Main Guide To Scuba Diving

Content

Introduction .....................................

Dive Enviorment .......................................

Equipment ..........................................

Aquatic Life .........................................

Human Biology ......................................

Physics .........................................

Dive Planning ...........................................

Conlusion ............................................

Citations .............................................

Pg.1

Pg. 2

Pg. 3-5

Pg. 6-14

Pg. 15-16

Pg. 17-19

Pg. 20-22

Pg. 23-24

Pg. 25

Pg. 26

(Reef Magic Cairns Cruises, “Corals”)

Content Introduction

Pg.2

Are you looking for adventure? Love nature? Love exploring the unexplored? Scuba diving delivers both adrenaline and intensity, taking on challenges like planning, training or relaxing and discovering the underwater environment. There is always something new to explore, you cannot outgrow diving. Scuba Diving, a recreational activity that allows a diver to breath underwater, using a Scuba. Unlike other types of diving, the scuba is filled with compressed air, allowing the diver to dive in the water through a period of time without going back to the surface or holding their breath. Currently, this activity is slowly becoming more popular and available worldwide. The history of Scuba Diving originates centuries way back, when technology or the idea of breathing underwater was still developing.

Back in the days, people used simple resources so they could breath underwater, collecting and mining pearls or hunting for fish. Even though their methods weren’t nearly as effective or safe as modern diving technology, the concept of breathing underwater had always exist-ed. There was stories that described how people used natural materials to help them breath underwater. An example is that in the 500BC, a greek solider used a hallow reed, a plant, to breath underwater for hours after diving off his ship. After the 1700, there were many attempts to create a rebreathing device, however it wasn’t until 1940s where Jacques Cousteau, a scientist and engineer Emilie Gagnan, successfully created one that works. A decade later, recreational diving technology started to develop and after a long period of time, and has advanced to the modern diving technology (Sanford, Trevor). This guide to Scuba diving is filled with useful tips and instructions on the context you will need to know to earn your certificate and to help you safely enjoy your Scuba Diving journey. To earn your licences and to be certified, you will need to pass through the Open Water Diver Course, contact your local diving centres for more information.

(Camel Dive Club & Hotel)

Chapter 1.

Dive Enviorment

Pg.3(Reef Magic Cairns Cruises, “Wally”)

Part of dive planning is having knowledge in the different dive environments and how it will affect your dive.

VisabilitySize, Distance and Colour LossOne effect underwater is that the direction changes and magnifies things by about a third, therefore depending on the perspective, things would look larger than out of the water. This is because light changes direction slightly when it transfers from water into the air in the mask. Water also affects light, as the deeper you go the darker it gets. As you go deeper, colour is absorbed and as light travels through water, it makes certain colours absorb faster than others. As you go deeper, red is adsorbed first, followed by orange, yellow, green, blue and purple.Distant object tends to become more colourful as you get closer.

Factors affecting VisibilityThe main principles affecting visibility underwater are the water movement, weather, plankton and bottom composition. The increasing or decreasing amount of suspended particles from these factors can also affect visibility.

Water Movements: Kicks and currents can stir up bottom composition like sentiments and reduces visibility. In contrast, currents can improve visibility by carrying away low visibility water and replacing it with clearer water.

Weather: Waves, created from winds, can stir up the bottom composition, even causing runoff into the water. In contrast, offshore winds can push water towards the sea, replacing the water with clearer visibility.

Microscopic Organisms or Planktons: Under some conditions, planktons can use photosynthesis to reproduce at a great rate, clouding the water.

The Bottom Composition: Small particles from mud or rock bottoms can remain suspended in the water for a long period of time. The basic types of bottom composition are silt/mud, sand, rock, coral and vegetation.

Try to Avoid Bottom Contact as Much as Possible: First of all it can reduce visibility, secondly contact with bottom may present hazards like scrape or cuts you receive through corals and rocks. Lastly, many aquatic organisms such as corals that live in the bottom may be injure or destroyed as they are quite fragile.

