PADI Open Water Diver Manual_02

Above water, you see, hear and move about ina familiar and comfortable manner thatseems “normal” because you’re used to it. Butunderwater, you’re in a new world where see-ing, hearing and staying warm differ from inair. You probably noticed this during yourfirst confined water dive (or you will).

Water is about 800 times denser than air,which is why light, sound and heat act differ-ently in water. Let’s look more specifically atsome of these differences so you can beginadapting to them during your dives.

Seeing and Hearing UnderwaterYou reach for your buddy and . . . you miss.What happened? Underwater things some-times look closer than they really are.

As you learned in Section One, the humaneye needs air to focus, which your mask pro-vides. However, even though your eyes canfocus, you still have some optical effectsbecause light travels at different speeds inwater and in air. When light changes speedgoing from water to air (like when it entersyour mask), it shifts its course slightly (thisis called refraction) which magnifies every-

TWO

Adapting to the Underwater World

Adapting to theUnderwater World

Respiration

Dive Equipment

Buddy System:Communicationand Procedures

Confined WaterDive Preview

Underline/highlight the answers tothese questions as you read:

1. How does looking at some-thing underwater affect itsapparent size?

2. How does water affect lightintensity and color?

3. How does being underwateraffect hearing?

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MAINObjectives

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thing about 33 percent. This makes things look larger and/orcloser, depending on your perspective.

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White light, such as sunligcolors mixed together. As wthrough water, the water aby one: first red, followed byellow. Since each color mathe total light, less light reincreases and the water ab

What big eyesyou have.When light changesspeed going from waterto air, it shifts its courseslightly, magnifyingeverything about 33percent. This makesthings look larger and/orcloser, depending onyour perspective.

Water also affects sound. Youize that the underwater worlworld. You’ll hear many newsounds, like snapping shrimppassing in the distance. Sounin air, so you’ll be able to heacan’t in air.

Unless you use special electrwon’t be talking much undervocally, and a few divers can

76 Open Water Diver Manual

Water affects light in otherways. As you descend, you’veprobably noticed there’s less ofit. This is because light reflectsoff the water’s surface, scattersoff particles in the water, andthe water absorbs it directly.However, water doesn’t absorblight uniformly.

ht, consists of allhite light travelsbsorbs colors oney orange andkes up part ofmains as depthsorbs each color.

This makes deeper water darker and lesscolorful. Red, orange or yellow objects oftenappear brownish, gray or black. To see morevivid colors on deeper dives, you may wantto take an underwater light, which providesunfiltered light and reveals color.

’ll quickly real-d is not a silent and interesting, grunting fish, and boat enginesd travels farther in water thanr things at distances that you

Rainbow.As white light travels through water, thewater absorbs colors one by one: first red,followed by orange and yellow, with greenand blue last.

Sound also travels about four times faster in water than inair. This makes it difficult to tell where a sound comes from.Underwater, sound usually seems to come from directly over-head, like listening to a mono recording through headphones.

onic communications gear, youwater. You can attract attention even make themselves under-

standable yelling through a regulator,but you’ll usually limit underwatercommunication by sound to attractingyour buddy’s attention. The easiestway to do this is to rap on your tankwith your dive knife or something elsesolid. Your buddy will hear the rap-ping, but may have to look around tofigure out where the sound comes from.

Heat Loss Underwater

Underline/highligthese questions a

4. How does theloss in water of body heat

5. What should shiver continu

MAObje

1. Underwater, what you look at will be:a. reduced 25%.b. reduced 33%.c. magnified 25%.d. magnified 33%.

2. Water absorbs light, causing (checkall that apply):a. it to get darker as you go deeper.b. colors to become more vivid withdepth.c. colors to become less vivid withdepth.d. None of the above.

3. Underwater, sounds:a. don’t travel very far.b. are easy to locate.c. often seem to come from directly

QUICKQUIZ Self Assessment 1

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Being cold takes the fun out of diving,and beyond enjoyment, there’s thepotential for a serious health threat ifyou get too cold. In air, you lose bodyheat as it transfers from the skin intothe air, and as perspiration cools theskin through evaporation. Water con-ducts heat about 20 times faster thanair does, meaning that for a given tem-perature, water cools you much faster.In air, 30°C/86°F is warm, but in waterit becomes chilly after a while.

Left unchecked, body heat loss canlead to hypothermia, a serious condi-tion in which your body cools so muchit can’t function normally. To avoid

this, you use insulation (wet suits anddry suits), especially when diving inwater colder than about 24°C/75°F. Tostay comfortable, you may want towear a wet suit in even warmer water.

Exposure suits don’t really “keep” youwarm, but slow down heat loss enoughthat you stay comfortable throughoutthe dive. This means that even withan exposure suit, you will chill if youstay in the water long enough.Continuous, uncontrollable shiveringis your body’s warning signal thatheat loss has reached a critical level.

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ht the answers tos you read:

rate of body heatcompare to the rateloss in air?

you do if you begin toously underwater?

INctives

overhead.

How’d you do?1. d. 2. a, c. 3. c.


1. Water absorbs heat about_________ times faster than air.a. 10b. 15c. 20d. 30

2. Beginning to shiver continuouslymeansa. you should swim faster to warmup.b. you should immediately end thedive, dry off and seek warmth.

How’d you do?1. c. 2. b.


Underline/highlight the answer tothis question as you read:

6. How should you move under-water to compensate for theincreased resistance of water?

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When you begin to shiver continuously, getout of the water immediately, dry off andseek warmth.

An important point is that modern wet suits anddry suits do an impressive job — even in fairly coolwater, you don’t have to get cold. If you feel coldwhile diving, you’re probably not wearing enoughinsulation. Ask your PADI Professional for advicewhen buying your exposure suit.

Motion in WaterOne of the interesting things about diving is thatit’s exciting and relaxing at the same time. Youwant to avoid getting out of breath, and there’s lit-tle reason for hurrying anyway.

Water’s density makes it resist movement. If you’veever tried to run in waist-deep water, you’ve experi-enced this. So, you conserve energy by movingslowly and steadily. Avoid rapid or jerky movementsthat waste energy and cause you to use air faster.Take your time and you’ll stay under longer and go farther.

Your profile in the water relates to this, too. If youstreamline yourself by swimming level and keepingyour hoses and equipment tucked in close, you save

Sleek = easy.Streamlining by swimming level and keeping your hoses and equipmenttucked in close saves energy by reducing drag. Wearing more weightthan you need pulls your hips down and requires extra air in your BCD,which creates more drag. Your PADI Professional can help withsuggestions on streamlining your equipment.

energy because there’s much less drag against thewater. On the other hand, if you wear more weightthan you need, it tends to pull your hips down, andyou don’t swim horizontally. You need more air inyour BCD, which raises your upper body and cre-ates more drag. All of these cause you to use airfaster and tire quickly.

Even when you’re streamlined and weighted prop-erly, swimming fast or working causes you to tirequickly. Learn to pace yourself, take it easy andrelax while diving.

You probably noticed that you can’t breathe water.Hence the tank. But even though you breathe airunderwater when you scuba dive, it differs a bitfrom breathing at the surface. Let’s look at why itdiffers, and how you breathe most effectively whilescuba diving.

Breathing EfficiencyEach breath you take contains oxygen, which yourbody uses to create energy. This is why you needoxygen to live.

When the airreaches your lungs,your blood absorbsthe oxygen and car-ries it throughoutyour body as it circu-lates. It picks upwaste carbon dioxidefrom the cells andreturns it to thelungs, so when youexhale, the waste carbon dioxide leaves.

The oxygen and carbon dioxide transfer only withinyour lungs. The air passages to and from your lungs— your mouth, throat and windpipe — contain air

Respiration

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1. The best way to move underwateris:a. as rapidly as possible.b. slowly and smoothly, relaxed.

How’d you do?1. b.


In this subsection on Adapting to theUnderwater World, you learned:

s Objects are magnified 33 percentwhen you see them underwater,making them look closer and/orlarger.

s Water absorbs light and colors.

s It’s hard to tell sound direction underwater.

s Water absorbs heat about 20 timesfaster than air.

s If you start to shiver continuously, getout of the water, dry off and seekwarmth.

s It’s best to move slowly and stayrelaxed underwater.


7. How do you breathe underwa-ter for maximum efficiency?

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Summary PointsSummary Points

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that plays no direct part in oxygen and carbon diox-ide transfer. These are called dead air spaces.Snorkels and regulators increase the dead air spaceby increasing the volume of the air passages.

When you inhale, the first air that reachesyour lungs is air left in the dead air spacesfrom your previous breath. This air is highin carbon dioxide. If you take shallow breaths, youinhale proportionately little fresh air and propor-tionately high carbon dioxide. You essentially re-breathe the air from your dead air spaces. Shallowbreathing isn’t efficient because so little of the airyou move actually takes part in oxygen and carbondioxide exchange.


1. For maximum efficiency, underwa-ter you should breathe:a. slowly and deeply.b. quickly and shallowly.

How’d you do?1. a.



8. What are eight symptoms ofdiving overexertion?

9. How do you prevent divingoverexertion?

10. What should you do if youbecome overexerted while div-ing — either at the surface orunderwater?

MAINObjectives

Dead air.Your mouth, throat and windpipecontain air that plays no direct part inoxygen and carbon dioxide transfer.These are called dead air spaces.Snorkels and regulators increase thedead air space.

ArtificialDead AirSpace

NaturalDead AirSpace

SNORKEL REGULATOR

ArtificialDead AirSpace

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On the other hand, with a deeper breath you drawin proportionately more fresh air. This means deepbreathing is more efficient breathing. For maximumbreathing efficiency, you want to breathe slowly anddeeply underwater. When using scuba, inhale andexhale more slowly and deeply than normal — notan exaggerated amount, but a bit more than usual.Breathe the same way when using a snorkel, butyou may need to exhale sharply and rapidly fromtime to time to blow out water.

OverexertionIf you try to maintain an elevated activity levelwhile diving — like swimming against a current,swimming long distances or carrying excessiveweight — you may experience overexertion. The

Stop!If you experience overexertionsymptoms underwater, stop allactivity, breathe deeply and rest.Catch your breath. Hold on to anobject for support, if possible,and relax.

