Glossary of underwater diving terminology: T–Z#Ve

{{Glossary of underwater diving terminology ToC}}

Subsection: Top, Ta, Te, Ti, To, Tu

{{glossary}}

{{term|1=tank factor}}

{{defn|1={{ghat|See: {{diving term|baseline}} }} }}

{{term|1=taravana}}

{{defn|1={{ghat|Main article: Taravana }}

A form of decompression sickness originally observed among Polynesian island natives who habitually did multiple repetitive deep breath-hold dives.{{cite book |last1=Rahn |first1=H. |last2=Yokoyama |first2=T. |title=Physiology of Breath-Hold Diving and the Ama of Japan. |year=1965 |publisher=National Academy of Sciences - National Research Council |location=United States |isbn=0-309-01341-0 |url=http://archive.rubicon-foundation.org/3279 |access-date=2008-04-16 |page=369 |archive-date=29 December 2010 |archive-url=https://web.archive.org/web/20101229101727/http://archive.rubicon-foundation.org/3279 |url-status=usurped }}{{cite journal |last=Wong |first=R. M. |title=Taravana revisited: Decompression illness after breath-hold diving |journal=South Pacific Underwater Medicine Society Journal |volume=29 |issue=3 |year=1999 |issn=0813-1988 |oclc=16986801 |url=http://archive.rubicon-foundation.org/6010 |access-date=2008-04-16 |archive-date=21 August 2009 |archive-url=https://web.archive.org/web/20090821162235/http://archive.rubicon-foundation.org/6010 |url-status=usurped }}}}

{{term|1=task loading}}

{{defn|1={{ghat|Main article: Task loading }}

A multiplicity of responsibilities leading to an increased risk of failure on the part of the diver to undertake some key basic function which would normally be routine for safety.{{cite web |url=https://scubadiverlife.com/training-fundamentals-task-loading/ |title=Training Fundamentals: Task Loading |website=scubadiverlife.com |first=Marcus |last=Knight |date=29 September 2019 |access-date=25 September 2023 }} }}

{{term|1=taut wire system}}

{{defn|1={{ghat|See: Dynamic positioning#Positioning systems }}

A constant tension wire from a vessel to a weight on the seabed used as a reference to detect movement of a dynamically positioned vessel from the reference point.}}

{{glossary end}}

Subsection: Top, Ta, Te, Ti, To, Tu

{{glossary}}

{{term|1=team redundancy}}

{{defn|1={{ghat|See: Team redundancy }}

System for sharing backup equipment and skill diversity.}}

{{term|1=technical diving}}

{{defn|1={{ghat|Main article: Technical diving }}

An extension of the scope of recreational scuba diving to applications with greater technical complexity and higher inherent risk. Definitions vary, but diving with multiple breathing gases, helium based gases, closed circuit rebreathers, or under extensive overheads are generally considered as technical diving. There is no sharp distinction from other forms of recreational diving.{{cite web |url=https://scubadiverlife.com/what-is-technical-diving/ |website=scubadiverlife.com |access-date=25 September 2023 |title=What is technical diving? |date=2 October 2018 |first=Yvonne|last=Press }} }}

{{term|1=tech ring}}

{{defn|1=D-ring welded to a {{diving term|belt slide}} so that it can not fold down against the webbing. Intended to make it easier to fit and remove snaps.}}

{{term|1=temperature stick}}

{{term|1=tempstick|multi=yes}}

{{defn|1={{ghat|Also: "thermal profile monitor", "TPM" }}{{ghat|See: Rebreather diving#Temperature monitoring }}

An array of temperature sensors mounted in a rebreather scrubber canister along the path of gas flow to monitor the temperature as an indication of the advance of the exothermic reaction front of the scrubber, providing an indication of scrubber depletion.}}

{{term|1=tension leg platform}}

{{term|1=tension leg rig|multi=y}}

{{defn|1={{ghat|Main article: Tension-leg platform }}

A vertically moored floating structure normally used for the offshore production of oil or gas, particularly suited for water depths between 300 and 1500 meters. The platform is permanently moored by means of near vertical tethers at each of the structure's corners and virtually all vertical motion of the platform is eliminated.{{cite book |last1=Ye |first1=J. |date=2020 |pages=1–11 |chapter=Tension-Leg platform |editor1-last=Cui |editor1-first=W.|editor2-last=Fu |editor2-first=S. |editor3-last=Hu |editor3-first=Z. |title=Encyclopedia of Ocean Engineering |publisher=Springer |location=Singapore |doi=10.1007/978-981-10-6963-5_4-1 |url= |isbn=978-981-10-6963-5 |s2cid=240816013 }} }}

{{term|1=test of pressure}}

{{defn|1={{ghat|See: Decompression sickness#Test of pressure}}

Diagnostic procedure for decompression sickness. The diver is recompressed, and if the symptoms reduce, it may be assumed that the diver has decompression sickness and hyperbaric treatment will be effective. The test is not entirely reliable{{cite journal |url=https://www.researchgate.net/publication/8110537 |title=Consensus Factors Used By Experts in the Diagnosis of Decompression Illness |first1=John J. |last1=Freiberger |first2=Sean J. |last2=Lyman |first3=Petar J. |last3=Denoble |first4=Carl F. |last4=Pieper |first5=Richard D. |last5=Vann |journal=Aviation, Space, and Environmental Medicine |date=January 2005 |volume=75 |issue=12 |pages=1023–8 |pmid=15619855 }}}}

{{term|1=test pressure}}

{{defn|1={{ghat|See: Hydrostatic test#Testing procedures}}

Pressure at which a pressure vessel such as a gas storage cylinder or hyperbaric chamber will be hydrostatically tested for revalidation. Usually 1.5 or 1.67 x working pressure for gas storage cylinders.}}

{{term|1=tethered ascent}}

{{defn|1={{ghat|See also: Scuba skills#Emergency ascents }}

Ascent controlled by a line from the diver to a fixed point at the bottom. This may be used to control depth and rate of ascent when the diver has inadvertently lost complete control of buoyancy due to loss of ballast weight, so cannot attain neutral buoyancy at some point during the ascent, and needs to do decompression. CMAS require this skill for their Self-Rescue Diver certification.}}

