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.