In Section 4 of PADI’s Open Water Diver eLearning (Chapter 4 of the Open Water Diver Manual), you have learnt some important concepts about equipment handling, using dive computers and tables together with some further diving skills.
The knowledge review section at the end of the fourth Chapter of the Open Water Diver Manual (or eLearning section 4) will test your knowledge about diving equipment (dive lights, logbooks, dive planning software), your health and fitness, and how dive computers and tables work.
Being knowledgeable with those concepts will help you become a good diver and get you ready for the open water diver “in-water” sessions.
In case you get some of the answers wrong, you should not worry. It’s however super important to discuss answers that you do not fully understand with your diving Instructor.
If you are looking for answers and explanations to other PADI Open Water knowledge review sections, check out the following links:
- PADI OWD Section 1 Knowledge Review Answers Explained
- PADI OWD Section 2 Knowledge Review Answers Explained
- PADI OWD Section 3 Knowledge Review Answers Explained
- PADI OWD Section 5 Knowledge Review Answers Explained
- PADI Open Water RDP Knowledge Review
- How to Use PADI Dive Tables
During an underwater cleanup, my buddy and I fill a large mesh utility bag with several kilograms/pounds of garbage. We should
Answer: Carry the bag in our hands.
Whenever you are carrying some objects that are not part of your scuba diving equipment, you should carry them in your hands.
Tying objects that you pick up underwater to your diving equipment can be extremely dangerous as you cannot quickly release them in case of emergency.
Diving Tip: Never tie to your BCD objects that you pick up while diving. Whether it’s a ghost net or a car tire or some plastic bottles, you should always carry them in your hands. You can also use a mesh bag for greater comfort.
I have a bit of a cold but feel I can manage the dive well enough, so it is okay to dive.
Answer: False
If you experience cold symptoms and the like, you should not scuba dive. Although you might have a false impression of feeling fit, you might experience problems in equalizing while descending.
Ascending from a dive can also be tricky if you have cold symptoms. In fact in case air gets trapped in your ears or sinuses, you might experience a reverse squeeze or reverse block.
A reverse squeeze happens whenever air is trapped in your dead air spaces and cannot be released.
Diving Tip: If you experience a reverse squeeze while ascending, you should halt your ascent, allow some time for equalization to occur, eventually descend a bit before trying again.
Exertion from swimming hard, carrying equipment, climbing a ladder, long walks wearing gear, and heat stress from wearing an exposure suit in a hot climate can lead to heart attack in predisposed individuals. These factors can also cause problems for people with other cardiovascular conditions.
Answer: True
Exertion, and particularly overexertion can lead to heart attacks in predisposed individuals. This is actually common in many sports and physical activities, and scuba diving is no exception.
One factor you should pay particular attention to is that in the case of scuba diving, also wearing an exposure suit in a hot climate can lead to a heart attack.
This is particularly the case for exposure suits that are overly tight in the neck area.
If you are interested in further details on how to choose the right exposure suit, check out my posts on scuba drysuits and wet suits.
- How to Choose the Perfect Scuba Wetsuit: A Complete Guide
- How to Choose the Perfect Scuba Diving Dry Suit?
Before diving, I should refrain from using (choose all that apply)
Answer: Alcohol, Tobacco
Alcohol and/or Tobacco consumption can be very dangerous in scuba diving for different reasons.
Alcohol consumption affects your judgment, this tends to worsen while scuba diving. Additionally, alcohol consumption dehydrates you and accelerates body heat loss. A dive in relatively warm water can result colder than it actually is, impacting your overall air consumption and dive time.
Smoking significantly affects the efficiency of both respiratory and circulatory systems. It raises the risk of lung overexpansion injuries and DCS and should be avoided before and after diving.
Note that some scuba diving agencies (see GUE for example) are really not flexible when it comes to smoking and rightfully so.
Given the increasingly higher popularity of legal / medical cannabis, I think it is also useful if you read this article from DAN on Cannabis and Diving.
