Diving History and Skills Overview

Section 1: The Ultimate Dive Experience

• Diving is a magical and captivating activity exploring an untouched world
• Skills learned during the SSI Open Water Diver course will be valuable for future dives.
• SSI provides top-tier diving education, emphasizing preservation of underwater environments.
• Divers must embrace a personal ethic of respecting aquatic resources by leaving them as found.
• Diving's history highlights the evolution from breath-hold techniques to self-contained underwater breathing apparatus (SCUBA).
• Early divers used primitive methods (e.g., reeds, bags), but these were limited by factors like water pressure.
• The diving bell, an early diving device, was shaped like an inverted bucket, allowing divers to stay underwater for longer periods.
• The diving bell contained limited air, making ascent necessary to replenish air.
• Later, diving suits and helmets, enclosed diving bells with watertight openings, emerged.
• Diving technology improved to use pumps that could deliver air at depth under pressure.
• This is pivotal in the progression of diving techniques.

A Brief History of Human's Attempts to Enter the Aquatic Realm

• Human fascination with the underwater world dates back to recorded history, reflecting a deep-seated urge to explore the unknown.
• Early divers utilized breath-hold techniques, limited by respiratory capacity.
• Ancient civilizations demonstrated diving skills for various reasons (food, work, exploration).
• Progress in diving techniques was influenced by the necessity and desire to explore the underwater world.

Consequences of Diving Emerge

• Physiological issues like "rheumatism," later recognized as pressure-related diving injuries, emerged with increasing bottom time.
• Caisson disease, which results from decompression sickness, was observed during the construction of underwater structures.
• Paul Bert's studies on decompression and physiological effects of pressure underscored the need for deeper understanding.
• The development of decompression chambers became critical to prevent or manage decompression sickness.
• Other issues, like nitrogen narcosis, emerged from deeper depths and longer stays, demonstrating the limits of human tolerance to pressure differences
• Concerns about divers' health and safety became increasingly important as diving depths and periods underwater increased.

Diving in Context

• SCUBA (Self-Contained Underwater Breathing Apparatus) was a major innovation, enabling divers to breathe air independently at various depths.
• Developed in the 1940s by Cousteau and Gagnan, SCUBA introduced independent life-support systems.
• Diving technology enables greater control and freedom in underwater exploration.
• Significant advancements in diving equipment have revolutionized underwater activities.
• Important aspects of safe diving include dive planning, equipment safety, and knowing pressure considerations.

The Weight of Air and Water

• Air has a weight of approximately 1.29 grams per liter; one atmosphere equals approximately 1.0 bar of pressure.
• Water pressure increases with depth linearly (approximately 0.1 bar per meter).
• The greater depth, the greater pressure due to water weight.
• The pressure difference can lead to issues like ear, sinus, and lung squeeze.

Absolute and Gauge Pressure

• Absolute pressure is the total pressure exerted on a point. It includes atmospheric pressure and any additional pressure from depth.
• Gauge pressure is a more practical measure. It is the difference between absolute pressure and atmospheric pressure, which is usually 1 bar on the surface.
• Pressure readings on gear will be displayed as gauge pressure.

Pressure-Related Diving Injuries

• Pressure differences between ambient pressure and the pressure in air spaces can create problems.
• Boyle's Law states that at constant temperature, the volume of a gas is inversely proportional to the pressure.
• Increased pressure reduces the volume of air spaces and vice-versa.
• The relative volume changes are most significant in the shallow zones (0 to 10 meters of water or less)

The Ear

• The middle ear and eardrum are sensitive to pressure changes.
• Equalizing the pressure is crucial to avoid adverse consequences .
• Techniques for equalization include swallowing, jaw rotation, and the Valsalva maneuver.

The Sinuses

• Equalizing pressure in the sinuses is vital to avoid damage to the sinus membranes.
• Ascending or descending slowly, or stopping as needed to equalize.

The Lungs

• Lung squeeze occurs in certain conditions (e.g., snorkeling, freediving).
• When pressure decreases rapidly, the air spaces in the lungs can cause adverse outcomes.
• Prevention (e.g., ensuring lungs are full of air before descending) is paramount.

Equipment-Related Squeeze

• Masks and diving suits are susceptible to pressure changes; issues can be avoided according to diving technique.
• Equalization techniques are necessary to adjust for pressure differences.

Reverse Squeezes

• Reverse squeezes happen during ascent - the volume of air-filled spaces increases as the surrounding pressure decreases.
• They typically affect the sinuses, ears, tooth, and intestinal areas.
• Slow ascent and equalization techniques are crucial in these cases.

Your Mask

• Masks provide clear underwater vision, and seal effectively to prevent water from entering.
• Cleaning and maintenance procedures keep masks in top condition.
• Adapting to underwater visibility is vital.

Your Snorkel

• Snorkels enable breathing while maintaining a relatively upright position in the water.
• Proper technique for clearing a snorkel keeps the air passage clean.

Your Fins

• Fins propel divers through the water, reducing the need for hand or arm movement.
• Proper selection and use of fins provide efficient underwater propulsion.

Your Dive Boots

• Dive boots offer protection to the feet.
• Proper usage and condition of dive equipment is critical.

Your Gloves and Mitts

• Gloves and mitts offer protection from irritants and cold.
• Diving-specific types and thicknesses are available for various types of diving.

Your Exposure Suit

• Exposure suits (e.g., wetsuits, drysuits) protect divers from the water’s cold, and thermal issues.
• The selection of the proper suit depends on dive conditions.

Water Temperatures

• Water temperatures vary, posing challenges for divers.
• Maintaining body temperature is vital for preventing hypothermia.
• Exposure protection varies according to the dive location and depth.

Adaptation to the Aquatic Environment

• Water immersion presents different sensory experiences.
• Divers may need to adjust to these differences, including vision, illumination, and temperature.
• Underwater visibility is impacted by factors such as turbidity, current, and ambient light.

Constant Waves

• The ocean’s constant motion can affect the body and movement of a diver.
• Being aware of the current and water is vital for safe diving.

Vision Underwater

• Underwater vision can present challenges, as light is affected by water and the diver’s position in the water.
• Immersion in water causes changes in the visual experience but also offers unique perspectives.