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125 Cards in this Set
- Front
- Back
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what are the most important things to consider when selecting a divers mask?
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Comfort (fit) and seal also tempered or safety glass
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why can you never dive with swim goggles?
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the nose must be inside the mask so you can equalize you ears during descent.
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why are snorkels over 15 inches (38 cm) not recommended?
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there is to much dead air space
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what kind of fins are desirable for scuba divers and why?
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large bladed, open heel fins because they can be used in a wide variety of environmental conditions
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what is the most important consideration when renting or buying gear?
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proper fit
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when rinsing a regulator, what should you do?
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always leave it attached to the tank or have the dust cap in place.
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Never allow what into the first stage?
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moisture
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what are 3 features common to all buoyancy control devices?
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overpressure relief valve, inflation/deflation hose and low-pressure inflator hose
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what are 3 types of alternate air sources that are in common use today?
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octopus rigs, completely redundant systems and integrated regulator into the BCD inflation/deflation hose.
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What is the safest alternate air source?
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completely redundant systems.
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according to regulations of US dept. of transportation, scubda tanks must be hydrostatically tested every how many years?
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5
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visual tank inspections are required every how many years?
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once a year
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scuba tanks should always have to what to prevent what from entering?
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should always have pressure to prevent moisture from entering.
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what is the most important functional feature of a weight belt or weight system?
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means for ditching the weights immediately and easily.
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Why are weight systems used?
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Primarily to offset the positive buoyancy created by the wet suit.
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the primary purpose of the exposure suit is to....
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preserve body heat during dives
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the exposure suit can also prevent what?
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stings, scrapes and cuts during dives
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while diving, most dive computers should, at minimum, display what?
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maximum depth, current depth, actual bottom time and remaining allowable bottom time
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you should have your regulator serviced by a certified repair tech at least how often?
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once per year
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what does the first stage do?
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reduces tank pressure
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the stage of the regulator is...
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the first stage
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what do the second stages do?
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reduce intermediate pressure to ambient pressure
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2 types of material scuba tanks are made of
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steel and aluminum
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what are the stamped/engraved markings on the scuba tanks?
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date of hydrostatic test, serial number, and type of material
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what is a lubber line?
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the direction of travel line on the compass (important for navigating)
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the submersible pressure gage displays what?
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cylinder pressure and should be constantly monitored
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the depth gauge displays what?
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dive depth and should be constantly monitored
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the watch or time monitor measures what?
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actual dive time and should be constantly monitored
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what is the dive knife used for?
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a took for digging, cutting, pounding and prying- not as a weapon
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atmospheric pressure at sea level is what?
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14.7 pounds per square inch or 1.0 atmosphere absolute (1.0 bar)
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what is the weight of freshwater?
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62.4 pounds per cubic foot.
1000 kg/m3 |
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what is the weight of seawater?
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64.0 pounds per cubic foot
1025 kg/m3 |
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air (most commonly used by recreational scuba divers) is composed of what gases?
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78% nitrogen
21% oxygen 1% trace gasses |
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refraction causes what under water?
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objects appear larger and closer when looking through a mask during a dive
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absorption of light in water does what?
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removes colors as you descend in the water
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what is the first color to fade in water
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red
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sound travels how much faster in water than does in air?
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4 times which makes determining the direction or source of sound difficult
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a diver's body heat is lost primarily through.... what?
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conduction at rate of approx. 25 times more rapidly than in air, making thermal protection a priority
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what would help a diver reduce drag and amount of exertion during a dive?
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streamlining their body position and gear
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when are you at a state of equilibrium or saturation?
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when the pressure of nitrogen is balanced between the air and your body
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what happens in the state of gassing or being under saturated?
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when the pressure of nitrogen is greater in the air then in your body
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what happens in the state of out gassing or super saturation?
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when the pressure of nitrogen is less in the air than in your body
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what are 3 methods of measuring air pressure?
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BAR, atmospheres, and pounds per square inch
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what is absolute pressure?
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gauge (water) pressure plus atmospheric (air) pressure or total pressure exerted on an object
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what is gauge pressure?