Medications can create problems when diving, so I should use prescription drugs and over-the-counter medications with caution. Any drug that affects my judgment, thinking and/or reactions should generally not be used before diving.
Answer: True
Some medications can have the very same effects of Alcohol and Tobacco consumption while scuba diving.
In case you are taking medications I strongly recommend you check with your doctor or medical advisor whether they might have a negative impact on scuba diving.
It is recommended that pregnant women do not dive.
Answer: True
In your PADI open water diver theory you have learnt that scuba diving while pregnant should be avoided. Although there is no strong medical evidence suggesting that diving is harmful for pregnant women, there is some evidence suggesting that it can affect the fetus.
If you would like to have further information and medical evidence on diving while pregnant, I suggest to take a look at the following article from DAN.
If you are interested in learning more about scuba diving while pregnant, check out my dedicated post.
As a new PADI Open Water Diver, I should refresh my dive skills with a PADI Scuba Review after ___________ of inactivity.
Answer: Six Months
Just like any other sport, if you do not practice scuba diving frequently you are most likely to forget concepts related to safety, equipment, and problem management.
This would inevitably result in higher risk while scuba diving for the first time after several months of inactivity.
This is why PADI recommends to take a Scuba Review after 6 months of inactivity.
Diving Tip: Even if you like diving in warm waters, it is always a good idea to dive locally also in lakes, quarries, or swimming pools to keep your diving skills and knowledge up to date.
One reason it is important to be certified as a PADI Enriched Air Diver, or under the supervision of a PADI Enriched Air Instructor, before using enriched air nitrox is to avoid oxygen toxicity problems.
Answer: True
Although diving with Enriched Air (or Nitrox) has many benefits, it exposes divers to an increased level of oxygen.
At given depths a high percentage of oxygen in your breathing gas may simply be toxic for your body.
This is why we refer to oxygen toxicity in relation to Enriched Air Diving.
Oxygen toxicity may be extremely dangerous as it can result in convulsions underwater, which are likely to lead to drowning.
Diving Tip: Never dive beyond you the limits of your current training. This applies to depth limits, no-decompression limits, equipment and breathing gasses.
If you would like to know more about Nitrox Diving, check out my Ultimate Guide to Enriched Air Diving.
During a dive, I begin to have a headache, feel ill and dizzy. Are these possible symptoms of contaminated air?
Answer: Yes
Contaminated air is tricky. Particularly if the source of contamination is carbon monoxide which is odorless, tasteless, and colorless.
The only way to detect abnormal levels of carbon monoxide in your breathing gas is by analysing the gas in your scuba cylinder with an electronic carbon monoxide detector.
In case you feel ill and dizzy during a dive, there are high chances you have been breathing contaminated gas and should abort the dive.
Diving Tip: Although carbon monoxide is odorless and tasteless, some other sources of contamination are not. This is why it is always important to smell and check your breathing gas before starting a dive.
To avoid contaminated air, I should have my cylinder filled only at reputable scuba air sources.
Answer: True
To avoid the risk of contaminated air you should indeed have your cylinders filled only at reputable scuba air sources.
Some of the elements to look for to check the risk of contamination is whether the compressor used to fill in your scuba cylinders is located close to engine exhausts, high traffic areas, or possible other pollutants.
The two primary factors that influence how much nitrogen dissolves into my body tissues during a dive are ________ and _________.
Answer: depth, time
Depth and time are the most important factors in determining the extent to which nitrogen dissolves into your tissues.
This is actually the main reason why no-decompression limits include both a depth and a time limit.
If I exceed established depth and time limits while diving and then surface, bubbles can form in my body tissues, causing decompression sickness.
Answer: True
If you exceed depth and time limits while scuba diving and surface without doing a safety stop, you might expose yourself to DCS.
Bubbles will form in your body tissues and might start moving around causing pain in your joints.
After a dive, a diver has numbness, tingling and weakness in the arms. Are these possible signs/symptoms of DCS?
Answer: Yes
Symptoms of DCS include:
- fatigue.
- joint and muscle aches or pain.
- clouded thinking.
- numbness.
