Padi Scuba Flashcards
(146 cards)
1
Q
Why does a nail sink and a ship floats?
A
Buoyancy. An object is positively buoyant when it displaces more weight in water than its own weight.
2
Q
How can you affect your buoyancy?
A
BCD, lead weight, breathing
3
Q
If you descend to 10m/33ft, what is the pressure, air volume, and air density?
A
2 bar/ata and 1/2 air volume, x2 air density
4
Q
What happens when you ascend from 30m/99ft to the surface?
A
Air volume quadruples.
5
Q
What is the pressure, air volume, & density at 30m/99ft
A
4 bar/ata, 1/4, x4
6
Q
Which air spaces are most effected by descent?
A
Ear, lungs, and mask
7
Q
What is a squeeze?
A
When pressure outside airspace is greater than the pressure inside.
8
Q
How do you avoid a squeeze?
A
Equalize the air space by adding air to the spaces as you descend (through throat for ears and through the nose for the mask).
9
Q
How do you equalize your ears and sinuses?
A
Pinch your nose and gently blow and/or swallow and wiggle your jaw.
10
Q
If you feel discomfort from a squeeze…
A
ascend a short way and try to equalize
11
Q
If you can’t equalize…
A
discontinue the dive. Do not use medication or ear plugs.
12
Q
What happens to the air in your lungs when you ascend?
A
It expands. Continue to breathe normally upon ascent.
13
Q
What is the most important rule of scuba diving?
A
Breathe continuously and NEVER hold your breath. Otherwise lung expansion is the most serious injury possible.
14
Q
What is a reverse block or reverse squeeze?
A
Pain from expanding air trapped in an air space on ascent. Avoid gassy foods. Uncommon.
15
Q
The deeper you go, the (shorter OR longer) your air will last.
A
Shorter
16
Q
Denser air is (harder OR easier) to breathe
A
Harder
17
Q
Why do you need a mask?
A
In water everything is blurry, the mask provides an air space so our eyes can focus. A mask must cover your nose.
18
Q
What size things should a scuba mask have?
A
Tempered glass, a comfortable feet, nose or finger pockets, low profile, adjustable locking strap, wide field of vision.
19
Q
What are the most important selection features of a mask?
A
Fit and comfort.
20
Q
How do you prepare a new mask?
A
Remove the protective chemical with a cleanser and adjust strap.
21
Q
What are the three general procedures for maintaining scuba gear.
A
Rinse throughly with fresh water after every use, keep out of direct sunlight, store in cool, dry place.
22
Q
What is the snorkel for?
A
Lets you rest with your face in the water. Easier breathing in rough conditions. Less tiring if you need to swim back.
23
Q
What features should your snorkel have?
A
Large bore, not excessively long, smooth round bends.
24
Q
How do you prepare the snorkel for use?
A
Attach to the left side of the mask.
25
What is a BCD?
Buoyancy Control Device.
26
What 5 features should you BCD have?
Proper size for ample buoyancy. Large diameter hose/valve, low pressure inflation system, over pressure relief, adjustable.
27
How should you adjust the BCD before use?
With the BCD deflated, adjust to fit snuggly. When fully inflated it shouldn't feel restrictive.
28
In additional to regular gear maintenance, for a BCD you must also (2 things)
Rinse the inside and outside with fresh water. Store partially inflated.
29
What does a scuba tank do?
Stores high pressure air to use while diving.
30
What are the two types of valves?
K-valve (simple) and J-valve (warns you when you're running out of air. Yoke valves and DIN valves are how you connect to the regularator.
31
Make sure to check for a ______ when setting up your regular and tank.
the o-ring to make the air tight seal.
32
What extra maintenance steps are there for tanks?
Open the valve to drain it. Close is all the way to with a few PSI left.
33
What does the regulator do?
Reduces the air pressure from your tank. Delivers air on demand when you breathe.
34
You can manually control the air flow on a regular with the ....
purge valve.