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absolute pressure minus 1 atmosphere
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what is positive buoyancy?
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an object displaces an amount of water weighing more than itself
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what is negative buoyancy?
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an object displaces an amount of water weighing less than itself
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what is neutral buoyancy?
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an object displaces an amount of water weighing the same as itself
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what can adversely affect a diver's air consumption rate?
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large physical size, high anxiety, and poor fitness level
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what are good ways to stay in shape of diving?
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swimming and snorkeling
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pressure in the middle ear is equalized through a part of the body called what?
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Eustachian tube
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how does a scuba diver become dehydrated during a dive?
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it is due to moisturizing dry inhaled air with each breath
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what to do to stay hydrated during a dive?
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drink plenty of fresh water
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what are symptoms of nitrogen narcosis?
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similar to alcohol intoxication (ascend slowly to a depth where symptoms vanish)
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what could cause a block or reverse block?
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a diver's inability to equalize their ears during ascent
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what could cause an ear squeeze?
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a diver's inability to equalize their ears during descent
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what would be a result of an irregular breathing pattern while diving?
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carbon dioxide excess.
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what are symptoms of carbon monoxide poisoning?
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headache, dizziness, nausea, dark red fingernails and lips, respiratory distress or arrest and/or unconsciousness
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how to avoid carbon monoxide poisoning
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filling tanks at reputable dive centers and always smelling the air before using any tank
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what do you do to prevent air embolism?
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breathe normally and continuously at all times, never hold your breathe, always ascend slowly and control buoyancy
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never exceed the maximum ascent rate of what?
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30 feet per minute
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a diver with blood and mucous in their mask upon surfacing will most likely have had a....
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sinus squeeze
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what relieves sinus squeeze?
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Valsalva
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decompression sickness does what?
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causes joint pain (most common symptom) and symptoms usually occur within 1 hour of surfacing but can occur up to 24 hours later
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shivering is a symptom of....
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hypoterm (indicates dive should be ended)
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what ways will help to avoid emergencies caused by over exertion?
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maintain good health and fitness
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what is a thermocline?
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point of sudden change in water temperature
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what are 3 general categories of currents?
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standing, tidal and transitory
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standing
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river, gravity currents
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tidal
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currents influenced by moon
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transitory
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temporary, rip currents
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a dive team caught in a rip current, taking them in a direction they do not want to go, should swim how?
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at a right angle to the current
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ways that tidal action affects diving conditions include..
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changing entry and exit conditions. they may reverse directions and change speed and power.
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most surface waves are caused by what?
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wind
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what is surge?
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underwater movement of water caused by wave action that you will experience when diving in areas close to shore or near surface
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examples of natural navigation aids that divers may use during dives include....
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ripple marks in the sand, sun brightness/available light, bottom contours, currents, surge, position of sea fans
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almost all injuries from aquatic life are caused by....
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defensive action on the part of the animal
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to render first aid for stings....
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remove stinging material and apply neutralizing agent.
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to render first aid for venomous fish wounds...
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flush the wound to clean, soak in hot water, and obtain medical attention
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what is recommended when diving in low visibility areas?
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holding hands or use of a buddy line
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what is your first source of assistance if a situation arises?
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your dive buddy
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a sport/recreational diver should never plan to execute.....
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decompression dives
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the most common symptom of decompression sickness (DCS) is...
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joint pain
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treatment of decompression sickness and air embolism is....
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recompression and then slow decompression in a hyperbaric chamber
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what is Divers Alert Network (DAN)
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a worldwide emergency network of hyperbaric chambers and diving physicians
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for optimum no-decompression bottom times (this means more time underwater), plan what?
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plan repetitive dives so that each successive dive is to a shallower depth
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if a diver exceeds a no decompression limit, the diver must....
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do a mandatory decompression stop, water for symptoms of DCS, avoiding diving for at least 24 hours and avoid flying for at least 48 hours
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what can greatly reduce the risk of decompression sickness?
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during an ascent, after EVERY DIVE, a 3-5 minute safety decompression stop at 15 ft will be completed before surfacing
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according to NAUI what is a repetitive dive defined at?