Depth (ft)

0

15

50

100

250

Pg.4

TemperatureIn many environments, the water temperature changes depending on the the season. This affects the exposure suit you need to wear. Also, Depth is another factor that affects temperature, usually the deeper you go, the colder it gets. When planning a dive, it is important to choose your exposure suit based on the deepest part of the dive to prevent medical conditions like hypothermia.

In water, sound travels four times faster than air. Therefore it is difficult to determine where the sound came from, for example a boat may sound closer underwater compared to on the surface.

Hearing

SunlightDuring diving, you are mostly under sunlight. How much light you are under or how warm you are before or after a dive, can easily cause sunburn. Wear protective clothing and put on lots of suncream. Good quality sun glasses can prevent your eyes from the exposure of the sun as long term exposure can harm them.

Fresh Water and Salt WaterIt is great diving in both fresh (lakes, rivers) and salt water (ocean), The basic skills you learn in Scuba Diving can apply to both environments but there are some distinct features in each enviorment:

- In fresh water, you are less buoyant, this is because fresh water is less denser than salt water. This means that the weight and amount of air in your BCD can differentiate depending on the environment.

-Salt water environments tend to have a more variety of aquatic life

- Commonly, In fresh water, a very distinct temperature change can be felt in the recreational diving depth range (40m)

- Freshwater environments are probable to bottom composition like sand, which can be stirred up easily compared to saltwater environments.

-There are more differences in currents and wave patterns in salt water environments

Pg.5

(Ng, Clemand)

Equipments

Chapter 2.

Pg.6(Ong, Alice. “Hawksbill Turtle”)

Dive Masks

Why do I need a Mask?To see and observe underwater, you will need a dive mask. With the mask, your eyes can focus clearly and allows you to see underwater. It also allows you to equalise when you get a squeeze (Refer to Chapter 5). You do not using googles in diving because it does cover your nose, and you cannot equalise with googles resulting in injuries.

Features And Kinds Of Masks:Low Profile: A mask that gives you a more broad field of view. It requires less air for equalizing and clearing of water.

Wide Vision Field: Mask that have a special shape to assist in more field of vision. Some have side windows so you can even see the sides during diving.

Silicone Colour: Depending on the divers opinions, some likes the feel of the material of silicone rubber, while some just like the flare of black.

Frame Colour: To match the rest of the kit.

For new mask, it is recommended to scrub the inte-rior with a mask cleaner to remove protective chem-icals on the new mask, if it is not removed, it can increase the fog tendency.

SnorkelWhat is the use of snorkels when we have the cylinders to supply air? - You can use a snorkel at the surface to save air supply in your cylinder

-It makes it easier to breath when there are splashing waves that could get into the mouth, especially when there are snorkels with a splash guard (prevents splash water from being swallowed)

-At the surface, you can use your snorkels and adjust your gear or looking down. It saves air.

-If you come up with little air remaining, and you re-alise that you need to swim a long way before getting on the boat or on shore, you can switch to using a snorkel.

Features and Considerations:Flexible lower portion- The snorkel mouthpiece can be out of the way when not in use, like during underwater.

Self Drain Valve- Prevents drinking seawater and makes it easier to blow out the water

Splash guard- From waves and currents, it prevents large amount of water to fall into the snorkel

Colour- Bright colours are mostly considered by divers, to match your other gears.

Pg.7

(Yu, Cherie. “Dive Mask”)

(Yu, Cherie. “Splash Guard”)

(Yu, Cherie. “Snorkel”)

FinsWhy Do I Need Fins?Fins can increase the surface area for the legs muscles, so you can move through water more faster and more efficient.

Basic Fin Styles:Adjustable fins- Open in the heel and can be strapped on. To provide warmth and protection against corals, wet suit boots can be worn.

Full Foot Fins- It covers the heels and are fit like snug shoes and slippers. You usually wear in barefoot or with a thin sock for warmth and to prevent damage to the skin. There are different blade sizes, some suited for scuba and some for snorkelling.

The larger and stiffer the blade, the more strength it needs but the more thrust you will get. Small flexible blades take less muscles but may be inefficient.