35
What is the most important feature when selecting a regulator?
Ease of breathing.
36
What's an SPG and what does it do?
Submersible Pressure Gauge. Tells you how much air you have remaining. Must be checked frequently.
37
What additional maintenance steps are there for an SPG?
Don't drop or bang it. Secure it so it doesn't drag or snag.
38
What are three reasons to dive with a buddy at all times?
Assistance. Reminders. Emergency assistance. OR Practically. Safety. Fun.
39
How much more denser is water than air?
About 800 times more dense
40
What does refraction do to you vision?
It makes objects appear a third bigger.
41
What colors are lost first in water depth?
Red, Orange, Yellow
42
How does water affect sound?
It travels 4x faster in water. It's difficult to tell where it comes from. Rap on your tank to get their attention.
43
How much faster does water conduct heat?
About 20 times faster so water chills you faster than air.
44
How can you tell you need to get out of the water immediately?
When you are uncontrollably shivering.
45
How do you conserve energy underwater?
Avoid jerky movements. Move slowly.
46
When swimming your body should be horizontal or angled?
Horizontal to eliminate drag.
47
How do you breathe efficiently while diving?
Take slow & deep breathes (to avoid the dead air in shallow spaces.)
48
What are the symptoms of overexertion?
Fatigue, labored breathing, suffocation, weakness, anxiety, headache, tendency to panic.
49
What should you do if you feel overexertion.
Stop and rest, hold an object for support, signal for help.
50
How do you breath past water?
Airway control. Inhale slowly if water enters. Inhale cautiously and slowly after clearing. Use tongue as a splash guard.
51
If you need to cough...
hold second stage regulator and cough into it.
52
Why use an exposure suit? (2 reasons)
To prevent heat loss and prevent scraps.
53
Wet suits are [more/less] buoyant the deeper you dive?
less
54
To avoid overheating...
Put suit on last. Keep hood off. Keep out of sun. Keep jacket unzipped. Cool off in water. Hydrate.
55
What does a weight system do?
To let you sink and offset positive buoyancy.
56
What is the most important feature on a weight system?
Quick release. Make sure to wear it outside of equipment so you can release it with one hand.
57
You need more weight in [cooler/warmer] water.
Cooler
58
How do you determine weight?
Enter water with all gear. With regulator in, deflate BCD and hold breath. Should float at eye level. Exhale and you should slowly descend. If you are using a full cylinder, add 5 lbs.
59
What is the alternate air second stage?
You can use it and give your buddy your regulator when they have run out of air?
60
What are two alternate air source configurations that you can use yourself?
An ascent bottle or pony bottle.
61
Where should you alternate air source be secured?
In the triangle between your chin and lower rib cage.
62
What does the low pressure inflator do?
It inflates the BCD.
63
What does the dive knife do?
Cut, measure, pry, saw and pound.
64
When packing for diving, pack in the ______ order.
Reverse.
65
What do dive instruments measure?
Time, depth, temperature, (possibly SPG) and compass.
66
What are two ways for gaining attention of a diver?
Touch or sound (wrapping on cylinder)
67
Why do you carry a whistle?
To get attention at the surface.
68
Why should you never wave at boats?
It means "help".
69
What are nine points to agree when diving with a buddy.
1. Entrance/exit. 2. Course to follow. 3. Depth limit. 4. Time limit. 5. Communications. 6. How to stay together. 7. What do if separated. 8. Emergency procedures. 9. Dive objective.
70
What does Begin With Review And Friend stand for?
```
B - BCD
W - Weights (clear relase)
R - Review each other's releases
A - Confirm enough air, regulator works, know where secondary regulator are
F - Final check
```
71
Stay within _________ of you buddy.
a meter or a few feet.
72
If separated from buddy?
Search for a minute and then surface.
73
What are the six elements that affect underwater conditions?
Temperature, visibility, water movement, bottom composition, aquatic life, sunlight.
