Diving Equipment the Diver Wears Has a Tremendous Impact on the Diver’S Ability to Work Comfort- Ably, Safely, and Efficiently (Bachrach and Egstrom 1986)
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Diver and Diving Support Equipment 5 5.0 GENERAL The type of diving equipment the diver wears has a tremendous impact on the diver’s ability to work comfort- ably, safely, and efficiently (Bachrach and Egstrom 1986). Although equipment is a big factor in diver performance, equipment alone cannot make up for a diver’s lack of abili- ty in the water. A good diver must have a high level of fit- ness and must be comfortable in the water. A competent diver should be able to dive with most any type of equipment provided he has been trained to use it. Selecting the right dive gear for a scientific dive is a mat- ter of defining the objectives of the dive and the location. For some work, snorkeling equipment may be all that is required, while for other jobs surface-supplied gear may be the best choice. A diver must become totally familiar with new equipment before entering a working situation. With all diving equipment, remember that streamlin- FIGURE 5.1 ing is an essential factor in making it easy for the diver to Dive Mask with Nose Pocket swim and maneuver under water. The more equipment the diver wears, the more drag and change of center of gravity will be created. Each piece of equipment should have a def- inite purpose on a particular dive; and if it is not going to 5.1 BASIC EQUIPMENT be used, it should not be carried. Streamlining is crucial to 5.1.1 Face Masks productivity for the scientific diver. Face masks for scuba diving are designed to cover the Given the durability of most diving gear, making the eyes and nose. The nose must be included inside the mask right selection at the time of purchase is critical, since it is to allow the diver to equalize the pressure inside the mask hard to justify equipment replacement if the equipment is by exhaling through his nostrils. This is one of the reasons not worn out. By talking with diving officers and other sci- that goggles that cover only the eyes are not acceptable for entific divers, the preferred models of gear for a particular diving. location and type of diving are easily identified. A critical issue in selecting a mask is the fit. The mask The NOAA Diving Program has a standardized equip- must fit comfortably and not leak. To test the fit, the diver ment program whereby all active NOAA divers are issued places the mask against his face as he would when wear- dive equipment. The program, which includes yearly main- ing it normally, but without using the strap to hold the tenance and testing of all scuba regulators, pressure and mask in place. The diver then inhales through his nose, depth gauges by a factory-trained NOAA technician, pro- holds his breath, and attempts to make the mask seal vides standardization of equipment for all NOAA divers against his face. If no air leaks into the mask and the mask and helps ensure quality control. stays in position, it can be considered to be a good fit, as 5-1 long as it is comfortable. Divers with mustaches having dif- Many snorkels today are available with top mounted ficulty achieving a mask seal may have to use some type of valves that help to keep water out of the snorkel while substance such as Vaseline® on their mustaches to achieve surface swimming. These valves are not designed to seal a proper seal. the snorkel under water but to keep spray from flooding Many divers find that a nose “pocket” is a useful fea- the snorkel while the diver swims on the surface. These ture of a mask in that it provides a means for the diver to can be extremely effective and make surface swimming pinch his nostrils closed in order to aid in equalizing the much easier. pressure in his ears (see Figure 5.1). Other features include Most modern snorkels use plastic rings or attachment purge valves and double feather edge seals. A purge is a devices to connect the snorkel to the diver’s mask. These one-way valve through which water can be expelled that rings allow the snorkel to be easily removed from the enters the mask. Water can also be removed from a mask mask, so that the mask can be stored in a protective box without a purge. A double feather edge is a type of sealing for transport to and from the dive site or during airline (double) edge on the material that fits against the face. travel. Once it is determined that the mask fits properly, the In the United States, the snorkel is traditionally mount- next most critical feature is visibility. Side windows in the ed on the left side of the diver’s head, since the regulator is masks can enhance peripheral vision (Egstrom 1982), but routed over the diver’s right shoulder. In Europe, the oppo- can sometimes produce a “rear view effect.” Mask win- site arrangement is sometimes employed since the regula- dows are made from safety-tempered glass. Additionally, tor may be directed over the diver’s left shoulder. some masks have downward lenses or optical devices that will help the diver see more of the equipment mounted on 5.1.3 Fins his chest and waist. Fins for scuba diving are usually much more rugged For divers who require glasses, prescription lenses are and have larger blades than those used for snorkeling or available that will fit many popular dive masks. For swimming. The fins provide propulsion for divers who are divers who have a common prescription and do not need heavily encumbered with equipment and make underwa- bifocals, many dive stores stock lenses for their more pop- ter swimming much easier. Human leg muscles are very ular mask styles. Divers who have an unusual prescrip- efficient for underwater propulsion when properly tion will need to order specially prepared lenses for their equipped. masks. When divers are fully geared up, it may not be possible The lenses of new masks need to be washed with a for them to use their hands for swimming purposes, since mild liquid detergent, such as dishwashing detergent, to straps and thermal protection suits inhibit normal arm help remove any chemicals that may remain from manu- movement. In addition, scientific divers are usually carry- facturing and may cause the mask to fog. ing instruments, slates, or other equipment that make it impractical to use their arms for swimming. 5.1.2 Snorkels The human leg provides propulsion under water by A snorkel is an indispensable piece of equipment for moving the levers of the body, i.e. the femur and tibia, to the open water scuba diver using self-contained open cir- provide thrust through the use of the fins. Since these bones cuit gear (see Figure 5.2). The purpose of the snorkel is to are of different lengths in each individual, providing a differ- allow the diver to swim more easily on the surface without ent mechanical advantage for each diver, there is no one fin consuming the compressed gas in his cylinder. that will work best for each person. A fin that works very Ideally, the snorkel should not exceed 14 inches in length and should have the minimum number of bends possible. If the snorkel has a corrugated hose, allowing it to bend easily, the inside bore of the hose must be smooth, not ribbed. Small diame- ter snorkels, and those with corrugated hoses with internal ribs, produce high breathing resistance, add substantially to equipment dead air space (where no gas exchange takes place), and a corrugated hose also makes elimination of all water in the snorkel all but impossible. FIGURE 5.2 FIGURE 5.3 Snorkel with Attached Snorkel Holder Adjustable Heel Strap Fins 5-2 NOAA Diving Manual 5.2.1 Dive Skins There are many different types of thin suits available that provide sun protection as well as protection from coral cuts, scrapes, and stinging creatures such as jellyfish. These suits are form fitting, have good stretch, and are generally referred to as “dive skins” or just “skins.” Skins made from Lycra® provide good protection from the sun but do not provide any thermal protection. There are also suits made from Lycra® combined with additional materials such as polyolefin microfibers which provide good wind resistance. Dive skins may be worn in tropical waters when the diver’s activity level is relatively high. During warm water dives where the diver will remain relatively inactive, a wet FIGURE 5.4 suit or Polartec® skin, which provides insulation equivalent Full-foot Fins to a 2-millimeter suit without the same buoyant properties of a wet suit, is recommended. In some cases where buoy- ancy is desirable, wet suits made from rubber are recom- mended. 5.2.2 Wet Suits Wet suits are made from foam neoprene, a synthetic material with thousands of tiny closed cells that are filled with nitrogen gas (see Figure 5.6). The suits are designed to allow water to enter the area between the diver’s skin and the suit. Ideally, a wet suit should fit snugly, allowing only a minimum of water inside the suit. This thin layer of water is warmed up by the diver’s body and provides rea- sonable comfort at moderate temperatures. A cold water wet suit usually provides a double layer of insulation over FIGURE 5.5 the torso. Booties Wet suits come in a variety of thicknesses, one mil- limeter up to seven millimeters.