Features and Considerations:Material- Different materials affect performance and makes the fins heavier or lighter

Split Fin- Some divers prefer the kicking characteristic of fins that are split in the centre

Vents- Some fins have holes to let water pass through in other to assist performances

Quick Release Strap- Quick release buckles that makes removing easier

Spring Straps- For adjusting fins, spring straps auto adjust for a proper fit every time is is worn

Pg.8

(Yu, Cherie. “Fins”)

(Yu, Cherie. “Adjustable Fins”)

Scuba Kit

The scuba kit forms the most importance during underwater, there are four equipment systems integrated into one package:

BCD (Buoyancy Control Device) - Holds the kit together and allows you to adjust buoyancy throughout the dive

Regulator- Delivers breathing air at the surrounding pressure when you inhaled and direct exhaled air into the water.

Cylinder- Holds the high pressure breathing air supplied by the regulator during the dive.

Weight System- Holds lead weight to counter the positive buoyancy of your body and some of the equipment, it also made for dropping some or all the

weight in an emergency.

BCD- Buoyancy Control Device

A

B

C

Pg.9

(Cressi)

Components that makes up the BCD:

A- Inflatable bladder, a durable bag that inflates or deflates to change the buoyancy

B- Cylinder Bag and Harness/Jacket, the bladder integrates with a harness that holds the cylinder on your back.

C- Low pressure inflator mechanism, to prevent rupturing in the bladder due to overfilling, BCD have one or more overpressure valves that automatically releases air if the BCD is too full. There is

also a quick dump valve that lets you manually release air than using the LPI, this is usually recommended by the divemasters so you can control your own buoyancy.

Weight System- BCD have specially weight pockets that can release or drop during an emergency. The more weight, the more useful it is. Weight belt are usually used and prefered by divers. They are belts tied on the waist with weights on. This helps control the buoyancy and the ability to stay

balanced in the the water.

BCD should be fit snuggly but not resist breathing when fully inflated.

(Paul)

(PADI) Pg.10

Regulators

The regulator regulates the airflow from the cylinder to the diver.

Regulator Options:The most important consideration is the choosing of a regulator that is ease of breathing.

(ScubaDivingFanClub)

A- Second Stage

B- Inflator hose

C- Alternative Air Source

D- SPG

E - First Stage

A- You breath from the second stage. It reduces pressure from the first stage to the pressure around you and delivers air only when you inhale. When you exhale it has a one way valve to vent the carbon dioxide out. There is a purge button to let you manually release air from the cylinder

B- Low pressure inflator hose is the the hose that supplies air to the BCD inflator.

C- The alternative air source, is an extra second stage for sharing air with a buddy when there is an emergency such as running out of air. Most are brightly colour so a buddy can locate it easily.

D- The SPG- Submersible Pressure Gauge, it tells you the air pressure remaining in the cylinder so you can manage your air supply. The simplest design is a hose that reads the pressure in bar(metric) or psi. It may also have a built in dive computer.

E- The first stage is the hub of the regulator, It is a simple device that supply air to other components. It connects to the cylinder valve either by screwing or with a yoke (clamp system). The first stage reduces cylinder pressure to an intermediate pressure which is about 7-10 bar above the surrounding pressure.

Pg.11

Cylinders

The scuba cylinder is a container made to store high pressure air. It consists of the cylinder and the valve.The valve controls the airflow to and from the cylinder.

Options and FeaturesYoke and Din- The yoke system holds the first stage to the cylinder with a clamp system. With the DIN system, the regulator is threaded into the valve. The yoke system is more widely established.

Filling Cylinders: Have the cylinder filled only with air. Under pressure, oxygen can become toxic (Oxygen Toxicity).

(Soljaguar)

Yoke Din

Clamp Threaded

Pg.12

(Big Blue Scuba Diving International)

(Reef Magic Cairns Cruises. “Clownfish”)

Wetsuit and Drysuit (Exposure Suits)

Wet SuitIt is a common exposure suit because it provides insulation and protection and depend on various sizes on how much insulation you want. Wetsuits insulates you however does not keep you dry. Water sweeps into the wrist, ankles, neck and gets trapped. Your body quickly heats up the trapped water and the material, neoprene, slows heat loss.