74
What is a thermocline?
Temperature difference as great as 15-20 degrees between layers of different water.
75
How to you measure underwater visibility?
How far you can see horizontally?
76
What affects visibility?
Water movement, weather, suspended particles, bottom composition.
77
What should you do when visiblity is poor?
Stay closer to your buddies. Use your compass, note bottom features. Ascend and descend along the boat line or shore bottom.
78
In extremely clear water, the bottom of the water appears [closer/further] away.
closer.
79
When there is a mild current....
Being dive swimming into current. Avoid long surface swims. You'll make better progress on the bottom.
80
Instead of swimming against a current....
Don't fight it. Swim perpendicular against the current to shore or a boat.
81
What types of bottom compositions are the easiest to stir up?
Silt and mud.
82
What problems can you the bottom composition include?
Entanglement or Scrapes
83
Bottom contact should be ___________
avoided.
84
When near aquatic animals...
Move slowly and smoothly.
85
Nearly all injuries from animals...
are minor and result from human carelessly. Stings, punctures, and scrapes.
86
If you see a potentially aggressive animals
Remain still and calm on the bottom. Don't swim towards it. Watch what it does. If it stays, slowly swim along the bottom and exit the water.
87
Precautions
Treat all animals with respect. Be cautious in murky water. Avoid shiny jewelry. Wear gloves. Stay off the bottom. Move slowly and carefully. Watch where you put your body. Don't approach things you don't recognize.
88
If you get entangled.
Keep calm. Stop and back slightly. Don't turn around.
89
Waves are formed by...
wind blowing over the surface. Strong winds over several hours can create bad conditions.
90
Waves in break water slightly _____ than their height.
deeper
91
What is backrush?
After wave breaks, it flows under on coming waves. Dissipates at about 1M. Stronger in steeper shore lines.
92
What is a rip current?
When waves push water over barriers and funnels back through a narrow opening. Can be strong and carry you away from the shore quickly. If you get caught in one, establish buoyancy and swim parallel to shore to get out of it.
93
What are offshore currents?
Permanent large scale currents cause by earth's rotation.
94
Generally the best diving is at _____ tide.
high
95
Longshore tides push you....
parallel to the shore.
96
Plan your dive with your buddy and then
dive the plan
97
What are the front and back of boat called?
Bow is the front and stern is the back.
98
What is the right and left side of a boat called?
Starboard is right, port side is left.
99
Prevent surface problems...
diving within your limitations, relaxing while you dive, establish and maintain buoyancy.
100
If you have problems at the surface...
immediately establish buoyancy by inflating the BCD or discarding weights. Wave, yell, and whistle.
101
What are the four steps to assisting a diver?
Establish buoyancy for both of you. Clam the diver. Help the diver reestablish breathing control. Assist the diver to boat or shore.
102
Prevent problems by...
relaxing while you div. keeping a close watching your air supply. diving within your limitations.
103
If you are running out of air, you can...
Make a normal ascent. Ascend using an alternate air source. Make a controlled emergency swimming ascent while exhaling continuously by making an "ah" sound.
104
Buddy breathing can be used...
if there is only a single regulator.
105
To make a buoyant emergency ascent...
drop your weight while exhaling continuously by making an "ah" sound.
106
To inflate your BCD after running out of air...
inflate it by mouth.
107
If your regulator fails...
it will free flow. Breathe the air like drinking from a water fountain. Do not seal it in your mouth. Ascend immediately.
108
Prevent entanglement...
by moving slowly, watching where you go, and keeping equipment streamlined.
109
If you can entagled...
stop, think, work slowly. Get your buddy to help. Don't twist or turn. You may need to take equipment off. You may need to cut.
110
What are the causes of a near drowning?
Swallowing water, extreme fatigue, entanglement, and lung over-pressurization.
111
If a diver appears to lose conscious.
