Glossary of SCUBA Diving - S

S

SAC rate

Surface Air Consumption rate: A measure of air consumption in units of pressure over time, usually psi/minute, adjusted to surface pressure, used to esimate air endurance of a cylinder of specific size. Useful for those who work in imperial units..

safety stop

Further information: Decompression (diving)#Safety stop

A voluntary (not required by the decompression schedule) additional decompression stop intended to reduce risk of decompression sickness.

salt water aspiration syndrome

A reaction of the lungs to inhalation of a mist of salt water

samba

Contractions experienced by breathhold divers when approaching hypoxic blackout.

saturation diving

Diving procedure where the divers remain pressurised for periods of several days or weeks and decompress only at the end of the period.

saturation spread

Saturation diving system.

SCBA

Self Contained Breathing Apparatus (not for underwater use).

scooter

Diver propulsion vehicle used by scuba divers to increase range underwater.

SCR

Semi-closed circuit rebreather: A rebreather (q.v.) which either dumps part of each breath to the environment or continuously adds gas and dumps the excess. Compare with closed circuit rebreather (CCR) (q.v.).

screw gate carabiner

A clip mechanism which can be locked in the closed position by turning a threaded barrel.

scuba

also SCUBA

Self Contained Underwater Breathing Apparatus. May be open or closed circuit.

scrubber

Canister containing material (sorb) which chemically combines with carbon dioxide to remove it from the gas passed through the canister.

secondary drowning

A complication of aspiration of water or other fluids into the lungs.

semi-dry suit

A wet suit with wrist and ankle seals, and usually a more watertight zipper than usual, to reduce flushing of water through the suit.

separator

Device which facilitates the separation of liquid particles from the compressed gas, usually with a drain to periodically remove accumulated liquid from the system.

serial compartments

A decompression model based on the assumption that diffusion is the limiting mechanism of dissolved gas transport in the tissues, in which there is perfusion transport for one compartment, and diffusion between a series of compartments,

serial number

1. Number stamped on the cylinder by the manufacturer in the shoulder area which identifies the cylinder. In combination with the manufacturer’s identification this will be unique to the cylinder.

2. Character string, including number, marked on an item of equipment by the manufacturer to uniquely identify it.

shallow water blackout

A loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold dive in water typically shallower than five metres (16 feet), when the swimmer does not necessarily experience an urgent need to breathe and has no other obvious medical condition that might have caused it.

shore diving

Diving from a shore entry.

shot line

A rope between a float at the surface, and a sufficiently heavy weight holding the rope approximately vertical.

sidemount

A scuba diving equipment configuration which has diving cylinders mounted alongside the diver, below the shoulders and along the hips, instead of on the back of the diver.

sidemount staging

The practice of using sidemount configuration (bungee loops and/or buttplate rails) as a means for stowing stage/deco cylinders when otherwise diving in back-mounted scuba

silica gel

A desiccant filter medium used to adsorb water.

silt-out

A situation when underwater visibility is rapidly reduced to zero, usually when a diver disturbs silt deposits.

single point mooring

A loading buoy anchored offshore, that serves as a mooring point and interconnect for tankers loading or offloading gas or liquid products. SPMs are the link between geostatic subsea manifold connections and weathervaning tankers. They are capable of handling any size ship, even very large crude carriers (VLCC) where no alternative facility is available

sinkhole

A natural depression or hole in the Earth's surface caused by karst processes — the chemical dissolution of carbonate rocks - or suffosion processes for example in sandstone

sintered

Particulate or granular material bonded together by the application of pressure and sufficient heat to partially melt the surface of the particles and weld them together. The product is usually porous.

skin

also skins, or dive skins

A lycra suit worn by a diver in warm water or under a wet suit.