You wear an exposure suit on dives to keep warm, and protected against accidental stings, cuts or abrasions.

There are mainly 3 primary exposure suits: Wet suit, Dry Suit and Skin Suit

Skin SuitAlso known as, body suits, it provides little or no insulation. Therefore this is usually worn in warm waters to prevent from sunburn and scrapes.

Dry SuitIt provides the most insulation. They keep you dry except the head and hands. Dry suit is usually used in cold water like under ice. The dry suit itself provides insulation which makes it effective for cold water diving.

A

C

B

A

B

Water sweeps into the wetsuit from the wrist, neck, ankles and gets trapped. Your body (A), heats up the trapped water (B) with body heat and the neoprene (C), and slows down heat loss.

Dry suits provides the most insulation because there is a layer of air (A) trapped between the skin and and the suit (B), which can slow heat loss.

Pg.13(Yu, Cherie. “Wetsuits.”)

Dive Computers

Most divers own and use a dive computer, and are considered the standard equipment in diving. The dive

computer uses the depth, and time information and apply it to a decompression model to track the dissolved nitrogen in your body during a dive. It also calculates how much time you have remaining before you have to ascend. There are many more functions available in a dive computer that will help prevent dangers and to insure a safe dive (“Dive”). Look at your dive

computer manual before using.

Pg.14

(Yu, Cherie. “Computer Watch.”)

(Ong, Alice. “Shark Dive.”)

Chapter 3.

Aquatic Life

Pg.15(Reef Magic Cairns Cruises. “Fish.”)

Aquatic life is one of the main attractions for diving. Observing and interacting with plants and animals that are only found

in the ocean, is one of the privileges of being a diver.Many aquatic plants and

organisms are harmless, however some may injure you.

You can avoid injuries by being alert and aware of where these organisms live and how they behave, Most injuries

are a result of human carelessness and defensive responses by animals.

Passive and Active InterationsThere are two kinds of interaction with aquatic life: passive and active. Passive interactions are those that does not disturb aquatic life, like photography, watching, and more. Active interactions are those that affect aquatic life directly, like feeding, hunting, scaring, touching and more. In general, it would be the preferred to have passive interactions, to limit disruption to aquatic organisms, therefore can observe and interact with them in their natural environment.

Goal for divers: To set a good example as underwater ambassadors and help preserve the aquatic environment for future generations.

Prevening Injuries from Aquatic Organisms Harmful and hazardous aquatic organisms are mostly that stings, punctures or bites.

Those that stings or bite mostly include, but not limited to:-Jelly fish-Portuguese man o war-Lionfish/Scorpion Fish-Stingrays-Sea urchins-Cone Shells-Moray eels-Trigger fish

There are organisms that are typically not thought as hazardous, but can injure when divers don’t use their common sense. An example is during mating seasons, male seal lions may protect its female and become aggressive when they think a diver is a threat.

If a large or potentially aggressive animal appear, you should remain calm and still, by staying at the bottom and enjoy this rare experience. If it seems to be overly curious or aggressive, swim along the bottom, keeping an eye on it and exit the water.

Pg.16

(Reef Magic Cairns Cruises. “Nudibranch.”)

(Reef Magic Cairns Cruises. “Lionfish.”)

(Reef Magic Cairns Cruises. “Moray Eel.”)

(Reef Magic Cairns Cruises. “Anemonefish.”)

(Reef Magic Cairns Cruises. “Green Turtle.”)

Chapter 4.

Human Biology

Pg.17(Ong, Alice. “Palau.”)

Air is considered a single gas and in Scuba Diving, it is related to the depth-pressure-volume-density relationship.