{{term|1=tethered diving}}

{{defn|1=Diving with a lifeline between the diver and a surface tender.{{cite report |url=https://archive.epa.gov/region10/diving/web/pdf/use-of-tethered-scuba-for-scientific-diving-aaus-2012.pdf |editor1-last=Pollock |editor1-first=N.W. |work=Diving for Science 2011. Proceedings of the American Academy of Underwater Sciences 30th Symposium. |location=Dauphin Island, AL |publisher=AAUS |date=2011 |title=Use of Tethered Scuba for Scientific Diving |first1=Sean |last1=Sheldrake1 |first2=Rob |last2=Pedersen |first3=Chad |last3=Schulze1 |first4=Steven |last4=Donohue |first5=Alan |last5=Humphrey }} }}

{{term|1=tether management system}}

{{defn|1={{ghat|Also: TMS }} The TMS is either a garage-like structute which contains and supports the ROV during lowering through the splash zone or, on larger work-class ROVs, a separate assembly mounted on top of the ROV. The purpose of the TMS is to lengthen and shorten the tether so the effect of cable drag where there are underwater currents is minimized.{{cite book |title=The Maritime Engineering Reference Book: A Guide to Ship Design, Construction and Operation |date=2008 |pages=728, 730–783 |chapter=10 - Underwater vehicles |editor1-first=Anthony F. |editor1-last=Molland |isbn=9780750689878 |publisher=Butterworth-Heinemann |doi=10.1016/B978-0-7506-8987-8.00010-X }} }}

{{term|1=Thalmann algorithm}}

{{defn|1={{ghat|See also: {{gli|VVAL18}} }}

{{ghat|Main article: Thalmann algorithm }}

The Exponential/linear decompression algorithm used in the 2008 US Navy decompression tables.{{cite journal|author= |title=VVAL-18M: New algorithm on deck for Navy divers |journal=Diver Magazine |date=September 2008 |volume=33 |issue=7 |url=http://www.divermag.com/v2/index.php?option=com_content&view=article&id=36 |url-status=unfit |archive-url=https://web.archive.org/web/20110710134553/http://www.divermag.com/v2/index.php?option=com_content&view=article&id=36 |archive-date=July 10, 2011 }} }}

{{term|1=therapeutic recompression}}

{{defn|1={{ghat|See: Hyperbaric medicine, Decompression practice#Therapeutic decompression, and Decompression sickness#Treatment }}

A procedure for treating decompression sickness by recompressing the diver, thus reducing bubble size, and allowing the gas bubbles to re-dissolve, then decompressing slowly enough to avoid further formation or growth of bubbles, or eliminating the inert gases by breathing oxygen under pressure{{rp|Ch. 15}} }}

{{term|1=therapeutic schedule}}

{{defn|1=Procedure for hyperbaric treatment involving recompression to relieve symptoms, followed by decompression at a rate unlikely to cause a relapse. Use of special breathing gas, particularly oxygen, to increase the rate of elimination of inert gases is common.}}

{{term|1=thermal profile monitor}}

{{defn|1={{ghat|See: {{gli|temperature stick}} }} }}

{{term|1=thermocline}}

{{defn|1={{ghat|Main article Thermocline }}

A thin but distinct layer in a large body of fluid, in which temperature changes more rapidly with depth than it does in the layers above or below.{{cite encyclopedia |last=((Britannica, The Editors of Encyclopaedia)) |title=thermocline |encyclopedia=Encyclopedia Britannica |url=https://www.britannica.com/science/thermocline |access-date=16 June 2023 }} }}

{{term|1=thermodynamic decompression model}}

{{defn|1={{ghat|See: Decompression theory#The no-supersaturation approach }}

Hypothesis that bubble formation during decompression will not occur provided absolute ambient pressure exceeds the total of the partial gas tensions in the tissue for each gas.{{cite journal |last1=LeMessurier |first1=H. |last2=Hills |first2=B.A. |year=1965 |title=Decompression Sickness. A thermodynamic approach arising from a study on Torres Strait diving techniques |journal=Hvalradets Skrifter |volume=48 |pages=54–84 }}}}

{{term|1=thirds}}

{{defn|1={{ghat|See: {{diving term|rule of thirds}} }} }}

{{term|1=three part shackle}}

{{defn|1={{ghat|Also: "bolt and nut shackle", "bolt shackle" }}

A shackle which uses a bolt as the pin, secured with a nut. The nut may be locked with a split pin for greater security. The bolt may rotate in the shackle under load without great risk of unscrewing the pin}}

{{term|1=through-water communications}}

{{defn|1={{ghat|See: through-water communications }}

Wireless voice communications transmitted through the water}}

{{term|1=thumb the dive}}

{{defn|1=Terminate the dive by signalling exit to surface at a time or place other than the planned turning point.}}

{{term|1=thunderflash}}

{{defn|1=Friction initiated noisy but relatively harmless pyrotechnic device designed for military exercises, with civilian use for diver recall.}}

{{glossary end}}

Subsection: Top, Ta, Te, Ti, To, Tu

{{glossary}}

{{term|1=time to fly}}

{{defn|1=The surface interval necessary after diving to reduce tissue gas concentrations to a level where the risk of decompression sickness due to the pressure reduction experienced in normal commercial airliners is acceptable.}}

{{term|1=tinnitus}}

{{defn|1={{ghat|Main article Tinnitus}}

The perception of sound within the ear in the absence of corresponding external sound. Usually a constant tone.}}

{{term|1=tissue compartments}}

{{defn|1={{ghat|See: Decompression theory#Tissue compartments }}

Hypothetical body tissues which are designated as fast and slow to describe the rate of saturation.}}

{{term|1=tissue half times}}

{{defn|1={{ghat|See: Decompression theory#Tissue half times}}

The time it takes for the tissue to take up or release 50% of the difference in dissolved gas capacity at a changed partial pressure.}}

