Diving Equipment

Equipment We will cover 3 categories: basic essential useful

Basic equipment Mask Snorkel Fins (& boots)

Masks Human eyes cant focus in water Masks trap a layer of air in front of eyes with a pane of glass

Masks must form a waterproof seal with the face have a nose grip to allow equalisation have tempered glass

Snorkels Curved rubber tube with mouthpiece Allow snorkellers to breathe face-down at surface Some have output valves to expel water

Snorkel valves Without valveWith valve

Fins offer propulsion for minimum effort allow divers to swim on surface and at depth with speed, endurance and power

Fin types Full-footOpen-heel

Full-foot fins Fit like a shoe Worn over bare feet More common for surface swimming Warm water only

Open-heel fins Foot pocket with open heel Held to foot by springs or straps Can be worn over boots More common among divers

Fin straps Plastic buckleFin springs

Essential equipment Cylinder Regulator Diving suit Weight system Buoyancy control device Depth gauge Watch

Cylinders

a.k.a. tanks contain compressed air divers need underwater

Cylinder types steel or aluminium 1015 litre volume – 12 l tanks are most common Air compressed to bar – litres of air

Regulators

Allow us to breathe at appropriate pressure Pressure reduced in two stages – First stage attached to tank – Second stage attached to mouthpiece Extra hoses supply air to other equipment – buoyancy control devices, dry suits, etc.

Regulators

Weights

Humans float in seawater – Especially in diving suits Weights offset this extra buoyancy Usually on nylon belt – Other systems: harness, integrated in BCD

Attaching weight belts Weights should be secure on belt Belt should be tight around waist

Depth gauges and watches

Knowing depth and time is essential – Only way to avoid decompression sickness Gauges and watches must be accurate and reliable Watches should be rated to 100 m Most divers use dive computers

Diving suits

Irish seawater surface temperature range: 7°15°C Hypothermia is a risk Protective thermal clothing is necessary

Suit types Semi-dry suitsDrysuits

Wet suits Two-piece suits – long johns – jacket with hood Neoprene body: 38 mm – Neoprene wrists and seals

Wet suits Provide insulation through suit material Trap a layer of water against skin, which is warmed by body

Neoprene Foam rubber Nylon lining

Neoprene Foam rubber core Bubbles are kept separate to avoid absorption Fabric outer layer for strength and durability Excellent thermal protection

Dry suits one-piece suits with single zip opening – Boots attached – Hoods are usually separate water-tight neck and wrist seals – Latex or neoprene

Dry suits Insulate through material and/or undersuits trap a layer of air between diver and water Air added/removed through valves

Neoprene dry suits neoprene: 49 mm provide built-in insulation are cheap(er) to maintain

Membrane suits Thin material – no thermal protection – usually non-stretch Require insulating undersuits

Dry suit seals Neoprene seals Long-lasting Non-allergenic Form a less effective seal than latex Latex seals Need replacing every 1– 2 years More flexible Form a tighter seal

Dry suit zips Rear-entryFront-entry

Buoyancy control devices

a.k.a. BCDs provide face-up flotation at surface buoyancy control at depth

Buoyancy control at depth Underlying theory in Buoyancy lecture At depth: air is added to BCD On ascent: air is removed

BCD design Inflatable internal bladder direct-feed hose from regulator Inflation mouthpiece Inflate/deflate valves Overpressure valves

BCD use Surface life jacket Buoyancy adjustment Alternate air supply

BCD use Surface life jacket Allows you to rest at surface Protects incapacitated divers Helps when waiting for the boat

BCD use Buoyancy adjustment Pressure compresses diving suits at depth Adding air to BCD compensates for this......but needs to be removed on ascent

BCD use Alternate air supply Most BCDs allow you to breathe through the inflation mouthpiece This is emergency-only and requires training and practice

BCD precautions Avoid uncontrolled ascents – vent air gently and gradually on ascent Dont use as a lifting device Dump air during ascent – not before

Useful equipment Knife Torch Dive computer Safety marker Kit bag

Knives Useful for cutting out from entanglements Must be secured – locking sheath or lanyard Line/net cutters are also useful

Torches Useful for Adding light Returning colour Night diving

Dive computers Comparatively recent development Constantly recalculate depth and time Help to avoid decompression sickness

Safety markers Allow coxswains to track you Keep other boats away Reduce waiting time for boat pick-up

Kit bags Keep your kit ship-shape on board Can be mesh or waterproof

Care and maintenance General care and maintenance Equipment-specific care and maintenance

General care and maintenance Wash everything in fresh water after diving Dry in the shade – rubber degrades in sunlight – cylinder pressure increases in sunlight

Maintaining diving suits Wash in fresh water after dive Dry in the shade Wash zips (and lubricate dry suit zips) Store on hanger away from sunlight

Maintaining BCDs Visually inspect for damage Test direct-feed and mouthpiece Check overpressure valves Check mouthpiece dump valve Check it fits comfortably Periodically sterilise internal bladder

Questions

1. The snorkel is designed to (b) permit breathing on surface The snorkel is used for breathing in a face-down position, on surface

Questions 2. Seeing through a mask is achieved by (a) placing a layer of air between eyes and water Our eyes see clearly in an air medium. Water must be kept out by the mask.

Questions 3. The mask should cover your nose to allow pressure equalisation

Questions 4. Basic equipment consists of (c) Mask / snorkel / fins

Questions 5. Which of the following items of equipment are essential? (a) & (c)

Questions 6. Wet suits are worn in cold water to keep a diver (c) They keep the diver warm by acting as insulation and by reducing the flow of cold water around the body

Questions 7. Wet suits are made of (b) Foam neoprene Foam neoprene: a rubber filled with neoprene gas bubbles which insulates the body from cold and is resistant to corrosion from oil, salt, and sun

Questions 8. Wet suits should be (c) Close fitting Close-fitting suits will slow down the flow of cold water thus keeping the diver warm and minimising heat loss

Questions 9. Dry suits will (b) keep you warmer than a wetsuit Generally, the dry suit will be warmer than the wetsuit because of the insulation worn next to the skin (provided that it does not leak).

Questions 10. Semi-dry suits have seals to keep (b) water in the suit Semi-dry suits have seals to retain water warmed by body heat.

Questions 11. A buoyancy device is (b) essential A buoyancy device is essential to divers and should be worn travelling to and from the dive site, as well as during the dive.

Questions 12. The buoyancy control device is designed (c) to maintain a face-up position on surface A properly-designed buoyancy device will provide a face- up position on surface, which may be required if a diver is tired or has had an accident.

Questions 13. The buoyancy device inner bladder should be sterilised regularly to (a) preserve internal hygiene Inside the buoyancy is warm and damp: an ideal breeding ground for germs.

Questions 14. The buoyancy device should be washed (b) immediately after use Wash often in fresh water: warm water if possible. This will prevent soft corrosion from the sea and chlorine corrosion from swimming pools.