Theory for Advanced Scuba Divers E-Book

Karsten Reimer

• Herausgeber: BoD - Books on Demand
• Kategorie: Lebensstil
• Sprache: Englisch

Seitenzahl: 296

Veröffentlichungsjahr: 2025

Beschreibung

This textbook is ideal for all recreational divers who have discovered the joy of their hobby and want to get more involved in the sport. It covers all the theory required for Advanced Open Water Diver and/or 2-star diver certification. It also includes some practical examples in the form of short film clips that can be accessed online via QR codes. This book does not overload you with unnecessary knowledge, but leads you directly to an internationally recognised diving certification for advanced recreational divers. The book also includes the two speciality courses in underwater navigation and group leadership, which are required by most of the CMAS and R.S.T.C diving associations.

Leseprobe

All the information contained in this book has been compiled by me to the best of my knowledge and based on decades of experience in training scuba divers and diving instructors. However, as I am "only" human, errors may have crept in, even though I have had this book proofread several times by many other experts. I can therefore shift at least some of the blame to others if this book should nevertheless contain errors. I am very sure that this book does not contain any serious errors and therefore cannot provoke any diving accidents. Nevertheless, I do not accept any liability, obligation or guarantee should an accident occur as a result of reading my book or due to any inaccuracies in this book. I therefore strongly recommend that you only use this book as an accompaniment to and as part of professional diving training by a professionally trained diving instructor licensed by a recognised umbrella association (CMAS or R.S.T.C.). Even if there are no legal requirements for recreational divers in some countries, you should not go underwater with a scuba equipment without professional help. Protected trade names or trademarks or brand names and logos are not always specially labelled. The absence of such indications does not mean that the product is a free brand name, a free trade mark or a free company logo. Make absolutely sure before you commit a trade mark infringement, as this could be very expensive for you. Not all companies accept such offences without complaint, and American companies in particular often face astronomical fines.

Foreword

This book is a guide to acquiring the theoretical knowledge required to pass the examinations for the diving licence mentioned on the title page. Diving theory without the ballast, so to speak! For those who want to delve deeper into the subject matter, there are many good and more comprehensive textbooks on the market. This book contains the additional knowledge required to pass the diving certifications IDA AOWD (Advanced Open Water Diver), IDA ** Diver and the two speciality courses Group Management and Underwater Navigation and is therefore not a textbook for beginners. If you want to start diving, I recommend the IDA Diver * Basic Theory for Recreational Divers textbook and a good diving instructor, preferably from the IDA ranks.

ISBN 9783756827589

Before you complete the diver ** training in the IDA system, which is equivalent to the CMAS Germany system, it is necessary to attend the two speciality courses (SC) Underwater Navigation (Compass) and Group Management. These courses are, in addition to a CPR course, a prerequisite for participation in a diver ** course at IDA; therefore these courses are also included in this book.

The male form of address is used in this book to simplify writing. Of course, this does not mean that only men may or can dive. There are even voices in the "diving scene" who claim that women are the better ones.

In view of the often irresponsible willingness of my male contemporaries to take risks, this is a thesis that I would definitely subscribe to.

Although

Divers are men who can live and work under water or in unbreathable air. Divers are men of great muscular strength, with healthy organs. There is no other profession that makes such high demands on physical fitness as the profession of a diver - not only occasionally. Carrying the almost 100 kg of heavy armour out of the water, or moving this mass while walking underwater, breathing under rapidly changing pressure and, last but not least, the most strenuous work under an air supply that is not always perfect, demand athletic muscles, healthy lungs, a strong heart and perfect functioning of all organs. Divers are men of great mental strength, intellect and impeccable morals. They have to brave so many dangers that their presence of mind and powers of observation are subject to the highest demands. At the same time, performing useful and fast diving work is the real art of the diver, which is what makes his work valuable in the first place. An unswerving sense of duty must drive him to ensure the quickest and most effective solution to the task at hand, using all his physical and mental strength.