1. Symptoms of overexertion include(check all that apply):a. labored breathingb. euphoriac. anxietyd. a feeling of suffocation

2. To prevent overexertion (check allthat apply):a. wear a lot of weight.b. pace yourself.c. know your limits.d. avoid prolonged heavy exertion.

3. If you become overexerted:a. stop all activity and rest.b. swim rapidly into the current.

How’d you do?1. a, c, d. 2. b, c, d. 3. a.


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symptoms include fatigue, labored breathing, a feel-ing of suffocation, weakness, anxiety, headache,muscle cramping or a tendency to panic.

Overexertion results when your body demands airfaster than breathing can deliver it. This can hap-pen more easily underwater because you’re breath-ing dense air, you’re moving against water resis-tance, and scuba regulators have limits on howmuch air they can deliver.

Obviously, you want to prevent overexertion.Know your physical limits and pace yourselfto avoid breathlessness. Move slowly andavoid prolonged exertion. If you experience overex-ertion symptoms underwater, stop all activity,breathe deeply and rest. Catch your breath. Anyfurther activity only adds to your body’s oxygendemand. Hold on to an object for support, if possible,and relax until your breathing returns to normal.

If you experience overexertion at the surface, estab-lish buoyancy (by dropping weights, if necessary)and stop moving. Rest and catch your breath. Signalfor help if necessary. Once you recover, proceed at aslower pace.

Airway Control and Breathing GoalsYou’ll find that it’s not unusual to have a smallamount of water in your regulator or snorkel, par-ticularly after clearing it. No problem — you use

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airway control to avoid accidentally drawing a fewdrops into your throat.

82 Open Water Diver Manua

Underline/highlight the athis question as you rea

11. What are three technused for airway cont

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Proper airway control means to: 1) Always inhaleslowly if water enters your regulator, snorkel or mouth,so you don’t pull it into your throat; 2) always inhalecautiously and slowly after clearing your snorkel or reg-ulator; and 3) use your tongue as a splash guard byputting the tip on the roof of your mouth when youbreath past small amounts of water. Looking downwardslightly helps keep the water in the second stage andout of your mouth. After you breathe slowly past the

water, exhale sharply to expel the water from your mouth, regula-tor or snorkel. With practice, you’ll find you can use airway con-trol to breathe past a surprising amount of water.

nswer tod:

iquesrol?

es

If you ever accidentally inhale somewater, you’ll choke and cough a bit.Not to worry, this is how your bodykeeps water out of your lungs. Staycalm, hold your snorkel or regulatorin place with a hand and cough intothe mouthpiece as you need to.Each cough helps clear the regula-tor/snorkel, so you’re solving bothproblems at once. Swallowing mayhelp you to stop coughing, resumebreathing and regain airway con-trol. Airway control typicallybecomes a natural habit with a lit-tle experience.

To summarize, your breathing goalsunderwater: Always breatheslowly and deeply and continu-ously when using scuba. Strive to develop airway control.

In the last section, you learned about masks, snorkels, fins, BCDs,tanks, valves, regulators, and the SPG. That’s not a bad start, butas you know there’s more. Let’s look at exposure suits and theiraccessories, weight systems, alternate air sources, dive knives,

Dive Equipment

l

1. Techniques for airway controlinclude (check all that apply):a. inhaling slowly if water entersyour regulator or snorkel.b. inhaling cautiously after clearingyour regulator or snorkel.c. using your tongue as a splashguard.

How’d you do?1. a, b, c.


equipment bags and dive instruments.

In this subsection on Respiration, youlearned:

s For maximum efficiency, breatheslowly and deeply.

s Overexertion symptoms includefatigue, labored breathing, a feelingof suffocation, weakness, anxiety,headache, muscle cramping and atendency to panic.

s You prevent overexertion by stayingrelaxed and knowing your limits.

s If you become overexerted, stop allactivity and rest.

s Airway control lets you breathe pastsmall amounts of water.

Summary PointsSummary Points

Form fitting.Made from colorful Lycra, nylon or asimilar material, body suits providefull-length abrasion and sunburnprotection. They don’t insulate much, so they’re primarily worn in tropical waters.

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Purpose. You’ll want to use an exposuresuit in virtually all diving activities for twobasic purposes: to reduce heat loss, and toprotect you from minor scrapes, stings andabrasions.

Styles. You can use three basic styles ofexposure suits, each with its own character-istics of how much exposure protection itprovides: the body suit, the wet suit and thedry suit.

Body suits — Made from colorful Lycra,nylon or a similarmaterial, body suitsprovide full-lengthabrasion and sun-burn protection.They don’t insulatemuch, so they’re pri-marily worn in tropi-cal waters. You maywear a body suit tohelp you slide into awet suit more easilyand for extra warmthin a wet suit. Bodysuits fit your figureclosely, and you can get them in brightcolors and patterns.

Wet suits — Wetsuits are by far themost common form ofexposure suit. Youcan get them inmany styles, patterns and thicknesses, mak-ing them suitable for insulation in water ascold as 10°C/50°F to as warm as 30°C/86°F.

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12. What are the two reasons forwearing an exposure suitwhile diving?

13. How do dry suits and wetsuits insulate divers?

14. Why must a wet suit fitsnugly?

15. What two properties may anexposure suit lose due toincreased water pressure atdepth?

16. What three factors should youconsider when selecting anexposure suit?

17. What four procedures apply tocaring for an exposure suit?

MAINObjectives


When you explore the fragile environment around corals, sponges and otheraquatic life without exposure suit protection, you tend to be cautious. After all,you need to watch what you touch to prevent abrasion or a minor sting.

Wearing exposure suits takes away this incentive, which canmean harm to the environment unless you keep its welfare inmind. Hopefully, you wouldn’t intentionally kick, kneel on orbump against fragile aquatic life, but exposure suits make itmore difficult to tell when you do it accidentally. Realize thateven a light touch can harm or kill some organisms. Break a25 cm/ 10 in piece of coral, for example, and you’ve destroyeda decade of growth.

By being aware and using some simple techniques, you canminimize accidental damage:

1. Swim next to the reef rather than above it. This avoids dam-age from your fin kicks.

2. Watch your buoyancy, and don’t dive overweighted. Stay neutral to avoid the ten-dency to drag along the reef where your legs and feet can destroy things.

3. Turn sideways when you look under ledges. Your tank adds some height, and it’s notalways easy to estimate how much. If you turn sideways, you reduce the likelihoodof bashing your tank against the reef.

4. If you need to swim over the reef, swim well above it.

5. Keep your hoses secured and don’t let anything dangle.

In general, avoid touching living organisms underwater. Keep inmind that just because you are safe from the reef doesn’t meanthe reef is safe from you.

EXPOSURE SUITS

Exposure Protection Doesn’tMean Reef Protection

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http://www.projectaware.org/

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Wet suits reduce heat loss by putting a layer of insu-lating foam neoprene over your skin. Wet suits gettheir name because you get wet while wearing them— water enters at the wrists, ankles and neck andgets trapped between your skin and suit.

Dry suits — Dry suits can provide more insulationthan wet suits by keeping you dry. They provide themost thermal protection of all suits used by recre-ational divers, and make a noticeable difference inhow long you stay comfortable at temperatures ofabout 18°C/65°F. In water colder than about 10°C/50°Fthey’re the main option for a comfortable dive.

Versatile.Wet suits are by far the most common formof exposure suit. You can buy them in manystyles, patterns and thicknesses, makingthem suitable for insulation in water as coldas 10°C/50°F to as warm as 30°C/86°F.

Air conducts heat relatively poorly, so the dry suitinsulates you with a layer of air, plus insulatingmaterial that may be an undergarment within thedry suit, or the dry suit material itself. Unlike a wetsuit, in a dry suit everything between your skin andthe water reduces heat loss, and also unlike a wetsuit, they fit relatively loosely.

Your body quickly heats the water, and then as longas it remains trapped, you only lose heat as it radi-ates slowly through the wet suit material. If watercirculates in and out of your suit, however, you lose alot of heat to incoming cold water. This is why wetsuits have to have a snug fit. You can get wet suits inmany colors that go with the rest of your kit.

You read earlier that since dry suits create an airspace, you need to equalize them just like any otherair space. You also need to release expanding air asyou ascend. To do this, dry suits fill with air directlyfrom your cylinder via a low-pressure inflator similarto the one on your BCD. This adds another hose toyour regulator. Dry suits also have an exhaust valvefor releasing air as you ascend.

Diving with a dry suit isn’t difficult, but it requiressome special instruction — a short course you can usuallycomplete over a weekend. If you’ll use a dry suit during thiscourse, your instructor will orient you to its use during one

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Max insulation.Dry suits provide the most thermal protection of allsuits used by recreational divers, and make anoticeable difference in how long you staycomfortable at temperatures of about 18°C/65°F. Inwater colder than about 10°C/50°F they’re the mainoption for a comfortable dive.

of your confined water dives. In any case, remember that coldwater doesn’t take the fun out of diving — being cold does. Witha dry suit, you can dive in surprisingly cold water in reasonablecomfort, which is a good thing because you find some of the bestdive sites in water below 15°C/60°F.

Features. Of the three styles of exposure suits, the wet suit hasthe widest array of available features. This is because of the verydiverse environments in which you can use a wet suit. Commonwet suit options include length, one-piece or two piece, longsleeve or short, thickness, color, pads for the knees and elbows,pockets, and zipper position. Dry suits also have most of theseoptions, but since they’re intended for cooler water, they coveryour entire body.

Materials. As mentioned earlier, body suits, which are the sim-plest exposure suits, are made of thin nylon or Lycra. Wet suitsare made from closed-cell neoprene foam lined on both sides bynylon or another material (for strength and appearance). Closed-cell means that the bubbles in the foam differ from sponge foam


How they hold heat.Wet suits reduce heat loss by putting a layerof insulating foam neoprene over your skin.You get wet, but your body quickly heats thewater and you only lose heat as it radiatesslowly through the wet suit material. A drysuit insulates you with a layer of air, plusinsulating material (an undergarment or thedry suit material itself). In a dry suit every-thing between your skin and the waterreduces heat loss.