{{term|1=TNT}}

{{defn|2=1|1=Total Nitrogen Time: Residual nitrogen time plus actual dive time. Equivalent time of hyperbaric exposure for a repetitive dive used with some decompression tables. {{cite web |url=https://rec2tecscuba.com/docs/NAUI-Air-Dive-Tables.pdf |title=Air Dive Tables |website=rec2tecscuba.com |access-date=9 July 2023 }}}}

{{defn|2=2|1=Trinitrotoluene, a high explosive}}

{{glossary end}}

Subsection: Top, Ta, Te, Ti, To, Tu

{{glossary}}

{{term|1=toolbox talk}}

{{defn|1={{ghat|Also: "TBT" }}

A meeting held at the start of each shift or prior to any project critical operation, where the diving supervisor or the diving supervisor’s delegate and shift personnel discuss the forthcoming tasks or jobs and the potential risks and necessary precautions to be taken.}}

{{term|1=top up}}

{{defn|1={{ghat|See also: {{diving term|air top}} }}

To reconnect a partially filled cylinder and add gas until the pressure is within tolerance of the required charging pressure when corrected for temperature.}}

{{term|1=touch contact signals}}

{{defn|1={{ghat|See: {{diving term|Rimbach system}} }} }}

{{term|1=Toynbee manoeuvre}}

{{defn|1={{ghat|Main article Ear clearing }}

Method of equalising the middle ears by pinching the nose and swallowing.}}

{{term|1=trait anxiety}}

{{defn|1={{ghat|See: Anxiety#Trait}}

A tendency to respond with anxiety in the anticipation of threatening situations.}}

{{term|1=transect}}

{{defn|1={{ghat|Main article Transect}}

A path along which one counts and records occurrences of the phenomena of study.{{cite web |url=https://www.oxfordreference.com/display/10.1093/oi/authority.20110803105325217 |title=Overview: transect |work=Oxford Reference |access-date=9 July 2023 }}{{cite web |title=Transect |work=Merriam-Webster.com Dictionary |publisher=Merriam-Webster |url=https://www.merriam-webster.com/dictionary/transect |access-date=8 July 2023 }} }}

{{term|1=transfill}}

{{defn|1={{ghat|Also: "decant" }}

Fill cylinder with gas by transfer from a cylinder with higher pressure.}}

{{term|1=transfill whip}}

{{defn|1=High pressure hose and end fittings used to {{diving term|decant}} between cylinders. Usually includes purge valve and may include pressure gauge.}}

{{term|1=trauma shears}}

{{defn|1={{ghat|Also: "bandage scissors" or "paramedic shears"}}

{{ghat|Main article Trauma shears}}

Blunt tipped slightly serrated shears with angled blades sometimes used by divers as a safety cutting implement in place of a knife or line cutter.}}

{{term|1=travel gas}}

{{defn|1=Gas mixture used for descent and ascent when the {{diving term|bottom gas}} is not suitable for breathing at shallower depths.}}

{{term|1=traverse}}

{{defn|1=Pass through a cave by entering at one point and exiting at another.}}

{{term|1=treatment table}}

{{defn|1=A depth, time and breathing gas profile designed to treat a diver for decompression illness.}}

{{term|1=tremie}}

{{defn|1={{ghat|Main article Tremie }}

A pipe, through which concrete is placed below water level. The top of the tremie is above water and open, and the bottom end is kept below the surface of the poured concrete.}}

{{term|1=triangular profile}}

{{defn|1=A triangular dive profile is one in which, after a descent at constant rate, and a short bottom time at maximum depth, the diver maintains a constant, slow ascent to the surface or first decompression stop. A plot of depth against elapsed time takes a triangular shape.}}

{{term|1=triglide}}

{{defn|1={{ghat|See: {{diving term|belt slider}} }} }}

{{term|1=trilam}}

{{term|1=trilaminate|multi=y}}

{{defn|1=Material used for dry suit shells made of a layer of waterproof rubber laminated between two layers of woven textile.}}

{{term|1=trimix}}

{{defn|1={{ghat|Main article Trimix (breathing gas)}}

Mixture of three gases for breathing. Oxygen, nitrogen and helium are the gases used. The gas fractions will usually be specified.}}

{{term|1=trim weight}}

{{defn|1={{ghat|See Diving weighting system#Trim}}

Ballast weight placed to improve a diver's {{gli|trim}}.}}

{{term|1=tripping line}}

{{defn|1=A line attached to the top of an open parachute lifting bag and at the other end to an anchor point. Its purpose is to invert and thus empty the bag if it becomes detached from the load.}}

{{term|1=try-dive}}

{{term|1=try dive|multi=y}}

{{term|1=tryout dive|multi=y}}

{{defn|2=1|1=Guided dive using unfamiliar equipment as a marketing technique, in the hope of convincing the diver that the product is worth buying. Some instruction or guidance on the use and characteristics of the product is usual. Similar in concept to test driving a motor vehicle, and similarly, generally offered to qualified operators, except for rebreathers, where one qualifies on a specific type.}}

{{defn|2=2|1=Also called "Discover Scuba Diving by PADI."{{cite web|url=https://www.padi.com/courses/discover-scuba-diving |title=Discover Scuba Diving |website=www.padi.com |access-date=9 July 2023 }} A single dive experience under the direct supervision of a recreational instructor offered to uncertified novices in the hope of them deciding to purchase entry level training. Some instruction on the essential skills and risks is generally provided, and the dive is generally conducted in benign conditions.{{cite web |url=https://diveraid.com/start-diving/try-dive/ |title=Try Dive |website=diveraid.com |access-date=9 July 2023 }} Compare with {{diving term|resort diving}}.}}

{{glossary end}}

Subsection: Top, Ta, Te, Ti, To, Tu

{{glossary}}

{{term|1=tube}}

{{defn|1={{ghat|Also: "Kelly tubes" or "Kellys" }}

A seamless transportable compressed gas container, with a water capacity exceeding {{convert|150|L|cuft}} but not more than {{convert|3000|L|cuft}}; Often mounted horizontally in manifolded groups on a trailer or intermodal container frame.}}

{{term|1=TUP}}

{{defn|1=Transfer under pressure Transfer of personnel between hyperbaric environments, usually between a closed bell and a saturation system, or between a portable recompression chamber and a multi-occupant chamber}}

