Technical diving 291242 221570097 2008-06-25T02:45:07Z Legis 1337739 /* Definition of 'technical diving' */ deep diving '''Technical diving''' is a form of [[scuba diving]] that exceeds the scope of [[recreational diving]]. Technical divers require advanced training, extensive experience, specialized equipment and often breathe [[Breathing_gas|breathing gases]] other than [[air]] or [[standard nitrox]]. ==Definition of 'technical diving'== The concept and term 'technical diving' are both relatively recent advents,<ref>In his 1989 book, ''Advanced Wreck Diving'', author and leading technical diver, Gary Gentile, commented that there was no accepted term for divers who dived beyond agency specified recreational limits for non-professional purposes. Revised editions use the term "technical diving", and Gary Gentile has subsequently published a further book in 1999 entitled ''The Technical Diving Handbook''.</ref> although divers have been engaging in what is now commonly referred to as technical diving for decades. There is some level of professional disagreement as to what the term should encompass. Broadly, technical diving is any type of SCUBA that is considered higher risk that conventional recreational diving. However, some advocate that this should include [[penetration diving]] (as opposed to [[open-water diving]], whereas others contend that pentrating overhead environments should be regarded as a separate type of diving. Others seek to define technical diving solely be reference to the use of decompression. Certain minority views contend that certain non-specific higher risk factors should cause diving to technical diving. Even those who agree on the broad definitions of technical diving may disagre on the precise boundaries between technical and recreational diving. The following table tries to set out the broad indicative parameters of what is normally regarded as technical rather than recreational diving. {| class="wikitable" style="margin: 1em auto 1em auto" |+ '''Technical Diving''' ! width="150"|Activity || width="285"|Recreational || width="285"|Technical |- | align="center"|[[Deep diving]]|| align="center"|Maximum depth of 130 feet<ref>Most recreational diving agencies recommend diving no deeper than 100 feet, and suggest an absolute limit of 130 feet.[http://www.padi.com/english/common/courses/rec/continue/deepdiver.asp]</ref> || align="center"|Below 130 feet |- | align="center"|[[Decompression stop|Decompression diving]]<ref>There is a reasonable body of professional opinion that considers decompression diving to be the sole differentiator for "technical" diving.<sup>[http://www.divessi.com/techxr SSI]</sup></ref>|| align="center"|No decompression || align="center"|Decompression diving |- | align="center"|[[Gas blending|Mixed gas diving]]|| align="center"|Air and [[Nitrox]] || align="center"| [[Heliox]], [[Heliair]] and [[Trimix]] |- | align="center"|[[Wreck diving]]|| Penetration limited to "light zone" or 100 foot <br />depth/penetration|| align="center"|Deeper penetration |- | align="center"|[[Cave diving]]|| Penetration limited to "light zone" or 100 foot <br />depth/penetration<ref>Some certification agencies prefer to the term "cavern diving" to cave penetration within recreational diving limits.</ref>|| align="center"|Deeper penetration |- | align="center"|[[Ice diving]]|| colspan="2" | Some agencies regard ice diving as recreational diving;<sup>[http://www.padi.com/padi/en/kd/icedivercourse.aspx PADI]</sup> others as technical diving.<sup>[http://www.naui.org/technical_divers.aspx NAUI]</sup> |- | align="center"|[[Rebreather]]s|| colspan="2" | Some agencies regard use of semi-closed rebreathers as recreational diving;<sup>[http://www.padi.com/padi/en/kd/semiclosedrebreather.aspx PADI]</sup> others as technical diving.<sup>[http://www.naui.org/technical_divers.aspx NAUI]</sup> |- | align="center"|[[Solo diving]]|| Recreational diving requires buddy system|| align="center"|Solo diving<ref>Some training agencies regard solo diving within the "recreational" sphere.<sup>[http://www.tdisdi.com/index.php?did=60&site=3 SDI]</sup></ref> |} ===Depth=== Technical dives may be defined as being either dives to depths deeper than 130 feet / 40 meters or dives in an overhead environment with no direct access to the surface or natural light. Such environments may include fresh and saltwater caves and the interior of shipwrecks. In many cases, technical dives also include planned decompression carried out over a number of stages during a controlled ascent to the surface at the end of the dive.<ref>[http://www.idc-mexico.com/dive_college/go_tec.html]</ref> The depth-based definition is derived from the fact that breathing regular [[air]] while experiencing pressures causes a progressively increasing amount of impairment due to [[nitrogen narcosis]] that normally becomes serious at depths of 100 feet / 30 metres or greater. Increasing pressure at depth also increases the risk of oxygen toxicity based on the [[partial pressure]] of oxygen in the breathing mixture. For this reason technical diving often includes the use of breathing mixtures other than air. These factors increase the level of risk and training required for technical diving far beyond that required for recreational diving. This is a fairly conservative definition of technical diving. ===Inability to ascend directly=== Technical dives may alternatively be defined as dives where the diver cannot safely ascend directly to the surface either due to a mandatory [[decompression stop]] or a physical ceiling. This form of diving implies a much larger reliance on redundant equipment and training since the diver must stay underwater until it is safe to ascend or the diver has left the overhead environment. ====Decompression stops==== A diver at the end of a long or deep dive may need to do decompression stops to avoid [[decompression sickness]], also known as the "bends". Metabolically inert gases in the diver's breathing gas, such as [[nitrogen]] and [[helium]], are absorbed into body tissues when breathed under high pressure during the deep phase of the dive. These dissolved gases must slowly be released from body [[Biological tissue|tissue]]s by pausing or "doing stops" at