Wet Suit

Skin

WaterSkin

InsulatingMaterial/Air

Dry Suit

WET SUITDRY SUIT

Water

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in that the bubbles don’t connect. Neoprene foam won’tsoak up water like a sponge, nor will water flowthrough it.

It’s the thousands of tiny closed-cells that make wetsuits buoyant. If you’ve not tried it yet, even a partialwet suit has enough buoyancy to float you comfortablyat the surface. Without weight to offset the suit’s buoy-ancy, it’s quite difficult to get below the surface.

You can fiprene. Aland wrist

A neopreprene anrics insulundergarately warundergarsame sui

Because ant than ments, thAnother adon’t loseyou add aand insul

Suit in a suit.In addition to a dry suititself, you need a specialundergarment like the onethis diver is wearing. Theundergarment provides theinsulation, and the dry suitkeeps you dry.

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The gas trapped in the neoprene foam bubbles pro-vides excellent insulation, but as you descend, theycompress from water pressure. Consequently, a wetsuit loses buoyancy and insulation the deeper youdescend. You compensate for reduced buoyancy byadding air to your BCD; to stay warm, choose a wetsuit based on the depth you’ll be diving.

nd dry suits made from several fabrics, including neo-l dry suits have a special watertight zipper and neck seals to keep the water out.

ne dry suit gets most of its insulation from the neo-d the air inside it, while dry suits made from other fab-ate with special undergarments — in fact, without thements, you’d chill in these dry suits, even in moder-m water. The advantage is that you can vary thements to suit the temperature, so you can use thet whether you’re diving in water 24°C/75°F or 2°C/36°F.

you fill them with air, dry suits tend to be more buoy-wet suits. However, with modern suits and undergar-ey’re not that much more buoyant in most cases.dvantage of a dry suit is that with most types, you buoyancy or insulation with depth. As you go deeper,ir to the suit, maintaining both normal buoyancy ation.

Selection and Purchase. You buy an exposure suit based almostentirely on the environment you intend to dive in. The mostimportant considerations — regardless of whether you choose abody suit, wet suit or dry suit — are warmth (insulating abil-ity), fit and comfort. Fit is especially important with wet suits; if

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a stock suit doesn’t fit you well, a custom wet suit doesn’t cost thatmuch more, yet makes a huge difference in comfort.

Don’t underestimate how important your exposure suit will be —your comfort depends on it. Look at the total picture. For instance, thetwo primary drawbacks of a dry suit are that it’s a higher initialinvestment than a wet suit, and it requires more predive and post divecare. But if you live in a cooler climate, the added insulation maymean you make longer dives, dive for a longer part of the year, andmake more dives in a day. Your PADI Instructor, Dive Center or Resortcan recommend the best exposure suits for your needs and whereyou’ll be diving.

Preparation. Body suitsand wet suits generallyrequire no special prepa-ration before use. Somedry suits do requirepreparation, however,this varies from suit tosuit. Consult the owner’smanual included withthe suit.

Maintenance. All expo-sure suits have fourbasic maintenancesteps: 1) rinse, 2) dryinside out, 3) store and4) lubricate dry suit zip-pers periodically. Storewet suits on a wide plas-tic or wooden hanger(not wire); store drysuits folded gently withthe zipper on top, or asdirected by the manu-facturer. Always dry andstore suits out of directsunlight.

Avoid leaving your wetsuit tightly folded or

Open Water Diver Manual

1. The two reasons for wearing anexposure suit are (check two):a. thermal protection.b. so you can disregard whetheryou bump into the reef.c. to protect against minorscrapes, abrasion and stings.

2. A ____________ suit insulatesyou with a layer of neopreneagainst your skin, whereas a________ suit insulates you witha layer of air and other insulatingmaterial.a. dry, wetb. wet, bodyc. body, dryd. wet, dry

3. A wet suit must fit snugly to:a. maintain streamlining.b. keep the suit from coming off.c. minimize water circulation andretain heat.

4. As you go deeper, a wet suit maylose what two properties?a. fit and comfortb. buoyancy and comfortc. buoyancy and insulationd. insulation and fit

5. When purchasing an exposuresuit, you need to consider (checkall that apply):a. fitb. comfortc. thermal protectiond. looking really attractive

6. To care for your exposure suit,you should (check all that apply):a. hang it on a wire hanger.b. rinse it after each use.c. dry inside out.d. store on a hanger (for wetsuits).

How’d you do?1 a, c. 2. d. 3. c. 4. c. 5. a, b, c. d isa consideration, but not a necessaryconsideration. 6. b, c, d.


packed for extended periods. At the creases the closed-cellscollapse, reducing their ability to insulate. Coated-fabricdry suits may stick together if folded or stored too long;storage recommendations for dry suits vary, so consult themanufacturer’s literature.

Modern wet suit zippers seldom need lubrication if yourinse them properly after use. You lubricate dry suit zip-pers with a special zipper wax — never use silicone lubri-cant on a dry suit. Minor suit repairs can be made easilywith special cement available from dive stores.

Exposure Suit AccessoriesIn cooler water — below about 21°C/70°F — you needexposure protection for your head, hands and feet as wellas the rest of you, and you may prefer these in warmerwater. You also need to protect your feet and hands fromcuts and abrasion. You get this protection through expo-sure suit accessories — namely hoods, gloves and boots.

Underline/highlight the answers to thesequestions as you read:

18. Why do you need a hood and whatare the three basic types of hoods?

19. Why should you avoid an exces-sively tight-fitting hood?

20. What are two reasons for wearingdive gloves?

21. What are three reasons for wearingwet suit boots while diving?

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Hoods. Your head can account for up to 75 percent of your body heatloss if you leave it uninsulated. You may want it in warmer water,but you definitely want to consider a hood any time you dive inwater below about 21°C/70°F. Hoods provide some abrasion protec-tion as well.

Wet suits, and most dry suitsused by recreational divers, useneoprene wet suit hoods. Youcan choose from a variety ofthicknesses in three basic types:bibbed hoods, nonbibbed hoodsand hooded vests.

Over head.Bibbed hoods (right) flareinto a broad flange, or “bib”that you tuck under the neckof a wet suit jacket, or into aspecial collar on some drysuits. Dry suits with insulatedneck seals use nonbibbedhoods. (left)

Bibbed hoods flare into a broadflange, or “bib” that you tuckunder the neck of a wet suitjacket, or into a special collar onsome dry suits. In wet suits, thebib creates a snug fit between your neck and the jacket and mini-mizes water circulation. In dry suits, the bib insulates the neck sealto eliminate a cold spot. Dry suits with insulated neck seals use non-bibbed hoods. Some divers use a hooded vest, which gives you all the

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90 Open Water D

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benefits of a bibbed hood, plus extra insula-tion for your entire torso.

Divers who live in cooler climates may notselect a separate hood at all, but may insteadchoose an exposure suit with a permanentattached hood. You can find both wet suitsand dry suits with this configuration.

ers.tect your hands on virtually everywater, you may use lightweightloves (“reef” gloves, left); in water, wet suit gloves providerotection (center); thick wet suitrn in coldest water (right).

Select a hood that fits snugly, but not tootightly. A hood that’s too tight can compressarteries in your neck (the carotids), whichyour brain perceives as high blood pressureand responds by signaling your heart to slow.This can cause light-headedness and, if youkeep the hood on, fainting and unconscious-ness. A hood this tight will be uncomfortable, so don’t try toendure it and wear it anyway. Purchase your hood based oncomfort and fit.

Tender fingYou want to prodive. In warmer noninsulating gmoderately coolinsulation and pmitts may be wo

Gloves. Your hands don’t have much natural insulation, mak-ing them susceptible to heat loss. In colder water, they maybecome numb and lose dexterity if you don’tprotect them. You may find it difficult to oper-ate your equipment and perform other safety-related tasks. In warmer water, your handsmay soften after you’ve been in a short time,making them especially vulnerable to scrapes,cuts and stings.

it.ction consists ofemirigid soles

semihard rubber,es for traction

So, you want to protect your hands on virtu-ally every dive. In warmer water, you may uselightweight noninsulating gloves (“reef”gloves); in moderately cool water, wet suitgloves provide insulation and protection. Inthe coldest water, you might want to buy thickwet suit mitts, or with a dry suit, dry gloves(common in commercial diving, but not socommon in recreational diving).

Although gloves provide protection, don’t treat them as alicense to touch anything you want. First, you can still get cutor stung through gloves, and second, your touch can damage or

Put your foot inTypical boot construneoprene foam with smolded from hard orwith textured surfacand protection.

iver Manual

http://www.projectaware.org/

injure aquatic life. Use common sense, and becareful to protect the underwater environment.

1. You need a hood because as muchas _________ percent of bodyheat loss can occur there.a. 25


Underlinthis que

22. In wprevdivesure

MOb

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Boots. Even if you dive exclusively in tropicalwaters, you may still want to purchase wet suitboots (also called “booties”) for three reasons:Warmth (particularly in water below 21°C/70°F),protection against cuts, scrapes and bruiseswhile walking to and from the water, and forcomfort when wearing adjustable-strap fins.

Typical boot construction consists of neoprenefoam with semirigid soles molded from hard orsemihard rubber, with textured surfaces fortraction and protection. In some models, the solewraps up over the heel and toe for protectionand longer wear. Some boots have side-entry zip-pers, which helps when putting them on.

Dive boots fit either by shoe size or S, M, L, XL,XXL, etc., and should be comfortable withoutbeing excessively large or small. Your instructor,resort or dive center can help you choose prop-erly fitting boots.

b. 50c. 75d. 90

2. A bibbed hood:a. does not get tucked into a wetsuit jacket.b. is never used with any type drysuit.c. None of the above.

3. An excessively tight hood:a. can cause you to faint, so youshouldn’t wear it.b. will be the warmest, so it’s thebest bet.c. usually loosens in water, soyou’ll find it comfortable while diving.

4. You wear gloves for insulation and:a. to protect your hands.b. so you can touch anything youwant.

5. Wet suit boots (check all thatapply):a. insulate your feet.b. provide protection against cutsand scrapes.c. provide comfort with adjustablestrap fins.