{{term|1=turbidity}}

{{defn|1={{ghat|Main article Turbidity}}

The cloudiness or haziness of a fluid caused by individual particles (suspended solids) that may be invisible to the naked eye, similar to smoke in air}}

{{term|1=turn the dive}}

{{defn|1=Start the return on a dive which has reached the planned turning point in terms of depth, time, gas supply or distance.}}

{{term|1=twilight zone}}

{{defn|1=Deeper than 60 m in the sea, or the part of a cave or cavern that has dim but discernible ambient light.}}

{{term|1=type 1 wet bell}}

{{defn|1={{ghat|See: Diving bell#Type 1 wet bell }}

Wet diving bell (q.v.) with no direct supply of gas and services to the bell. Diver umbilicals lead directly to the surface control point.}}

{{term|1=type 2 wet bell}}

{{defn|1={{ghat|See: Diving bell#Type 2 wet bell }}

Wet diving bell (q.v.) with umbilical supply of gas and other services to the bell, from which they are distributed to the divers umbilicals from a control panel in the bell.}}

{{glossary end}}

{{Glossary of underwater diving terminology ToC}}

{{glossary}}

{{term|UBA}}

{{defn|1=Underwater breathing apparatus: Equipment used to supply breathing gas to an underwater diver. Usually refers to the part of the system carried underwater by the diver.}}

{{term|1=UDT vest}}

{{defn|1=Underwater Demolition Team vest, An inflatable surface life-jacket worn by underwater demolition teams. Similar in style and a precursor to the horse-collar style buoyancy compensator.{{cite web |url=https://www.sosmarine.com/product/udt-underwater-demolition-life-jackets-sos-9960/ |title=UDT Underwater Demolition Life Jackets SOS-9960 |website=www.sosmarine.com |access-date=26 September 2023 }} }}

{{term|1=UHMS}}

{{defn|1=Undersea and Hyperbaric Medical Society}}

{{term|1=umbilical}}

{{term|1=umbilical cable|multi=yes}}

{{defn|1={{ghat|See: Umbilical cable#Diver }}

{{ghat|See also: {{diving term|bell umbilical}}, {{diving term|diver umbilical}}, {{diving term|excursion umbilical}}, and {{diving term|ROV umbilical}} }}

Life support hose and cable bundle connection to a surface supplied diver or diving bell. Comprises gas supply hoses, pneumofathometer, a strength member and communications cable, and may also include gas reclaim hose, hot water hose and hoses for hydraulic or pneumatic power, and electrical and optical cables for ancillary equipment. Underwater television cameras and cabling can also be carried as a component part of the umbilical or can be taped or banded to it on a temporary basis. Also refers to the power, control and instrument cable for a ROV.}}

{{term|1=umbilical changeout}}

{{defn|1={{ghat|See: Surface-supplied diving skills#Umbilical changeout }}

Emergency procedure to disconnect the umbilical and connect a replacement in situ during the dive. Usually only used when a delay in recovering the diver or bell is likely. }}

{{term|1=umbilical cutter}}

{{defn|1={{ghat|See: Diving bell#Closed bell }}

Mechanism fitted to a closed bell which allows the occupants to sever the bell umbilical from inside the sealed and pressurised bell in the event of an umbilical snag that prevents bell recovery. The device is typically hydraulically operated using a hand pump inside the bell, and can shear the umbilical at or just above the point where it is fastened to the top of the bell.{{cite web|url=https://www.uniquegroup.com/item/1186/BellEquipment/Umbilical-Cutter.html |title=Umbilical cutter |website=www.uniquegroup.com |access-date=22 June 2019}}}}

{{term|1=undertow}}

{{defn|1={{ghat|Main article Undertow (water waves) }}

A subsurface flow of water returning seaward from shore as result of wave action.{{cite journal |title=Mass flux and undertow in a surf zone |first=I. A.|last=Svendsen |year=1984 |journal=Coastal Engineering Journal |volume=8 |issue=4 |pages=347–365 |doi=10.1016/0378-3839(84)90030-9}}}}

{{term|1=underwater blackout syndrome}}

{{defn|1={{ghat|Also: "hyperventilation-induced blackout" }}

Loss of consciousness due to hypoxia during a breath-hold submersion preceded by hyperventilation where alternative causes of blackout have been excluded.}}

{{term|1=unscrambler}}

{{defn|1={{ghat|See: {{diving term|speech unscrambler}} }} }}

{{term|1=upline}}

{{defn|1={{ghat|Also: "Jersey upline" }}

{{ghat|See: Decompression equipment#Upline}}

A fairly substantial natural fibre rope which is deployed from the bottom using a small lift bag to provide the equivalent of a shotline. The lower end is tied off to the bottom, usually on a wreck, and the diver ascends on the line to avoid being swept away from the site by currents. After reaching the surface, the last diver cuts the line and it sinks back down, Natural fibre is used so the line rots away over a few years.}}

{{term|1=upstream}}

{{defn|1=Against the flow.{{cite web |url=https://www.collinsdictionary.com/dictionary/english/upstream |title=upstream |work=www.collinsdictionary.com |access-date=12 July 2023 }} }}

{{term|1=upstream valve}}

{{defn|1={{ghat|See: Diving regulator#Upstream vs downstream }}

Valve, (usually regulator first stage or demand valve), where the valve mechanism moves against the flow when opening, and the pressure difference over the valve tends to close it.{{cite book |last=Harlow |first=Vance |title=Scuba regulator maintenance and repair |year=1999 |publisher=Airspeed Press |location=Warner, New Hampshire |isbn=0-9678873-0-5 |chapter=1 How a regulator works |pages=1–26}}}}

{{term|1=uptake}}

{{defn|1=(also gas uptake) See {{diving term|ingassing}} }}

{{term|1=upwelling}}

{{defn|1={{ghat|Main article Upwelling }}

An oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water.{{cite web |url=https://oceanservice.noaa.gov/education/tutorial_currents/03coastal4.html |title=Upwelling |publisher=National Ocean Service, NOAA |website=oceanservice.noaa.gov |access-date=16 June 2023 }}}}