Manual for divers Hermann Stelzner Director and Chief Engineer of Drägerwerk Lübeck 1931

Contents

1.0 Why do we dive? A little history

1.1 Diving equipment according to IDA standard and EN (Euronorm)

1.2 The minimum equipment for Open Water dives with Scuba equipment

2.0 SC Underwater Navigation

2.1 Course objective

2.2 Natural Navigation

2.3 Navigation with aids

2.3.1 The compass

2.4 The Earth's magnetic field

2.5 Handling the compass

2.6 What is a bearing?

2.7 Compass malfunctions

2.8 The bearing line

2.9 The cross bearing

2.10 The deviation

2.11 Course examples

3.0 SC Group management

3.1 Course objective

3.2 Prerequisites

3.3 Types of group management

3.4 Planning the dive

3.5 Briefing

3.6 Partner check

3.7 Tasks of the group leader

3.8 Debriefing

3.9

Typical errors

3.10 Safety rules

3.11 Practical exercises

3.12 Recommendations for the composition of diving groups

4.0 Advanced Open Water Diver (AOWD)

4.1 Course objective

4.2 Learning content

4.3 Basic principles of deep diving

4.4 Basics buoyancy, trim, fin stroke techniques

4.5 Night diving basics

5.0 Diver

5.1 Course objective

6.0 Diving physics

6.1 Basics

6.2 The 5 laws in brief

6.2.1 Henry's law

6.2.2 Archimedes' law

6.2.3 The law of Boyle & Mariotte

6.2.4 The law of Gay Lussac

6.2.5 The law of Dalton

6.2.6 The Joule Thomson effect

7.0 Acoustics

7.1 Basics

8.0 Optics

8.1 Basics

9.0 Temperature influences

9.1 Basics

10.0 Diving medicine

10.1 The respiratory organs

10.2 The heart - Foramen Ovale or right-left shunt

10.3 Barotrauma and respiratory injuries

10.3.1 Barotrauma of the ears

10.3.2 Barotrauma of the lung

10.3.3 The Laryngospasm (spasm of the glottis)

10.4 Toxicity of breathing gases

10.4.1 Depth limit with compressed air - Nitrogen

10.4.2 Depth limit with compressed air/Nitrox - Oxygen

10.5 Essouflement

10.6 Saving breathing

10.7 The reflexes

10.8 Wet and dry drowning

10.9 Decompression sickness

10.10 Working with the decrompression table

10.11 Dehydration

10.12 Injury caused by marine animals

11.0 Diving practice

11.1 Iron rules of diving

11.2 The rescue chain

11.3 Hypo- and hyperthermia

11.4 Diving and nutrition

11.5 Diving and drugs

12.0 The dive calculations

12.1 General information on the dive calculations

12.2 Dive calculations

13.0 Environmentally friendly behaviour

Emergency card

Acknowledgement

What is IDA

Annex

Glossary

Declaration of health status form

1. A little history

There are many reasons why people are motivated to go underwater. In prehistoric times, the main reason was certainly to obtain food in the form of fish, mussels or molluscs. Once you have eaten your fill, the other possibilities of diving come into play, namely the realisation of profits or warfare, that's just the way we humans are.

This pigskin suit constructed by Leonardo da Vinci around 1500 to enable the sinking of the Turkish war fleet. Whether the air supply, which is supplied via 2 air bellows should have worked, is still unclear today, but it is doubtful.

Also about the chances of survival of the diver, who with this Diving bell in the 16th century is nothing at all known.