How’d you do?1. c. 2. c. 3. a. 4. a. 5. a, b, c.

OverheatingAn important note regarding wet suits, dry suitsand their accessories: Because they’re such goodinsulators, out of water on a warm day you can

overheat in them. Youcan follow these pointsto avoid overheating:

1. Set up all your equip-ment before putting onthe exposure suit. Putthe suit on at the lastpossible moment.

2. Once you have thesuit on, limit your activ-ity as much as possible.

e/highlight the answer tostion as you read:

hat six ways can you ent overheating before a when wearing an expo- suit?

AINjectives

Chapter Two 91


1. To prevent overheating before a dive(check all that apply):a. exercise to promote perspiration.b. put your exposure suit on at thelast possible moment.c. keep your hood off as long aspossible.d. cool off in the water.

How’d you do?1. b, c, d.



23. What are two types of weightsystems?

24. What’s the most importantfeature of any weight system?

25. How do you determine howmuch weight you need for adive?

MAINObjectives

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3. Stay out of the sun as much as possible.

4. Keep your hood off, or at least pulled back offyour head as long as possible.

5. Leave your jacket unzipped as long as possible.

6. Cool off by entering the water, or sprayingdown with a hose (common on dive boats) asmuch as you need.

Weight SystemsPurpose. If you ask most people why diversstrap lead to themselves, the most likely answerwould be, “To make you sink,” which would be alogical, common-sense answer. A wrong answer,but logical and common sense anyway. If you’relike most people, you naturally float, and if youwear a wet suit or dry suit, you will float. So,you’ll often wear a weight system to let you sink— not make you sink. This isn’t splitting hairs —you want to just offset your positive buoyancy,which allows you to sink. If you’re properlyweighted, you do not sink like a stone.

Styles, Features and Materials. You can get twobasic weight system types: the weight belt, andthe integrated weight system. Both use leadweights, and both have a quick release thatallows you to release your weight with one handin an emergency. The quick release is the mostimportant feature on any weight system.

Weight belts have the longest history as weightsystems; they’re the most common, though diversuse other weight systems more and more. Thetypical weight belt consists of 5 cm/2 in nylonwebbing threaded with weights and a quickrelease buckle. Variations include different beltmaterial and pocketed belts that you can adjustmore easily. A few belts use lead shot for com-fort, either in specific weight pouches, or in one

Chapter Two 93

If you select a weight belt as your weight sys-tem, you’ll want to set it up so that it’s comfort-able, and so the weight stays where you put it.Some divers who wear a lot of weight also putpart of their weight in an integrated weight sys-tem, and part on a belt, distributed so thatditching either results in ample positive buoy-ancy in an emergency.

First, determine how long you need the belt tobe. The free end should protrude about 15 to20 cm/6 to 8 inches from the buckle whenyou’re wearing it. You’ll probably need to trimyours — but don’t do it until you’ve figured outthe right amount of weight you need on it.Alternatively, many weight belt buckles let youtake up slack at the buckle end and route itback under the belt. This way you don’t have tobuy a new belt if you need more weight and

length later. If this isn’t an issue, trimming thebelt eliminates excess webbing.

Either way, measure the belt with all theweights and the buckle on it as it fits aroundyour wet suit. After cutting the belt to the rightlength, you singe the cut edge to keep it fromunraveling. A butane lighter works well for this.Before singeing, you may want to round thecorners first, to make it easier to pass the endof the belt through the buckle.

Try to distribute the weights evenly, so thesides mirror each other. Leave a space in thecenter of your back where the tank goes, andleave about 10 cm/4 in clear next to the buckleso you can work it easily. Finally, after you’rehappy with the weight distribution, use retainingclips so they stay put.

Setting Up a Weight Belt

WEIGHT RETAINERS

Retainer

Weights

Retainer

Threading Weight Retainersfor Block Weights

Weights

Threading Weight Retainers for BulletWeights (keeps weights from slipping)

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giant pouch with exactlythe weight you need. Thelatter is very comfort-able, but much moretrouble to set up.

Weight systems usually integrate with the BCD, though afew integrate with a separate harness you wear underyour BCD. They vary widely, but like the weight belt, theyalso have a quick release or releases for one hand weightditching in an emergency.

Remember that you need to wear your weight system soit’s clear of all other equipment and you can releaseweight quickly with one hand in an emergency. Note thatsome integrated weight systems will have two quickreleases — that’s fine because you don’t have to be able torelease all your weight, but enough weight to assure posi-tive buoyancy in an emergency.

Selection and Purchase. Whether you buy a conventionalweight belt or a weight system depends on your prefer-ences, and how much weight you’ll need (usually more incooler water to offset the buoyancy of your exposure suit).It’s something to consider when selecting your BCD, sincethat’s where you’d probably have an integrated system.


Ballast on board.Weight belts are the mostcommon weight systems,though divers use othertypes more and more. Thetypical weight belt consistsof 5 cm/2 in nylon webbingthreaded with weights and aquick release buckle. Weightsystems usually integratewith the BCD and have aquick release or releases forone hand weight ditching inan emergency.

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Preparation. See the sidebar for weight beltbasic setup. Integrated weight systems vary,consult the manufacturer literature. Animportant part of setup is determining howmuch weight you need. Here’s how you do it— you’ll practice with your instructor duringthe confined water dives:

1. Enter the water with all your equipmenton and your estimated weight requirement.

2. Keep your regulator in your mouth, andstaying at the surface, deflate your BCD andhold a normal breath. Be ready to kick orhold onto something in case you’ve got toomuch weight.

1. The two types of weight systemsare the weight belt and the inte-grated weight system.True False

2. The most important feature of aweight system is:a. comfort.b. fit.c. a quick release.d. easy adjustment.

3. If you’re properly weighted, you will:a. sink quickly.b. float at eye level with an emptyBCD and holding a normal breath.c. None of the above.


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3. You should float at eye level. If not, add orsubtract weight until you do. You can holdweights while you figure out how much youneed, then adjust your weight system.

4. As a final check, exhale. You’ll begin toslowly descend if you’re properly weighted.

5. If you’re using a full cylinder, now add asmall amount of weight (usually about 2 kg/5lbs). Why? Remember, air has weight (that’s why itcauses pressure). As you use up the air in your tank,the tank gets lighter. Using a single cylinder, addingabout 2 kg/5 lbs compensates so that you’ll have aboutthe proper weight at the end of your dive with a near-empty cylinder.

Maintenance. Most weight systems require very littlemaintenance, aside from a brief rinse after use. Inte-grated weight systems may have additional require-ments, so consult the manufacturer instructions.

Do handle weight systems carefully. Dropping a weightbelt can break gear and cause injury. Scuba units withintegrated weight systems usually won’t stand well, even

Chapter Two 95

How’d you do?1. True. 2. c. 3. b.

on level solid ground, so be sure to liethem down or secure them in place.

Alternate Air SourcesPurpose. If you pay attention to yourSPG and plan your dive conservatively,

it’s unlikely thatyou’ll run out of airunderwater.Nonetheless, youneed to be able tohandle such anemergency; you’llpractice a fewresponses duringyour confined waterdives. Among themost desirableoptions is to use analternate air source,

which you practiced using during your

96 Open Water Diver Manu


26. What’s an alternate air source?

27. What two types of alternate airsource require the help andcooperation of another diver?

28. What type of alternate air sourcedoes not require the help andcooperation of another diver?

29. Why it is important to speciallymark an extra second stageused as an alternate air source?

30. How and where should youattach your alternate air source?

MAINObjectives

Just in case.The extra regulatorsecond stage is thealternate air sourcesecond stage, alsocalled an “octopus.” Forease of use, it typicallyhas a hose longer thanthe primary secondstage that you put inyour mouth.

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first confined water dive. An “alternateair source” is any second stage you mayuse, other than your own primary secondstage, to ascend while breathing normally.

a

One for two.An alternate inflator regulatorcombines the functions of a low-pressure BCD inflator and a secondstage, so you find it on your BCD hose.With this alternate air source, thedonor usually gives the buddy theprimary second stage and switches to the alternate inflator regulator.

Styles and Features. The alternate airsources most recreational divers userequire your buddy’s help, though youcan use some on you own.

Alternate air sources that requireanother diver include the alternate airsecond stage and the alternate inflatorregulator.

The extra second stage on your regulatoris the alternate air source second stage(also called an “octopus”) type. For easeof use, it typically has a hose longer thanthe primary second stage that you put inyour mouth.

l

An alternate inflator regulator combines thefunctions of a low-pressure BCD inflatorand a second stage, so you find it on yourBCD hose. With this alternate air source,the donor usually gives the buddy the pri-mary second stage and switches to thealternate inflator regulator.

In either case, with this type of alternate airsource, your alternate allows you to assistyour buddy, or your buddy to assist you.Obviously, having an extra second stagedoesn’t do you any good if there’s no air inyour tank.

Know where to look.Mark your alternate airsource so your buddycan identify it quickly.Secure the alternate inthe triangle formed byyour chin and the lowercorners of your rib cage.

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The pony bottle is an alternate air sourcethat you can use independently. It’s a small

scuba tank normally strapped alongside your main tank,with its own regulator. Another alternate air source youcan use is the self contained ascent bottle, which is asmall air cylinder with a very simple regulator that hasjust enough air to reach the surface. You usually strapthese to your BCD in a special holster. Most divers whohave a pony bottle or self containedascent bottle also have an alternate sec-ond stage for sharing air with an out-of-air buddy.

Selection. Most divers prefer alternateair source second stages and alternateinflator regulators because they cost lessand have less bulk and maintenancethan pony bottles. Some divers, though,prefer the added security that a ponybottle offers in some diving situations.Your instructor can help you choose themost appropriate alternate air source forthe type of diving that interests you.

Help yourself.The pony bottle (upper) is a small scubatank with its own regulator. The self con-tained ascent bottle (lower) is a small aircylinder with a very simple regulator that

h air to reach the surface.
Preparation. Whichever alternate airsource you select, you want to make iteasy to see and secure it so it doesn’t drag. Marking itclearly makes it easy to identify quickly and without
has just enoug

Chapter Two 97


1. An alternate air source is anymouthpiece, other than your pri-mary, that you can ascend withwhile breathing normally.True False

2. The __________is an example ofalternate air source that requiresbuddy assistance.a. alternate second stageb. self contained ascent bottlec. None of the above.