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more than one dive within a period of 24 hours
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what is the absolute minimum surface interval between 2 dives is...
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10 mins
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what is the recommended min surface interval btwn 2 dives?
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60 mins
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according to NAUI dive tables, dives to less than 40 ft are considered as...
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40 ft dives
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actual dive time and actual dive depth are applied to the NAUI dive table exactly as...
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represented on the table or as the next greatest time and//or depth shown on the table
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what is the max rate of ascent?
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30 ft per min
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what is the max rate of descent?
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75 ft per min
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what is the recommended rate of decent?
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30 ft per min
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according to NAUI, how long should you wait before flying after a conservative dive?
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12-24 hours
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if your buddy is in distress at the surface, what are 3 recommended actions to take?
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1. safely establish buoyancy for your buddy.
2. get them to relax or rest 3. tow them to the shore/boat talk to them to calm and reassure them |
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appropriate first aid measures for an unconscious scuba diver should include consideration of...
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1. drowning
2. air embolism 3. DCS |
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4 main actions you should consider in giving first aid for diving accidents are....
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1. maintain basic life support
2. call for help 3. treat for shock 4. deliver 100 % oxygen |
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what helps to prevent sea sickness
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settling yourself in a midway point of the boat and looking at the horizon
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what are hazards when diving in limited visibility or at night?
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increased anxiety, losing your buddy, disorientation and vertigo hazards
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what should you do if you're wearing an exposure suit?
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add buoyancy device to safely control buoyancy as you descend
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what are limits that must be established prior to every scuba dive?
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max bottom time, mac depth and min air pressure
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what are things that can make you incapable of sustaining the efforts sometimes demanded when participating in recreational diving
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inadequate sleep, a recent head cold, recent ingestion of drugs and poor fitness
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what do you do if the power inflation mechanism on your BCD sticks or freezes in the open position during a dive?
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immediately disconnect the inflator hose and vent air from the BCD as needed to maintain proper buoyancy
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first rule of scuba
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ALWAYS breathe (never hold ur breath)
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2nd rule of scuba
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always ascend slowly
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3rd rule of scuba
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never panic
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if you follow the 3 scuba rules, what can it prevent?
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air embolism and DCS
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whats the most effective way to descend while maintaining orientation and attempting equalization of the ears?
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going down feet first
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what will continued loosing of body heat in cold water do to you?
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produce muscle cramps, progressive immobility, insensitivity to pain, loos of reasoning ability and eventually unconsciousness
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what is physical fitness an important consideration for scuba divers?
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it helps prevent diving accidents due to exhaustion
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how do you check for neutral buoyancy or proper weighing?
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if you can take a normal breath, you're able to float at or near eye level
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symptoms of air embolism are.. and occur within how long of time out of water?
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4-6 mins
numbness, tingling, slurred speech, paralysis, respiratory and cardiac distress or arrest |
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what is the preferred action to take if you're alone and out of air at 30 ft in open water?
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it's an emergency swimming ascent
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what should you do it you're making an emergency swimming ascent?
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exhale continuously during the ascent and periodically attempt to inhale
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what is recommended when a dive team is diving from an anchored boat?
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to begin their dive against the prevailing current. they should also have a floating trail line 30 meters long w/ a buoy at the end
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what should you do if you and your buddy become separated?
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spend no more than 1 min looking for them, then ascend to the surface.
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what can help reduce the occurence of cramps during dives?
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potassium supplements
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how can you relieve a cramp in your calf?
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bend the toe of the fin toward the knee to stretch the muscle
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what indicates distress for a diver on the surface
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mask on forehead, waving their hand overhead and thrashing violently
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what should you do as soon as you reach a dive site
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observe conditions.
valuate conditions and make a sensible decision whether to dive or postpone. |
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when planning a safe dive one buddy team member should do what?
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act as the leader, must agree on activity/objective, set course to be followed, discuss contingency plans, emergency procedures and review hand signals
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what are common types of underwater entanglement?
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fishing line and aquatic plants
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