The bezel is for...
: Is there anyone with a particular use for the
: bezel of the SMP Bond? I think it can be
: used for mark the beginning or end of some
: interval of time. Also, why there are no
: arabig number in the bezel at positions
: corresponding to 5,10, and 15 minutes?
Livier, the rotating bezel on a dive watch is expressly designed and intended to be used to keep track of "bottom time" (time under water) while scuba diving. For example... say you start a dive at 7:40... you turn the bezel so that it reads 0 minutes at 7:40, 10 minutes at 7:50 mins, 20 at 8:00. In this way, you can tell at a glance just how long you've been under water. Because of the quick buildup of nitrogen in your bloodstream during longer dives, and also the fact that you expend your oxygen supply faster at a deep depth (or pressure, for that matter), regular recreational dives rarely last much longer than an hour. The bottom time is used to calculate the nitrogen saturation in your blood, which is done using a special table used by scuba divers, to be sure that the level of nitrogen in their bloodstream is minimized; this is especially important for repeated dives on a given day, or many dives over a few days. All gases (read: nitrogen) are more readily absorbed into liquids (read: blood) at higher pressures, and even the shallowest scuba dives (~30 feet) are performed at double atmospheric pressure, which allows nitrogen to be absorbed into your bloodstream. After that happens, when you surface (and the pressure is thus decreased), the dissolved nitrogen gas in your blood is released, forming bubbles of nitrogen gas in your blood stream. This is so immensely painful, that the term for this condition is "the bends"; aptly named because it leaves you "bent" over in excruciating pain. The importance of accurately measuring bottom time is the reason that the bezel only turns one way... counterclockwise... that way, even if it gets bumped during a dive, it will only cause you to OVER-estimate your bottom time (on the side of safety), whereas if the bezel were to be bumped the other way, you could UNDER-estimate your bottom time and extend your dive for too long, which means that you can also run the risk of running out of air... and then you are in a world of hurt. This is especially true because nitrogen buildup in the bloodstream (at depth) causes impaired judgement and coordination, disorientation, and feelings of euphoria (like sniffing a whip-it, or a dentist's nitrous oxide), also similar to drunkenness. When your oxygen runs low, this all makes for a very dangerous situation. But, I've droned on far too long on this topic.... as for the numbering pattern on the bezel... I don't know. But, I use the rotating bezel everyday for various things besides diving... timing eggs, pasta, all sorts of miscellaneous tasks... if only it had an alarm, I wouldn't burn them all. Incidentally, this nitrogen issue is also closely related to the need for a helium release valve; Because of the toxicity of nitrogen at high pressures, when people need to spend long periods of time in high-pressure environments, whether underwater or not, (deep-sea researchers, some scientists and construction workers, etc), air in their living areas (read: submarine, deep-sea diving suit, hyperbaric chamber, caisson, etc) is nearly nitrogen-free... the nitrogen is replaced by an inert, non-toxic gas, usually helium, which has atoms small enough to squeeze through the seals in any watch... and when you decrease the pressure... out pops your crystal. See the articles on this elsewhere on this website. Cheers! -- Dan
