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If you know your RIB from your HB, avoid tangling your SMB line round your 1st stage and know the ppO2 @ 9m of your Nx50 deco mix, then your on the wrong page. However, if you haven't a clue what we're talking about - come on in. Welcome to the ukrs Jargon Buster! All those weird and wonderful TLA's (three letter acronyms) and terms used by divers will be explained in plain(ish) English.
0-9999 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
10l, 12l, 15l, 10m, 30m, 1st Stage, 2nd Stage, A-Clamp, AAS, ABLJ, Absolute Pressure, ACI, AD, AI, AOW, Argon, Auto Air/AirII, Back Plate, Bar, Barotrauma, BCD, Bends(The), BS-AC or BSAC, Buddy, Buddy Check, Buddy Monitoring, Buoyancy, Cave, Cavern, CCR, Chamber, CI, Club Diver, Computer, Console, Cylinder, DCS, Deco or Decompression, Deco Mix, Delayed SMB, Demand Valve (DV), Diluent, DIN Fitting, Dive Timer (DT), Diluent, Diving Suits, DL, DM, Dump, EAD, EAN or EANX, EC, Fenzy (Frenzy) Bottle Gas, GPS, HB, Heliox, HID, HP, Inspiration, KISS, Lantern, LP, Lycra, Manifold, Mix, Narcosis (Narcs), Nitrox (Nx), No Stop, Novice, OC, Ocean Diver, Octopus, Overhead Environment, OW, OWI, OWSI, PADI, Partial Pressure (pp), Pillar Valve, Pony, Port, Re-breather, Redundancy, Reel, Regulator, Repetitive Dive, RIB, Rig, SAA, Safety Stop, SCUBA, SCR, Scrubber, Semi-Dry, Shot Line, Skin, SMB, Sofnolime, Spare Air, Stab Jacket, Stage Bottle, Strobe, Suicide bottle, Tables, Technical Diving, Trimix, Twin Set, Turtle, Vis, Wet Suit, Wing, YBOD, Y-Valve
The Numbers Game...
Top10l, 12l, 15l : Refers to the size of air cylinders used in the UK, the number measures in litres the space inside the cylinder (this is technically known as the water capacity). So and empty 15l cylinder contains 15 litres of air, double the air pressure (2 BAR) and it contains 30 litres of air.
10m, 30m : The depth in metres.
1st Stage : Part of a Regulator, the central part that attaches to the diving cylinder. Apart from serving as the cylinder attachment the 1st Stage is also a pressure reducing valve that reduces the cylinder pressure (200+ BAR at the start of a dive) to a lower 10 to 15 BAR pressure. There are ports (screw fittings) on the 1st stage that tubes to feed other equipment attach to, there are normally four low pressure ports (LP Feed) and two high pressure (HP Feed) ports.
2nd Stage : The part of the regulator you breathe from, also known as a demand valve.
Aisfor..
TopA-Clamp : A type of fitting for connecting the regulator 1st stage to the cylinder pillar valve. The pillar valve is clamped into a frame on the regulator 1st stage, the assembled item resembles the letter 'A'. The A-Clamp is the 'traditional' way of connecting the 1st stage to a cylinder and is used throughout the world.
AAS : Alternative Air Source. A 'spare' demand valve (often referred to as an octopus) carried by a diver for their own use or their buddy's use should something go wrong with their normal equipment.
ABLJ : Adjustable Buoyancy Life Jacket. An older style of BCD that is still used by some divers. Looks like a standard 'over the head' life jacket (it is sometimes called a horse collar) but the amount of air in it can be controlled. Now replaced by the Stab Jacket BCD for most diving.
Absolute Pressure : The pressure currently acting on a divers body, as you read this you should be experiencing an absolute pressure of 1 BAR, i.e Atmospheric pressure. Each 10m of water above you adds 1 BAR, so a diver at 30m is at 4 BAR absolute pressure - 4 times the normal atmospheric pressure. When we breath at depth we breath at absolute pressure (the demand valve makes sure of this), so at 30m (4 BAR) we use twice as much air as at 10m (2 BAR).
