diving equipment
Post on 22-Mar-2016
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Diving Equipment
EquipmentWe 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 valvesWithout valve With valve
Fins• offer propulsion for minimum
effort• allow divers to swim on
surface and at depth with speed, endurance and power
Fin typesFull-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 strapsPlastic 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 typesSemi-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
NeopreneFoam 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 sealsNeoprene 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 zipsRear-entry Front-entry
Buoyancy control devices
Buoyancy control devicesa.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 useSurface life jacket
• Allows you to rest at surface• Protects incapacitated divers• Helps when waiting for the
boat
BCD useBuoyancy adjustment
• Pressure compresses diving suits at depth
• Adding air to BCD compensates for this...
• ...but needs to be removed on ascent
BCD useAlternate 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
TorchesUseful 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
Questions1. The snorkel is designed to
(b) permit breathing on surface
The snorkel is used for breathing in a face-down position, on surface
Questions2. 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.
Questions3. The mask should
cover your nose to allow pressure equalisation
Questions4. Basic equipment consists of
(c) Mask / snorkel / fins
Questions5. Which of the following items of equipment
are essential?(a) & (c)
Questions6. 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
Questions7. 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
Questions8. 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
Questions9. 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).
Questions10. Semi-dry suits have seals to keep
(b) water in the suit
Semi-dry suits have seals to retain water warmed by body heat.
Questions11. 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.
Questions12. 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.
Questions13. 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.
Questions14. 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.
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