3. The __________ is an example ofan alternate air source that you canuse independently.a. alternate second stageb. alternate inflator regulatorc. None of the above.

4. It’s important to mark your alternateair source clearly so:a. your dive center can recognize itduring servicing.b. you or a buddy can locate it with-out confusion in an emergency.

5. You want to secure the alternate airsource on the front of either shoul-der securely so it doesn’t drag butcomes loose with a firm tug.True False

How’d you do?1. True. 2. a. 3. c. 4. b. 5. False.Locate it in the triangle formed by yourchin and the corners of your rib cage.


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confusion in an emergency. To make it conspicuous,you can select a bright color second stage (yellow ispopular) or have a bright color hose, or both. Yousecure the alternate to your chest in the triangleformed by your chin and the lower corners of yourrib cage, which gives you or a buddy quick and easyaccess to it.

Don’t let your alternate air source drag or dangle.This can damage it, and the environment, and itcan fill with sand or mud, making it difficult orimpossible to use if needed. You want to secure it sothat it remains in place, but releases quickly foruse with a firm tug. Your dive center should havequite a few devices that do this.

Maintenance. Care for your alternate air sourcelike any other regulator and/or scuba tank.

Low Pressure Inflator
Purpose. You’re probably familiar with low pres-sure inflators, which you use to quickly and easilyinflate your BCD with one hand. Like the SPG andthe alternate air source, the low-pressure inflator ismandatory equipment.
Styles, Features,Materials andSelection. When youselect a BCD, it willhave a low pressureinflator, so you don’tnormally have tochoose it separately.Although you canget different vari-eties, operationallymost low pressureinflators are more similar than different. An excep-tion might be if you decide to invest in an alternateinflator regulator; most BCDs don’t come with theseas standard equipment, so your dive center orresort would install it for you.


31. Why do you need a low pres-sure inflator?

MAINObjectives

Preparation. When you get your BCD and regulator,you’ll need the low pressure hose installed on your reg-ulator. This should be done by your PADI Dive Centeror Resort. The only other preparation is to connect thelow-pressure inflator during equipment assembly,which you’ll do several times during this course.

Maintenance. Following the normal maintenance pro-cedures for your BCD will cover the maintenance of thelow-pressure inflator.

Dive Knives Comes with the package.When you select a BCD, it will have a lowpressure inflator, so you don’t normally have tochoose it separately. There are different varieties,

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Purpose. You carry a dive knife or tool so you have apractical tool at hand, for safety and for convenience.
Besides the obvious use — cutting — you can measure,pry, saw and pound, always being mindful not to harmaquatic life. Your dive knife isn’t a weapon. In someareas, local law prohibit or regulate divers’ knives, orprohibit dive centers and resorts from selling them.
Styles, Features andMaterials. You canchoose from a variety ofdive knives, ranging inmaterial, size and fea-tures. They differ fromother knives primarilyin the metal used tomake them and thedesign of the blade and

1. You need a low pressure inflator a. to allow you to quickly and easilyinflate your BCD with one hand.b. to control the BCD inflation pres-sure to a low setting.

How’d you do?1. a.



32. Why do you need a dive knifeor dive tool?

MAINObjectives

but most low pressure inflators are similar.

handle. At minimum, adiving knife should: 1)be made from stainlesssteel (or titanium), 2)have both a sharp cut-

ting edge and serrated sawing edge, and 3) come with asheath or holder.

33. What three features shouldyou consider when selecting adive knife or dive tool?

Selection and Purchase. Beyond those three minimumfeatures, you may also want to consider the sheathdesign and where you carry the knife (inside of yourcalf, on the thigh, arm or weight belt, attached to aninstrument console, etc.). Be aware that some countries

Chapter Two 99

require a license for possession of aknife.

Maintenance. Most dive knives are madefrom stainless steel, but they still rust.Rinse your knife in fresh water afteruse, and carefully sharpen and clean itas needed according to the manufac-turer’s instructions. You can choose somehigher end dive knives made from tita-nium, which require less maintenance.

Gear (Equipment) Bags

Styles, FeaturesSelection. It’s tethat any large sbut think againbe heavy and saconventional zipdestroying luggafor the purpose.equipment bag blarge enough forexcept your tankdry suit if you hand weights wougear, and dry surately because tprotection.) Themade of heavy-dresists rotting azipper that wonequipment bagssuch as shouldeand padding. A


Look sharp.You carry a diveknife or tool so youhave a practical toolat hand, for safetyand for convenience.

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Purpose. You’ll want to buy somethingto get your dive equipment to the divesite and that something is a gear bag orequipment bag. On a boat, it keeps yourequipment together so you don’t lose itand so someone else doesn’t pick it up by mistake.

, Materials andmpting to think

ack will work,. Dive gear canlt water corrodespers, quicklyge not intendedChoose youry picking one everything, weights and

ave one. (Tanksld damage other

its travel sepa-he zipper needs bag should beuty fabric thatnd have a large’t corrode. Many have featuresr straps, pocketsgood gear bag

1. You need a dive knife (check all thatapply):a. as a practical tool.b. for safety.c. as weapon for self defense.

2. The three features to look for in adive knife include (check all thatapply):a. smooth edgeb. serrated edgec. sheathd. butt cap

How’d you do?1. a, b. 2. a, b, c.


isn’t cheap, but will cost lessin the long run because itlasts, and because you’re lesslikely to lose or damage thecontents. Options includebackpack designs that let youcarry them hands free, or

designs with wheelsto make life easier in airports and park-ing lots.

Preparation. You pre-pare an equipmentbag by packing prop-erly. Pack for divingwith your equipmentin the reverse orderin which you’ll needit. This way you don’thave to pull everything out of the bag to get kittedup. When getting out of your gear after the dive,put it right into your bag to avoid losing it or get-ting it mixed in with other diver’s gear.

Maintenance. Empty and rinse your equipmentbag after each use. Allow it to dry before storing it.


34. Why do you need an equip-ment bag?

35. How do you pack an equip-ment bag before a dive?

MAINObjectives

1. You need an equipment bag to carryyour gear to the dive site.True False

2. The ideal way to pack your bag fordiving is:a. with items of the same colortogether.b. in the reverse order in which youwill need it.

How’d you do?1. True. 2. b.


Right tool for the job.It’s tempting to think thatany large sack will workas a gear bag, but divingquickly destroys luggagenot intended for thepurpose. Choose yourequipment bag by pickingone large enough foreverything except yourtank, weights and dry suitif you have one.

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Dive InstrumentsSince you’re not a fish, you don’t have instinctsthat tell you everything you need to know under-

water: time, depth, direction, temperature and air supply(not that fish would need an air supply). You use diveinstruments to provide this information at a glance.

Underwater timepieces. As you progress through thiscourse, you’re going to learn that you can’t stay underwateran unlimited time, even if you have enough air. Every divehas a time limit, which changes with depth, so you need toknow how long you’ve been underwater.

You can time your dive with either a water resistant watch,or with a bottom timer. Underwater watches include analog

Chapter Two 101



36. What five types of reference infor-mation can you get from diveinstruments?

37. What are two types of underwatertimepieces used for diving?

38. Why do you need a depth gauge?

39. What is the purpose of a dive computer?

40. What are three reasons that youneed an underwater compass?

MAINObjectives

Where’d the time go? Underwater watches include analog(time displayed by hands) and digital(time displayed numerically) models.Using an analog watch, you measureelapsed time against a rotating scale(bezel) you set at the beginning of thedive; with a digital watch, you normallyuse the stopwatch function.

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(time displayed by hands) and digital (time displayednumerically) models. Using an analog watch, you measureelapsed time against a rotating scale (bezel) you set at thebeginning of the dive; with a digital watch you normallyuse the stopwatch function. Both types must be checked atthe start and end of the dive. In choosing a watch for div-ing, be sure to choose one that’s rated for depth, not justwater resistance. Most watches intended for scuba divinghave a depth rating of 200 metres or more, and will lastfor years as they’re designed to withstand far greaterpressures than recreational divers will ever experience.

Bottom timers are pressure-activated stopwatches thatautomatically start when you begin your descent, and stopwhen you return to the surface. Today, most modern bot-tom timers are digital and track your time between dives(you need to know that, too). The majority combine withdigital depth gauges or dive computers into a singleinstrument.

Handle underwater timepieces with care, and rinse themafter each dive. Most modern timepieces are fairly mainte-nance-free beyond that; consult the manufacturer instructions.

Depth gauge. As mentioned, you have time limits basedon depth, so you need to know how deep you are. For that,you need a depth gauge, which you can find in a widevariety of types, styles and price ranges. Like underwatertimepieces, there are both analog and digital models, withthe electronic digital types the most popular today. Depthgauges are considered mandatory dive equipment.

Treat your depth gauge like any other precision instru-ment. Protect it from rough handling and rinse it aftereach dive, following the manufacturer’s instructions. Someanalog depth gauges can be damaged by exposure to thereduced pressures at altitude. Keep your depth gauge outof prolonged direct sunlight.

Dive computers — Dive computers are by far the mostcommon dive instruments and have become standardequipment. Your computer is usually one of your firstequipment investments. Your computer combines your

Find your way.A dive compass will be liquid-filled to make itpressure resistant, and to help stabilize thecompass needle. The preferred type of compasshas a reference mark called the lubber line andindex markers that you align over the compassneedle to maintain a directional heading.

Three gauges in one.Dive computers combine your depth gauge, timerand sometimes your SPG into a single instrumentthat reads the data and computes the remainingallowable dive time you have at any point. You canchoose from a wide variety.

Just how warm is this water? You can get a thermometer as a separateinstrument, but today they’re more commonly partof your SPG.

