Hands-On: The Bühlmann Decompression 02 Is A Tool’s Tool In A World Of Wannabes

In use, the Bühlmann Decompression 02 allows you to pre-plan depth, bottom time, and decompression stops via its rotating decompression dial, then track total dive time and ascent using its bezels and hands. This is how the three top-mounted crowns work: the central crown (no. 2) is used to set the time and manually wind the Sellita SW-300 movement. This is also used for setting the fly/no-fly function. Before a dive, unscrew crown number 3 at 1 o’clock to rotate the decompression dial beneath the blue center dial to display the depth and bottom time combination you need. Pushing it in and screwing it in place locks the deco dial for diving. The crown 1 at 11 o’clock is used to unlock and lock the TDT (total dive time) inner bezel, to rotate it, and align it with the minute hand. You can then measure descent time and bottom time (BT) using the TDT bezel, and measure ascent rate using the seconds hand (not more than 10m per 1 min). Once the first decompression stop is reached, you’ll turn the outer DS bezel clockwise (the TDT bezel does not turn), aligning the zero marker of the DS bezel with the minute hand to measure the duration of the decompression stop. Repeat this for your ascent rate using the seconds hand, then repeat it for each additional decompression stop using the DS bezel. During the dive, it helps you monitor descent, bottom time, ascent rate, and decompression pauses in a clear, mechanical way. After the dive, the Fly/No-Fly indicator serves as a visual reminder of surface interval discipline rather than a medical clearance.

[Edit Note: Recreational diving (as described by PADI) is trained and intended as no-decompression diving, in which the diver would stay within the no-decompression limits (NDLs) and not require decompression stops beyond the standard “safety stop” at 5M for 3 minutes. While a safety stop is always recommended, and a decompression stop may be required depending on the realities of a dive (e.g., when the NDL is exceeded), specifically planning for decompression stops is not within the scope of recreational diving and is not recommended without technical dive training.]