margin of air remaining.
The bezel is marked in minutes, typically with the first 15-20 minutes highlighted since this period is most critical for decompression calculations. The triangle or pip at zero indicates your dive start time when aligned with the minute hand.
Never trust a bidirectional bezel for dive timing. Only ISO-certified dive watches with unidirectional bezels are safe for tracking underwater time. A bezel that rotates both directions could accidentally indicate less elapsed time, potentially leading to decompression sickness or air exhaustion.
Luminous Markers
Proper dive watches have luminous markers on the dial and hands visible in dark underwater conditions. The minute hand should be easily distinguishable from the hour hand, as confusing them underwater could lead to dangerous timing errors. Check that your watch's lume is charged (expose it to bright light) before any dive.
Screw-Down Crown
The screw-down crown creates a watertight seal essential for water resistance under pressure. Before any dive, verify the crown is fully screwed down. Develop a habit of checking this as part of your pre-dive equipment inspection.
Pre-Dive Preparation
Servicing and Testing
Before diving with any watch, ensure it has been recently serviced and water resistance tested. Gaskets degrade over time, and a watch that was water-resistant last year might not be today. Annual pressure testing is recommended for any watch used during dives.
If you're unsure about your watch's current water resistance, have it tested before risking it underwater. The cost of testing is minimal compared to potential damage from water ingress or, more importantly, the safety risk of equipment failure during a dive.
Before every dive: verify crown is screwed down, check bezel rotates smoothly in one direction only, ensure lume is visible in shadow, confirm the watch shows correct time, and visually inspect for any cracks or damage to crystal or case.
Strap Considerations
Use an appropriate strap for diving. Metal bracelets should have secure clasps with diving extensions to fit over wetsuits. Rubber straps are ideal for diving, being comfortable, durable, and unaffected by water. Leather straps are unsuitable for underwater use.
Ensure the strap is secure but not too tight. Your wrist may swell slightly at depth, and a too-tight strap becomes uncomfortable. The watch should be snug enough not to rotate freely but loose enough to remain comfortable throughout the dive.
Using the Bezel Correctly
Proper bezel operation is the key skill for dive watch use. Here's the correct procedure:
Setting the Bezel
Just before entering the water, rotate the bezel so the zero marker (usually a triangle or pip) aligns with the minute hand's current position. This marks your dive start time. As minutes pass during the dive, the minute hand moves away from zero, indicating elapsed time.
For example, if you enter the water when the minute hand points at 12, align the bezel's zero with 12. When the minute hand reaches 3, you've been underwater for 15 minutes. When it reaches 6, 30 minutes have passed.
Reading Elapsed Time
Throughout the dive, read the bezel position relative to the minute hand. The number on the bezel aligned with (or just passed by) the minute hand indicates minutes elapsed. The highlighted first 15-20 minutes on the bezel help you track critical early dive time precisely.
- Setting the bezel after entering the water (dive time already started)
- Forgetting to check bezel position throughout the dive
- Confusing hour and minute hands in low visibility
- Not practicing bezel reading before actual dives
Safe Diving Practices
The Watch as Backup
Modern recreational divers typically use dive computers that continuously calculate no-decompression limits and remaining air time. Your dive watch should serve as a backup timing device, not the primary instrument. If your computer fails, your watch allows you to track elapsed time and execute a safe ascent based on your dive tables or training.
Always know your planned maximum dive time before entering the water. Monitor your watch periodically throughout the dive to confirm you're within planned limits, even when using a computer.
Never Adjust the Crown Underwater
Under no circumstances should you operate the crown while submerged. Even with a screw-down crown fully seated, water pressure can force moisture past gaskets if the crown is unscrewed. Never try to adjust time, wind the watch, or perform any crown operation while underwater or with a wet watch.
If your watch stops during a dive, note the time on your computer and abort the dive using tables as backup. Deal with the watch issue after surfacing.
Depth Limitations
Know your watch's depth rating and stay well within it. A 200-metre rated dive watch is suitable for recreational diving, which rarely exceeds 40 metres. The additional rating provides a safety margin for the dynamic pressures encountered during active diving versus static laboratory testing.
Never approach the rated depth limit of your watch. Professional saturation divers use watches rated far beyond their actual working depths for good reason.
Post-Dive Care
Rinsing
After every saltwater dive, rinse your watch thoroughly with fresh water while rotating the bezel to flush salt deposits from the mechanism. Salt is corrosive and will damage both the bezel action and the case finish if left to dry. Pay particular attention to the crown and bezel areas where salt can accumulate.
Drying and Inspection
Dry your watch completely with a soft cloth. Inspect for any signs of moisture inside the crystal, which would indicate water ingress requiring immediate professional attention. Check that the bezel still rotates smoothly; salt or debris can make it sticky.
Condensation under the crystal, water droplets visible inside, fogging that appears after temperature changes, or sudden accuracy problems all indicate water ingress. Stop wearing the watch immediately and take it to a watchmaker to prevent further damage.
Training and Practice
Before using a dive watch for actual dives, practice with it. Wear the watch during surface activities, set the bezel, and read elapsed time until the process becomes automatic. Practice in a pool or shallow water where mistakes don't carry serious consequences.
Consider taking a formal diving course if you haven't already. Proper dive training covers emergency procedures, dive table use, and equipment management that contextualise your watch's role in overall dive safety.
When Not to Rely on Your Watch
Certain situations require extra caution:
Unfamiliar watches: Don't use a new or borrowed watch for serious dives until you've practiced with it extensively in shallow water.
Watches that haven't been serviced recently: If you're unsure about water resistance, have the watch tested before trusting it underwater.
Damaged watches: Any visible damage to the crystal, crown, or case could compromise water resistance. Get the watch checked before diving.
A dive watch is a reliable tool when properly maintained and correctly used. By understanding its features, following safe practices, and never exceeding its capabilities or your own, your timepiece becomes a trusted companion for underwater adventures around Australia's magnificent reefs and coastlines.