Both open and closed bells were the first apparatus used by divers to breath underwater. Divers are advised to evaluate water conditions before diving an area for the first time to ensure safety.
There is no argument that the art of breath hold diving was the first skill developed by divers. Probably the earliest effort to obtain air at depth was through long reeds similar to our snorkels. At depths more than two or three feet this could have caused injury to early divers.
To safely go deeper divers needed air pumped to them or a reliable, portable air supply. If the former – perhaps a diving bell – was used, it had to be large enough to contain the diver. Both systems mentioned above are considered self-contained underwater breathing apparatus (SCUBA) and supply air to the diver at a pressure equal to the water at depth. Beginning nearly 3,000 years ago, both open and closed bells were the first apparatus to permit underwater breathing by divers.
Knowledge is one side of the triangle of safety. Safety in diving will take on new meaning when divers fully understand what they see. Since water conditions are mainly linked to atmospheric conditions, reading the water must begin before a dive. This is a critical first step toward safety when diving an area for the first time.
While still on the surface – Stop, Look and Listen. Wind is air in motion. Wind generates waves and helps cause currents. If you can hear wind as it blows through poles, wires, around buildings and through boat rigging, it is strong enough to generate waves that may be troublesome. If it is an offshore wind, with offshore waves, it can be even more of a problem. This is particularly true of waves that are short and choppy, making swimming difficult. Waves generated by an onshore wind are usually less difficult to cope with and may even be useful in returning from the dive.
Before entering the water, look for the presence of major current flow. Such currents will usually be apparent by a line of discolored water where two bodies of water meet and, frequently, by a distinctive surface grunge line of befouled water. If there are any pollutants in the water they will probably be in the grunge line.
Once divers are in the water they are subjected to whatever the water is doing. The first important step to dive safety is to become aware of as many aspects of the surrounding water as possible. During descent divers should keep oriented with wind, waves and currents. When reaching the bottom relate this orientation to bottom conditions; the direction of currents, swells, surge and movement of marine life. Unless diving from a chase boat, it is usually preferable to move against the current. Return to the dive site is then down current. When a return to the dive site is likely to be a surface swim, adjust the dive pattern to permit the return to be in the direction of the wind and waves.
ONE MORE U/W EARTHQUAKE
An interesting and unusual U/W earthquake was reported by Jack Steinmetz. Jack was working on a 14 inch pipeline in 270 feet of water. He and his dive partner were inside a dry welding habitat making a hyperbaric weld. Jack wrote, “While making the final adjustments to the alignment, both ends of the pipe suddenly started to jump about. My dive partner thought the DPV (dynamic positioning vessel) was malfunctioning and running off, dragging the habitat by our umbilical.” Jack relayed the events to the surface personnel on the WADS (Welding and Diving Station). The divers were ordered to make an emergency evacuation of the habitat, return to the bell and to the saturation system on the vessel.
Things calmed down a bit and the welders returned to their habitat. After a few hours back on the job word came down to them, “You have just ridden out a magnitude 6.0 quake centered near us.” Jack said in closing, “The earthquake on the bottom was very much like one on the surface except for the lack of a rumbling noise.”