We scuba divers don't necessarily focus on making a profit, but each of us has probably "plucked" a net or rope from a boat propeller for a small fee in the form of a bottle of wine or a small donation to the club's coffers. We prefer to leave the warfare to the professionals from the military, even if we have "borrowed" one or two pieces of equipment from them. After all, nitrox and rebreather diving is and was the military's profession long before our tec divers and underwater photographers discovered it for themselves. Apart from professional divers, to which I now count all those who dive for a living, diving as a recreational sport is practised exclusively for more or less private pleasure. Of course, this does not mean that recreational divers generally dive unprofessionally. There are recreational divers who pursue their hobby so intensively that the boundary between hobby and profession slowly but surely becomes blurred. At the latest after completing the IDA *** training or an equivalent course from another organisation, the diver is faced with the question of whether he should not make his hobby his secondary or even main profession. And that's a good thing, because even diving instructors get old and end their careers at some point. And so we need the next generation to ensure that our wonderful hobby doesn't die out and lose the race against egoshooters or game consoles.

Diving is a natural sport that constantly challenges us physically and mentally and expands our intellectual horizons in many different directions. This begins, for example, with relatively low-material apnoea diving, continues with material-intensive underwater photography and ends with costly rebreather diving. There are courses for underwater archaeology, freshwater and saltwater biology, diving in caves or sea caves and much more. The IDA training portfolio for scuba divers comprises almost 80 different courses, plus the corresponding courses for instructors as well as courses for lifeguards and first aid instructors. So there is something for everyone.

Compared to the pictures from back then, the reader will recognise the differences to today's standard diving equipment. The two scuba divers in the top picture are preparing for a dive in very cold water and in the pictures below you can see what professional divers can do underwater today. Of course the professionals can do much more, but this is another story.

1.1 Diving equipment according to IDA standard and EN (Euronorm)

The European Union has not only determined the bending radius of bananas and cucumbers or the maximum power consumption of a hoover and issued directives for them, but has also achieved more meaningful things (personal and possibly, depending on your point of view, unqualified comment by the author). For example, there are not only standards for the composition of diving equipment, but also standards for diving training (see page 6).

Experienced divers, the most common level of training in the accident statistics, will no doubt smile at the following list, but the EU representatives and the experts who compiled this list have certainly put some thought into it.

Of course, everyone realises that the following items of equipment are part of a complete diving kit, but the devil is in the detail and therefore very close at hand. In my many years as a diver, I have experienced more than once that one of the diving group has forgotten an item of equipment. A plastic bag was pulled over their hands instead of the gloves they really needed when diving in cold water. We still had booties at home and so we dived without them, in heel strap fins. The regulator blew off and so the dive was carried out on the partner's octopus. The lead was missing and so we collected stones until the pockets of the jacket burst. And I have had this experience more than once, although it was often my diving students who organised this dangerous nonsense. This proves once again that the best training is useless if the will to dive is too strong and commons sense is neglected.

I could now describe in epic detail the accidents that can occur with the behaviour I have described above, but I will leave that to your imagination. I'll just say this much: hands that are only "protected" with a plastic bag against 4 degree Celsius cold water tend to become numb and immobile. When opening the zips on the suit or the booties after the dive, or when trying to do so, the effect of hypothermia in the hands becomes apparent.

In the event of a diving accident, the EU directives are used to clarify the question of fault if there are no national directives. And I could well imagine that the judge will interpret it negatively if you did not give your diving partner any air during the following hand signal due to your immobile hands. Not to mention the hopefully still possible reaction of your diving partner.

DIN -EN standards:

EN 14153-1 Supervised Diver corresponds to the Basic Diver

EN 14153-2 Autonomous Diver corresponds to the IDA Diver *.

EN 14153-3 Dive Leader corresponds to the IDA diver ***

EN 14413-1 Scuba Instructor Level 1

corresponds to the IDA Diving Instructor Assistant

EN 14413-2 Scuba Instructor Level 2

corresponds to the IDA Instructor *

ISO standards:

ISO 11121 - Discover Scuba Diving

ISO 24801-1 Supervised Diver

ISO 24801-2 Autonomous Diver corresponds to the diver * / OWD

ISO 24801-3 Dive Leader corresponds to the diver ***

ISO 24802-1 Scuba Instructor Level 1 is equivalent to Assistant

Instructor

ISO 24802-2 Scuba Instructor Level 2 corresponds to the

Instructor *

1.2 The minimum equipment for open water dives with SCUBA equipment according to IDA standard and Euronorm!

ABC equipment complete (mask, snorkel and fins)

You can read more about these items of equipment in the IDA textbook Basics-Theory for SCUBA divers ISBN 9783756827589

.

