Let us examine the parameters that are fundamental for a good divers watch. The ability to record time is crucial for all underwater activity. There are a number of different methods of recording the amount of time the diver has spent submerged, including the chronograph functions the simplest method is the bezel. As many things that are taken for granted nowadays, the rotating bezel in watches has been developed by the armed forces, and was incorporated in dive watches as well with the addition of time marked increments on the ring to allow the elapsed time so as to be easily read. The bezel must be reliable in its use, must have a serrated edge in order to be controlled by the divers usually wearing gloves and also must not be easily knocked off from the position the diver set before the dive.
The case in diver’s watches is perhaps the most important element in its design since the problem here is the watch to mitigate the force of water pressure. The issue in our case is compressibility, since the watchcases contain an air-filled void housing the movement. The deeper the diver descends, the water surrounding the case becomes pressed more and more against the timepiece. Enough pressure would start to flex the casing parts as the pressure build-up outside is far greater than the pressure inside. To combat this, a proper divers watch must be extremely well engineered and tough, with components cleverly designed like high quality O-rings or extremely machined high grade stainless-steel.
The caliber is hugely important, since it permits the diver to time his descent. The problem here is shock and magnetism. When diving it is very easy to knock the wristwatch on a reef or against a rock since underwater currents are powerful. Impact can cause water ingress due to a ruptured case or a smashed glass, and that’s why the case must be solid, and the glass must be extremely hard (usually sapphire crystal), protected by a thick disc, sealed to the case and secured in place with a locking ring. The force of the knock creates a momentum of its own which continues to act upon the delicate parts inside the watch, even when the outer case has reached a standstill. Violent shocks are the most fatal enemy for a mechanical wristwatch, and the common example of a watch stopping after it falls from our hand or starting to exhibit abnormal timing rate is not rare. A good dive watch must have an extremely well thought-out anti-shock system, and internal shock resistance built into the jewels, which retain the parts of the movement most at risk. The dive watch must also have the ability to withstand magnetic fields, which can cause components like the gear-train or the hairspring to run poorly.
Last but not least, a proper dive watch must have an improved legibility at depth. The dial must be extremely well thought-out and uncluttered, so the diver cannot make an error when reading his timings during a decompression stop; something that can prove fatal. Divers watches must have, ideally a large colored minute hand that will not be easily confused with any other hand underwater. We must understand that daylight cannot penetrate the depths and colors start to fade after 6 meters. Most well designed divers have bright orange minute hands or even orange dials and have special paint, which glows in the dark placed on strategic places (dial markers, hands, bezel). In the old days manufacturers used Radium, Tritium, and Prometheum – all highly radioactive materials – whereas nowadays the vast majority uses Super-Luninova which is non radioactive and non toxic. So now that you know what to look for, shop wisely and be safe when diving.
