STARS Open Water Diver Manual

Index

Orientation
Transform into a Fish on Your Holidays
Certificate of Fitness for Diving
Certification Card (C-Card)
 
Dive Equipment
Mask
Snorkel
Fins
Gloves/Boots
Diving suits
Weights
Tank
Regulator
Backup Scuba
BC
Gauge
Other Equipment 1
Other Equipment 2
Other Equipment 3
Equipment Setup
Equipment Maintenance
 
Underwater Environment
Topography and Artificial Structures 1
Topography and Artificial Structures 2
Ocean Conditions 1
Ocean Conditions 2
Poisonous Sea Life 1
Poisonous Sea Life 2
Aggressive Sea Life
 
Underwater Physiology
Light and Color
Sound
Drag/Buoyancy
Heat Absorption
Air Composition
Breathing and Circulation Mechanism
Diver Breathing /Air Consumption
Pressure
Pressure and Gas Volume
Lung Over-expansion Injury
Air Embolism
Gas Poisoning
Hyperventilation
Skip Breathing
Decompression Sickness (DCS)
The Human Body’s Air Spaces
Squeeze and Equalization
Specific Squeeze Types
Reverse Block and Equalization
Specific Body Air Cavities and Reverse Block
 
Plan and Rules
Diving Site Selection
Leader and Member
Buddy System
Equipment
Health Maintenance
Refresher Course
Cancellation and Modification
Emergency Plan
Communication
Air Consumption Ratio
Dive Table
Change of the internal nitrogen quantity
Comparison of the internal nitrogen quantity
Constitution of the Dive Table
No-decompression Dive Limit
Residual Group
Surfacing Time
Nitrogen Disappearance Time
Surface Interval Time
No-decompression Dive Limit for the second diving
Residual Nitrogen Time
Residual Group for the second diving
Decompression Stop
Safety Stop
Time Until Safe To Fly
Other attention
Work Sheet
Making a Dive Plan
Multi-Level Diving
Manners
 
Diving Skills
Donning Snorkel Set
Snorkel Clear
Fin Work
Donning the Weight Belt
Head First
Equipment Setup
Entry
Descent
Regulator Clear
Mask Clear
Regulator Recovery
Buoyancy Control
BC Donning and Removal
Weight Belt Donning and Removal
Equipment Release
Dealing with Emergencies 1
Dealing with Emergencies 2
Dealing with Emergencies 3

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Air Consumption Ratio

Once you know how much air you breathe in a one-minute period, it is possible to calculate how long a dive you can complete. You can also see on a minute-by-minute basis the strong effects of pressure on the air consumption ratio.


  1. Starting pressure – ending pressure = total air consumption (by pressure)
  2. Air consumption pressure x tank volume = total air consumption (by volume)
  3. Total air consumption (by volume) ÷ diving time (by minutes)
    = total air consumption (by volume)/minute
  4. Total air consumption (by volume)/minute ÷ average depth pressure
    = air consumption ratio


Practical Dive Time

Since we are limited to our tank’s capacity, our dive time is also limited. It is important to calculate your air consumption ratio, since it varies widely - advanced divers’ air consumption ratio is about 20L/minute, while beginners average about 40L/minute.

Remember, we leave 50 bar reserve in our tank at exiting for safety. As a rule, you should use the following for calculating your air consumption ratio.
We use litre (L) for tank volume; and we use bar to denote pressure.


Practical Dive Time Calculation

Volume capacity of tank usedx(starting tank pressure - 50)÷40÷maximum depth


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