Scuba/Open Water Diver Manual

Open Water Diver Manual Summaries

ISBN: 978-1-878663-16-0 (c) PADI 2010

Underwater World

• Whether an object sinks, floats or does neither in water depends on its weight and is displacement.
• You'll use lead weight and a BCD, as well as lung volume, to control your buoyancy.
• The body is made up mostly of in-compressible liquid, so you only feel pressure on the air spaces, which hold compressible air.
• There's a proportional relationship between pressure, air volume and density.
• You can use one of three techniques every metre / few feet to equalize your ears to prevent a squeeze while descending.
• You exhale into your mask through your nose to prevent a squeeze.
• Never continue to descend if you can't equalize.
• The most important rule in scuba diving is to never hold your breath.
• Don't dive with a cold or allergy congestion, even with decongestant.
• The deeper you go, the faster you use up your air supply.
• When scuba diving, breathe slowly and deeply, and avoid getting out of breath.

Dive Equipment and The Buddy System

• Comfort and fit are the two most important criteria in purchasing dive gear
• You can't use goggles for scuba diving because they don't enclose your nose
• You need to rinse your equipment in fresh water after each use
• The jacket BCD is by far the most common BCD used by recreational divers
• Your scuba cylinder needs an annual visual inspection, and periodic pressure (hydrostatic) testing
• You never leave scuba cylinders stating unattended - you block/secure them when transporting so they can't fall or roll.
• Regulators reduce cylinder pressure in two stages to breathing pressure
• A regulator's most important feature is ease of breathing
• You need to have your regulator professionally serviced annually
• Have the dust cap in place and don't push the purge button when you rinse your regulator
• You need an SPG (submersible pressure or contents gauge) so you can tell how much air you have at any time during the dive
• You always dive with a buddy for safety, practicality and fun
• You can make all your dive gear match and look good without sacrificing comfort, fit or important features

Adapting to the Underwater World

• Objects are magnified when you see them underwater, making them look closer and/or larger
• Water absorbs light and colors
• It's hard to tell sound direction underwater
• Water absorbs heat about 20 times faster than air
• If you start to shiver continuously, get out of the water, dry off and seek warmth
• It's best to move slowly and stay relaxed underwater

Respiration

• For maximum efficiency, breathe slowly and deeply
• Overexertion symptoms include fatigue, labored breathing, a feeling of suffocation, weakness, anxiety, headache, muscle cramping and a tendency to panic
• You prevent overexertion by staying relaxed and knowing your limits
• If you become overexerted, stop all activity and rest
• Airway control lets you breathe past small amounts of water

Dive Equipment

• Wet suits and dry suits insulate you, but differ in that you get wet in a wet suit and stay dry in a dry suit
• You should avoid wearing an excessively tight hood
• You want to wear gloves while diving for thermal protection and to avoid cuts, scrapes and stings
• Although you're protected (to a large extent) from the environment, remember that the environment isn't protected from you - use care to avoid damaging aquatic life
• Be cautious to avoid overheating in your exposure suit
• The most important feature in a weight system is the quick release
• Locate your alternate air source in the triangle formed by your chin and the corners of your rib cage
• Look for a dive knife with both smooth and serrated edges and a sheath
• You need dive instruments to tell you depth, direction, temperature, time and air supply

The Dive Environment

• Temperature, visibility, water movement, bottom composition, aquatic life and sunlight affect dive conditions
• A thermocline is an abrupt transition to colder water
• Plan your dive accounting for the water temperature at your planned depth
• When possible, use a visual reference for descending and ascending
• When diving with a current present, head into the current during the dive
• If caught in a current, don't fight it - swim across the current, or establish buoyancy and signal for assistance
• Avoid bottom contact by staying neutrally buoyant
• Most aquatic life injuries result from carelessness - watch where you put your hands, feed and knees
• Wear gloves and an exposure suit to reduce the likelihood of aquatic life stings and cuts
• Sunburn is entirely avoidable
• Surf diving requires special training and techniques
• If you get caught in a rip current swim parallel to shore until you're out of it

Dive Planning and Boat Diving

• Planning your dive plans your fun
• A dive plan doesn't have to be complex, nor take a lot of time, nor be inflexible, but you do need to follow it
• Boat diving has many benefits that make it popular
• You want to inspect and pack your gear appropriately before a boat dive
• Different parts and areas on a boat have nautical terms you should know
• Be careful when moving around on a rolling boat with your gear on
• Listen to crew briefings and procedures, where to enter and exit the water, and other techniques and emergency considerations
• Don't get under another diver who's climbing the boat ladder
• You may choose to avoid seasickness by taking seasickness medication