In Scuba diving, there are four issues that are related to the component gases in air:-Oxygen Toxicity-Decompression Sickness-Contaminated Air-Gas Narcosis

Oxygen ToxicityIn our life we need oxygen to live however under high pressure, oxygen is toxic. This is caused when air is breathed deeper than a specific depth. High oxygen percentages may also create combustion risks with the equipment. If a diver use a higher percentage of oxygen, the toxic effect can be seen at shallower depths(Sawatzky, K. David). Therefore to avoid it, don’t exceed a maximum depth of 40 meters/130 feet for recreational diving.

Contaminated AirThis is very rare in scuba diving, scuba air must be very pure and has no trace of contaminants like oil vapour and more. Trace contaminants like carbon monoxide can be harmless at the surface but when breathed underwater while being pressured, it can become toxic.

Possible causes:- Getting a cylinder filled at an improper source

-Improper maintenance of the filling system

-High level of contaminant in the source gas

Contaminated air may smell and taste bad but can be odourless.

A diver who has breathed contaminated air can have symptoms like dizziness, headaches, nausea and more. To avoid this, it is better to get the cylinder to be filled with a proper source like professional diving centres to ensure good air quality.

Gas Narcosis Many gases including oxygen and nitrogen cause an intoxicating effect under pressure. Called gas narcosis. It impairs good judgment, clear thinking and timely responses needed to manage and avoid problems underwater. Gas narcosis is thought to be caused by an increased dissolved gase in the body tissues slowing nerve impulses that travel between the brain and the nerve systems. To avoid this problem, try to not dive too deep. Some signs and symptoms may include: Feeling “drunk”, slow thinking, inappropriate laughter, loss of coordinations and more.

Pg.18

Decompression Sickness

Decompression Sickness also called bends, is a physiological effect on the forming of gas bubbles in the body due to a rapid transition from a high pressure environment to a lower pressure one (“Decompression Sickness”).

During a dive, the increasing pressure causes nitrogen from the breathing air to be absorbed into the tissues of the body. The longer you are underwater, the more nitrogen your body absorbs. Therefore the factors that influence how much nitrogen you absorb depends on the depth and time.

When you ascend from a dive, the excess nitrogen normally dissolves out of your body by respirationand if the amount of excess nitrogen is within accepted limits, your body will normally get rid of it in a few hours. If the excess nitrogen in the body is too high, when you ascend, the nitrogen in the body may come out of the solution faster than the body could handle. It can cause nitrogen bubbles to form within the blood and body tissues, like bubbles forming when you open a coke and the pressure is released. The bubbles forming in the tissues and blood can cause a serious medical condition which blocks the flow of blood: Decompression Sickness.

This can cause coughing difficulty breathing, chest pain, severe shock, paralysis, joint or limb pain and more. Even though depth and time are the main factors that can cause DCS, there are other secondary factors that can also affect the developing of this sickness. Some secondary factors include: fatigue, cold, illness, age, alcohol consumption before/after a dive, dehydration and more.

To prevent this, it is recommended that in between the 18 hours of the end of the dive, no flying is involved and going to a high altitude, this is because going to a higher altitude lowers the pressure around you at the surface, meaning the dissolved nitrogen would come out of the solution faster than at sea level. flying over mountains right after diving can cause Decompression sickness. Slower ascent rates and decompression stop will be advised to lower the rate of DCS. Diving well within the limits of your dive computer can also reduce the chances of DCS (“Avoiding”).

Decompression stops = If you exceed your computers no stop time, it will command you to do a decompression stop at a following depth, and for certain minutes, before you can ascend. Stopping at the decompression stop can allow nitrogen to flow out of the body in a normal pace that does not cause DCS, before ascending further.

No Stop time = No stop time is the maximum time you can spend at a given depth and still ascend directly to the surface, if the no stop time is exceeded, you must make decompression stops.

Pg.19

Chapter 5.

Physics

Pg.20(Ong, Alice. “Jack.”)

Pg.21

Water Pressure and Air VolumeDepth and PressureRight now, the air around you actually has weight. At sea level the pressure is expressed as one bar(metric). While underwater, there are more pressure because water has weight and combines with the atmosphere’s pressure. Since water is so much denser and heavier than air, 10 meter exerts the same pressure as the whole atmosphere. Therefore as you descend 10 meters, the water pressure increases by 1 bar.