ACI : Assistant Club Instructor. A BS-AC trainee instructor qualification.
AD : Advanced Diver. A BS-AC diver qualification.
AI : Advanced Instructor. A BS-AC instructor qualification.
AOW : Advanced Open Water. A PADI diver qualification.
Argon : An inert gas sometimes used by divers to inflate their dry suits, argon is used because it is a much better insulator from the cold than normal air.
Auto Air/Air II : Another form of AAS. A demand valve that is built in to the inflator/deflator control of a BCD.
Bisfor..
TopBack Plate : Part of a different type of diving rig, rigid (normally stainless steel) that is designed to carry a twin set of cylinders. Used in conjunction with a wing BCD
BAR : A measure of pressure, 1 bar = atmospheric pressure. The amount of air in a cylinder is measured in BAR, it is typically about 220 BAR at the start of a dive and 50 BAR at the end.
Barotrauma : A general term to describe a physical injury caused by a change in pressure.
BCD : Buoyancy Control Device. Normally the term used for the waistcoat like jacket that divers wear to which most of their equipment is attached. The BCD contains a bag that can be inflated and deflated, this controls the buoyancy of the diver.
Bends (The) : The 'general public' term for what we call DCS. 'The Bends' is actually a mild form of DCS where bubbles form in joints such as elbows, to relive the pain and pressure people tend to continually bend their arms - hence the name 'The Bends'.
BS-AC or BSAC : The British Sub Aqua Club. A UK diver training agency.
Buddy : Your diving partner, in the UK we normally dive in twos - a buddy pair.
Buddy Check : A pre-dive check where two divers check each others dive equipment and explain how it all works.
Buddy Monitoring : Keeping an eye on your buddy during a dive and checking that everything is OK.
Buoyancy : Whether something floats, sinks or hovers in the water. Negative Buoyancy = sinking, Neutral Buoyancy = hovering, Positive Buoyancy = rising or floating. Divers should be at (or near) neutral buoyancy at all times so that they are in total control of where they are in the water, this is achieved by injecting air into or dumping air from their dry suit or BCD.
Cisfor..
TopCave : A (normally rock) tunnel with no immediate route up or out. Cave diving is a very specialised form of diving requiring special training, equipment and techniques. Without all three of those it is very dangerous!
Cavern : A depression in a rock race or the 'twilight zone' entrance to a cave. A cavern constitutes an overhead environment but for a cavern you can clearly see the light and the way out. When you reach the stage where you can't see the light any more you are in a cave!
CCR : Closed Circuit Rebreather. A type of rebreather that uses oxygen sensors and controls the level of oxygen being breathed. Makes very efficient use of gas and cuts down the time needed for deco.
Chamber : Short for decompression chamber. A medical facility where a diver can be pressurised to simulate diving pressures. Used to treat DCS amongst other things.
CI : Club Instructor. A BS-AC instructor qualification.
Club Diver : A SAA diving qualification.
Computer : A small piece of diving electronics worn on the wrist or included in the console. It constantly displays information such as current depth, maximum depth, dive time and remaining no stop time. It can calculate the decompression requirements for the dive. Most UK divers carry a dive computer.
Console : Part of a regulator, contains some of the instruments used by a diver. Typically there is a pressure gauge showing how much air is left in the cylinder, a depth gauge to show how deep you are and a compass to navigate with. The console attaches to one of the HP Feeds of the 1st Stage.
Cylinder : The steel or aluminium bottle or tank containing our breathing (normally...) gas. They come in various sizes up to 15l and two pressure ratings, the standard 232 BAR and the newer 300 BAR.
Disfor..
