Deep diving (scuba diving)

from Wikipedia, the free encyclopedia

Deep diving refers to falling below a certain water depth when scuba diving . It is not possible to name a uniform depth limit from which deep diving begins. For some divers, falling below the personal depth record is a deep dive . Others adhere to the non-uniform definitions of the diving associations . For example, PADI offers a specialty course (also part of the Advanced Open Water Diver training) that defines deep diving as falling below the 18 m limit that the Open Water Diver certification includes. ISO 24801-2 (Autonomous Diver) sets the same limit at 20 m. There are some states where deep diving is legal. PADI considers 40 meters to be the maximum depth for recreational divers. Often, anything below this 40m limit is also referred to as deep diving by PADI. What is certain, however, is that from a depth of around 30 to 40 m the risk of deep intoxication becomes very probable and from a water depth of 66 m the oxygen in the air becomes toxic , since from this depth the partial pressure of oxygen above the critical limit of 1 , 6 bar would be. Therefore, diving with different breathing gas mixtures and in some cases according to different rules and different or additional equipment must be carried out underneath . The risk of diving accidents increases from these water depths, which is why deep dives below 40 m should only be undertaken by experienced divers.

record

The record for deep diving without an armored suit is 332.35 meters. This record was set on September 18, 2014 by the Egyptian Ahmed Gabr near Dahab in the Red Sea . Ahmed Gabr was underwater for 14 hours and breathed a total of 10 different breathing gas mixtures from 92 compressed air cylinders . Since then there have been several attempts to beat this record. However, these attempts all failed because of the High Pressure Nervous Syndrome , which affects the effect of the inhaled helium from the heliox at around 30 bar ambient pressure.

Professional divers

Professional diver welds underwater

It is possible to dive to depths of 500 m and more without an armored suit. Today, professional and technical divers routinely perform dives to depths of up to 200 m. The saturation technique is used. Divers have to spend some time in a decompression chamber after the dive to cure the oversaturation. Diving at very great depths is only possible by carrying several diving bottles filled with different mixtures, such as Trimix or Heliox . Depending on the depth, you have to switch to another bottle with the correct mixture. Breathing a mixture that is not adapted to the depth can mean death at great depth. The regulators and measuring devices built for recreational diving are sometimes not designed for extreme depths, which is why professional divers often use different equipment than recreational divers. It is not uncommon for equipment depots to be set up underwater during dives, as decompression stops can take several hours. The bottles stored in the depots are used to breathe during the long decompression period.

scuba diver

A safe ascent from 30 m water depth takes at least 3 minutes. Exceeding these rates of climb increases the risk of decompression sickness very much. If the no-stop time has been exceeded, decompression stops at different depths must be observed. Beginners in particular can be overwhelmed by this. As the depth increases, the no-stop times decrease, the ascent times increase and the decompression stops increase. From a depth of about 30 m (depending on the daily form and individual constitution), deep intoxication (nitrogen narcosis) is to be expected, which often occurs without any preceding symptoms . The deep intoxication is created by the nitrogen - in the breathed air - which has a narcotic effect from a certain partial pressure .

With normal compressed air and without special preparations, a depth of 60 m should not be exceeded. There is a lower risk of death, as the partial pressure of oxygen exceeds the recommended limit of 1.5 to 1.7 bar . There is a risk of oxygen poisoning (oxygen toxicosis). With Nitrox (Enriched Air) the diving depth cannot be increased. The big advantage of Nitrox compared to compressed air is only a longer no-stop time in shallow water. Although this increases the time reserves, this can be an argument against the use of Nitrox in deep dives due to the increase in oxygen toxicity (due to the enrichment of the air mixture with oxygen). It is possible, at great risk, to dive up to 75 m deep with normal compressed air. Diving associations do not recommend such extreme deep dives for good reason. Due to the deep intoxication that occurs, there is a risk that divers succumb to gross misjudgments and thereby put their lives in great danger. In the worst case scenario, a diver can become unconscious from the narcotic effects of nitrogen underwater. Therefore it is generally not recommended to descend deeper than 56 meters with compressed air.

Most diving organizations recommend that recreational divers do not exceed a depth of 40  meters . Only a few organizations allow recreational divers even 50 or 60 meters. All deeper dives are usually classified as technical diving.

Individual evidence

  1. ↑ Recreational diving services - Requirements for the training of recreational scuba divers - Part 2: Level 2 - Autonomous diver (ISO 24801-2). ISO , accessed April 29, 2015 .
  2. ↑ The PADI Deep Diving Course. PADI; Retrieved July 1, 2013.
  3. ↑ Deeper diving with compressed air. ( Memento from June 23, 2012 in the Internet Archive ) Peter Rachow; Retrieved July 1, 2010.
  4. ↑ Lothar Becker: Nitrox manual. 2nd Edition. Delius Klasing Verlag, Bielefeld 2007, ISBN 978-3-7688-2420-0 .
  5. ↑ a b Susanna Petrin: Deadly Depth , May 19, 2020, NZZ
  6. ↑ a b c deep diving. Frank Dolacek; Retrieved July 1, 2010.
  7. ↑ Online computer MOD. harztaucher.de; Retrieved July 12, 2010.
  8. ↑ Arguments for and against diving with Nitrox. Peter Rachow; Retrieved July 12, 2010.
  9. ↑ Peter Rachow: Deep diving with compressed air: Diving outside the classic limits of recreational divers: Physiology, decompression, practice. (PDF) p. 7. Revised May 14, 2002; accessed December 23, 2015.
  10. ↑ Divers FAQ. How deep can you dive? dive.steha.ch, accessed on January 12, 2018 : “Recreational divers normally do not dive deeper than 56 meters, because below that the oxygen in the breath becomes toxic (= poisonous). There is a risk of acute oxygen poisoning. "
  11. ↑ Dive Leader. Do you want to extend your personal diving skills and plan and lead dives for others? British Sub-Aqua Club, accessed on March 1, 2019 (English): " The training also prepares you to dive to depths of up to 50 meters in a range of challenging conditions, following a series of post-qualification depth progression dives. "
  12. ↑ Plongée en bouteille. Plonger en bouteille et se former au sein de la FFESSM. Fédération française d'études et de sports sous-marins, accessed on March 1, 2019 (French): "... à partir de 18 ans: brevet plongeur level 3 (P3), autonomy à 60 m ."