Transcript Equipment
Diving Equipment Equipment We will cover 3 categories: • basic • essential • useful Basic equipment • Mask • Snorkel • Fins (& boots) Masks • Human eyes can’t 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 valve With valve Fins • offer propulsion for minimum effort • allow divers to swim on surface and at depth with speed, endurance and power Fin types Full-foot Open-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 buckle Fin springs Essential equipment • • • • • • • Cylinder Regulator Diving suit Weight system Buoyancy control device Depth gauge Watch Cylinders Cylinders • a.k.a. tanks • contain compressed air divers need underwater Cylinder types • steel or aluminium • 10—15 litre volume – 12 l tanks are most common • Air compressed to 200—300 bar – 2000—4500 litres of air Regulators 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 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 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 Diving suits • Irish seawater surface temperature range: 7°—15°C • Hypothermia is a risk • Protective thermal clothing is necessary Suit types Semi-dry suits Drysuits Wet suits • Two-piece suits – long johns – jacket with hood • Neoprene body: 3—8 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: 4—9 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-entry Front-entry Buoyancy control devices 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 • Don’t 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 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 faceup 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.