PADI OW Section 5 Knowledge Review Answers

*PADI Knowledge Review 5 tests your understanding of dive tables, diving skills and attitude*

In Section 5 of PADI’s Open Water Diver eLearning (Chapter 5 of the Open Water Diver Manual), you have learnt some important concepts about using dive computers and tables together with some further diving skills.

You have also learnt some additional concepts about being a diver which will turn useful in your Advanced Open Water Course.

Chapter 5 (or eLearning section 5) knowledge review section will test your knowledge about using dive tables, diving skills and general diving awareness and attitude.

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 dive Instructor.

If you are looking for answers and explanations to other PADI Open Water knowledge review sections, check out the following links:

Table of Contents

My buddy and I have just finished a dive to 15 metres/50 feet for 60 minutes. We want to return to the same site and depth and stay another 60 minutes. We can ______________________ to see about how long we have to remain at the surface to have enough no stop time.

Answer: Wait and check our no stop times on our computers periodically, use the dive computer plan mode if available, use a dive planning app, check the RDP Table or eRDPML.

The essential concept behind this question is that you should not underestimate the importance of surface interval. You should also not attempt to approximate the length of a surface interval by yourself.

A shorter than necessary surface interval may lead to increased levels of nitrogen in your bloodstream, exposing you to higher risk of nitrogen narcosis or DCS.

To determine the amount of time you should spend on your surface interval, you can either use you dive computer, dive planning app, dive tables, or the eRDPML.

Going to altitude after diving may be a problem because

Answer: Most decompression models are based on surfacing at sea level.

The lower pressure at altitude can allow the excess nitrogen in your body tissues to come out of solution faster than at sea level. This can cause bubbles that increase the risk of decompression sickness.

Diving at altitude is extremely fun and require specialised training. If you are planning some lake diving, I strongly suggest you take PADI’s Altitude Diver Specialty to ensure you have adequate training.

Remember that diving beyond the level of your training is one of the most common and dangerous mistakes divers make.

I’ve just finished a single no stop dive with my buddy. We have not been diving in the past several days, and this is the only dive we make. Based on current recommendations, the minimum surface interval before we fly is

Answer: 12 Hours

Following the flying after diving recommendations is essential to avoid being exposed to higher risks of DCS.

If you would like to learn more about flying after diving regulations, check out my post on flying after diving.

4. I need to use special altitude diving procedures when diving at an altitude greater than

Answer: 300metres / 1000 feet

Although many lakes are well below 1000 feet high, whenever you are planning some lake or river diving you should consider whether the altitude is higher or lower than 300metres / 1000 feet.

Whenever you are planning a dive at heights greater than 300metres / 1000 feet, make sure you have the adequate training.

If I am cold or exercise a lot during a dive, I may surface with more nitrogen than calculated by my dive computer or dive tables.

Answer: True

*Cold water diving requires an adequate exposure suit*

Do not forget that dive tables and dive computers are based on “standard algorithms”. One example of such algorithms is the Bühlmann’s algorithm.

Although decompression algorithms tend to be quite accurate, they are of course not specific to your physical conditions or dive conditions.

Depending on the level of exertion during a dive, you might therefore end up with nitrogen levels that are higher than the ones calculated by dive tables or by your dive computer.

At the end of a dive, my dive buddy’s foot gets tangled in an abandoned fishing net. It takes five minutes to get free, but that delays our ascent making us exceed our no stop limit. This means that before we surface, we will have to make a(n) ___________ stop to return our nitrogen level from outside the accepted limits.

Answer: Emergency decompression

In case you exceed your no stop limit, whatever the reason, you should always make an emergency decompression stop before ascending.

This will substantially reduce the risk of DCS as it will allow your nitrogen level to return within acceptable limits, and reduce the probability of bubbles formation.

On a dive boat, after coming aboard two divers discover they accidentally surfaced without making an emergency decompression stop. They should __________, and not dive for at least 24 hours.

Answer: Relax, breathe oxygen, and check themselves for DCS symptoms

If you mistakenly skip an emergency safe stop the first thing you should do consists in preventing DCS. This is done by relaxing, avoid overexercising, and breathing oxygen.

Secondly, you should check yourself for possible symptoms of DCS.

Even in case you do not have any DCS symptoms, you should not dive for at least 24 hours. This will ensure that you decrease the chances of developing DCS in your subsequent dives.

In an emergency decompression situation, I find I won’t have enough air to complete all the required stop time. I should

Answer: Stop as long as I can but save enough air to surface and exit safely.

To the extent possible, you should always do a safety stop or an emergency decompression stop if required.

While doing so, you should however not jeopardize the possibility of reaching the surface safely.

This is why, you should always have a buffer of air that allows you to surface safely.

*Never skip an emergency stop or safety decompression stop*

To help a diver with suspected decompression illness, I should (choose all that apply)

Answer: Monitor the diver’s breathing and provide CPR as necessary,contact emergency medical care,provide emergency oxygen.

If you suspect your buddy has decompression illness, you should monitor her breathing and check for any irregularity, if needed provide CPR, contact the emergency medical care and provide oxygen.

If you are further interested in how to rescue a diver, you should definitely continue with PADI’s Advanced Open Water Course, and subsequently sign up for the Rescue Diver Course.

Nearly all cases of decompression illness require treatment

Answer: In a recompression chamber.

Almost all cases of decompression illness require treatment in a decompression chamber.

This is why whenever you have the suspect of having DCS it is essential to get in touch with your doctor and ask for an expert opinion.

During a dive, I feel I’m having trouble thinking clearly. I should

Answer: Signal my buddy and ascend to a shallower depth.

If you are having trouble thinking clearly, you might be under nitrogen narcosis. This phenomenon is quite frequent at greater depths.

An almost immediate solution is to ascend a couple of meters. This will reduce the nitrogen levels in your bloodstream.

On a standard underwater compass, the magnetic north needle

Answer: Points to magnetic North.

This question is quite straight forward. If the magnetic north needle is not pointing to the magnetic north, your compass is broken and needs to be changed.

My buddy and I want to travel in a straight line using a compass, I should point the ___ in our desired travel direction, then rotate the _ until the _ is/are over the ________.

Answer: Lubber line, bezel, index marks, magnetic north needle

As a PADI Open Water Diver, I have been trained to a maximum depth of ________ (or the actual depth I reached, if shallower).

Answer: 18 metres/60 feet

Remember that you should never exceed the limits of your training. This includes depth limits, but can also apply to specific technical equipment, diving environments and breathing gasses.

Summing Up

Have you completed all the knowledge reviews and final exam? It’s now time to head over to the practical in water scuba skills.

If you want to review the answer to other Knowledge Review Sections, check out the following links: