Dive WWII: Our Secret History - Netflix

Mon 24 June 2019

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Tags netflix Documentary English

A deepwater dive team search the seabed off the coast of Northern Ireland for the forgotten shipwrecks of WW2's Battle of the Atlantic. Jules Hudson helps identify the wrecks, and reveals how the city was critical to Allied victory. Maritime historian and underwater explorer, Ian Lawler, leads a team of deep water divers to the ocean floor off Northern Ireland. He and the team are searching for the forgotten shipwrecks of WW2's longest, most epic naval campaign, The Battle of the Atlantic. Presenter Jules Hudson joins Ian and two naval experts as they attempt to piece together the stories of the wrecks using the dive team's underwater footage. What they discover reveals the unique role played by the city of Londonderry in fighting the battle. And while the divers continue their mission at sea, Jules hunts on land for the final clues to the forgotten story of the battle.

Dive WWII: Our Secret History - Netflix

Type: Documentary

Languages: English

Status: Ended

Runtime: 60 minutes

Premier: 2013-05-27

Dive WWII: Our Secret History - History of scuba diving - Netflix

The history of scuba diving is closely linked with the history of scuba equipment. By the turn of the twentieth century, two basic architectures for underwater breathing apparatus had been pioneered; open-circuit surface supplied equipment where the diver's exhaled gas is vented directly into the water, and closed-circuit breathing apparatus where the diver's carbon dioxide is filtered from unused oxygen, which is then recirculated. Closed circuit equipment was more easily adapted to scuba in the absence of reliable, portable, and economical high pressure gas storage vessels. By the mid twentieth century, high pressure cylinders were available and two systems for scuba had emerged: open-circuit scuba where the diver's exhaled breath is vented directly into the water, and closed-circuit scuba where the carbon dioxide is removed from the diver's exhaled breath which has oxygen added and is recirculated. Oxygen rebreathers are severely depth limited due to oxygen toxicity risk, which increases with depth, and the available systems for mixed gas rebreathers were fairly bulky and designed for use with diving helmets. The first commercially practical scuba rebreather was designed and built by the diving engineer Henry Fleuss in 1878, while working for Siebe Gorman in London. His self contained breathing apparatus consisted of a rubber mask connected to a breathing bag, with an estimated 50–60% oxygen supplied from a copper tank and carbon dioxide scrubbed by passing it through a bundle of rope yarn soaked in a solution of caustic potash. During the 1930s and all through World War II, the British, Italians and Germans developed and extensively used oxygen rebreathers to equip the first frogmen. In the U.S. Major Christian J. Lambertsen invented an underwater free-swimming oxygen rebreather. In 1952 he patented a modification of his apparatus, this time named SCUBA,(an acronym for “self-contained underwater breathing apparatus”), which became the generic English word for autonomous breathing equipment for diving, and later for the activity using the equipment. After World War II, military frogmen continued to use rebreathers since they do not make bubbles which would give away the presence of the divers. The high percentage of oxygen used by these early rebreather systems limited the depth at which they could be used due to the risk of convulsions caused by acute oxygen toxicity. Although a working demand regulator system had been invented in 1864 by Auguste Denayrouze and Benoît Rouquayrol, the first open-circuit scuba system developed in 1925 by Yves Le Prieur in France was a manually adjusted free-flow system with a low endurance, which limited the practical usefulness of the system. In 1942, during the German occupation of France, Jacques-Yves Cousteau and Émile Gagnan designed the first successful and safe open-circuit scuba, a twin hose system known as the Aqua-Lung. Their system combined an improved demand regulator with high-pressure air tanks. This was patented in 1945. To sell his regulator in English-speaking countries Cousteau registered the Aqua-Lung trademark, which was first licensed to the U.S. Divers company, and in 1948 to Siebe Gorman of England, Siebe Gorman was allowed to sell in Commonwealth countries, but had difficulty in meeting the demand and the U.S. patent prevented others from making the product. The patent was circumvented by Ted Eldred of Melbourne, Australia, who developed the single-hose open-circuit scuba system, which separates the first stage and demand valve of the pressure regulator by a low-pressure hose, puts the demand valve at the diver's mouth, and releases exhaled gas through the demand valve casing. Eldred sold the first Porpoise Model CA single hose scuba early in 1952. Early scuba sets were usually provided with a plain harness of shoulder straps and waist belt. Many harnesses did not have a backplate, and the cylinders rested directly against the diver's back. Early scuba divers dived without a buoyancy aid. In an emergency they had to jettison their weights. In the 1960s adjustable buoyancy life jackets (ABLJ) became available, which can be used to compensate for loss of buoyancy at depth due to compression of the neoprene wetsuit and as a lifejacket that will hold an unconscious diver face-upwards at the surface. The first versions were inflated from a small disposable carbon dioxide cylinder, later with a small direct coupled air cylinder. A low-pressure feed from the regulator first-stage to an inflation/deflation valve unit an oral inflation valve and a dump valve lets the volume of the ABLJ be controlled as a buoyancy aid. In 1971 the stabilizer jacket was introduced by ScubaPro. This class of buoyancy aid is known as a buoyancy control device or buoyancy compensator. A backplate and wing is an alternative configuration of scuba harness with a buoyancy compensation bladder known as a “wing” mounted behind the diver, sandwiched between the backplate and the cylinder or cylinders. This arrangement became popular with cave divers making long or deep dives, who needed to carry several extra cylinders, as it clears the front and sides of the diver for other equipment to be attached in the region where it is easily accessible. Sidemount is a scuba diving equipment configuration which has basic scuba sets, each comprising a single cylinder with a dedicated regulator and pressure gauge, mounted alongside the diver, clipped to the harness below the shoulders and along the hips, instead of on the back of the diver. It originated as a configuration for advanced cave diving, as it facilitates penetration of tight sections of cave as, sets can be easily removed and remounted when necessary. Sidemount diving has grown in popularity within the technical diving community for general decompression diving, and has become a popular specialty for recreational diving. In the 1950s the United States Navy (USN) documented procedures for military use of what is now called nitrox, and in 1970, Morgan Wells, of (NOAA) began instituting diving procedures for oxygen-enriched air. In 1979 NOAA published procedures for the scientific use of nitrox in the NOAA Diving Manual. In 1985 IAND (International Association of Nitrox Divers) began teaching nitrox use for recreational diving. After initial resistance by some agencies, the use of a single nitrox mixture has become part of recreational diving, and multiple gas mixtures are common in technical diving to reduce overall decompression time. Nitrogen narcosis limits the depth when breathing nitrox mixtures. In 1924 the US Navy started to investigate the possibility of using helium and after animal experiments, human subjects breathing heliox 20/80 (20% oxygen, 80% helium) were successfully decompressed from deep dives, Cave divers started using trimix to allow deeper dives and it was used extensively in the 1987 Wakulla Springs Project and spread to the north-east American wreck diving community. The challenges of deeper dives and longer penetrations and the large amounts of breathing gas necessary for these dive profiles and ready availability of oxygen sensing cells beginning in the late 1980s led to a resurgence of interest in rebreather diving. By accurately measuring the partial pressure of oxygen, it became possible to maintain and accurately monitor a breathable gas mixture in the loop at any depth. In the mid 1990s semi-closed circuit rebreathers became available for the recreational scuba market, followed by closed circuit rebreathers around the turn of the millennium. Rebreathers are currently (2018) manufactured for the military, technical and recreational scuba markets.

Dive WWII: Our Secret History - Professional scuba training and certification - Netflix

Professional diving is done as a part of the work the diver is employed to do, and as such is generally subject to occupational health and safety regulation. This extends to training, certification and the asssociated training standards. Commercial diver training is often regulated by national or state government, so details and standards tend to vary internationally, but there are systems in place for recognition of minimum standards between jurisdictions, allowing some international portability of commercial diver certification. In some jurisdictions a distinction is made between industrial commercial diving and professional diving as part of scientific or public safety occupations, where a variety of regulatory exemptions may apply. In situations where exemptions apply, the training and certification through recreational agencies may be recognised for professional diving activities where this is not permitted for industrial commercial diving. Military diving is frequently independent of commercial diving regulation, and military diver training is usually controlled by the armed forces which employ the divers. In some cases there is recognition of military diver qualifications for work in the civilian industry, in other cases not. The American Academy of Underwater Sciences (AAUS) is a group of scientific organizations and individual members who conduct scientific and educational activities underwater. It was organized in 1977 and incorporated in the State of California in 1983. The purpose of the AAUS is to facilitate the development of safe and productive scientific divers and scientific diving procedures through education, research, advocacy, and the advancement of the AAUS Standards for Scientific Diving Certification and Operation of Scientific Diving Programs. These are the consensual guidelines for scientific diving programs in the US, and are recognized by Occupational Safety and Health Administration as the “Standard” for scientific diving. These standards are followed by all AAUS Organizational Members allowing for reciprocity between institutions. Each institution is responsible for upholding the standards within its program and among its divers. The AAUS peer reviews the standards on a regular basis, so they represent the consensus of the scientific diving community and state-of-the-art technologies. The CMAS Scientific committee compiled and edited the UNESCO Code of Practice for Scientific diving between 1977 and the publication of the document as Unesco technical papers in marine science 53 in 1988. The International Diving Schools Association (IDSA) was formed in 1982 with the primary purpose of developing common international standards for commercial diver training. The Association has published basic tables for international comparison of training standards for commercial divers and some specialist non-diving qualifications such as diving supervisors, diving medical technicians and life support technicians based on consensus of members. The International Diving Regulators Forum (IDRF) confirmed its principals and purpose at their meeting in London in September 2009. The statement of principals and purpose states “The forum has agreed to work together towards mutual recognition to identify and implement best practice in diver training and assessment with the objective of harmonising cross-border diver training outside Europe.” The organisation has since changed its name to International Diving Regulators and Certifiers Forum (IDRCF) Members of the IDRF include ADAS (Australia), DCBC (Canada), HSE (UK), PSA (Norway), and the Secretariat General to the Sea Progress Committee (France). UK HSE Diving at work regulations Australian Diver Accreditation Scheme (ADAS) and Australian scientific diving CoP South African Diving Regulations - 2001, 2009, previous to 2001, 2018, CoP for commercial diver training Various Canadian standards and regulations

Dive WWII: Our Secret History - References - Netflix


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