Chapter 8- Limited Visibility and Night Diving Limited Visibility and Night Diving 211 Indeed, while it may seem that your range of vision will be limited in the night, you will find, as other divers have, that the reward is a newfound appreciation in the microcosm. Small coral polyps often open up at night. You will find that your air may last longer as you limit your attention to a small and interesting section of the reef or bottom, as opposed to hurrying by, oblivious to some of the most fascinating sights. Even the most mundane dive sites seem to undergo a transformation after the sun goes down. The Preparations Rewards have their way of demanding tribute before they can be collected. Pay your dues by becoming completely comfortable in the water with your skills and your equipment before making a night dive. Dive the area in daylight first. Choose an area with easy entry, calm, shallow water, and prominent landmarks. Remember that orientation and judgment of distance are difficult at night. Arrive before dark, if possible, to re-orient yourself and to prepare your equipment for the dive. Keeping Track of Where You Are A compass is a must for night diving. Even more helpful is a daytime orientation to the spot to key in on specific underwater landmarks. For shore dives, consider the use of two “range lights” set up in a line, with one higher than the other, to show you the path back to your exit point after surfacing (figure 8-5). These can be two lanterns on the beach or a similar alignment of battery powered lights, which could also be of different color. Don’t have the misfortune of using a porch light or street light for a return reference only to have it turn off before you get back to shore! A surface float can be lighted by placing a chemical glow stick in a plastic milk container. For boat diving, chemical glow sticks can be placed on the anchor line for reference. It is a good idea to have someone on shore when beach diving and essential to have someone in the boat while you are night diving from a vessel. FIGURE 8-5. LINING UP SHORE LIGHTS FORM A RANGE AND PROVIDE A LINE OF POSITION. Handling Equipment Clearly, human beings have been given too few hands to efficiently night dive. How do you adjust your BC while holding your light, while reading your depth gauge, and while carrying your camera? For your first few night dives, try to limit extraneous equipment and use gear with which you are familiar. Your first experience is truly not the place to try out a new mask or buoyancy compensator. The answer to the extra hand is buddy cooperation. You hold the light while your partner reads the depth gauge and maintains the reference ascent rate. Your buddy holds the light while you make camera adjustments. One holds the bag while the other puts in lobster! EQUIPMENT As night diving has become more popular, manufacturers have made equipment improvements to make the activity easier. Many gauges now glow in the dark, making them easy to read even without direct light. It is recommended that you carry a knife for diving at night. Whistles may be needed for signaling divers on the surface. Night divers use a minimum of two lights per diver. Small mini-lights are a great back-up in case of primary light failure. They allow a check of gauges during ascent to get you back to the surface. A powerful primary underwater light will brighten the way and make a night
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