DFA Pro Prepared Diver Module

Diving within the no-decompression limits (NDL) allows you to:

avoid mandatory decompression stops (ceiling)

Safety Stops are supposed to take place between:

10 to 20 feet (3 to 6 meters) for 3 to 5 minutes

Breathing compressed gas at depth can impair your tolerance to exertion due to:

increased gas density

Which of these statements is true regarding your fitness to dive?

Fitness to dive implies both physical exercise capacity and health.

Why should you limit the depth and time of your dive?

to control risk of decompression sickness

to minimize nitrogen narcosis

to avoid severe breathing limitations

Which of the following is true about anxiety in diving?

Taking small steps can help you build confidence gradually

The pressure at 33 feet of seawater is how many times the pressure at the surface?

two times

All else being equal, as a diver dives deeper, they consume the air in their tank ______________.

faster

If you start with 2700 psi of air in your tank, when should you plan to turn the dive?

1800 psi

Water is 800 times denser than air, so it takes more work to move through it. This is because of what?

drag

To move forward as efficiently as possible, divers should maintain a horizontal position.

True

Aligning your body in the direction you want to travel, like an arrow, is known as?

trim

The faster you swim through the water, the ______________.

more drag you will create

more energy you will use

faster you will consume gas

If you are correctly weighted and your tank is full at the start of a dive, you should be able to float at eye-level with zero air in your BC.

False

To relax while diving, the best way to breathe is?

slow and steady, normal breaths

“Dead air space” refers to ______________.

air in the regulator second stage, snorkel or upper airway that is not fully changed over during breathing

What part of the ear is physiologically most affected by changes in pressure?

middle ear

The tympanic membranes (ear drums) can be ruptured by a pressure difference between the outer ear and the middle ear. What is the range of pressures by which the tympanic membranes can rupture?

4.5 to 10.0 psi

The most common cause of a reverse block on ascent is difficulty equalizing on descent.

True

What is the likely cause of alternobaric vertigo?

pressure difference between the middle ear spaces

Dizziness and vertigo are interchangeable terms.

False

If you experience discomfort on ascent what should you do?

none of the above

Which of the following are common concerns about using decongestants prior to diving?

They can wear off during the dive, allowing a return or worsening of swelling/inflammation.

Effectiveness can diminish when using them over longer periods of time.

Decongestants may not be compatible with the individual’s health history (i.e. hypertension).

If not taken within the correct time frame relative to diving, they may not reach full potential

All the following are acceptable techniques for enhancing equalization during descent except:

increasing your speed during descent to shorten any discomfort you experience

Sinus barotrauma can cause which of the following types of discomfort or pain?

pain behind the eyes or in the forehead, cheeks

pain in an upper tooth

The inner ear is an essential part of what mechanisms?

balance and hearing

You are neutrally buoyant when ______________.

you displace the same amount of water as you and your equipment weigh

If you and your equipment displace an amount of water that weighs less than you, you will ______________.

sink

All else being equal (same tank, dive gear, body weight, etc.), compared with muscular divers, divers with more body fat will require?

more weight because they are less dense

As a diver descends, the wetsuit ______________.

gets compressed thinner

When a neutrally buoyant diver in a wetsuit descends, air must be let out of the BCD to regain neutral buoyancy.

False

Dive tanks stay the same size throughout a dive, but ______________.

they get lighter as the air is breathed

During the ascent at the end of a dive, air in the BCD will ______________.

expand and need letting out

To establish horizontal trim (like an arrow) while diving, ______________.

adjust the weights and the tank up or down for your specific needs until everything is balanced

During the ascent phase of your dive, your body is exposed to ______________.

considerable decrease in pressure

One way to improve your safety when diving is to ______________.

conduct a shallow safety stop

Henry’s Law states:

When a given gas is in contact with a given liquid, the gas dissolves in the liquid proportionally to its partial pressure above the liquid’s surface.

The greater your depth during a dive, the ______________ nitrogen will dissolve into your body tissues from the compressed air you’re breathing.

more

Divers consume more gas as they dive deeper because:

they need to breathe the same volume of air regardless of depth

Lung over-expansion injuries are caused by ______________.

ascending while not exhaling

Buoyancy tends to ______________ during ascent.

increase

Most computers are designed for an ascent rate of ______________.

30 feet per minute

If you accidentally experience a rapid ascent and you start feeling unwell, you should ______________.

report your symptoms to your buddy, boat captain, dive leader, or instructor, and seek professional evaluation

One of these is not a responsibility of the dive professional (instructor/operator):

to take care that you don’t run out of air while diving

In terms of emergency preparedness, a good pre-dive briefing should include:

introduction of crew members holding appropriate minimum qualifications

availability and location of first aid kit and emergency medical oxygen

a dive plan, including a diver recall system

Regarding cleanliness, order, maintenance, and attention to details:

cleanliness is an indicator of good maintenance and a well-run operation

Regarding air quality and equipment safety, which of the following is correct?

an air quality certificate should be displayed or readily available

Regarding emergency oxygen availability, which of the following is correct?

a demand valve is the preferred method for delivering high concentrations of oxygen

When diving from a boat, which one is correct?

always make sure you understand and are comfortable with the crews instructions

When shore diving, which one is correct?

currents can prevent you from returning to your entry point

must always avoid areas with heavy boat traffic

proper foot protections when walking on rocky bottoms

Which is the most essential component of an Emergency Action Plan (EAP)?

contact the EMS

information regarding how to call DAN

flow chart for managing a diving accident

Regarding water entry and exit procedures from a boat:

the crew will determine the best water entry and exit procedures