Thermometer

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depth gauge, timer and sometimes your SPG into a sin-gle instrument, but this is far more than to make a con-venient package. Your dive computer applies depth andtime information to a decompression model to keep trackof nitrogen that dissolves into your body during a dive,and in so doing constantly tells you the time you haveremaining. This can be done with tables (you’ll learnhow), but your dive computer does it more efficiently soyou have more dive time, as well as more conveniently.Dive computers give you more freedom in the way youdive, making them one of the most significant advancesin dive equipment. You’ll learn more about using divecomputers in Sections Four and Five. Your PADIProfessional can help you choose one suited to you andwhere you’ll be diving.

Compass. A compass helps you know where you are andwhere you’re going, which is useful because being under-
water can throw off your sense of direction. Having andusing a compass lets you follow a designated course, findyour way to the exit, and know where you are at alltimes. Sometimes it comes in handy at the surface, suchas in low-visibility conditions like fog.
A dive compass will be liquid-filled to make it pressureresistant, and to help stabilize the compass needle. Thepreferred type of compass has a reference mark calledthe lubber line and index markers that you align overthe compass needle to maintain a directional heading.You’ll learn a bit about compass navigation later on inthe course.

As with other dive instruments, rinse your compassafter each dive, avoid dropping it and keep it out ofdirect sunlight.

Thermometer. Although not an essential dive instru-ment, a thermometer makes diving more comfortable bygiving you a temperature reference. With experience,you learn how much exposure protection you need for agiven temperature, making it easier to plan a comfort-able dive. You can get thermometers as separate instru-ments, but today they’re more commonly part of one ofyour other gauges, such as your SPG.

Chapter Two 103

Submersible Pressure Gauge (SPG). You learned aboutthe SPG in Section One, but it’s repeated here because it’sa mandatory instrument for diving, so it would be odd notto at least mention it while discussing dive instruments.

Instrument consoles. You can wear dive instrumentsindividually on your wrist, or you can combine them intoa single console attached to your SPG. Consoles puteverything in one place so you get all your information ata glance. They also reduce your gearing up time, since youdon’t need to strap anything on.

On the other hand, some divers find wearing gauges onthe wrist more effective for streamlining. A console is rel-atively large compared to an SPG alone, making consolesmore likely to protrude or dangle. Gauges on your wristcan’t dangle.


1. The reference informationyou get from dive instru-ments includes (check allthat apply):a. timeb. temperaturec. direction

2. Underwater timepieces canbe (check all that apply):a. dive watchesb. bottom timersc. lap timers

3. You need a depth gaugebecausea. local dive regulationsrequire one.b. underwater time limitsrelate to depth.

4. A dive computer provides anunderwater library reference,such as a giving you factsabout aquatic life.True False

5. Reasons for having anunderwater compass include(check all that apply):a. monitoring your air supply.b. determining where to findyour exit point.c. following a course.

How’d you do?1. a, b, c. 2. a, b. 3. b. 4. False.A dive computer determines yourdive time remaining based onyour depth and the elapsed divetime. 5. b, c.


Underline/highlight theanswers to these questions asyou read:

41. What are two ways of gaining the attention ofanother diver underwater?

42. What are two ways of com-municating with anotherdiver underwater?

43. What are the 25 standardhand signals (visually) andwhat does each mean?

44. What should you do if youget an underwater recall?

MAINObjectives

Altogether.Consoles put instruments in one place, whichreduces your gearing up time, since you don’t needto strap anything on. On the other hand, somedivers find wearing gauges on the wrist moreeffective for streamlining because a console isrelatively large compared to an SPG alone, makingconsoles more likely to protrude.

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Section One introduced you to the buddy system, and how it’s important for safety andfun. Let’s look at some of the ways you com-municate with your buddy underwater, andsome of the procedures for an effective buddy system.

CommunicationSound travels well in water, but voice com-munication isn’t an option without electroniccommunication systems. As a result, you domost of your talking with your hands — bysignaling or writing on a slate.

Buddy System: Communication and Procedures

Speak in gesture.You do most of your talking underwater with your hands —by signaling.

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Gaining attention. For hand signals to do anygood, your buddy has to look at you. Thismeans you tap your buddy’s shoulder or rap

s Wet suits and dry suits insulate you, but differin that you get wet in a wet suit and stay dryin a dry suit.

s You should avoid wearing an excessively tighthood.

s You want to wear gloves while diving for ther-mal protection and to avoid cuts, scrapes andstings.

s Although you’re protected (to a large extent)from the environment, remember that theenvironment isn’t protected from you — usecare to avoid damaging aquatic life.

Summary PointsSummary PointsIn this subsection on Dive Equipment, you learned:

on your tank to get attention. Don’t startleyour buddy when you do this.

Signals. After gaining your buddy’s attention,you can communicate by writing on a slate orby using hand signals. The primary drawbackto using a slate is that writing takes a lot of

Chapter Two 105

s Be cautious to avoid overheating in your expo-sure suit.

s The most important feature in a weight sys-tem is the quick release.

s Locate your alternate air source in the triangleformed by your chin and the corners of yourrib cage.

s Look for a dive knife with both smooth andserrated edges and a sheath.

s You need dive instruments to tell you depth,direction, temperature, time and air supply.


1. Stop, hold it, stay there 2. Something 4. OK? OK. (glove on)

5. Distress, help 6. O 7. OK? OK. (one hand occupied)

8. Danger 10. Go down, going down

11. Low on air 13. Buddy breathe or share air

Common hand signals.Signals may vary somewhat, soreview them when planning a dive with a new buddy.

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is wrong OK? OK.

K? OK. (on surface at distance)

9. Go up, going up

12. Out of air

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14. Come here 15. Me, or watch me 16. Under, over, or around

17. Level off, this depth 18. Go that way 19. Which direction?

20. Ears not clearing 21. I am cold 22. Take it easy, slow down

23. Hold hands 24. Get with your buddy 25. You lead, I’ll follow

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1. To get your buddy’s attention underwcan touch your buddy or:a. rap on your cylinder.b. blow your whistle.

2. The two methods of communicatingare using a slate and:a. hand signals.b. Morse code.

3. Identify the following:

a. ________ b. ________ c.

4. If you receive an underwater recall, a. swim to the boat immediately.b. cautiously surface and look to theinstructions, or as directed in the br

How’d you do?1. a. 2. a. 3. a. okay, b. let’s go up, c. o

QUICKQUIZ Self Ass

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time, so you’ll use hand signals when you can. The illus-trations show standard underwater hand signals (take afew minutes to learn them — they’re pretty intuitive),plus you and your dive buddy can invent and improvisesome as needed. Because signals vary somewhat, reviewthem when you dive with a new buddy for the first time or two.

Communication at the surface. Sometimesyou need to communicate with someone onshore or a boat while you’re at the surface.You can use hand or audible signals. Theillustrations show some of the commonhand signals, and as you can see, wavingmeans “HELP!” So don’t wave as a greet-ing. To get attention, you’ll want to carry awhistle as standard equipment. A whistlecarries a long way and gets attention with-out expending much energy (as opposed toyelling). Attach it to your BCD hose whereit’s out of the way, but easy to get to anduse. You can also get a whistle/horn pow-ered by your low pressure hose; they’requite loud, but it’s a good idea to carry aregular whistle, too, in case you need tosignal but have no air left in your tank.

When at the surface, be cautious regardingboats and boat traffic. Many divers carryinflatable signal tubes that alert boats totheir presence at the surface. They’re alsouseful when trying to get the attention ofsomeone on a boat or shore at a distance.

ater you

underwater

__________

you should:

boat fori

u

essment 16

Underwater recall. Most dive charter boatshave a recall procedure to get your atten-tion while underwater, which can includeelectronic underwater sirens, banging onsomething metal, starting and revving the

boat engine and other methods. The crew will explain therecall during the briefing. If you get the recall, cautiouslysurface and look to the boat for instructions. Don’t swimtoward the boat until the captain signals that it’s okay to

efing.

t of air. 4 b.


45. What nine considerationsshould you discuss with yourbuddy when planning a dive?

46. What are the steps of thePredive Safety Check?

47. If you lose contact with yourbuddy underwater, whatshould you do?

MAINObjectives

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do so. Depending on thecircumstances, the boatcrew may brief you onslightly different proce-dures for a recall.

Buddy SystemProcedures

In Section One,you learned yourresponsibility as

a buddy includes helpingyour buddy avoid prob-lems and assisting whenneeded. You provide“extra” eyes and handsfor your buddy, and vice

Have a plan.You and your buddy should plan your dive

.
versa. There are ninespecific points to agreeupon with your buddy to coordinate your efforts andoptimize both your safety and enjoyment.
1. Agree on appropriate entry and exit points andtechniques.

2. Choose a course to follow.

3. Agree upon time and depth limits.

4. Establish and review communications.

5. Establish a returning air pressure.

6. Discuss the technique you’ll use to stay together.

7. Agree on what to do if separated.

8. Discuss emergency procedures.

9. Agree on your dive objective. “Let’s just lookaround,” is as much of an objective as you need,but check that your buddy has the same objective.

together and dive your plan together

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110

Begin — B — BCD With — W — Weights

Review — R — Releases

And — A — Air

Friend — F — Final Okay

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Plan your dive together and dive your plan together.Before each dive, run through each other’s equipment usingthe predive safety check. Use the phrase Begin With ReviewAnd Friend to help you remember the checks:

Begin — — BCD — Check adjustment, operation, lowpressure inflator connection, and thattank is firm in the band. If appropriatefor the entry technique, make sure it’spartially inflated.

With — — Weights — Check for proper weighting,and that the quick release system is clearfor ditching. Weight belts should have aright hand release.

Review — — Releases — Make sure you’re familiarwith your buddy’s releases and how theywork. Check each other to make surethey’re secure.

And — — Air — Confirm that you both have ampleair for the dive, that your valves are open,that regulators and alternate air sourceswork, and that you know where to findand how to use each other’s alternate airsources.

Friend — — Final Okay — Give each other a finalinspection looking for out of place equip-ment, dangling gauges, missing gear, etc.

F

A

R

W

B

Open Water Diver Manual

Make a habit of performing this check — withexperience you’ll do it quickly and almost intu-itively. If it helps you remember, make up yourown recall statement for BWRAF.