Two independent regulators.

For cold water dives (water temperature 10˚ Celsius and below, at the planned water depth) on two separately lockable valves.

The two regulators can either be mounted on a double or on a single tank.

Which of the two combinations you choose depends solely on the amount of air required or, if the amount of air is not the criterion, on the equipment currently in the diver's store.

Example 1

10 litre tank with double valve and LP hose for the dry suit

LP stands for low pressure and HP for high pressure. There are several outlets for LP on the first stage. Depending on the manufacturer, the medium pressure is between 5 bar and 15 bar for the regulators, the dry suit and the jacket and one or two outlets for high pressure (tank pressure) for the pressure gauge and possibly a radio transmitter for the dive computer (to show the tank pressure on the display).

Example 2

Double 7 litre tank, connected by a lockable bridge and two separately lockable valves. The valve in the centre (also known as the manifold) of the bridge allows the two tanks to be used either separately (2 x 7 litres) or as a unit (14 litres).

The inclined reader may now wonder what all this tangle of tubes is for and whether it is really necessary to go into the water with so much equipment ("Gedöns" in North German). In terms of diving safety, the answer to this question is a clear "yes". In the past, when everything was undoubtedly better, we dived with minimal equipment and still survived. But since we (should) continue to develop and there were no airbags in cars in the past, but today no one disputes that these things have saved lives and continue to do so every day, we accept these hoses as necessary and live with them. Speaking of hoses. Your main unit should have a LP hose of 90-120 cm. If your partner gets into difficulty breathing and indicates this (see photo and film via QR code),

then simply give him your main regulator and then take your second regulator yourself. In this way, you can end the dive without alternate breathing, which can also bring a certain restlessness or uncertainty to the dive. It also has a psychological effect if you give your partner the regulator from which you have been breathing yourself. Your partner now has a problem; otherwise they would not have given you the "I've run out of air" sign and this problem could worry him, depending on their experience and "coolness". It is therefore a little reassuring if your partner gets a regulator that works reliably and also allows enough freedom of movement for both divers due to its hose length. To ensure that your second regulator and the octopus are also working properly, you should check these regulators frequently and breathe from them from time to time during the dive. If, in an emergency, you hand your partner a regulator that is stiff or contains sand, for example, the situation can escalate very quickly and this should be avoided at all costs. So always make sure that all your equipment is working properly at all times.

The configurations shown on the previous pages are intended for diving in cold water (water temperature below 10° Celsius) and when a dry suit is used. The distribution of the outlets (dry suit, jacket, regulators) must be selected in such a way that the so-called "cold load" is distributed in such a way that icing of the regulators (here primarily those of the first stages) cannot occur. The cooling load is the sum of all effects caused by the cold. Firstly, of course, we have the water temperature, which has a negative effect on all our equipment and (usually) on us. And then, of course, there is the amount of air that we take from the tank via the first stages of our regulators. Of course, this includes not only the air we take out by breathing, but also the air we put into the jacket and the drysuit. As experienced or fairly experienced divers, we know that air that expands removes heat from the immediate surroundings, i.e. it cools. See also the IDA book "Basic Theory for Scuba Divers". Here is the main statement on this topic once again:

