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NAUI Master Scuba Diver 214 Limited Visibility and Night Diving distinctive so they won’t be readily confused with other lights in the dive area. Be careful to avoid the use of lights which might resemble navigational aids, especially flashing red, green, or white lights. Amber or yellow are good alternatives. Strobe lights can be used on the group leader, on the anchor line, or near a beach exit point for easy identification. For shore diving, the surface float can be marked with a chemical glow stick inside a plastic milk bottle. The Night Dive If possible, pick a calm, familiar, shallow spot for your first dive. Avoid kelp, big surf, and wave-washed rocks at night. Stick to open water areas. Boat dives to shallow or protected reefs are excellent. It is a good idea to limit the area to dive to a reasonable boundary. Check the area earlier in the day, and make sure your gear is ready. Take a moment to go over the dive plan with your partner. Set up your return light(s). Don your gear and do a last minute check in a lighted area. Activate your “chem light” or personal marker light before entering the water. When entering the water from shore, lie down and swim in shallow water, remaining close to your buddy. This will prevent you from falling down or getting knocked down. Take bearings on the point where you wish to exit before submerging so you can navigate during the dive to finish near your exit point. If you have a long surface swim and conditions allow, you might want to keep your light switched off to conserve batteries. When to Terminate a Night Dive You should agree to terminate the dive when one of the following occurs: • Failure of either diver’s primary light source with no back-up available. • When either diver’s air pressure reaches 35 bar (500 psi) (in standard cylinders) or a higher pressure, depending on depth. • If either diver is excessively cold. • If the divers are separated and cannot find each other underwater. • The planned end of the dive has arrived. Check with your buddy once you reach the diving area, and test your lights before descending together. You may experience disorientation or vertigo from lack of a point of reference during the descent. Shining your light on your bubbles or using a descent line helps prevent this. Once on the bottom, be alert to surge and current, lest you be swept into unseen obstructions. Move slowly and stay together, looking not only from side to side, but up and down as well. Do not shine your light into your buddy’s eyes, but instead on the chest or the ocean bottom if you are near it. Agree on an attention gaining signal, such as rapid wiggling of the light, covering and uncovering the light, or line pulls. A buddy line may be used. You will also notice that it is helpful to hover just above the bottom to prevent the sand or silt from clouding the water. Some divers in special environments prefer to adjust themselves to slight negative buoyancy on the bottom to avoid floating unaware toward the surface. Lights permit us to communicate more easily at night, both underwater and on the surface. Shine your light on your own hand to communicate with hand signals. To signal with the light (figure 8-8), the following signs are universally used: • OK is expressed by circling with your light. • Distress is expressed by rapidly swinging your light in an overhead arc. • Attention is conveyed by the back and forth, sideto side motion of your light. If you should become separated; stop, turn slowly, and look for your buddy’s light, lightstick, or bubbles. Locating your buddy’s light will be easier if you shine your light away from the direction you are searching, or press your light against your chest. If you do not locate your buddy after one minute, you should surface. Your buddy should do the same. Leave your light on after reaching the surface. When your buddy is sighted, signal by making a large “O” for OK on the air with your light. Your buddy should return the signal. Descend again after getting back together and checking your reference points. During ascent, shine your light on your bubbles and gauges to judge the rate of ascent. Keep one hand over


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