TopDCS : Decompression Sickness, the modern term for a whole host of very nasty things (the 'bends' is one minor form of DCS) that can happen if you break the rules or things go badly wrong. During a dive nitrogen is forced into a divers body due to the pressure, when returning to the surface this nitrogen disperses again. If this happens to quickly (a bit like opening a pressurised can of fizzy drink) bubbles can form and cause DCS. A large part of diver training is on what causes and how to avoid DCS.
Deco or Decompression : The process of a diver 'returning to normal pressure' after a dive and allowing the nitrogen absorbed (see above) to disperse. For more advanced diving you have to stop on the way up and wait for your body to adjust to the new (reduced) pressure, this is called a deco stop. Most diving is what is known as No Stop diving, just coming up slowly is enough for the diver to decompress safely. Decompression continues when the diver is back on the surface, after a days diving it can take over 24 hours for all the extra nitrogen absorbed to fully disperse.
Deco Mix : A special mixture of gasses (usually Nitrox) to be breathed during a decompression stop. Breathing a high percentage of oxygen speeds up decompression.
Delayed SMB : See SMB
Demand Valve (DV) : The part of a regulator that you put in your mouth and breathe from. It supplies air 'on demand' when you want it, the mechanics of a DV always supply you air at absolute pressure, so a breath of air at 30m is actually 4 times the amount of air you would breathe on the surface.
Diluent : A CCR uses two gas supplies. Oxygen is added when its level is too low, and diluent is added when its too high.
DIN Fitting : A type of fitting for connecting the regulator 1st stage to the cylinder pillar valve. There is a male screw thread on the 1st stage which screws into a female thread on the pillar valve.The DIN fitting is the modern way of connecting the 1st stage to a cylinder, it is used exclusively on high pressure (300 BAR) cylinders.
Dive Timer (DT) : A simple electronic device for recording current depth, maximum depth and time of a dive. Similar to a dive computer but it does not calculate decompression.
Diving Suits : Different types of diving suits are used for different water temperatures and diving conditions, the following is a brief summary - Lycra or Skin : A thin body stocking used in tropical water, main purpose is to protect against abrasion and stings. Wet Suit : A thicker neoprene material that works by trapping a layer of water between the body and the suit, this forms and insulating layer. Semi-Dry Suit : An improvement on the wet suit, seals at the wrist and neck limit the amount of water that flows in and out of the suit. Dry Suit : Completely sealed from the water, dry inside. Diving dry suits have air valves that the diver uses to inflate/deflate the suit, as well as insulation the suit can also be used for buoyancy control. Most regular UK divers use dry suits.
DL : Dive Leader. A BS-AC diver qualification.
DM : Dive Master. A PADI diver qualification.
Dump : A valve to allow the, or the action of, getting rid of (dumping) air from a BCD or a dry suit.
Eisfor..
TopEAD : Equivalent Air Depth. When using Nitrox as a breathing gas it has the effect of 'simulating' a shallower dive made breathing air, for dive time calculation purpoes (see Tables) the EAD can be used for working out our no-stop time when using Nitrox.
EAN or EANX : Enahnced Air Nitrox. It means the same as nitrox. Jargon for jargon's sake.
EC : Emergency Cylinder. A small cylinder (0.4l) connected to the BCD. Can be used to inflate the BCD and/or in conjunction with an Auto Air provide a very small redundant AAS. EC's are mainly a British peculiarity, not many other countries use them.
Fisfor..
TopFenzy (Frenzy) Bottle : Another name for an EC.
Gisfor..
TopGas : Breathing gas (of whatever mix).
GPS : Global Positioning System. Electronic navigation aid that uses satellites to give a very precise read-out of your position.
Hisfor..
TopHB : Hard Boat, a term used to describe a larger dive boat, typically an in-shore trawler in the case of UK diving.
Heliox : A special breathing gas mix containing helium and oxygen only, this is a comercial diving gas, TriMix is sometimes used for a very advanced form of UK diving.
HID : High Intensity Discharge. A very energy efficient and expensive type of torch.
HP : High Pressure. Normally used when taking about regulators, in the case of regulator pressures high pressure is the current pressure in the cylinder, which could be up to 300 BAR.
