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Compass When you are swimming under water and visibility is poor, a compass is an important reference instrument, if not essential. Some divers use a compass on every dive, including when diving in clear, tropical water. A compass can also be critical on the surface if it is foggy and you cannot see the beach or boat. A compass consists of a magnetized needle that aligns itself with the earth’s magnetic field. The needle will point towards magnetic north as long as there are no magnetic influences nearby that can cause the needle to deviate or turn away from its specified direction. This constant reference to magnetic north enables you to know your position or direction of travel under or above the water relative to the north-seeking needle. A diving compass must: • Be filled with liquid to withstand pressure and dampen needle movement under water. • Have a reference line, called a “lubber line”, used as the direction of travel. • Have a means, such as a rotating bezel, to show a selected bearing or direction (figure 2-29). Maintenance Your regulator, alternate air source, and gauges are your life-support system under water and should be carefully maintained. Maintenance of your regulator first and second stages, alternate air source, and gauges can be divided into steps you can take as a user to keep your regulator in top condition, and steps that must be performed by a qualified repair technician. You should replace the dust cap that fits over the inlet to the first stage whenever your regulator is off a cylinder. The dust cap must be dry before you fit it over the inlet to the first stage. The first stage contains precision moving parts and O-rings. If water, sand, or dust get into the first stage, they can damage the moving parts, affecting the performance of your regulator and making it difficult for you to breathe. Some dust caps use an O-ring to create a seal with the first stage. If the dust cap requires an O-ring and it is missing, you will see an empty groove in the cap. Be sure to replace the O-ring to ensure that you are sealing the inlet closed. At the end of each diving day, you should rinse your regulator with fresh water to remove salt crystals or other impurities (figure 2-30). Always be sure to let water run through the mouthpiece and exhaust tees on the second stage. However, you should never press the purge button when running water through the mouthpiece. This could cause water to enter the hose to the first stage and get into the first stage of the regulator from there. You should soak your regulator (if it does not have a DIN connector), alternate air source, and gauges overnight in fresh water at the end of a dive trip, and then rinse them thoroughly. Let the regulator dry completely and then store it in a cool, dry place. Do not coil the hoses tightly or allow them to hang at an angle with weight on them, which causes kinks at the hose ends. Hoses that have been stressed can spring leaks and must be replaced. At least once per year, you should have your regulator serviced by a certified repair technician. Repair technicians are trained by the manufacturers in the proper methods to service their regulators and also to spot problems and correct them. The repair technician will take the first and second stages apart, clean all the metal parts, and replace the O-rings and other nylon or silicone parts of the regulator. The repair technician NAUI Scuba Diver 30 Diving Equipment FIGURE 2-29. DIVING COMPASSES ARE FILLED WITH LIQUID TO WITHSTAND PRESSURE, AND SHOULD HAVE A LUBBER LINE AND ROTATING BEZEL.


20490TC
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