{{glossary end}}

{{Glossary of underwater diving terminology ToC}}

Subsection: Top, Va, Ve, Vi, Vo, Vu

{{glossary}}

{{term|1=Valsalva maneuver}}

{{defn|1={{ghat|Main article: Valsalva maneuver }}

Technique for equalising the middle ear by moderately forceful attempted exhalation against a closed mouth and blocked nose}}

{{term|1=valve cage}}

{{defn|1={{ghat|See: Scuba cylinder valve#Valve cage }}

Structure or frame fitted to scuba cylinder to protect the cylinder valve or manifold and regulator first stage from impact damage and {{diving term|roll-off}} .}}

{{term|1=valve drill}}

{{defn|1=Safety exercise in which the diver shuts down, tests regulators and re-opens the manifold valves on a twin set in a specific order.}}

{{term|1=valve guard}}

{{defn|1= protective structure or frame fitted to the top of a bulk storage cylinder to protect the cylinder valve from mechanical damage.}}

{{term|1=van}}

{{defn|1=Enclosed portable compartment with diving spread support equipment. Often built into an intermodal container.

Exanples:

• DDC van, containing control panels for deck decompression chamber operation,
• Machinery van, containing hydraulic power pack, compressor, air banks or similar equipment}}

{{term|1=Van der Waals equation}}

{{defn|1={{ghat|Main article: Van der Waals equation }}

Thermodynamic equation of state for a real (non-ideal) gas.{{cite book | first1 = Robert J. | last1 = Silbey | first2 = Robert A. | last2 = Alberty | first3 = Moungi G. | last3 = Bawendi | title = Physical Chemistry | edition = 4th | year = 2004 | publisher = Wiley | isbn = 978-0471215042}}}}

{{term|1=vasoconstriction}}

{{defn|1={{ghat|Main article: Vasoconstriction }}

The narrowing of blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries and small arterioles.}}

{{term|1=vasodilation}}

{{defn|1={{ghat|Main article: Vasodilation }}

The widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large veins, large arteries, and smaller arterioles.}}

{{glossary end}}

Subsection: Top, Va, Ve, Vi, Vo, Vu

{{glossary}}

{{term|1=venous gas embolism}}

{{defn|1={{ghat|See: Decompression (diving)#Bubble formation, growth and elimination }}

Inert gas bubbles formed in the venous circulation. }}

{{term|1=venting breath}}

{{defn|1=Breathing pattern intended to vent gas from a rebreather loop, usually by exhaling through the nose.}}

{{term|1=venting tube}}

{{defn|1=Rubber tube closed with a stopper and normally attached to the chest area of an otherwise valveless dry suit, enabling the latter to be completely deflated before entering the water or inflated in the water to make the suit buoyant if required.[https://drive.google.com/open?id=0Bw7z_4bLjOOEcmt6eVBRbjBBMU0 Skinner's handbook for skin divers, 1956 edition]. Retrieved on 26 April 2019. }}

{{term|1=vertical entry}}

{{term|1=vertical drop entry|multi=yes}}

{{defn|1={{ghat|See: Scuba skills#Entries }}

An entry technique for relatively high drops, up to and sometimes exceeding 3 m. The feet are overlapped and the legs kept straight. The body and head are kept vertical and the mask and DV held against the face with one or both hands, elbows tucked in. The intention is to hit the water vertically, with the least likelihood of knocking off or damaging vital equipment.{{rp|249}} }}

{{term|1=vertigo}}

{{defn|1={{ghat|Main article: Vertigo }}

A type of dizziness, where there is a feeling of motion when one is stationary.}}

{{term|1=VGE}}

{{defn|1={{ghat|See: {{gli|venous gas embolism}} }} }}

{{glossary end}}

Subsection: Top, Va, Ve, Vi, Vo, Vu

{{glossary}}

{{term|1=viewport}}

{{defn|2=1|1=Glass or plastic window on a diving helmet or mask.}}

{{defn|2=2|1=Window on a hyperbaric chamber or manned submersible .}}

{{term|1=VIP}}

{{defn|1=Visual Inspection Programme (US). Annual visual internal inspection of a scuba cylinder.}}

{{term|1=visibility}}

{{term|1=viz|multi=y}}

{{defn|1={{ghat|See: Underwater vision#Visibility, turbidity and nephelometry }}

The distance through the water at which an object can just be seen against the background. Often defined as the distance at which a Secchi disc perpendicular to the sight line can first be seen when moving towards it. It can vary depending on direction illumination, and depth.{{cite web |url=https://www.seabird.com/water-visibility |title=Water Visibility Research |website=www.seabird.com |publisher=Sea-bird Scientific |access-date=24 October 2021 }}}}

{{term|1=visual gap}}

{{defn|1={{diving term|gap|Gap}} between guidelines which is small enough that each line can be seen from the other.}}

{{term|1=visual jump}}

{{defn|1=The procedure of crossing a {{gli|visual gap}} (q.v.) without the use of a jump line.}}

{{term|1=visual inspection}}

{{defn|1=Internal and external inspection of a pressure vessel as part of revalidation procedure}}

{{term|1=Visual Plus}}

{{defn|1={{ghat|See: Eddy-current testing }}

Eddy current crack detection test procedure for parallel neck threads of aluminium cylinders.{{cite web |url=http://www.visualplus.net/ |title=Advanced Inspection Technology |website=www.visualplus.net |access-date=16 June 2023 }} }}

{{term|1=Viton}}

{{defn|1={{ghat|Main article: Viton }}

Synthetic flourocarbon based elastomer suitable for oxygen service O-rings.}}

{{term|1=volume tank}}

{{defn|1=A pressure vessel connected to the outlet of a gas supply and used as a gas reservoir.}}

{{term|1=voting algorithm}}

{{term|1=voting logic|multi=yes}}

{{defn|1={{ghat|See: Redundancy (engineering)#Voting logic, Rebreather diving#Managing cell failure in an electronic rebreather control system }}

The logical procedure in which rebreather electronics compare output from multiple sensors when sensors produce significantly different values, suggesting that one or more are faulty, and choose which signals should be ignored, assuming statistical independence of the sensors, which may not be valid. }}