Therefore:At sea level: the total pressure is 1 barAt 10 m underwater: The total pressure is 2 barAt 20 m underwater: The total pressure is 3 barAnd Continue On.

Depth Pressure

0m/0ft 1 bar/ata

10m/33ft 2 bar/ata

20m/66ft 3 bar/ata

30m/99ft 4 bar/ata

40m/132ft 5 bar/ata

50m/165ft 6 bar/ata

Air Volume And Density- Water cannot be compressed, therefore the volume and density does not change. However pressure do change the volume and density of air.

As the pressure increases (You go deeper), the gas volume decreases because the gas molecules get compressed. However the density increases because all the molecules are compressed in a smaller area. Air volume and density change proportionally with pressure. Meaning if you descend from the surface to 10 meters, the pressure is doubled to 2 bar, the volume halves and the density doubles.

Depth Pressure Air Volume

Air Density

0m/0ft 1 bar/ata 1 x1

10m/33ft 2 bar/ata 1/2 x2

20m/66ft 3 bar/ata 1/3 x3

30m/99ft 4 bar/ata 1/4 x4

40m/132ft 5 bar/ata 1/5 x5

50m/165ft 6 bar/ata 1/6 x6

Using a balloon in context, at 40 m, the balloon has only 1/5 of the air volume compared to 0m, when the ballon ascend, it will expand and grow. This means that the balloon will keep growing and stretching past it’s failure point until it bursts. To prevent this the balloon should be unsealed to vent the expanding air when ascending.

10m

0m

The MOAT IMPORTANT rule in Scuba Diving:If during ascend, you were to hold your breath, this can cause damage to your lungs, casing it to over expand. Like the balloon example, being sealed at depth and ascending, it would expand and burst. This can cause lung ruptures injuries and are difficult to treat since by forcing air into the bloodstreams, it can cause paralysis and death. To avoid this, when anytime the regulator is not in your mouth, keep blowing small air bubbles to allow air to flow out of your body.

Pg.22

The Effects Of Decreasing Pressure On Body Air SpacesWhen pressure is increased, the air spaces in your body does have an impact. This is because the air space in your body is being compressed. As the air volume decrease (descending), water pressure pushes in on body tissues surrounding the space. The three major body air spaces are ears, sinuses, mask. If you don’t adjust for the increasing pressure on a body air space, you can get a squeeze. A squeeze causes discomfort, one of the effects is that the pressure that pushes your eardrum and surrounding tissues inward. It can cause injury by pressure imbalance that pushes tissues into air space. This is because there is a greater pressure outside the air space than inside it.

This can be prevented by adding air into the air space while descending: Equalization. This keeps the pressure equal with the outside pressure, therefore staying at their normal volume. To equalize your ears and sinuses, pinch your nose and blow gently against it. Do not continue to descend if you are unable to equalize, it can lead to serious injuries.

Mask Sinuses Ears

Nitrogen

Oxygen

Types of Air in CylinderAs a diver, when underwater you breath air. Air is a mix of several gases. The component gases of air are nitrogen, oxygen and more than a dozen gases in very small amounts. In diving, we ignore the gases that make up less than one percent of air, so we consider air to be 79% nitrogen and 21% are oxygen.

Enriched Air NitroxThis is another blend of air that can be use during diving, however divers need to be qualified. It has the same components gases as air but the proportions are different. Enriched Air Nitrox is a blend of 22% or more oxygen and the rest is nitrogen. Using this blend has its own advantages and disadvantages such as divers feeling less exhausted compared to using air but can increase the risk of oxygen toxicity.

Breathing UnderwaterUnderwater, the pressure reduces an air volume by compressing the molecules closer together. This means the deeper you go, the denser air is, and the more difficult to breath the air compared to surface level, therefore you uses more energy. Additionally, breathing faster takes more energy. So, take slow, deep breaths. It is the most efficient way to breath while scuba diving. It saves energy, and makes you air last longer. Slow, deep breathing can also handle stress and anxiety.

(Ong, Alice. “Jellyfish.”)

