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Your First Scuba Diving Experience

Submitted by admin on 2009-02-19 | Last Modified on 2010-06-15

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What to expect from your pool or tank simulation:

Confined water dives are a great way to get a feel for what you can expect out in nature. They give ample opportunity to become confident in applying the physics you studied in order to dive, as well as familiarizing yourself with all of the initially strange gear.

You will soon come to understand why the practice of learning habits you will apply underwater in a simulative environment is highly beneficial. These include becoming independent from the walls as there are no sides to hanging into in the ocean or quarries, as well as leaving your tank lying on its side so it doesn't get knocked over.

Keep an eye on every detail your instructor teaches and you will soon benefit from the demonstration. Being clear about every skill is essential as this will assist you to learn the important reason for its existence, and how it plays its part in the dive.

Scuba Physics

Water pressure is an interesting phenomenon and can affect divers in many different ways. Due to the fact that this is not our natural habitat and we are not well-equipped genetically, it's important to be aware of the differences and how you may be affected in order to derive the most from the experience.


Water displacement

Archimedes bath of the millennia that sent him running naked down his street shouting: "Eureka!, Eureka!" after realizing water displacement, may assist in understanding the reason a small heavy object goes straight to the bottom, but a ship the size of the Titanic floats (well, used to float).

In the same breath, with volume being the contributing factor in this equation, the easiest way to describe the principle is the only method of equalizing displacement, is to match the weight of the object that has caused it. This way the 'displacement' (in this case - you) can remain neutrally buoyant and not float or sink.

Just as an axle of a car controls the wheels, forms a framework for the structure and determines general structure, acquired buoyancy skills allow you to occupy the body of water whilst navigating with total control of physics.

Your reinforcements for this process are weights and a Buoyancy Control Device or BCD. Inflating your BCD increases your volume and deflating decreases it. Simulated dives allow you to begin the process of fine tuning your buoyancy. Salt water is denser than fresh due to the salt consistency and therefore holds less displacement.

While swimming recreationally - in order to sink one needs to exhale, this decreases the body's volume through emptying the lungs and lowering one's capacity. This is where the fun starts, like any good analogy in which the subconscious mind represents water, you can manipulate your buoyancy with your breath in much the same way that yogis 'go within' to meditate.


On land, due to the equal distribution of air pressure inside and outside of your body, the air in passages that exist (lungs ears etc) are always in synch with the air outside. This needs to be taken into consideration when diving, due to the incompressible nature of most of the water-based matter.

A good example is flying, or driving at high altitudes on mountain passes. The air pressure changes and you feel the volume fluctuations in the body cavities. A quick pinching of the nose and a forceful exhale or wiggling the jaw from side to side usually equalizes the pressure inside and out.

Walking into a strong wind is a good example of the force of something that one cannot see, and this can be taken into consideration when reflecting on the above. When diving, the actual depth of your submersion exerts different pressure on your lungs and ears, as water's molecular matter is significantly heavier than air.

One specific aspect to be aware of is an occurrence known as squeeze, which you may have experienced when diving into the deep end of a pool. This is a perfect example of the body's temporary inability to cope with the short notice pressure change. Adjusting this in accordance with ascents and descents is called equalization, the combat mechanism to 'squeeze'.

A cardinal rule in diving is never to hold your breath. Either way the neglect of proper breathing will cause lung over-expansion (on ascent) or lung collapse (on descent) The lungs are sensitive to even slight pressure changes so the simulated dives are great opportunities to rid yourself of tendencies like holding your breath underwater. Your training will further detail the dangers of lung expansion and how to easily avoid a potentially dangerous situation.



The scuba diving mask also creates an air space that needs to be equalized during the dive. This is done by simply pinching closed your nose and clearing the ear ways in order to prevent 'mask squeeze'. Note that goggles cannot be used for diving.

The mask is an underestimated piece of gear. Consider how much fun you would have with a mask alone and then alternatively, how every piece of your gear would not mean very little without it. For this reason it would be advisable to buy one with all the necessary features, no holds barred.


Aside from saving tank air when you are on the surface, snorkels allow you to breath in rough surface conditions as well as assisting on the surface swim back to the boat or land, in the event that you run low on air. They are attached to the left side of your mask. Your regulator is on the right hand side.


Like any other fish, fins (flippers to some) serve to maneuver you through the water as effortlessly as possible and saving your arms from tiring unnecessarily. Make sure their fit is comfortable and inspect the straps regularly, as they tend to wear more easily than any other part of your dive gear.

The Tank

These high pressure aluminum or steel air containers hold varying capacities from 8 to 15 litres. Tanks and valves go hand in hand. The valve is the outlet from the tank, made from chrome plated glass. You will often hear of reference to the O-ring, which is a seal protecting the valve without which you cannot dive.

Ensure that you refill your tank at a well-respected air fill station. They are never filled with pure oxygen but compressed air for breathing.

It's important to be aware that tanks must never be left standing upright and unattended as they roll and can hurt someone or damage equipment. Accidents do happen, so plastic and rubber fittings should be present to assist in extra protection. Most dive boats have special racks and if you are on land, it is advisable to tie them down or secure them carefully.

Make sure the tank isn't leaking air, as this can be highly corrosive. Keep moisture out of it at all costs and avoid leaving it in the sun. Ensure that your tank is inspected regularly and that it undergoes all the necessary tests and maintenance to ensure peak performance.


The buoyancy control device is a type of life jacket inflated by using air from the tank with a low pressure inflator. Air is released from it via a valve or hose. These actions assist your lungs in determining your level of suspension in the water. It can also be used on the surface for floating, resting, swimming or rescue.

A standard BCD must accommodate you and all your equipment at the surface. Its large diameter inflation/deflation hose needs to maintain the function of releasing air quickly and easily when you need it.

It must have a pressure relief valve to prevent overexpansion upon rising as well as a low pressure inflation mechanism that connects it to the air in your tank. Ensure a snug fit so it does not cause any discomfort when you inflate it.

All these added features can become rather bulky, so ensure that your purchase is a streamlined product.

Some BCD's have integrated weight belt systems which are also highly recommended.


This device typically provides regular air flow when you inhale from the pressurized air supply in your tank. It consists of what is referred to as two stages, the first being the mechanism that connects the various other hoses to the tank and the second stage is the mouthpiece.

    A typical regulator has the following features:
  • An exhaust valve to control in and outgoing airflow in accordance with your breathing requirements.
  • The mouthpiece through which the air is inhaled. This is also equipped with a purge button for manual airflow control.
  • An alternate air source for easier access in the event of needing to share air with another diver. It is usually brightly colored in order to make is more easily distinguishable when needed.
  • A submersible pressure gauge to monitor air usage (SPG or contents gauge) Essential for regularly monitoring your air consumption during the dive.
  • A connecting hose to the low pressure inflator on your BCD.

Ensure when cleaning each piece of equipment for maintenance after a dive that you are well versed with regards to the needs of each piece, as they vary in methods required for optimal care.


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