During the dive, you and your buddy need to staytogether so you can lend assistance to each otherif necessary, not to mention because it’s more fun.Ideally, stay within a couple metres/a few feet ofeach other. Staying together is easier if you agreeon who will lead, your relative positions, and thegeneral course to follow until you both acknowl-

1. Dive plan considerations to discusswith your buddy include (check all that


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edge a change. If separated, the general guidelineis to search for each other for not more than oneminute, then surface and get back together. Insome instances it may be better to avoid surfac-ing to reunite. If this applies on a particular dive,it’s important to agree on another course ofaction that reunites you within a few minutes.

The buddy system only works when divers staytogether. Remember: It’s your responsibilityto stay with your buddy and follow therules, guidelines and recommendations for each other’s dive safety. No one can do it for you.

safety. No one can do it for you.

Predive Safety CheckAs you just read, you perform the predive safetycheck with your buddy before each dive. Startingin this confined water dive, you and your buddywill practice the check before each entry. By thetime you finish the course, you should have runthrough it many times. Remember BWRAF —BCD, Weights, Releases, Air and Final okay.

Entering the WaterDifferent types of dive sites have different types

Confined Water Dive Preview

Chapter Two 111

apply):a. the dive objective.b. what to do if separated.c. time and depth limits.d. the course to follow.

2. The BWRAF of the predive safetycheck stands for:a. BCD, Weights, Regulators, Air,Finishb. BCD, Weights, Regulators,Alternate air source, Finsc. BCD, Weights, Releases, Air, Finalokayd. BCD, Wolverine, Releases, Air,Final okay

3. If you lose contact with your buddy,the general procedure is:a. to wait where you are until yourbuddy relocates you.b. search no more than a minute, thenreunite on the surface.

How’d you do?1. a, b, c, d. 2. c. 3. b.

of entries — and different divers may even use differententries at the same site. In general, the best entry is usuallythe easiest. If you can wade or lower yourself in, that’s usuallybetter than a long drop. The idea is to enter without becomingdisoriented or knocking any equipment loose. Some generalrules for entries include:

1. Be sure the entry area is clear so you don’t hit anything oranyone getting in.


Here’s what you’ll be able to do when you suc-cessfully complete Confined Water Dive Two:

1. Perform the predive safety check.

2. Demonstrate appropriate deep-waterentry(s).

3. Clear a snorkel of water by using the blastmethod and resume breathing through itwithout lifting the face from the water.

4. Exchange snorkel for regulator and regu-lator for snorkel repeatedly while at thesurface without lifting the face from thewater.

5. Swim a distance of at least 50metres/yards at the surface, while wearingscuba and breathing through the snorkel.

6. Demonstrate a descent using the appro-priate five step method.

7. Completely remove, replace and clear themask of water while underwater.

8. Breathe underwater for not less than oneminute while not wearing a mask.

9. Demonstrate the response to a leakinglow pressure inflator by disconnecting the low pressure hose from the inflatormechanism.

10. At the surface in water too deep to standin, orally inflate a BCD to at least 1/2 fulland then fully deflate it.

11. Adjust for proper weighting, which isdefined as floating at eye level at the sur-face with an empty BCD and holding anormal breath.

12. React to air depletion by giving the out-of-air signal in water too deep to stand up in.

13. Demonstrate an ascent using the appro-priate five step method.

14. Remove weights at the surface with mini-mal assistance using the weight system’squick release mechanism.

15. In water too deep to stand up in, removethe weights, scuba unit and fins (if neces-sary), then exit using the most appropri-ate means. (Buddy assistance may beprovided.)

Skill RequirementsConfined Water

Dive Two

Skill Requirements

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2. If entering water too deep to stand in,have your BCD about half-inflated soyou’ll be buoyant.

3. Be sure your buddy is prepared toenter, too.

4. Hold your mask so the water doesn’tknock it off. This isn’t an issue withsome types of entries.

5. After entering, signal that you’re okayand clear the entry area to wait foryour buddy.

You can use the controlled seated entry toenter from a platform just above the water— like a dock, boat swim step or pool side.Sit on the platform with your feet danglingin the water. Turn slightly and reach acrossyourself with one arm so you place bothhands on the platform on the same side.Then, using your arms for support, gentlypivot so you turn and face the platform asyou lower yourself into the water. Once inand comfortable, let go of the platform andclear the entry area. Because you use yourarms for this entry, it may be a useful entrytechnique if you have a physical challengethat limits leg use.

When you must enter the water from araised platform such as a boat, wall or pier,you may use a giant stride entry. To do this, secure your equip-ment, check that your BCD is about half-inflated, place yourregulator in your mouth and hold your mask tightly in place.When your buddy’s ready, check the area below, then simplystep out with one foot.

Keep your legs spread until they hit the water, then pull themtogether in an upward kick to minimize how far you sink.Once in the water, give the okay signal and clear the entryarea for your buddy.

Chapter Two 113

Safety starts with a check.Beginning in this confined water dive, you and yourbuddy will practice the predive safety check beforeeach entry. By the time you finish the course, youshould have run through it many times. RememberBWRAF — BCD, Weights, Releases, Air and Finalokay.

In easy.You can use the controlled seated entry to enter froma platform just above the water — like a dock, boatswim step or pool side.

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You’ll practice the controlled seated entry, the giant stride and/or otherappropriate methods for entering water deeper than you can stand in.

Snorkel Breathing and Blast ClearingDuring this confined water dive, you’ll start making a habit of usingyour snorkel to save energy and rest at the surface without wasting

tank air. If you’re not used to using a snorkel, there’s notmuch to it: breathe slowly and deeply. Bite gently on themouthpiece, letting your lips seal around it and hold it inplace. When you put the snorkel in your mouth exhalebefore inhaling, and inhale cautiously, just in case there’ssome water in it.

To clear water from your snorkel, such as you’ll typically dowhen you surface and switch to it from your regulator, sim-ply exhale forcefully and sharply into it. This “blasts” thewater out of the barrel through the top and through theself drain valve. The “blast method” of clearing will removenearly all the water from the snorkel. Use airway control tocarefully breathe past any small amount left, and thenclear it with a second blast.

Remember: When using the blast method to clear asnorkel, the exhalation must be quick and forceful, asthough you are shooting a giant pea-shooter. Use this

method to clear any water sloshing into the snorkel while swimmingat the surface.

Snorkel clearing becomes automatic and easier with experience. Keepin mind that if there’s some water left in the snorkel, by inhalingslowly and using airway control, you can “bubble” the air through thewater until you have enough air for another blast.

Snorkel/Regulator ExchangesQuite often you’ll snorkel on the surface to the place where you wantto dive so you don’t waste air on the way. When you get there, youexchange your snorkel for your regulator. Since you can have waves orchop in the ocean or a lake, you may effectively have to do this withyour face in the water. So during this confined water dive, you’ll simu-late this by keeping your face in the water as you switch back betweenyour snorkel and regulator.


Blast! To clear water from yoursnorkel, simply exhaleforcefully and sharply into it.

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Find your regulator and hold it in your right hand. Take and a breathand then with your left hand, remove your snorkel from your mouth,put in your regulator (right hand), clear it and begin breathing. Facein the water — no cheating. When you surface after your dive, youexchange your regulator for your snorkel. To practice this, do the oppo-site. Take a breath, remove your regulator with your right hand andreplace it with your snorkel in the left. See why you wear your snorkelon the left side? Blast the water from your snorkel and inhale cau-tiously as you resume breathing. Blow small bubbles during theexchange so you reinforce the habit of never holding your breath with scuba.

You’ll practice exchanging your regulator and snorkel until you can doso with minimal effort, which is to say, until it’s boring. But thatmeans you know it.

Surface SnorkelingDuring this confined water dive, yourinstructor will have you practice swimmingon the surface while snorkeling with scubaequipment. Watch your body position. Keepyour arms at your side and the top of thesnorkel out of the water. Swim slowly andrelaxed with your fins below the surface formaximum efficiency. This may be easier ifyou look ahead, not down. You may find iteasier to swim on your side or backward(you may need to readjust the snorkel tip tokeep it out of the water).

DescendingDescending has five steps that you’ll start practicing during this con-fined water dive:

1. You and your buddy signal that you’re both ready to descend.

2. Orient yourself to something at the surface that will help you findout where you are when you resurface.

3. Switch from your snorkel to your regulator. Do this with your facein the water.

4. Check the time/ set your watch bezel or start your stopwatch. If you

Chapter Two 115

Right, left.Left, right.Practice exchanging yourregulator and snorkel withyour face in the water. Thisprepares you for doing so inopen water, where thesurface may not be as calm.

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don’t have an underwater watch, for practice look at your wristwhere you would wear your watch to simulate noting the time.

5. Slowly deflate your BCD and exhale to initiate a head up descent.Equalize your ears immediately upon submerging and do so fre-

quently during descent. You don’t need to be straightup and down like you’re saluting a general or some-thing, but staying in a generally head up position helpsyou stay oriented and makes it easier to equalize.

Always control your descent so you can stop or ascendat any time. Pay attention to your lung volume andadd air to your BCD to offset buoyancy lost to wetsuit compression. Descend slowly, keeping your finsbeneath you so you can kick upward if you need to.

No-mask BreathingIt doesn’t happen often, but it’s possible for you to lose your mask, soyou need to be able to breathe and swim with your nose exposed to thewater. This may sound more difficult than it is. With practice, you’lleasily be able to breathe throughyour mouth with no mask on whilekeeping water out of your nose.

At first, you may find it easier toinhale through your mouth andexhale through your nose. Afteryou’re comfortable with that, prac-tice inhaling and exhaling throughyour mouth only. If it feels likewater’s entering your nose, justexhale slightly through it to pushthe water out. Water won’t go inyour nose by itself unless you turnupside down or tilt your head back.If you need to look up without yourmask on, exhale through your nosewhile you do it.

With a little practice, you’ll discoverthat breathing without a mask is aseasy as breathing with one. Yourinstructor will have you do this for


Watch your buoyancy.Control your descent so youcan stop or ascend at any time.Pay attention to your lungvolume and add air to yourBCD to offset buoyancy lost towet suit compression. Descendslowly, keeping your finsbeneath you so you can kickupward if you need to.