S-lay

Method of laying underea pipelines by welding the sections together on the lay barge and deploying them from the stern horizontally guided by a "stinger" - a structure that supports the pipe string to control its bend radius.

sling cylinder

Further information: Diving cylinder#Open circuit

Independent cylinders with their own regulators carried clipped to the harness at the side of the diver.

slingshot valve

see Y-valve Further information: Diving cylinder#Other distinguishing features

SMB

Surface marker buoy.

snap shackle

A clip connector mechanism which locks when closed, can be operated without tools, and can usually be released under load.

snoopy loop

A heavy duty elastic band made from a slice of inner tube.

snorkel

Tube with a bend and mouthpiece used for breathing air from above the water surface when the wearer's mouth and nose are submerged.

snorkeling

also snorkelling

Swimming at the surface of the water while breathing through a snorkel. the snorkeller is almost always equipped with a diving mask or swim goggles, and usually swimfins.

snorkel keeper

Device to hold a smorkel in place at the side of a diving mask by fixing it to the mask strap

Snuba

Snuba is portmanteau of "snorkel" and "scuba" referring to a proprietory recreational surface supplied underwater breathing system supplied from a cylinder mounted on a small raft towed by the diver. see also Hookah.

solo diving

The practice of scuba diving alone, (without a "dive buddy").

sonic orifice

Metering device to provide constant mass flow of a gas.

sorb

also sodasorb

Carbon dioxide absorbent material used in rebreather or life support system scrubber to remove carbon dioxide from the breathing gas so it may be recycled.

speleothem

Also known as a cave formation: A secondary mineral deposit formed in a cave.

spider

Mask strap system for full-face masks with three or more straps. (commonly 5)

SPM

see single point mooring

spring suit

A wetsuit that covers the torso and has short sleeves and long or short legs

spud can

The foot on a leg of a Jack-up type oil platform designed to spread the load so that the rig does not sink too deeply into the sea-bed.

SPUMS

South Pacific Underwater Medicine Society

SSDE

Surface Supply Diving Equipment.

stage

see diving stage

stage cylinder

1. A cylinder used for a stage of a long penetration dive, also known as drop cylinder, which is placed on the distance line to be collected on the return.

2. Also generically used to refer to decompression gas cylinders carried as sling cylinders (q.v.).

staged decompression

The practice of making decompression stops.

stage-only diving

Further information: Sidemount#Terminology

The use of standard deco/stage cylinder configuration, without back-mounted cylinders, on an otherwise standard, or partially modified tec/rec BCD. The cylinders are attached to waist and shoulder D-Rings by direct bolt-snap, and no bungee cord is used in the upper attachment. May be confused with sidemount

standard diving dress

also Copper helmet or Heavy gear

Early free flow surface supplied diving equipment using a heavy canvas suit, copper helmet and corselet, and weighted boots.

standard operating procedure

Procedure compiled by an organisation prescribing the processes to be followed when performing specified tasks.

stand-by diver

Diver functioning as a safety backup to the working diver. Often on the surface at the dive control point, but ready to enter the water at very short notice on the instruction of the supervisor.

steamer

A full one piece wetsuit that covers the torso and the full length of the arms and legs.

stinger

An overboard extension at the stern of an offshore pipe lay barge used to provide additional support at the over bend of an S-lay during offshore construction.

stroke

Derogatory term used by DIR zealots to describe divers who do not follow DIR procedures and use DIR approved equipment and configurations.

subcutaneous emphysema

Gas under the skin resulting from lung overpressure injury.

submersible pressure gauge

also SPG

Gauge attached to the first stage regulator and used to monitor pressure remaining in the diving cylinder.

suicide clip

Derogatory term for clip mechanisms which are capable of clipping onto a line or other object without the active and intentional intervention of a user.

sump

A passage in a cave that is submerged under water.

supply lock

Small lock on a saturation life support habitat for transfer of relatively small items.

surface decompression

A procedure in which some or all of the staged decompression obligation is done in a decompression chamber instead of in the water.

SurD

see surface decompression

surface detection aids

Equipment, such as flags, surface marker buoys, flares, EPIRBs, mirrors, and whistles, carried by divers to maintain contact with dive boats or attract rescue when lost at sea.

surface equivalent volume

Gas volume adjusted to surface pressure. See also free gas volume

surface interval

The time spent by a diver at surface pressure after a dive during which inert gas which was still present at the end of the dive is further eliminated from the tissues.

surface marker buoy

also SMB

A buoy towed by a diver to indicate location to people at the surface.

surge

Reciprocating water movement parallel to the bottom surface caused by the passing of a wave overhead

sustained load cracking

The development of cracks in a material subjected over long term to static stress significantly less than the yield stress. There is a low but significant risk of this mode of failure in pressure vessels of AA6351 aluminium alloy.

swell

A series of surface gravity waves that is not generated by the local wind.