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SCUBA
Self contained underwater breathing apparatus What is the pressure change for each 10m/33ft of depth change? 1 bar/1 ata/1 atmosphere What is the relationship between my depth in water and the pressure? The deeper you go in water, the more the pressure increases Pressure is expressed as the weight of air What is the relationship between pressure, and the volume and the density of air? As pressure increases, the gas volume decreases and the gas density increases If I take a volume of air from one depth to another depth, how much will the volume and density change? Volume will be 1/ata# Density will be ata# What 3 major body air spaces does increasing pressure affect as I descend? Ears, sinuses, mask
What is a "squeeze"? The discomfort caused by pressure imbalance pulling tissue into the air space What is "equalization"? The addition of air to your air spaces as you descend How do I equalize as I descend? For ears and sinuses, pinch your nose and blow gently, or wiggle your jaw and swallow For mask, blow into it with nose How often should I equalize? Every meter/few feet, BEFORE you feel discomfort What should I do if I can't equalize? Stop your descent, signal problem and point to your ear, ascend a bit, and try again What can happen if I don't or can't equalize gently and keep descending? Fluid can rupture the eardrum Bruising around the face can occur Why does a congestion from a cold or allergy temporarily keep me from diving? Congestion might block normal air flow, making equalization difficult or impossible Why should I never dive with earplugs?1 / 15
Compared to the surface, air supply lasts 1/#ata as long along with other factors What's the most efficient way to breathe dense air underwater? Take slow, deep breaths How do I breathe to reduce anxiety when under stress? Do NOT breathe faster - keep breathing slowly What are my 4 breathing rules as a scuba diver?
- Breathe continuously and never holdyour breath2. Breathe slowly and deeply3. Don't allow yourself to get winded orout of breath4. If faced with a problem, stop, andreduce anxiety by breathing slowly anddeeply What is buoyancy? An upward force acting on an object in the water, canceling the pull of gravity 2 / 15 What causes buoyancy? The upwards force is caused by the water displaced by the object, and is
equal to the weight of displaced water positive buoyancy The object weighs less than the water it displaces, so it floats neutral buoyancy The object weighs the same as the water it displaces, neither sinking nor floating negative buoyancy The object weighs more than the water it displaces, so it sinks Why does salt water cause more buoyancy than fresh water? It has dissolved minerals in it, so a given volume weighs more than fresh water What 2 pieces of equipment do I normally use to control buoyancy? The weight system and the BCD (buoyancy control device) How does descending affect my buoyancy? The volume decreases, reducing buoyancy, so you ADD air to the BC How does ascending affect my buoyancy? The volume increases, adding buoyancy, so you RELEASE air from the BC
What are 2 basic fin styles? Full-foot and adjustable strap What consists of your scuba kit? Buoyancy control device, regulator, air cylinder, weight system What 5 components make up a BCD? Inflatable bladder, harness/jacket and cylinder band, low pressure inflator (LPI) mechanism, overpressure/quick dump exhaust valve, weight system inflatable bladder Controls buoyancy harness/jacket and cylinder band Holds cylinder on back low pressure inflator (LPI) mechanism Inflates bladder with air from your cylinder with the touch of a button overpressure/quick dump exhaust valve Vents air if the bladder is overfilled weight system Contain weight pockets that you release and drop in case of emergency What 2 special maintenance considerations do BCDs have? Rinse the inside of the bladder with fresh water, and store them partially
inflated to keep the bladder from sticking together What 5 components make up a regulator? First stage, second stage, alternate air source, low pressure inflator (LPI) hose, submersible pressure gauge (SPG) first stage Supplies air to all the other components, connecting to the cylinder valve by screw or clamp, reduces cylinder pressure to intermediate pressure (above surrounding pressure) alternate air source An extra second stage you use for sharing air with a buddyAttaches in triangle area between chin and hips second stage Reduces pressure to surrounding pressure, delivers air upon inhalation, vents exhalationGoes over right shoulder low pressure inflator (LPI) hose Supplies air to your BCD inflator submersible pressure gauge (SPG) 4 / 15
What is the most important feature in my weight system? A quick release that will enable you to float with an uninflated BC Why use more than 1 weight system? It will help distribute weight trim The orientation and balance of a swimmer in the water - the ideal is horizontal danger/hazard okay go up/end dive something's wrong 5 / 15 down/descend low on air okay distress/in trouble
How does being underwater affect the apparent size or distance of things? Refraction occurs, where light changes direction, and things are magnified by 1/ How does water affect light intensity and color? It reflects, scatters, and absorbs light in the roygbiv orderAs you go deeper, it gets darker 6 / 15 How does hearing differ underwater? It travels faster and longer How does water's density affect moving in water? It takes more energy the faster you try to swim What is "airway control"? The skill of breathing past remaining water without drawing any into your throat after clearing your regulator/snorkel What are 2 techniques for airway control? Inhaling slowly, looking down, and touching your tongue to the roof of your mouth as you inhale What are 8 symptoms of overexertion while diving? Fatigue, labored breathing, a feeling of suffocation, weakness, anxiety,
How do my buddy and I manage our air supply together while diving? Plan your dive around who breathes air the fastest.Subtract your reserve/ascent supply from your starting pressure to find out how much pressure you have for the 7 / 15 main part of the diveTo be safe, plan to use half your air coming down, and half coming back What are the 5 steps for a proper descent with scuba?