{{term|1=VPM}}

{{defn|1={{ghat|Main article: Varying Permeability Model }}

(also Variable permeability model). A decompression model and associated algorithms based on bubble dynamics.}}

{{term|1=VVAL18}}

{{defn|1={{ghat|Also: "E-L algorithm", "Exponential-Linear algorithm", "Thalmann algorithm"}}

{{ghat|Main article: Thalmann algorithm }}

Exponential-Linear algorithm used for the 2008 US Navy tables, which assumes exponential ingassing and a combination of linear and exponential outgassing rates.}}

{{glossary end}}

Subsection: Top, Va, Ve, Vi, Vo, Vu

{{Glossary of underwater diving terminology ToC}}

{{glossary}}

{{term|1=wah-wah}}

{{term|1=the wah-wahs|multi=y}}

{{defn|1=A noise inside the diver's head associated wth nitrogen narcosis in very deep air dives.{{cite magazine |url=https://indepthmag.com/the-call-of-the-wah-wah/ |title=The Call of the Wah-Wah |magazine=InDepth |access-date=15 August 2024 }} }}

{{term|1=wall diving}}

{{defn|1={{ghat|See: Underwater diving#Diving environment }}

Recreational scuba diving along the face of a near vertical cliff wall, particularly if the bottom is below the range of the diver's equipment and certification. This requires good buoyancy control.{{cite web |url=https://dtmag.com/thelibrary/wall-thrill-wall-diving/ |title=Off the Wall: The Thrill of Wall Diving |website=dtmag.com |publisher=DiveTraining |access-date=17 June 2023 }} }}

{{term|1=washout}}

{{defn|1=See {{diving term|outgassing}} {{cite web |url=https://indepthmag.com/thalmann-algorithm/ |title=Dial In Your DCS Risk with the Thalmann Algorithm |first=Tim |last=Blömeke |publisher=InDepth Magazine |website=indepthmag.com/ |date=3 April 2024 |access-date=27 January 2025}} }}

{{term|1=water capacity}}

{{defn|1={{ghat|See: Gas cylinder }}

Of a cylinder: The internal volume. The amount of water it would hold at ambient pressure at {{convert|20|C|F}} }}

{{term|1=water trap}}

{{defn|1=Mechanism to trap liquid water carried by compressed gas.}}

{{glossary end}}

{{glossary}}

{{term|1=weight belt}}

{{defn|1={{ghat|See: Diving weighting system#Weight belt }}

Ballasted waist belt worn by divers to compensate for excess buoyancy. For scuba and freediving, usually easily removed to establish positive buoyancy in an emergency.}}

{{term|1=weight harness}}

{{defn|1={{ghat|See: Diving weighting system#Weight harness }}

Webbing strap system to support diving weights, usually suspended from the shoulders and fastened around the waist. The harness may carry the weights directly, or they may be carried in pockets on the harness. For scuba diving the weights may be arranged for easy shedding.}}

{{term|1=weighting system}}

{{defn|1={{ghat|Main article: Diving weighting system }}

Weights, generally made of lead, to counteract the buoyancy of other diving equipment, and the belts, pockets or harnesses used to support them.}}

{{term|1=weight slider}}

{{term|1=weight stop|multi=yes}}

{{defn|1={{ghat|See: {{diving term|belt slider}} }} }}

{{term|1=welding shield}}

{{defn|1=Cover for the viewport area of a helmet or mask to filter excessive light and UV when welding or oxy-arc cutting.}}

{{term|1=wellhead}}

{{defn|1={{ghat|Main article: Wellhead }}

The assembly at the surface of an oil or gas well that provides the structural and pressure-containing interface for the drilling and production equipment.}}

{{term|1=wet bell}}

{{defn|1={{ghat|See: Diving bell#Structure of a typical wet bell }}

A mobile platform used to deploy and recover divers to and from working depth fitted with an air dome and on board emergency gas supply for use as safe haven in emergencies. There may be a main supply umbilical from the surface providing breathing gas to a manifold inside the wet bell and diver excursion umbilicals terminated at the wet bell, or the divers' umbilicals may be direct from the surface.}}

{{term|1=wet filling}}

{{defn|1={{ghat|See: Diving cylinder#Temperature change during filling }}

Filling scuba cylinders using a water bath for cooling the cylinders.}}

{{term|1=wet notes}}

{{term|1=wet-notes|multi=yes}}

{{defn|1=A small notebook of waterproof paper carried by some divers}}

{{term|1=wet pot}}

{{defn|1=1. Water filled hyperbaric chamber, generally for experimental work or training. See Diving chamber#Wet pot
2. Transfer chamber in a saturation system, where the bell is locked on and wet equipment removed after the dive.{{cite web|url=http://www.professionaldivingcentre.com/mini-4-man-compact-saturation-system/ |title=Mini- 4 Man Compact Saturation System |website=www.professionaldivingcentre.com |access-date=6 June 2023 }} }}

{{term|1=wetsuit}}

{{defn|1={{ghat|Main article: Wetsuit }}

A close fitting, thermally-insulating, foam neoprene diving suit that allows a limited volume and movement of water inside the suit.}}

{{term|1=whip}}

{{defn|1=Flexible high pressure gas hose with connector at the free end, used for temporary connections. The other end may be permanently connected to an installation or other equipment, or may also have a temporary connector. Whips are commonly named for their intended use, e.g. filling whip, for filling cylinders, decanting, transfill or transfer whip for decanting between cylinders, oxygen whip for oxygen transfer, blending whip, for decanting gases when blending gas, etc. Accessories may include a flow control valve, bleed valve, pressure gauge, and/or whip check.}}

{{term|1=whip check}}

{{term|1=whiplash arrestor|multi=y}}

{{defn|1=A cable or webbing strap connecting a hose end to the attachment point in addition to the hose end fitting, which restrains the movement of the hose if the connection is broken under pressure. Whip checks connecting two hose ends may also be attached to an anchor point to limit motion further if this is practicable.{{cite web |url=https://www.fastener.com.sg/safety-products/workplace-safety/safety-whiplash-arrestor/ |title=Safety whiplash arrestor |website=www.fastener.com.sg |access-date=26 October 2024 }}}}