And since Mr Joule (James Prescott Joule, British physicist, 1818 to 1889) and Mr Thomson (William Thomson, British physicist, 1824 to 1907) discovered that gases that expands at a nozzle extract the energy required for this from the environment and thus generate cold, the first stage is cooled down when breathing from the regulator. This process of cold generation is called the Joule-Thomson effect, after the gentlemen mentioned above. Now you may ask yourself, why is he telling me this? Because this Joule-Thomson effect can spoil your dive! It can always happen that a drop or two of water creeps into the first stage. Either because you did not press your thumb firmly enough on the high-pressure inlet of the first stage when flushing the first stage or because the compressor operator did not take the drying of the breathing air seriously enough. So if the droplet in the first stage encounters the cold of the expanding gas, it will freeze and impair the function of the first stage. As a rule, your regulator, i.e. the second stage, blows off uncontrollably until the tank is empty or your partner closes the valve of your tank. Due to the frozen water in the first stage, it can no longer close and the medium pressure increases until the second stage, due to its design, opens and releases the outflowing air into the water. This process is called internal icing.

Now let's take a look at the two configurations above. In principle, they are identical, differing only in the volume of the tanks. Quite apart from the fact that, as a rule and depending on the tank size, a double tank unit is better positioned on the back, as the centre of rotation of the tank unit is closer to the diver's body and therefore has less influence on the rotation around the longitudinal axis of the diver.

As a diver, you now breathe from the main regulator, which is connected to the main valve and plays the main role in terms of the "cooling load", as you breathe continuously from it and therefore cool the first stage down considerably. At the same time, you tare with the drysuit via the main regulator; however, in contrast to breathing, this only happens rarely and only in short (taring) blasts and therefore has a small influence on the first stage. One could now comment that it is not possible to speak of a distribution of the cooling load here, as both "air extraction points" are located at a first stage. But that is true..... The devil is in the detail here too, and we are concerned with safety when diving. Let's assume that the first stage of your main valve ices up and we or our partner have to close the main valve. With the configuration shown above, we have a complete system available as a redundancy (reserve, in German) at the second outlet and can finish the dive in peace. In other words, to end means to surface, not to continue. Your partner can now "hang" on to your octopus or, alternatively, your second automatic unit without having you to alternate breathing with him and the ascent can be carried out in peace.

If an accident occurs and we have to rescue our partner, we can use our jacket as a buoyancy compensator and rescue device, as it is located on the second outlet and is therefore supplied with air. If the jacket were connected to the first stage of the main regulator and the dry suit to the first stage of the second regulator, we would have to carry out a rescue using the dry suit as a rescue and buoyancy compensator, which is much more difficult than a rescue with the jacket. Anyone who has ever been in such a situation, whether intentionally or unintentionally, will surely agree with me that it is not easy, even for experienced drysuit divers, to rescue a person and at the same time buoyancy control over the drysuit to prevent them from "shooting up" to the surface or sinking. Strictly speaking, you would need many more hands in such a situation than we have, as we now have to operate our drysuit, possibly our jacket and the jacket of the casualty, but at the same time have at least one hand free to hold the casualty. If the person to be rescued is also travelling with the drysuit, it becomes very difficult to slowly ascend to the surface. But you can learn how to do this on a drysuit diver course (SC). But don't worry unnecessarily, modern regulators and modern compressor systems prevent such icing very reliably. If you now ensure that no water can enter the first stage when rinsing your regulator, icing is almost impossible. But never impossible, remember this when diving in cold water.

The dry suit is also called a constant volume suit, at least among professionals. Why? Quite simply, if the suit always has a constant volume, which we as divers can/should/must ensure, the buoyancy also always remains constant, according to Archimedes. The jacket is therefore only used for rescue in an emergency. If you make a mistake and, as usual, tare with the jacket, physics will make you aware of your mistake. When descending, if no air is put into the drysuit, a relative negative pressure is created compared to the external pressure and therefore water is sucked into the drysuit, which means "it gets wet and cold". As a rule, you will then realise your mistake quite quickly and can rectify it. But you will still get wet.

And if you are diving in warm water (temperature higher than 10° Celsius), simply leave out the LP hose for the dry suit and leave everything else as it is.