Iisfor..
TopInspiration : A popular rebreather model. See www.ambientpressurediving.com
Kisfor..
TopKISS : A type of rebreather. It differs from most other CCRs in that while it senses oxygen levels the diver is left to control them. See www.jetsam.ca
Lisfor..
TopLantern : A large and powerful underwater torch.
LP : Low Pressure. Normally used when taking about regulators, in the case of regulator pressures low pressure is about 8 - 10 BAR.
Lycra : See Diving Suits
Misfor..
TopManifold : A rigid tube that connects the two cylinders of a twin set together. The manifold connects between the pillar valves of the cylinders, it sometimes has its own 'isolation' valve in the middle - in which case it is an isolation manifold.
Mix : A term used to describe a breathing gas that is NOT normal air. Apart from normal air Nitrox and Heliox mixes are sometimes used.
Nisfor..
TopNarcosis (Narcs) : An 'altered state of mind' (effects can be similar to alcohol) that can affect divers at depth. Full name is Nitrogen Narcosis, it is caused by breathing the nitrogen component of your cylinder under pressure.
Nitrox (Nx) : A breathing gas mix where the percentage of oxygen (about 21% in normal air) has been increased and the percentage of Nitrogen (about 79% in normal air) decreased. Normally followed by a number that denotes the oxygen percentage - e.g. Nitrox32 is a mix containing 32% oxygen, 68% nitrogen.
No Stop: A type of dive where a decompression stop is not required.
Novice : A BS-AC diver qualification.
Oisfor..
TopOC : Open Circuit. Normal SCUBA gear, as opposed to rebreathers.
Ocean Diver : A BS-AC diver qualification.
Octopus : In diving terms this is a spare demand valve that is used as an AAS.
Overhead Environment : Any diving situation where there is no clear way up to the surface, typically inside a wreck or a cave.
OW : Open Water. A PADI diver qualification.
OWI : Open Water Instructor. A BS-AC instructor qualification.
OWSI : Open Water SCUBA Instructor. A PADI instructor qualification.
Pisfor..
TopPADI : Professional Association of Diving Instructors. An American based diver training agency offering standard training throughout the world.
Partial Pressure (pp) : One of the gas laws and a bit of mathematics that divers have to put up with! It is to do with gasses in a mixture, put simply it is the pressure of one of the component gasses. e.g. A cylinder contains 25% oxygen, 75% nitrogen. A pressure gauge shows that the cylinder is at 4 BAR, the partial pressure of the oxygen (ppO2) is 1 BAR, the pp of the nitrogen is 3 BAR.
Pillar Valve : The metal fitting in the neck of a cylinder. Consists of an on/off valve and a connection point for the regulator 1st stage.
Pony : A small (3ltr) cylinder with its own regulator that is carried as a redundant AAS.
Port : (LP or HP) An off-take from the 1st Stage of a regulator.
Risfor..
TopRe-breather : An alternative (expensive!) type of scuba set. The normal scuba gear that is used is known as 'open circuit', things are not re-used. For normal scuba gear your body only actually uses about 4% (it uses part of the oxygen content) of what you breathe, the other 96% (plus the 4% carbon dioxide your body generates) you send to the surface as bubbles. A re-breather works by 'keeping' what you breathe out, it cleans out the carbon dioxide and tops up the 4% your body has used from a small cylinder. You then 're-breathe' this cleaned and topped up gas ad-infinitum.
Redundancy : Having a piece of equipment that is totally redundant under normal circumstances, it is just there in case the main item of equipment fails. e.g. Many divers carry two torches, a main torch and a smaller spare in their pocket. To be truly redundant the equipment must not rely in any way the piece of equipment that it is it is the back-up for.
Reel : A drum, line and winder (like a giant sea fishing reel) carried by a diver and used for various things such as connecting to a SMB or as a 'back to where you started' navigation aid.