Pg.23

Chapter 6.

Dive Planning

(Reef Magic Cairns Cruises. “Feather Star.”)

Pg.24

Flying After DivingWhen planning for a dive, keep in mind of the flying limit after a dive as it may affect the risk of DCS (Decompression Sickness).As learned from chapter four, flying after diving is not recommended as it can increase the risk of Decompression Sickness. Over the years, recommendations for flying after diving have changed.

For no stop dives: -Single dives has a minimum of 12 hours before flying is recommended-Repetitive dives (diving everyday for several days) has a minimum of 18 hours before flying is recommended

Dives required emergency decompression stops:-A minimum of 18 hours is recommended before flying

These recommendations may not fully guarantee that decompression sickness will not fully occur because there are divers whose physiological makeups circumstances may still result in DCS. As for the aspect of diving, you are responsible for your own health and safety.

Altitude DivingAltitude diving is another type of diving, instead of starting or ending a dive at sea level, then descend-ing, altitude diving is diving at an altitude higher than 300m/1000ft above sea level. An example is diving in a mountain lake. With planning for altitude diving, you need to use altitude diving procedures. In some diving computers, there are automatic adjustment while some do not therefore cannot be use for this specific type of diving.

Cold or Strenuous DivesDuring diving, you need to avoid overexertion or hypothermia because if you get cold or exercise a lot during a dive, you may end up with more dissolved nitrogen in your body than calculated by the dive computer. This can increase the risk of DCS. If you are stressing yourself during a dive or feel cold, be more conservative. Stay within the no stop limits and have extra no stop dive time throughout you dives.

Planing a Minimum Surface Interval When making two or more dives, you commonly plan your dives by checking no stop times after your surface intervals. Surface intervals means the time the diver is out of the water between dives. You decide how long you want to dive and choose your maximum depth based on the no stop times. Planing a repetitive dive for a specific depth and time requires finding a minimum surface interval. This is to determine how long to wait after the first dive, so you can have the no stop time you want at the planned depth of the repetitive dive. There are three ways to find the minimum surface interval:

1. Wait and CheckAfter you dive, look at your dive computer and scroll to the no stop times and check it for your planned repetitive dive depth.

2. Use the plan mode on your diving computerSome dive computer has a mode that tells you what the no stop time is after you’ve been out of the water. Check your computer’s manual to look for the mode.

3. Use a tablet/smart phone appThere are dive planning apps you can get that calculates no stop times and to estimate minimum surface intervals.

Planning a dive is often the first step in organising a Scuba Diving trip. You plan a dive to ensure the dive will be safe and fulfils the goal of your trip. Issues like running out of air or having the need to do a decompression stop can be prevented if you planned well and follow your plan accurately, resulting in a successful and safe dive.

Pg.25

Conclusion

Go Explore!

After reading and understanding the context of this guide, you are ready to move on to the next step in getting your certification: the

final exam and the open water dives. You are half way there! Contact your local Scuba Diving centres to apply for the Open

Water Dive program and earn your certificate. Remember to always look back and review this guide to help you have a safe and

enjoyable diving experience.

(Aruba Scuba Dive Vacation Package)

Pg.26

Citations

Images:

B.C.D. Digital image. Cressi. N.p., n.d. Web. 3 Jan. 2016. <http://cressi-sub.it/FotoHiRes/HiResProduct.asp? CategoriaID=101002&titolo=B.C.D>.

Cylinder Valve. Digital image. Big Blue Scuba Diving International. 2005-2014 Big Blue, Feb. 2014. Web. 3 Jan. 2016. <http://big-blue.cn/newsletter/201402_en.html>.

Diving Regulators. Digital image. ScubaDivingFanClub. 2007-2015 - ScubaDivingFanClub.com, n.d. Web. 3 Jan. 2016. <http://www.scubadivingfanclub.com/Diving_Regulator.html>.

Diving with sea turtle. Digital image. Aruba Scuba Dive Vacation Package. N.p., n.d. Web. 03 Jan. 2016. <http://www.manchebo.com/Scuba-Diving-Vacation.html>.