Compressed air tank(s) (single or double unit)

BCD - Buoyancy control device

The weight belts comes in different shapes and can also be attached to the body in different ways. In general, the weight fulfils two tasks. Firstly, it should compensate for the diver's buoyancy, which is primarily caused by the neoprene, and secondly, it should establish the correct trim. Depending on the position in the water, which is determined by the equipment, it may be necessary to change the diver's trim so that he "lies" almost horizontally under water with a slight inclination towards the surface. This means that the diver does not have to constantly tilt his head back in order to look forwards. The position in the water can be trimmed, for example, by attaching small weight pockets to the legs at ankle height. Some jackets also have special pockets in which trim weights can be stored. It is also possible, if you are a little skilful, to attach trim weights to the lower end of the jacket's carrying shell. A little ingenuity is sometimes required here.

Underwater pressure gauge

The underwater pressure gauge (high pressure gauge), also known as a Finimeter in diving circles, is of course also part of a complete diving kit. The illustration shows a pressure gauge in a console, together with a depth gauge and a compass. You can do this, but you don't have to. If you want to swim an exact course, the compass should be held in front of you in order to take an accurate bearing. But to find your way roughly back to the shore, the compass can also be attached to the gauge hose.

In most cases, however, the pressure gauge is designed as a solo instrument and is then attached to the equipment in such a way that it cannot drag across the seabed or coral. I use a retractor as a mount, so the finimeter is always close to my body and I can still pull it off my body to be able to read it. Rigid mountings, such as hose holders or similar, have not worked well for me. A retractor is a stainless steel wire wound on a spool, which is automatically pulled back into the housing by a spring when the pull decreases.

Measuring instruments for depth (depth gauge or computer),

time (clock or computer) and possible

Decompression tables (decompression table or computer)

The above list shows that you can save yourself a lot of instruments if you have a dive computer. But please bear in mind that even a dive computer can fail and it is therefore advisable to always have a watch, depth gauge and deco table with you. This is a good advice, but most divers do not follow it, as it is very rare for a dive computer to fail. I don't follow this advice on my standard dives as I always know exactly how long and how deep I'm diving and therefore can't get into decompression sickness. To comply with the safety deco stop at 5 metres, for example, I only have to go to "my" reefballs and "hang out" there for a while.

The reefballs are exactly at a water depth of 5 metres and as they weigh up to 600 kg, nobody will move them. Reefballs are hollow concrete hemispheres with several large openings in them. They are intended to replace lost hard substrate and thus provide hiding places and colonisation grounds for underwater flora and fauna.

I’m allowed to say „my Reefballs“ because I’ve made them (15 pcs.) by myself and I brought them into the place where they now are. That’s not as easy as it sounds, because the German authorities, which have to give the permission to sink this reefballs are not very flexible and so I needed 2 years to get the permission. By the way, I have to rent the place under water and to pay 90.- Euro a year for almost 60 m2. And I had to buy a heavy duty lifting balloon to move the reefballs. But my friends and me had a lot of fun and no one dies.

See photo below:

However, if I am planning a dive that takes me to greater depths or requires longer diving times, I always take the recommended instruments with me. My dive computer has never left me, but once is always the first time.

The "all-purpose weapon" dive computer

Dive computers are available in many different designs, shapes and colours. Seek advice from your favourite dive shop and/or your diving instructor.

Depth gauge

If you decide to buy a depth gauge, get good advice here too. There are many different instruments and they don't just differ in price.

Diver's watch

Here, too, there are countless different models for scuba divers, but by and large they all display the time. With the exception of the Apple Watch Ultra, which can also be used as a dive computer. Of course, it is not only rational reasons that play a role when buying such a watch, but also the size of your wallet and, last but not least, fashion aspects. As the vast majority of scuba divers take care of their watch and therefore prefer not to take it with them when diving, you should consider beforehand what EXACTLY you want the watch for.

You can find more detailed information on the instruments in the IDA textbook 1 Basics - Theory for Scuba Divers, in specialised diving shops, in bookshops or from your diving instructor.