{{term|1=whip sock}}

{{defn|1={{ghat|Also: {{diving term|containment grip}}}}Whip check device which contains a short section of the whip within a braided tube which reduces wear and point loading on the hose, and constrains motion of the hose end more than a standard whip check in case of disconnection under pressure.}}

{{term|1=wing}}

{{defn|1={{ghat|Main article: Backplate and wing }}

Back inflation buoyancy compensator cell.}}

{{term|1=WKPP}}

{{defn|1=Woodville Karst Plain Project, a project to survey subterranean aquifers in Florida. }}

{{glossary end}}

{{glossary}}

{{term|1=woolly bear}}

{{defn|1=A wool or synthetic pile thermal under-suit worn under a diving dry suit, particularly with standard diving dress, often one-piece.}}

{{term|1=working pressure}}

{{defn|1={{ghat|Also: "charging pressure"}}

Maximum filling pressure rating for the cylinder at standard temperature.}}

{{term|1=work of breathing}}

{{defn|1={{ghat|Also: "WOB" }}

{{ghat|Main article: Work of breathing }}

{{ghat|See also: Breathing performance of regulators }}

The effort expended in inhaling and exhaling the breathing gas.}}

{{term|1=wreck diving}}

{{defn|1={{ghat|Main article: Wreck diving }}

Recreational or technical diving on and inside of shipwrecks.}}

{{term|1=wrist slate}}

{{defn|1=A small plastic writing surface attached to the diver's wrist}}

{{glossary end}}

{{Glossary of underwater diving terminology ToC}}

{{glossary}}

{{glossary end}}

{{Glossary of underwater diving terminology ToC}}

{{glossary}}

{{term|1=yoke adaptor}}

{{defn|1={{ghat|See also: CGA 850 connector system }}

A fitting used to connect a regulator or filling whip with a DIN thread connection to a {{diving term|CGA 850}} "international" connection cylinder valve.}}

{{term|1=yoke fitting}}

{{defn|1={{ghat|See also: CGA 850 connector system }}

A fitting used to connect a regulator or filling whip to a diving cylinder using the {{diving term|CGA 850}} "international" connection.}}

{{term|1=yoke valve}}

{{defn|1={{ghat|See also: CGA 850 connector system }}

A valve used to connect a regulator or filling whip to a diving cylinder using the {{diving term|CGA 850}} "international" connection, mostly used in the US and countries where US diving tourists are economically important.}}

{{term|1=Y-valve}}

{{defn|1={{ghat|Also: "slingshot valve" }}

{{ghat|See: Scuba cylinder valve#Dual outlet valves }}

Cylinder valve body with two outlets and two valve mechanisms which can be independently controlled so that two regulator first stages can be fitted. Similar to H-valve but in Y configuration.}}

{{glossary end}}

{{Glossary of underwater diving terminology ToC}}

{{glossary}}

{{term|1=ZHL-8}}

{{term|1=ZHL-16|multi=y}}

{{defn|1=Bühlmann decompression algorithms. Also ZHL-16a, b and c}}

{{term|1=zip tie}}

{{defn|1={{ghat|Also: "cable tie", "tie wrap"}}

{{ghat|Main article: Cable tie }}

Self-locking plastic strip used to connect objects together.}}

{{term|1=Z-knife}}

{{defn|1=Line cutting tool with a replaceable blade in a slot.}}

{{glossary end}}

{{Reflist|30em|refs=

{{cite book |editor-last=Bevan |editor-first=John |year=2005 |title=The Professional Diver's Handbook |publisher=Submex }}

{{cite book |last=British Sub-Aqua Club members |title=British Sub-Aqua Club Diving Manual |edition=10th |year=1982

|publisher=British Sub-Aqua Club |location=Ellesmere Port, Cheshire |isbn=978-0950678610|page=567}}

{{cite web |url=http://www.cavediver.net/forum/content.php/149-cave-diving-terms |title=Cave diving terms |last1=Huth |first1=William |access-date=4 February 2013 |archive-date=9 October 2019 |archive-url=https://web.archive.org/web/20191009130541/http://www.cavediver.net/forum/content.php/149-cave-diving-terms |url-status=dead }}

{{cite web|url=http://www.cmas.org/document?sessionId=&fileId=2965&language=1

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|last= |date=4 March 2014

|work=CMAS International Diver Training Standards and Procedures Manual Syllabus Number: 3.B.31 / BOD no 181 ( 04-18-2013 )

|publisher=CMAS|access-date=13 April 2017}}

{{cite web |first1=Fred |last1=Calhoun |title=The case for Dry-filling scuba tanks

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|archive-url=https://web.archive.org/web/20090920212823/http://fillexpress.com/library/dryfills.pdf |archive-date=20 September 2009 |df=dmy }}

{{cite report |publisher=European Diving Technology Committee |author=Staff, EDTC

|title=Inshore and Offshore Diving Industry Personnel Competence Standards (Draft) |chapter=7 Definitions |date=16 June 2017}}

{{cite web |url=http://www.stepsnetwork.com/incident_safety_alerts/bin/Hose%20Fatality.pdf

|title=SAFETY ALERT File Ref.: 03-04 Alert - Air lines & whip check Issued by: EGIS HSEQC Dept. Issue Date: 30 April, 2003 FATALITY - FAILURE OF AIR-HOSE CONNECTION|last=Staff|date=30 April 2003|work=File Ref: 03-04 Alert - Air lines & whip check |publisher=EGIS HSEQC Dept. |access-date=15 November 2013

|url-status=dead |archive-url=https://web.archive.org/web/20131212133410/http://www.stepsnetwork.com/incident_safety_alerts/bin/Hose%20Fatality.pdf

|archive-date=12 December 2013|df=dmy-all}}

{{cite book |last=Harlow |first=Vance |title=Scuba regulator maintenance and repair |year=1999

|publisher=Airspeed press |location=Warner, New Hampshire |isbn=0-9678873-0-5}}

{{cite web |last=Heinerth |first=Jill |title=Glossary of Rebreather Diving by Jill Heinerth |url=http://www.swiss-cave-diving.ch/PDF-dateien/GlossaryCCR012014Heinerth.pdf |website=www.swiss-cave-diving.ch |access-date=12 May 2021 }}