- Confirm that your buddy is ready2. Orient yourself to something3. Switch from your snorkel to your regulator4. Check your dive computer/timer5. Signal "descend" and slowly deflateyour BCD What are the 5 steps for a proper ascent with scuba?
- Signal "up" and confirm that your buddy is ready2. Check your dive computer/timer to besure you're within dive limits3. Look up and hold your BCD deflatorhose4. Ascend no
slower than your dive computer's maximum rate5. Look up, turn as you ascend, and staywith your buddy What is the maximum ascent rate? 18 m/60 ft//min What is a safety stop? A pause in your ascent between 6 m/20 ft and 3 m/10 ft to give your tissues extra time to release dissolved gases for at least 3 minutes When would I not make a safety stop? When you're assisting a diver who has an air supply problem or if you're low on air dive computer Tells you your time and depth underwater and guides you in keeping dissolved nitrogen in your body within accepted limits How do I measure/define visibility as a diver? The distance you can see horizontally underwater What 4 principles affect visibility? Water movement, weather, plankton, bottom composition 8 / 15
surge A back-and-forth motion caused by waves passing overhead undertow The water of waves flowing back to sea under incoming waves rip current When waves push water over a long obstruction and the water underneath funnels back to sea through an available opening What should I do if I get caught in a rip current? Establish buoyancy and swim at a sustainable pace parallel to the shore upwelling Usually caused by wind blowing from shore, pushing surface water away, resulting in cooler, deeper water rising towards the surface to replace it What 3 environmental conditions does tide generally affect? The current, depth, and visibility bow The front of the boat stern The back of the boat port 9 / 15
The left side of the boat as you face forward starboard The right side of the boat as you face forward leeward The side away from the wind windward The side toward the wind The bridge/wheelhouse The portion of the boat where the controls are head The boat's toilet facilities galley The boat's kitchen area swim step A platform on the stern that is close to water level What are characteristics of a responsive diver? They are breathing, alert, and active What are the 4 basic steps for assisting a responsive diver at the surface?
- Help reestablish breathing control2. Have the diver take slow, deep,breaths3. Give the diver a chance to rest
- Take lighter breaths and don't attempta safety stop as you ascend
- Use an alternate air source from your buddy
- Make a controlled emergency swimming ascent (CESA)
- Make a buoyant emergency ascent How do I make a controlled emergency swimming ascent (CESA)? When you have no air and are approximately 6-9 m/20-30 ft from the surface, look up and swim to the surface making a continuous ahhhhh sound into your regulator How do I make a buoyant emergency ascent? When you have no air and are very deep, ditch your weights, look up and swim to the surface making a continuous ahhhhh sound into your regulator How should I assist an unresponsive diver underwater and what is the priority? You want to get the diver to the surface. Hold the diver's regulator in their mouth and try to ascend at a safe rate
At a minimum, how many surface signaling devices should I have with me on a dive? At least 2 - one audible and one visual How close am I supposed to stay to a dive flag? Within 15 m/50 ft How far away are boaters supposed to stay from a dive flag? At least 30-60 m/100-200 ft For what 4 purposes might I carry a slate or wet book? Communication, to note dive plan limits, to record information during the dive, and for the unexpected What information do I typically record, at a minimum, regardless of what I choose? Date, dive site name/location, dive buddy, dive depth and duration, objective and description What can I do with dive planning software? Estimate how long your air supply will last and estimate the time your dive computer will allow on a dive 11 / 15 What is the composition of air to divers? 79% nitrogen and 21% oxygen