various depths during the ascent to the surface. In recent years most technical divers have greatly increased the depth of the first stops, so as to reduce the risk of bubble formation before the [more traditional] long shallow stops. Most technical divers breathe enriched [[oxygen]] [[breathing gas]] mixtures such as [[nitrox]] during the beginning and ending portion of the dive. To avoid [[Nitrogen narcosis]] while at maximum depth it is common to use [[trimix]] which adds a percentage of helium replacing nitrogen to the diver's breathing mixture. Pure oxygen is then used during shallow decompression stops to reduce the time needed by the diver to effectively rid themselves most of remaining excess inert gas in their body tissues and reducing the risk of "the bends." Surface intervals are usually required to prevent the residual nitrogen from building up to dangerous levels on subsequent dives. ====Physical ceiling==== These types of overhead diving can prevent the diver surfacing directly: * [[Cave diving]] - diving into a cave system. * [[Deep diving]] - diving into greater depths. * [[Ice diving]] - diving under ice. * [[Wreck diving]] - diving inside a shipwreck. ===Extremely Limited Visibility=== Technical dives in waters where the diver's vision is severely impeded by low-light conditions, caused by silt or depth, require an elevated level of aptitude because of the knowledge and skill required to operate in such an environment, and because visibility impairments are often caused by moving water currents. The combination of low visibility and swift current make these technical dives extremely risky to all but the most skilled and well-equipped divers.{{Fact|date=November 2007}} ===Gas mixes=== Technical dives may also be defined by the use of [[breathing gas]] mixtures other than air such as [[trimix]], [[heliox]], and [[heliair]]. This definition is derived from the fact that breathing a mixture with the same oxygen concentration as is found in [[air]] (roughly 21%) at depths greater than 180 feet / 55 meters results in a very rapidly increasing risk of severe symptoms of [[oxygen toxicity]]. The first sign of oxygen toxicity is usually a convulsion without warning. This convulsion usually results in a fatal accident, as the regulator falls out and the victim drowns. Sometimes the victim may get warning symptoms prior to the convulsion. These can include visual and auditory hallucinations, nausea, twitching (especially in the face and hands), irritibility and mood swings and dizziness. Increasing pressure due to depth also causes nitrogen to become narcotic, resulting in a reduced ability to react or think clearly (see [[Nitrogen narcosis]]). By adding helium to the breathing mix, divers can reduce these effects, as helium does not have the same narcotic properties at depth. These gas mixes can also lower the level of oxygen in the mix to reduce the danger of oxygen toxicity. Once the oxygen is reduced below 18% the mix is known as a hypoxic mix as it doesn't contain enough oxygen to be used safely at the surface. [[Nitrox]] is another common gas mix, and while it is not used for deep diving, it decreases the build up of nitrogen within the diver's body by increasing the percentage of [[oxygen]]. This reduces the [[nitrogen]] percentage, as well as allowing for a greater number of multiple dives vs "standard" air. The depth limit of Nitrox is governed by the percentage of oxygen used, as there are multiple oxygen percentages available in nitrox. Further training and knowledge is required in order to safely use and understand the effects of these gases on the body in a diving situation. ==Equipment== Technical divers may also use various forms of less common [[diving equipment]] to accomplish their goals. Typically technical dives involve significantly longer durations than average recreational scuba dives. As decompression stops act as a virtual overhead, preventing a diver with a problem from surfacing immediately, there is a need for redundant equipment. Technical divers usually carry at least two tanks, each with their own regulator. In the event of a failure, the second tank and regulator acts as a back-up system. Technical divers therefore increase their supply of available breathing gas by either connecting multiple high capacity [[diving cylinder]]s and/or by using a [[rebreather]]. The technical diver may also carry additional cylinders, known as stage bottles, to ensure adequate breathing gas supply for decompression with a reserve for bail out in case of failure of their primary breathing gas. ==Training== Technical diving requires specialised equipment and training. There are many technical training organisations: see the Technical Diving section of [[List of diver training organizations]]. [[Technical Diving International|TDI]], [[Global Underwater Explorers|GUE]], [[IANTD]] and [[NAUI]] seem to be popular at the time of writing. Recent entries into the market include [[Diving Science and Technology|DSAT]], the technical arm of [[PADI]]. The [[SSI]] Techical Diving Program [http://www.divessi.com/txr TechXR - Technical eXtended Range]] was launched in 2005. BSAC training has always had a technical element to its higher qualifications, however it has recently begun to introduce more technical level Skill Development Courses into all its training schemes, by introducing technical awareness into its lowest level qualification of Ocean Diver, for example, nitrox will become mandatory. It has also recently introduced trimix qualifications and continues to develop closed circuit training. ==See also== * [[Breathing gas]] * [[Carbon dioxide poisoning]] * [[Diving hazards and precautions]] * [[Oxygen toxicity]] * [[Rebreather]] * [[Solo diving]] * [[Trimix]] ==Footnotes== <references/> ==External links== *[http://www.rebreatherpro.com RebreatherPro]Jill Heinerth's interactive multimedia technical diving site *[http://www.liquidtravel.org/index.php?option=com_content&task=view&id=52&Itemid=35 Transitioning to technical diving] *[http://www.divinglore.com/TechnicalEquipment.htm Technical Diving Equipment] [[Category:Underwater diving]] [[de:Technisches Tauchen]] [[ja:テクニカルダイビング]] [[ru:Технический дайвинг]] [[sv:Teknisk dykning]]