No sweat.With a little practice, you’ll discover thatbreathing without a mask is as easy asbreathing with one. Your instructor will haveyou do this for one minute, which would belong enough to reach the surface on a typical dive.

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one minute, which would be long enough to reach the surface on a typ-ical dive. That way you can be confident you can surface under controlif you lose your mask and can’t relocate it.

Mask ReplacementIf you lose your mask underwater, chances are you’ll find it oryour buddy will hand it to you, and you’ll put it right back on.First, put the mask on your face, making sure there’s no hairor the edge of your hood trapped under the skirt. Otherwise, itwill leak.

Make sure the strap is out of the way by looping it forwardover the back of the hand holding the mask. Once you havethe mask properly positioned and the skirt unobstructed,either immediately clear the mask like you did in the first con-fined-water dive, or replace the strap and then clear it. Somepeople find that replacing the strap first makes mask clearinga little easier; others find that clearing the mask before replac-ing the strap helps them be sure they’ve properly seated themask. Use whichever works best for you.

Disconnecting the Low Pressure Inflator HoseIf your BCD (or dry suit) inflator mechanism were to stick orleak, it could begin inflating your BCD (or dry suit) by itself.To stop this, you disconnect the low pressure hose and thenend the dive. To simulate a sticking inflator, your instructor may haveyou hold down the inflation button with one hand, while you discon-nect the low pressure hose with the other. Remember to reconnect thehose after the exercise.

Inflating Your BCD OrallyIn Confined Water Dive One, you learned to inflate your BCD usingthe low pressure inflator. During this session, you’ll learn to do soorally. You might orally inflate it if you had no air in your cylinder, orif you had a problem with the low pressure inflator and disconnectedit. To orally inflate the BCD:

1. Take a breath.

2. Place the mouthpiece on the BCD hose in your mouth.

3. Open the valve by pressing the same button you use to release air.

Chapter Two 117

Strap on.After replacing your mask, you may findthat replacing the strap first makesclearing a little easier, or you may findthat clearing the mask first, thenreplacing the strap is easier.

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4. Blow about two thirds of the air in your lungs into the BCD hose.

5. Release the valve button.

Your mouth doesn’t have to be above water while you blow. Infact, you save energy if it’s not — simply lift your chin to takea breath, then relax with your face back in the water as youblow into the BCD mouthpiece. Lift your face to take the nextbreath, and repeat until you have sufficient buoyancy to stayup without kicking. Release the valve button between breaths;otherwise the water pushes the air back out and you’ll neverget it inflated.

Proper WeightingYour instructor will have you adjust your weight using themethod you learned earlier in this section:

1. Enter the water with all your equipment on and your esti-mated weight requirement.

2. Keep your regulator in your mouth, and staying at the sur-face, deflate your BCD and hold a normal breath. Be readyto kick or hold onto something in case you’ve got too muchweight.

3. You should float at eye level. If not, add or subtract weightuntil you do. You can just hold weights while you figure outhow much you need.

4. As a final check, exhale. You’ll begin to slowly descend ifyou’re properly weighted.

5. If you’re using a full cylinder, now add enough weight tooffset the weight of the air you use during the dive (usuallyabout 2 kg/5 lbs with a single cylinder).

Your instructor will help you get your weight set.

Air-Depletion ExerciseWatch your SPG regularly and you should never find your-self running out of air. Nonetheless, you should know what itfeels like when you’re running out of air so you have as


Another way.You might orally inflate your BCD if you had no air in your cylinder,or if you had a problem with yourlow pressure inflator.

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much advance warning as possible.

To simulate low air, your instructor will sit in front of youand close your tank valve as you continue to breathe fromyour regulator. You’ll feel the breathing effort graduallyincrease until you have difficulty getting a breath. At thatpoint, signal out-of-air, and your instructor will immedi-ately reopen the valve. Resume normal breathing.

Naturally, you want to avoid an out-of-air situation byalways keeping an ample reserve supply. You may needthis air to retrieve something you drop after surfacing, andto make sure you don’t completely drain your tank. As arule of thumb, plan to surface with at least 20-30 bar/300psi in your tank. Many divers reserve about 35 bar/500psi; the smaller the cylinder and the more complex thedive, the more reserve you want to keep. With proper plan-ning, you should be able to make a slow, comfortableascent, a three-minute safety stop at 5 metres/15 feet, andreach the surface without using your reserve. This is oneof the marks of a good diver.

AscentsBuilding on what you practiced in Confined Water DiveOne, a proper ascent has five steps that you learn andpractice starting in this confined water dive:

1. You and your buddy signal each other and agree to ascend.

2. Note the time of your ascent. (If you don’t have a watchfor this dive, simulate checking the time by looking atyour wrist.)

3. Hold your right hand over your head (so you don’t runinto anything) and hold up the BCD hose with exhaustcontrol with your left. As you’ll see, air expanding inyour BCD during ascent increases your buoyancy. Youneed to release air as you rise to keep your ascentunder control.

4. Look up and around, slowly rotating to make sure thearea above you is clear.

Chapter Two 119

The eyes have it.When you’re properly weighted, you shouldfloat at eye level with an empty BCD andwhile holding a normal breath.

Gasp? To simulate low air, your instructor will closeyour tank valve as you continue to breathe.When you have difficulty getting a breath,signal out-of-air, and your instructor willimmediately reopen the valve. Resumenormal breathing.

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5. Swim up slowly, at a rate no faster than 18metres/60 feet per minute (slower is fine),while breathing normally.

As soon as you and your buddy reach the sur-face, inflate your BCDs so you can float com-fortably and effortlessly. Make a habit ofkeeping your regulator in your mouth untilyou’ve inflated your BCD.

Weight Removal at the SurfaceIn an emergency at the surface, your firstreaction should be to be sure you can float.You’d usually do this with your BCD and lowpressure inflator, but if that doesn’t work(such as if you had an empty tank), your nextoption would be to ditch your weights. So thatyou’re familiar with this, your instructor willhave you practice using your weight systemquick release.

With a weight belt, reach down with yourright hand, flip the release, grasp the free (nobuckle) end and pull the belt clear of yourbody. That way you know it won’t hang upwhen you drop it. During this practice ses-sion, your instructor may ask you not to actu-

ally drop your weight (such as if it woulddamage the pool), or your instructor mayhave you drop it. Either way, before removingyour belt be sure there are no divers beneathyou who could be hurt by falling weights.

If you’re using a weight integrated system,you’ll use the system’s quick release.However, depending on the system configura-tion, to prevent pool damage, your instructormay remove all but one or two weights andhave someone catch them as they release, orhave you practice this in shallow water.

Deep Water ExitAt times you might need to remove yourweights, scuba unit and (perhaps) fins to exitthe water — like when diving from a smallboat. Since you already took your weights offin the last skill practice, your instructor willprobably have you learn to do this next.

First, remove your weight system (if youhaven’t already; if you have a weight inte-grated BCD, the weights can usually stay infor exiting) and hand it to your buddy, orplace it up on the pool deck. Next, slide out ofthe scuba unit — it is usually easiest to slideit off one shoulder first. Make sure you putenough air in it so that it doesn’t sink, thenhold it for your buddy to pull up on the deck.

Remove your fins last, if necessary. On a lowplatform, you may find it easier to leave themon because you can kick as you lift yourselfout. If you must remove your fins, to climb aladder for example, make sure you have solidcontact with something so you won’t driftaway from the exit. In open water, try to exitwhen the waves will help lift you onto theplatform, boat or rocks.


Out easy.To exit the water onto a low platform or small boat without aladder, you may remove your weights and scuba gear at thesurface, then lift yourself out.

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Chapter Two 121

Knowledge Review—Chapter 2

Knowledge Review—1. Check one. “Underwater, objects appear _______________ by 33 percent, making them

seem ________________ and/or _______________________ .”

a. minimized, smaller, further away b. magnified, larger, closer

2. Check one. “Since it travels about four times faster in water than in air, you will havedifficulty determining the origin of ____________ underwater.”

a. light b. sound

3. Fill in the blank with the appropriate word: faster or slower.“Water conducts heat away from your body ______________ than air does.”

4. Describe what you should do if you begin shivering continuously underwater.

5. Of the procedures you can follow to compensate for the increased resistance of waterwhile diving, check those listed here:

a. Streamline yourself and your equipment.b. Avoid rapid jerky movements.c. Move slowly and steadily.d. Pace yourself.

6. Check the statement that best describes the proper breathing pattern for diving.

a. Consistently rapid and shallow.b. Consistently slow and deep.

7. It is easy to prevent overexertion while diving. Check the proper preventative mea-sures listed here.

a. Move slowly and avoid extended strenuous activity.b. Use your arms rather than your legs for propulsion underwater.c. Know your physical limits.

8. Explain what to do if you become overexerted while diving.

a. Underwater:

b. At the surface:

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9. Check each statement that describes a technique used for airway control:

a. Use your tongue as a splash guard by placing the tip on the roof of your mouth.b. Inhale slowly.c. Avoid rapid, jerky movement.d. Inhale cautiously.

10. Explain why it is important not to wear a tight-fitting hood.

11. Check the appropriate answer. The most important feature of any weight system is:

a. the size and shape of the weights.b. the ease of adjustment.c. a quick-release mechanism.

12. Check one. An alternate air source should be ____________, so it can be quickly andeasily identified by a diver needing the device.

a. tucked under the weight beltb. conspicuously marked

13. Describe where you should attach an alternate air source to your body.

14. True or False: A diving knife is used as a tool (to measure, pry, dig, cut and pound),but is not intended to be, nor should be, used as a weapon. ____________

15. Identify the meaning of the standard hand signal illustrated here.

a. OK? OK b. Distress, help c. Out-of-air

16. Explain how to check for proper weighting.

17. List and describe the steps of the predive safety check, and explain when you shoulduse the check.

Student Diver Statement: I’ve completed this Knowledge Review to the best of my ability,and any questions I answered incorrectly or incompletely I’ve had explained to me, and Iunderstand what I missed.

Name ________________________________________________ Date ________________________Knowledge Reviews may not be reproduced in any form without the written permission of the publisher.

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PADI Open Water Diver Manual_02

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