Glossary of SCUBA Diving - C

C

cage diving

Diving in a cage designed to protect the diver from potentially aggressive large marine animals, usually sharks

CALM

Catenary anchor leg mooring. Named for the catenary curve of the anchor cables that hold the buoy in position. Also referred to as single buoy mooring, monobuoy or loading buoy.

camel

A closed lifting bag, usually cylindrical in form.

canister light

Dive light comprising a light head connected to a battery canister by a cable

canoe diving

Scuba diving from canoes, used when the dive site is beyond convenient swimming distances.

carbon dioxide poisoning

The toxic effects of carbon dioxide, due to incomplete elimination of carbon dioxide resulting from skip breathing, excessive work of breathing, scrubber failure in a rebreather system, or inadequate ventilation in a diving chamber or free flow helmet. Occasionally caused by contaminated gas supply.

carbon monoxide poisoning

The toxic effects of carbon monoxide, usually due to contaminated breathing gas supply.

cardio-pulmonary resuscitation

An emergency procedure which is performed in an effort to manually preserve intact brain function until further measures are taken to restore spontaneous blood circulation and breathing in a person in cardiac arrest

cascade filling

Decanting from several storage cylinders in succession, generally using a procedure to maximise charge pressures. Often used in partial pressure gas blending.

caustic cocktail

A mixture of water and carbon dioxide absorbent caused by flooding the scrubber, and which may reach the diver's mouth through the breathing loop. The alkalinity depends on the absorbent used.

cave arrow

Directional line markers which point the way to an exit.

cave line

1. see distance line

2. Small diameter braided synthetic cordage used for this purpose.

cave reel

A reel specifically made for cave diving, used to lay and recover large lengths of cave line which is used as a guide line to find the exit or a permanent guide line.

C-card or certification card

Plastic card issued to a diver by a certification agency as evidence of completed diver training and experience required for the level of certification.

CCR

Closed Circuit Rebreather: see also ECCR, MCCR.

ceiling

Solid overhead or decompression restriction to a safe direct vertical ascent to the surface

chain chaser

Ring or hook shaped components used for installing and recovering conventional mooring systems. The chaser is hooked around the chain and pulled in the direction of the ancor until it slides onto the anchor shank and is stopped by the crown. The chaser is then used to break the anchor out by pulling directly upwards.

chamber operator

Person competent to operate a diving chamber

charging pressure

Pressure stamped on a container for a permanent gas to indicate the maximum gauge pressure (measured or corrected to 15ºC) that may be applied at the time of filling.

chicken vest

Sleeveless neoprene wetsuit vest with attached hood.

Chinese lantern

Connection between pipeline end manifold (PLEM) and single point mooring buoy (SPM) using two to four separate flexible underwater hose strings.

chokes

Further information: Decompression sickness#Classification

A symptom of decompression sickness manifested by shortness of breath, caused by a large number of venous gas bubbles in the lung capillaries which interfere with gas exchange.

Christmas tree

also tree

An assembly of valves, spools, and fittings installed on top of the wellhead and used primarily to control the flow, usually oil or gas, out of the well.

closed bell

also dry bell Further information: Diving bell#Structure of a typical closed bell

A closed or dry bell is a pressure vessel for human occupation which is lowered into the sea to the workplace, equalised in pressure to the environment, and opened to allow the divers in and out. Divers may be decompressed in the bell or transferred under pressure to a hyperbaric chamber at the surface.

clump weight

A weight used to keep the guide wires of a diving bell aligned.

coded welder

Welder who is trained and qualified and assessed as competent for a specified type of welding under specified conditions.

commercial diving

Working under pressure: Occupational activity where gas is breathed at pressure in excess of atmospheric pressure, usually underwater.

combat swimmer

Person trained in scuba diving or swimming underwater in a military capacity which can include combat

completion

The process of making a well ready for production.

competent person

Person who is able to perform a task or operation safely and according to required procedures. May require formal assessment or accreditation, or registration with government body.

compressed air

Air at a pressure greater than ambient.

compressor

Machine which pressurises gas. Generally intake gas is at ambient pressure, outlet gas at higher pressure. High pressure breathing air compressor output pressure is usually 200 to 330 bar.

compressor log

Book or file containing records of compressor operation, filling of cylinders and maintenance records.

compressor operator

Person who operates a compressor, either to fill cylinders, or to provide breathing air to surface supplied divers.

condensate

Liquid resulting from phase change from gas due to cooling or pressure change.

contents gauge

see submersible pressure gauge

continuous decompression

Further information: Decompression (diving)#Continuous decompression

Decompression without stops. Instead of a fairly rapid ascent rate to the first stop, followed by a period at static depth during the stop, the ascent is slower, but without officially stopping. Ascent rate may vary with depth, usually slowing as the depth reduces.

contra-indications to diving

Conditions (usually medical) that indicate that a person should not dive.

controlled buoyant lift

A rescue technique used by scuba divers to raise an incapacitated diver to the surface from depth.

controlled emergency swimming ascent

also CESA

Emergency technique for surfacing, usually when no breathable gas is available at depth.

cookie

Personal non-directional line markers that mark specific locations, or the direction of one's own exit at line intersections.

copper hat or copper helmet

see standard diving dress

corselet

Further information: Standard diving dress#Suit description

Breastplate for a copper helmet and some other heavy helmets, which clamps to the diving suit, and to which the helmet is clamped

counterlung

Further information: Rebreather#Counterlung

Flexible bag or bellows in a rebreather which compenates for the change in volume in the loop during breathing.

CPR

see cardio-pulmonary resuscitation

critical difference hypothesis

Further information: Decompression (diving)#Critical difference hypothesis

Hypothesis that bubble formation during decompression will not occur if a critical pressure difference between tissue gas tension and inspired gas partial pressure is not exceeded.

critical pressure

Further information: Scuba gas planning#Critical pressures

Cylinder gas pressure which determines a safe limit to an underwater activity on scuba, such as start of ascent or turnaround during a penetration.

critical ratio hypothesis

Further information: Decompression (diving)#Critical ratio hypothesis

Hypothesis that bubble formation during decompression will not occur if a critical ratio of tissue gas tension and inspired gas partial pressure for a given gas is not exceeded.

critical volume hypothesis

Further information: Decompression (diving)#The critical volume approach

Hypothesis that symptoms of decompression sickness will not be evident if a critical volume of tissue gas bubbles is not exceeded.

cyalume

Trademark name Cyalume is a solid ester whose oxidation products are responsible for the chemiluminescence in a glowstick.

cyanosis

The appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface being low on oxygen

cylinder

1. Diving cylinder: Refillable compressed gas container of water capacity between 0,5 L and 150 L.

2. That part of a reciprocating compressor or booster in which the piston is moved to compress the air. The internal space is cylindrical with a circular section. The external surface is usually finned for air cooling.

cylinder boot

Rubber or plastic cover for the base of a scuba cylinder to protect it from abrasion, and in the case of domed end cylinders, to allow it to stand upright.

cylinder valve

Further information: Diving cylinder#The cylinder valve

Valve fitted to a compressed gas cylinder to control gas flow into and out of the cylinder. Also pillar valve.