NAUI Master Scuba Diver 212 Limited Visibility and Night Diving dive more enjoyable. Get the brightest light you can afford. Your enjoyment of night diving is directly tied to how comfortable you are and how much you can see. While relative “foot candle” ratings are useful for comparison of different models, the best demonstration is to turn the light on in a darkened room. Check the pattern on a wall. If it is too wide, the light won’t reach very far underwater. If it is too narrow, it may not light a reasonable area during, say, your search for lobster. Remember also that water causes significant attenuation (loss) of the light. Most dive lights may only reach about 6 m (20 feet) unless the water is extremely clear. Powerful cave diving lights can project much farther. Dive Lights At least one waterproof light is required for each diver on a night dive. There are a number of different types of lights and batteries available which suit different purposes (figure 8-6). A travel dive light should be compact and lightweight. If you spend a lot of time in remote locations away from power or if your budget is bare, a light that uses regular disposable batteries is appropriate. Several flashlight-size models are available that weigh less than one pound. They will not have the intensity or beam angle of a larger light, but their advantage is in their compact size. Many divers use a compact travel light as their sole light for night diving. A primary dive light is somewhat larger than a travel dive light. It will have greater power and a larger beam angle than smaller compact lights. They are also heavier and require more batteries. A typical hand-held dive light weighs about 2.5 kg (5.5 pounds) on land. A large cave diver’s light will often have a separate battery pack that is connected to the light by a cable. These can weigh as much as 5 kg (11 pounds). Advancements in LED and battery chemistry have made high power primary lights smaller, cheaper and with longer burn times. A stretchable or adjustable lanyard should be attached to your dive light to prevent loss. The stretchable or adjustable feature is important so your hand can pull free in case the light becomes caught. Some lights float and others sink. The ideal light would be slightly FIGURE 8-6. DIVE LIGHTS AT YOUR LOCAL NAUI DIVE CENTER. buoyant and float slowly upwards with the beam pointing up. This would make it easier to recover if lost. Battery Selection There are a number of different options for powering a dive light. The two main types of batteries are disposable and rechargeable. Disposable battery lights have a lower initial cost, require limited maintenance, and do not require electrical outlets for charging. They are ideal for traveling and occasional use. Most compact dive lights use either size AA or C batteries. There are two types of rechargeable batteries, gelcell and ni-cad. Gel-cell batteries have a burn time of around two hours and take about 15 hours to recharge. They require a periodic recharge maintenance program even when not in use. Ni-cad (nickel cadmium) batteries are commonly used in rechargeable dive lights. Small ni-cad AA or C cells can be used in a compact dive light. Larger dive lights have internal ni-cad battery packs which must be charged according to manufacturer’s instructions. Follow manufacturer’s rules carefully on charging cycles, as some lights can be damaged by overcharging or charging too fast. These batteries accept many recharges and have a burn time of 1 to 2 hours. Wattage output is relatively constant throughout the burn time, then it drops sharply. Over the long run, the most cost effective light is a rechargeable system. Batteries are expensive, and you’ll find that the rechargeable light quickly becomes a good investment. Rechargeable lights are also more environmentally acceptable. You may also want to pick up a
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