Regulator : The collective term for spider like collection of metal, tubes and bits of plastic that divers connect to their cylinder and then to various other bits and pieces of dive gear. It is made up of several parts, a 1st Stage, Demand Valve, Octopus, LP Inflators and Console.
Repetitive Dive : Any dive undertaken when there is still nitrogen in your body from a previous dive. See decompression.
RIB : Rigid Inflatable Boat, rigid hull with large inflatable tubes down each side (see the .gif on our home page!). A purpose built dive boat owned by clubs and some individuals.
Rig : The collective name for a complete set of diving equipment (BCD, cylinder, regulator...) used on a dive.
Sisfor..
TopSAA : Sub Aqua Association. A UK club based training agency. (Failure to mention the SAA in any UK diving review can result in emails from head office <g>.)
SCR : Semi Closed Rebreather. A rebreather that reuses most of the gas but lets some escape, replacing it with fresh gas that contains a higher level of oxygen.
Scrubber : The part of the rebreather that removes carbon dioxide. Contains sofnolime.
SCUBA : Self Contained Underwater Breathing Apparatus.
Safety Stop : A decompression stop, normally at about 5m, done just for safety. Not actually required by the dive tables but most divers do a safety stop.
Semi-Dry : See Diving Suits
Shot Line : A rope with a heavy weight at one end and a buoy at the other. Dropped onto a wreck or other sea bed feature and used to guide the diver to/from what they are diving on.
Skin : See Diving Suits
SMB : Surface Marker Buoy. A surface float, normally filled with air, that the diver controls via a line, it shows your cover boat (and anyone else) where a diver is. Divers often carry a delayed SMB, it is carried rolled up in a pocket and it's deployment is 'delayed' until the diver is preparing to come to the surface.
Sofnolime : The chemical in a rebreather that removes carbon dioxide. Common rebreathers contain enough to last three hours.
Spare Air : Trade name of a large 'aerosol' type device that is a complete cylinder and DV in one small unit, carried as a redundant AAS.
Stab Jacket : See BCD.
Stage Bottle : A cylinder containing a breathing mix to be used during a decompression stop.
Stop : A required (by the tables or the computer) decompression stop.
Strobe : An underwater photographers camera flash light. Also a small flashing light carried on a BCD to let other divers know where you are.
Suicide bottle : Many think that emergency cylinders contain too little air to provide much benefit, and that the risk of accidental inflation and subsequent injury from surfacing too quickly is too high.
Tisfor..
TopTables : Look-up tables that tell you how long and how deep you can safely go when you dive. They tell you how long you can stay at a depth and still do a no stop dive, some tables also tell you the decompression requirements if you stay longer than the no stop time. A dive computer also does these calculations for you and keeps you constantly updated on your decompression requirements during the dive.
Technical Diving : General term for an advanced form of diving involving special mixes and decompression stops.
Trimix : A specialised breathing mix consisting of oxygen, nitrogen and helium, used for a very advanced form of recreational diving.
Twin Set (or twins) : A diving rig comprising of two (normally equally sized) cylinders, both of which are intended to be used during a dive.
Turtle : Another name for an Inspiration.
Visfor..
TopVis : Short for visibility, the horizontal range of visibility when underwater. Normally between 5m and 15m in the UK, sometimes more, sometimes less.
Wisfor..
TopWet Suit : See Diving Suits
Wing : A type of BCD.
Yisfor..
TopYBOD : Yellow Box Of Death. Another name for an Inspiration. Some point to several deaths of divers using this rebreather, some of which haven't been explained, and say that its unsafe. Others say that there are thousands of them being used successfully and that many of the deaths were clearly caused by operator error. Everyone agrees that even the most experienced OC divers are novices again when switching to rebreathers.
Y-Valve : A special type of cylinder pillar valve. Instead of the normal one connection point for a regulator 1st stage there are two, adding a second regulator gives some redundancy.
© Keith Lawrence and others (Dec. 1997)
Updated by Anthony Chapman (Mar. 2003)