The decrompression table

Author: Dr Max Hahn

©VDST Association of German Scuba Divers

Available from the VDST shop

The diving suit

The diving suit is designed to protect you from cooling down and injuries. They are not only available in different material thicknesses and colours, but also sleeveless or legless, with or without a bonnet, with or without zips, with or without.......... In other words, pretty much everything a diver's heart desires and a complete list of all the options would go beyond the scope of this book. A diving suit should always be adapted to the situation and not just be worn out of thriftiness or an exaggerated desire to show off. A neoprene drysuit is not really suitable for a holiday in Egypt, while a 3 mm shorty is not suitable for ice diving. But you either already know this yourself or you will realise it when you try it out. I will therefore refrain from presenting the different types of wetsuit in detail here and prefer to concentrate on the essentials. If you have any questions about diving suits, ask at a specialist shop or ask your diving instructor for advice. It often makes sense to simply look at what other divers are wearing in this situation. Here are a few examples:

Five-finger gloves, also available as three-finger gloves (finger

Knives / cutting tools

As in real life, a knife is a tool and not a weapon. Even if, unfortunately, people misuse this tool time and again. The knife should therefore be designed in such a way that it can be used as a tool. Here too, please seek advice from a specialised dealer or your diving instructor.

The equipment listed here is the minimum configuration that every diver must carry. Special dives also require special equipment, as everyone should be aware. For example, hardly anyone will go on a night dive without an underwater lamp and no one will voluntarily enter an underwater cave without the appropriate equipment. So if you are interested in a "special form" of diving, I strongly advise you to attend the relevant speciality course (SC) and find out in detail what equipment you need. And please also bear in mind that the best equipment is worth nothing if you are not able to operate or use it correctly. As not every diving instructor can master all topics and special forms of diving, colleagues often specialise in a few topics and then offer these, which makes a lot of sense. It's better to have a diving instructor who only offers two or three different courses, but who has a perfect command of them, than a diving instructor who thinks he can do everything and who might put himself and his students in danger as a result.

Which brings us to the next topic. The standard repertoire of every IDA diving instructor includes the SC (special course) Underwater Navigation and the SC Group Management. You must successfully complete these two courses before you can start the Diver ** course. Why? Because as a diver ** you are already an advanced diver and therefore, in accordance with the IDA Standards, you are allowed to plan and carry out independent dives with divers who have equivalent training, i.e. other divers ** or equivalent training levels from other diving organisations. I'm sure you'll agree with me when I say that it makes sense to always know where you are and where you want to go. You should also know how to safely guide other divers underwater in such a way that all divers, including yourself, not only have a good dive, but also all leave the water healthy and complete. The IDA standards for divers and diving instructors can be found in the open download area of the IDA homepage www.ida-worldwide.com/de/download

So let's start with the SC Underwater Navigation.

2.0 Special course Underwater Navigation

2.1 Course objective

The participant should be able to determine his dive course and location during the dive and find his way back safely to the starting point of the dive.

After completing the course, he should

know and be able to use natural Navigation aids,

know and be able to use technical aids for Navigation,

be able to safely master dives using these aids.

2.2 Natural Navigation

Natural Navigation is based on what nature offers us as a guide. In other words, the sun, the moon, trees, mountains, lakes and the like. Humans have also created all kinds of Navigation aids, but these are not of natural origin. So roads, houses, google maps® and lots of other things. Under water, we have to do without most of the things we use for Navigation above water. Okay, in a full reservoir there are also roads and houses, but visibility is usually rather poor, so we can't use them in the same way as above water.

What is identical above and below water, however, is the earth's magnetic field. And that's why we divers like to rely on the compass. But more on that later.

What natural phenomena can we use for Navigation under water? Well, the sun and moon are available if the water is very clear and we don't dive too deep.

Then every body of water has a so-called depth profile, which is nothing more than the fact that it is first dry on the shore, then gets wet and the further we go into the water, the deeper it gets. And it doesn't matter whether we are diving in a lake or the sea. The fact is that the water becomes shallower towards the shore,