PADI. Equipments. Digital image. PADI. PAD 2016, n.d. Web. 3 Jan. 2016. <https://www.padi.com/scuba-diving/padi-courses/course-catalog/about-scuba-gear/>.

PADI Scuba Diver. Digital image. Camel Dive Club & Hotel. Camel Dive Club and Hotel, n.d. Web. 3 Jan. 2016. <http://www.cameldive.com/courses/on/padi-scuba-diver/>.

Paul. Weight Belt. Digital image. What Are Weight Belts And Why Do I Need Weights For Diving. Spearfishing Blog, 13 May 2015. Web. 3 Jan. 2016. <http://spearfishingblog.com/what-are-weight- belts-and-why-do-i-need-weights-for-diving/>.

Reef Magic Cairns Cruises. “Anemonefish” 2015. JPEG File.

Reef Magic Cairns Cruises. “Clownfish” 2015. JPEG File.

Reef Magic Cairns Cruises. “Corals.” 2015. JPEG File.

Reef Magic Cairns Cruises. “Feather Star” 2015. JPEG File.

Reef Magic Cairns Cruises. “Fish” 2015. JPEG File.

Reef Magic Cairns Cruises. “Green Turtle” 2015. JPEG File.

Reef Magic Cairns Cruises. “Lionfish” 2015. JPEG File.

Reef Magic Cairns Cruises. “Moray Eel” 2015. JPEG File.

Reef Magic Cairns Cruises. “Nudibranch” 2015. JPEG File.

Reef Magic Cairns Cruises. “Wally” 2015. JPEG File.

Ng, Clemand. “Scuba Diver.” 2010. JPEG File.

Ong, Alice. “Hawksbill Turtle.” 2012. JPEG File.

Ong, Alice. “Jack.” 2012. JPEG File.

Ong, Alice. “Jellyfish.” 2012. JPEG File.

Ong, Alice. “Palau.” 2015. JPEG File.

Ong, Alice. “Shark Dive” 2010. JPEG File.

Soljaguar. Photograph taken at Playa del Carmen, Mexico, in the Tortugas. Digital image. Wikipedia, 6 Aug. 2006. Web. 3 Jan. 2016. <https://commons.wikimedia.org/wiki/File:Buzo.jpg>.

Yu, Cherie. “Adjustable Fins.” 2015. JPEG File.

Yu, Cherie. “Computer Watch.” 2015. JPEG File.

Yu, Cherie. “Dive Mask.” 2015. JPEG File.

Yu, Cherie. “Fins.” 2015. JPEG File.

Yu, Cherie. “Snorkel.” 2015. JPEG File.

Yu, Cherie. “Splash Guard.” 2015. JPEG File.

Yu, Cherie. “Wetsuits.” 2015. JPEG File.

Information:

“Avoiding Decompression Sickness When Diving.” SDI TDI ERDI. Copyright 2015 - SDI | TDI | ERDI, 17 July 2012. Web. 03 Jan. 2016. <https://www.tdisdi.com/avoiding-decompression-sickness-when-diving/>.

“Decompression Sickness.” Encyclopedia Britannica. 2016 Encyclopedia Britannica, Inc, 9 Dec. 2014. Web. 03 Jan. 2016. <http://global.britannica.com/science/decompression-sickness>.

PADI. “Dive Computer.” PADI. PAD 2016, n.d. Web. 5 Jan. 2016. <https://www.padi.com/scuba-diving/pa-di-courses/about-scuba-gear/dive-computers/>.

Sanford, Trevor. “A Short History Diving.” PADI. PADI, 5 Dec. 2013. Web. 03 Jan. 2016. <http://www.padi.com/blog/2013/12/05/scuba-diving-a-short-history/>.

Sawatzky, K. David. “Oxygen Toxicity - How Does It Occur?” Dive Rite. 2016 DIVE RITE, Dec.-Jan. 2008-09. Web. 03 Jan. 2016. <http://www.diverite.com/education/rebreather/tips/oxygen%20toxicity/>.