{{cite web |url=http://www.imca-int.com/(F(uSBAynTT-lyY1Equ4jRo5jic2weOLPZqBWmONu9eokJaSdJH8_yEO7XAVF2AhMN-gH_DwpIK7Dj8HxMyN8KkGdPIwgY-zl_T7Ny0fSXFpEH8NFsPXJf5SK5xus5oTR2MR_3aJ8SgLoVuPJJuec-gNi1o9rg-j8gIDHa0dpF2Ik81))/media/264469/imcad057.pdf

|title=ADCI /IOGP /IMCA Diving Terms |last= |date=August 2016 |work=IMCA D 057

|publisher=International Marine Contractors Association |access-date=7 October 2016 }}{{Dead link|date=December 2019 |bot=InternetArchiveBot |fix-attempted=yes }}

{{cite web |url=http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=53655

|title=Recreational diving services -- Requirements for gas blender training programmes |last= |year=2012 |work=ISO 13293:2012 |publisher=International Standards Organisation |access-date=3 July 2016 }}

{{cite book |last=Jablonski |first=Jarrod |title=Doing it Right: The Fundamentals of Better Diving

|publisher=Global Underwater Explorers |location=High Springs, Florida |year=2006 |page=113

|chapter=Details of DIR Equipment Configuration |isbn=978-0-9713267-0-5 }}

{{cite web |url=https://www.uniquegroup.com/item/2378/CylindersGasBanks/Gas-Kelly-Tubes--Banks.html |title=Gas Kelly Tubes & Banks |publisher=Unique group |access-date=2 May 2018}}

{{cite book |last=Harlow |first=Vance |title=Oxygen Hacker's Companion |edition=4th |year=2001

|publisher=Airspeed Press |location=Warner, New Hampshire}}

{{cite journal |last1=Pearn |first1=John H. |first2=Richard C. |last2=Franklin |first3=Amy E. |last3=Peden |year=2015

|title=Hypoxic Blackout: Diagnosis, Risks, and Prevention |journal=International Journal of Aquatic Research and Education

|via=ScholarWorks@BGSU |volume=9 |issue=3 |pages=342–347

|url=https://www.researchgate.net/publication/302442886|doi=10.25035/ijare.09.03.09|doi-access=free }}

{{cite web |url=http://ndpa.org/loss-of-consciousness-in-breath-holding-swimmers/

|title=Loss of Consciousness in Breath-Holding Swimmers |last=Pollock |first=Neal W. |date=25 April 2014

|work=Fact Sheets, Water Safety |publisher=National Drowning Prevention Alliance (NDPA.org) |access-date=17 January 2017

|archive-url=https://web.archive.org/web/20170202024452/http://ndpa.org/loss-of-consciousness-in-breath-holding-swimmers/

|archive-date=2 February 2017 |url-status=dead }}

{{cite book |title=Arctic Underwater Operations: Medical and Operational Aspects of Diving Activities in Arctic Conditions

|editor-first=Louis |editor-last=Rey |edition=illustrated |publisher=Springer Science & Business Media |year=2012 |isbn=9789401196550}}

{{cite book|title=South African National Standard SANS 10019:2008 Transportable containers for compressed, dissolved and liquefied gases - Basic design, manufacture, use and maintenance |edition=6th |year=2008 |publisher=Standards South Africa |location=Pretoria, South Africa |isbn=978-0-626-19228-0}}

{{cite web |url=http://www.shipwreckexpo.com/shipwreckdivingequipment.htm |website=www.shipwreckexpo.com |title=Scuba Wreck Diving Equipment |last=Berg |first=Dan |access-date=25 October 2017 |archive-date=23 September 2019 |archive-url=https://web.archive.org/web/20190923093657/http://www.shipwreckexpo.com/shipwreckdivingequipment.htm |url-status=dead }}

{{cite web|url=http://oxforddictionaries.com/definition/english/thunderflash|archive-url=https://web.archive.org/web/20130110035023/http://oxforddictionaries.com/definition/english/thunderflash|url-status=dead|archive-date=10 January 2013|title=Thunderflash |last=Staff |website=oxforddictionaries.com }}

{{cite web |url=http://www.hfmgroup.com/professionalsupplies/thunderflashes.html |title=Thunderflashes |access-date=4 May 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130430144351/http://www.hfmgroup.com/professionalsupplies/thunderflashes.html |archive-date=30 April 2013 |df=dmy-all }}

{{cite book |title=US Navy Diving Manual, 6th revision |year=2006 |publisher=US Naval Sea Systems Command |location=United States |url=http://www.supsalv.org/00c3_publications.asp?destPage=00c3&pageID=3.9 |access-date=2008-06-08 |archive-date=2 May 2008 |archive-url=https://web.archive.org/web/20080502023541/http://www.supsalv.org/00c3_publications.asp?destPage=00c3&pageId=3.9 |url-status=dead }}

{{cite web|url=http://www.safetyrig.com/whipchecks.html|title=Whip checks|last=Staff|publisher=Safety Rig Oilfield and Industrial Safety Products|access-date=15 November 2013|location=Houston, Texas}}

{{cite web|url=http://www.americawestdrillingsupply.com/WhipSocks.asp|title=Whip socks|last=Staff|publisher=America West Drilling Supply|access-date=15 November 2013|archive-date=9 October 2019|archive-url=https://web.archive.org/web/20191009130548/https://americawestdrillingsupply.com/WhipSocks.asp|url-status=dead}}

}}

• [https://web.archive.org/web/20120822024753/http://www.glossary.oilfield.slb.com/MainIndex.cfm?ID=1 Schlumberger Oilfield Glossary]

{{Underwater diving}}

Underwater diving terminology

Category:Underwater diving lists

Category:Wikipedia glossaries using description lists

{{DEFAULTSORT:Glossary of underwater diving terminology: T-Z}}