Problem Management

• Most problems occur at the surface
• You prevent most problems by staying relaxed and diving within your limits
• If you have a problem at the surface, establish positive buoyancy and call for help if you need it
• A diver with a problem who is in control tends to respond to instructions, and to establish buoyancy
• A panicked diver tends to spit out the regulator, push off the mask and to not inflate the BCD or drop weights
• When assisting another diver, establish buoyancy, calm the diver, help the diver reestablish breathing control, and if necessary help the diver back to the boat or shore
• If you watch your SPG, it's highly unlikely you'll run out of air
• You can breathe from a free-flowing regulator by not sealing your lips on the mouthpiece
• Entanglement isn't a big deal if you react calmly and carefully untangle yourself
• Bring an unresponsive diver immediately to the surface, check for breathing and pulse, and begin rescue breathing and/or CPR as necessary
• Ask for help when you need it

Dive Accessories

• You use a surface float to support your dive flag, for resting and to carry accessories
• Use an appropriate dive flag when diving where boats may be present and according to local law
• Don't attach a full collecting bag to your gear
• Underwater lights have both day and night uses
• A spare-parts kit can help you keep from missing a dive
• Start and maintain a log of all your dive adventures
• To communicate with an underwater slate, you have to have one

Health for Diving

• Don't drink, smoke or take drugs before diving (or ever)
• Don't dive when you don't feel well
• Stay in good health
• Have a physical examination at least every two years
• Keep tetanus and typhoid immunizations current
• Pregnant women shouldn't dive
• Review your dive skills and knowledge after a period of inactivity

Breathing Air at Depth

• Air is 79 percent nitrogen and 21 percent oxygen
• Contaminated air symptoms include headaches, nausea, dizziness, unconsciousness, and cherry red lips and nail beds
• Don't have your cylinder filled with oxygen, and don't use enriched air unless certified in its use
• To avoid nitrogen narcosis, avoid deep dives
• Decompression sickness is caused by excess nitrogen forming bubbles in the body after a dive
• Stay well within dive table and dive computer limits, especially if secondary factors apply to you
• Signs and symptoms of DCS include limb and join pain, tingling, numbness, paralysis, shock, weakness, dizziness, difficulty breathing, unconsciousness and death
• Decompression illness (DCI) is a clinical term for both decompression sickness and lung over expansion injuries
• A diver with DCI should receive emergency oxygen, rescue breathing and CPR if necessary, and will require treatment in a re-compression chamber

Dive Tables and Dive Computers

• Dive tables and dive computers use mathematical models to estimate the theoretical nitrogen in your body before, during and after a dive
• People vary in their susceptibility to DCS, so no computer or table can guarantee you'll never get DCS, even within its limits - so dive well within table/computer limits
• A dive computer has some use advantages and disadvantages compared to tables, but it is neither more nor less valid
• Recreational divers only make no decompression (no stop) dives
• The RDP is the most popular recreational dive table, and it is the first one developed and tested exclusively for recreational diving
• The eRDPml and dive computers offer you more no decompression dive time when making multilevel dives
• You must account for nitrogen you absorb on a dive if you make a repetitive dive before your nitrogen levels return to normal
• Stay within the depth limit of your training and/or experience - generally:
  • 12 m / 40 ft - Scuba Divers
  • 18 m / 60 ft - Open Water Divers
  • 30 m / 100 ft - general recreational limit
  • 40 m / 130 ft - maximum limit
• Be a SAFE Diver: Slowly Ascend From Every Dive

Special Dive Table and Computer Procedures

• You should make a safety stop at the end of virtually all dives (except when an emergency prohibits it)
• A safety stop is a pause in your ascent between 3 and 6 meters / 10 and 20 feet for three minutes or longer
• Consider a safety stop mandatory if you dive deeper than 30 metres / 100 feet or reach any limit on the RDP or your computer
• For recreational divers, decompression is only an emergency procedure
• You need to follow special procedures when diving at an altitude greater than 300 metres / 1000 feet
• Follow the recommendations for flying after diving conservatively, and stay up to date with the most current recommendations
• Plan cold/strenuous dives with the RDP as though the depth were 4 metres / 10 feet deeper than actual - with a computer, be conservative using the most appropriate method for your computer

Using a Dive Computer and Basic Compass Navigation

• You should have your own computer while diving - don't try to share one
• Keep your computer turned on all the time
• The dive medical community recommends that you make your deepest dive first and plan successive dives to progressively shallower depths
• Stay well within computer limits
• Back up your computer with dive tables
• Underwater navigation skills add to dive fun and safety
• The compass lubber line always indicates your travel direction; the compass needle always points north