Quickly bring the diver to the surface and check for breathing. Establish ample buoyancy for both. Signal for help. Do rescue breathing. Get diver out of the water.
112
Keep a breathing but unconscious diver...
lying level on their left side whenever possible.
113
Remain within ________ of your dive flag
15 meters/ 50 feet
114
Why is contaminated air so dangerous underwater?
Pressure proportionally increases effects of contaminates.
115
If your air tastes or smells bad?
Don't use it. Discontinue the dive. Save it for analysis.
116
Pure oxygen in your tanks...
can poison you.
117
Nitrogen/gass narcosis creates a hazard by...
Impairing judgement and coordination, foolish behavior, anxious etc.
118
If you feel intoxicated or impaired...
ascend until the feeling leaves.
119
Increased pressure causes _______ to dissolve into body tissue.
nitrogen. Deeper + longer = more nitrogen.
120
If you exceed the limits of your body to dive deep and long, the nitrogen in your tissues causes...
Decompression sickness or the "bends"
121
What are the symptoms of decompression sickness?
Paralysis, shock, weakness, dizziness, numbness, tingling, difficulty breathing, joint and limb pain, unconsciousness and death, dull ache, prolonged fatigue
122
First aid for decompressions illness
Have diver lie down and breathe oxygen. Get help. Monitor for shock. Provide rescue breathing or oxygen. Lay breathing diver on left side. Get treatment immediately.
123
Why can't a dive computer's limit stop decompression sickness?
It's a model that doesn't take into account individual risk factors.
124
The No Decompression Limit is...
the maximum time you can stay at a depth and ascend without having to stop.
125
How long does excess nitrogen left in your body take to dissolve out of your body after a dive?
Several hours
126
Bottom time is...
the total time in minutes from beginning of descent until beginning of ascent.
127
Calculate any dive to 10m or less as...
10 meters.
128
Slowly ascened form all dives at a rate that does not exceed..
18m/60ft per minute
129
When planning a dive is cold water or strenuous plan the dive assuming the depth is...
4m/10 ft deeper than the actual depth.
130
Plan repetitive dives so that each successive dive is...
to a shallower depth.
131
Stop your ascend when you reach ________ and wait _______ minutes.
5m/15 ft and wait 3 minutes or longer
132
The maximum depth of recreational diving is...
40m/130ft
133
What is the adjusted no decompression limit?
The time limit for a repetitive dive that accounts for residual nitrogen.
134
What is RNT?
Residual Nitrogen Time, amount of nitrogen expressed in minutes for a specific depth that you add to your actual bottom time to account for residual nitrogen from previous dive.
135
How do you calculate the minimum surface times between dives?
Find the pressure group of your first dive. Then on table three, find the time you'd like your second dive to be in the lower number. See what pressure group that relates two. Then see the minimum amount of time between the pressure group of the first dive and the second dive in table 2.
136
What is the maximum depth of recreational diving?
18m/60ft
137
A safety stop is required if...
Your dive has been to 30m or deeper, your pressure group is within three pressure groups of the no-stop limit, you reach any limit on your dive computer.
138
If you exceed your limits for 5 minutes or less...
make an emergency decompression stop for 8 minutes and don't dive for 8 hours.
139
If you exceed your limits from more than 5 minutes
make an emergency decompression stop by 15 minutes and don't dive for at least 24 hours.
140
For multi-day dives, a minimum preflight surface interval of ______ hours is recommended.
18 hours
141
If a dive is strenuous or cold water, add ____ meters to your dive calculations.
4
142
Should you turn your computer off between dives?
No
143
If you and your buddy's computers disagree, which one should you follow?
The most conservative one.
144
What is the lubber line?
It is the straight line between 0 and 180 degrees that your body is traveling.
145
What does the bezel do?
Allows you to mark where the compass needle should stay aligned in order to keep going straight.
146
How do you return the way you came with a compass?
Rotate the bezel to the exact opposite of your original heading.