- weakness.
- paralysis.
- rash.
- poor coordination or balance.
Check out my latest post on DCS to learn all the details about decompression sickness and how to prevent it.
Secondary factors thought to contribute to DCS include (choose all that apply)
Answer: Age, Cold, Injuries, Poor Fitness/High Body Fat
Age, Cold, Injuries, Poor Fitness and High Body fat are other factors that might influence the risk of DCS, although there is less medical evidence supporting this conclusion.
A no stop dive means I can, ________ the dive, ascend directly to the surface without stopping if necessary (although I would normally plan a safety stop).
Answer: At any time during
Although no stop dives require no safety stops, I always suggest doing a safety stop every time you dive.
This is a form of risk management and prevention. In fact, in case you do several no stop dives without performing a safety stop, there are increased chances that you will forget to do a safety stop when it is actually needed.
Even if not required, doing a safety stop in each single dive will help you maintain good habits and high safety standards while diving.
If I am planning a dive to 12 metres/40 feet, my no stop limit will be ______ than my no stop limit for a dive to 10 metres/30 feet.
Answer: Shorter
The deeper your dive the shorter your no stop limit. In recreational diving, the maximum depth for no stop dives is 32 feet or 10 meters. Note however that this pretty much depends on how much time you will be staying at such depth.
Exceeding my computer or table’s ascent rate may increase my risk of DCS.
Answer: True
The recommended ascent rate is 30 to 60 feet (9 to 18 meters) per minute. Exceeding those limits or the limits set by your computer will definitely increase the risk of DCS.
On a repetitive dive, for a given depth my no stop limits will be ______ those of the first dive.
Answer: Shorter than
On a repetitive dive, for a given depth, your no stop limits will be shorter than those of your first dive.
This means that if on a repetitive dive you plan to stay at the same depth of the first dive, you will be allowed to stay less time until your computer will signal you to ascend slightly.
This is to avoid excessive build-up of nitrogen in your tissues which would then require you to do decompression stops.
I must use the same dive computer the entire day of diving, on all dives, and not share it with another diver.
Answer: True
Dive computers are adaptive to the dive profile. They are able to recognise repetitive dives, and compute no stop limits accordingly.
If you change computer between dives, you will risk of breaching the no stop limits without knowing and therefore taking the risk of DCS.
One of the first pieces of dive gear every diver should get is a dive computer. Check out my ultimate buyer’s guide on how to choose your first dive computer.
During a dive with my dive computer, my buddy and I will turn the dive based on the first limit we reach: remaining no stop time or air supply turn point.
Answer: True
While diving in a buddy team you should always be following the most conservative limit.
This implies that you will turn a dive based on the first limit you reach whether it’s no stop time, or air supply turn point.
When diving with a computer, it is recommended that I (choose all that apply)
Answer: Dive well within its limits, follow the most conservative computer – mine or my buddy’s, start at the deepest point and progress shallower, ascend slowly and make a safety stop.
The golden rule of diving with a dive computer is to follow its indications. This will substantially minimize the risk of accidents linked to excessive depth, wrong ascent rate, and shorter safety stop or surface interval.
When diving in a buddy team, you should always be following the most conservative computer. This will avoid exposing one of the two divers to increased risks.
During a dive, my dive computer fails, and I’m not using a backup. I should
Answer: Ascend, make a safety stop and end the dive.
If you do not have a backup computer and your computer fails you should end the dive by making a safety stop.
For the appropriate ascent rate and safety stop time, you may ask your buddy for help.
There is virtually no situation in which you should be continuing the dive using only your dive buddy’s computer.
One reason it is important to have environmentally friendly dive skills is to preserve the natural beauty for other divers.
Answer: True
Environmentally friendly dive skills help preserving the natural beauty for other divers. This means for example, maintaining good buoyancy and trim to avoid damaging coral formations.
Good buoyancy will also help avoiding lifting the bottom. Although this is less of a problem in open sea, it can be quite problematic for other divers in lakes or quarries where silt takes quite some time to settle back in the bottom.
