{{Short description|Work done underwater during diving operations}} '''Underwater work''' is work done underwater, generally by divers during diving operations, but includes work done underwater by remotely operated underwater vehicles and crewed submersibles.
Underwater work is the activity required to achieve the purpose of the diving operation additional to the activities required for safe diving in the specific underwater environment of the worksite, including finding and identifying the workplace, and where necessary, making it safe to do the planned work. Some of these activities have a wide range of applications in work suitable for a given diving mode, and are likely to be considered basic skills and learned during professional diver training programmes for the relevant mode. Others are specialist skils and are more likely to be learned on the job or on skills training programmes not directly related to diving.
==Occupational diving fields== There are several occupational specialty fields in occupational diving, and the work done in them may overlap. *{{annotated link|Aquaculture diving}} *{{annotated link|Aquarium diving}} *{{annotated link|Combat diving}} *{{annotated link|Commercial offshore diving|aka=Offshore diving}} *{{annotated link|Recreational dive guiding |aka=Dive leader}} *{{annotated link|Diver training}} *{{annotated link|Hazmat diving}} *{{annotated link|Media diving}} *{{annotated link|Nuclear diving}} *{{annotated link|Pearl diving|aka=Pearl hunting}} *{{annotated link|Police diving}} *{{annotated link|Potable water diving}} *{{annotated link|Public safety diving}} *{{annotated link|Reconnaissance diving}} *{{annotated link|Rescue diving}} *{{annotated link|Salvage diving}} *{{annotated link|Sewer diving}} *{{annotated link|Scientific diving}} *{{annotated link|Seaweed harvesting}} *{{annotated link|Shellfish harvesting}} (such as abalone, scallops, lobster) *{{annotated link|Ships husbandry diving}} *{{annotated link|Sponge diving}} *{{annotated link|Underwater archaeology}} *{{annotated link|Underwater construction diving|aka=Civil engineering diving, or "Civils"}} *{{annotated link|Underwater demolition|aka=clearance diving}} *{{annotated link|Underwater mineral extraction}}
==Work skills commonly used in professional diving occupations== There are several kinds of skill that may be needed in underwater work by occupational divers in various fields, and are often learned during entry level training.
===Underwater navigation=== {{main|Diver navigation}} *Pilotage involves navigation by naturally observable landmarks and phenomena, such as sunlight, water movement, bottom composition (for example, sand ripples run parallel to the direction of the wave front, which tends to run parallel to the shore), bottom contour and noise. Although natural navigation is taught on courses, developing the skills is generally more a matter of experience.<ref name="UKDivers" /> *Compass navigation is a matter of training, practice and familiarity with the use of underwater compasses, combined with various techniques for reckoning distance underwater, including kick cycles (one complete upward and downward sweep of a kick), time, and occasionally by actual measurement, which may involve the length of umbilical deployed. Kick cycles depend on the diver's finning technique and equipment, but are generally more reliable than time, which is critically dependent on speed. Techniques for direct measurement also vary, from the use of calibrated distance lines or surveyor's tape measures, to a mechanism like an impeller log, to pacing off the distance along the bottom with the arms.<ref name="CMAS-ISA 3-star" /> *Use of a guide line or jackstay. A guide line may be laid to facilitate navigation to and from the underwater workplace. This allows divers to travel to and from the workplace with minimal delay, even in poor visibility. A jackstay serves the same purpose in heavy duty format.
===Underwater searches=== {{main|Underwater searches}} Underwater searches are procedures to find a known or suspected target object or objects in a specified search area under water. They may be carried out underwater by divers, crewed submersibles, remotely operated underwater vehicles, or autonomous underwater vehicles, or from the surface by other agents, including surface vessels, aircraft and cadaver dogs.<ref name="Forensicmag 2015"/>
A search method attempts to provide full coverage of the search area. This is greatly influenced by the width of the sweep which largely depends on the method used to detect the target. For divers in conditions of zero visibility this is as far as the diver can feel with his hands while proceeding along the pattern. When visibility is better, it depends on the distance at which the target can be seen from the pattern, or detected by sonar or magnetic field anomalies. In all cases the search pattern should completely cover the search area without excessive redundancy or missed areas. Overlap is needed to compensate for inaccuracy and sensor error, and may be necessary to avoid gaps in some patterns.<ref name="Salvage manual 040" /><ref name="Hanekom and Truter 2007" />
*Diver searches: **{{annotated link|Circular search}} **{{annotated link|Pendulum search}} **{{annotated link|Jackstay search}} ***{{annotated link|Snag-line search}} **{{annotated link|Compass search}} ***Spiral box search ***Compass grid search ***Ladder search ***Swim-line search **{{annotated link|Directed search}} **{{annotated link|Towed search}} **Searches using hand held submersible sonar transponders **{{annotated link|Current drift search}} **{{annotated link|Depth contour search}} *Searches by submersibles, remotely operated vehicles and autonomous underwater vehicles *Searches by surface vessels *Searches by aircraft *Searches from the shore
===Rigging and lifting=== {{See also|Rigging (material handling)}} Most underwater rigging uses equipment and techniques common to rigging in other environments, except for the common use of buoyant lifting underwater, and the equipment designed and used specifically for that purpose. *Basic ropework, knots and splices, tackle *Rigging slings cargo nets and spreaders, lifting hooks and shackles *Lifting bags (variable buoyancy lifting equipment) *Chain blocks, tirfors and pullers
===Inspection, measuring and recording=== *{{annotated link|Underwater photography}} *{{annotated link|Underwater videography}} *{{annotated link|Tape measure#In surveying|Surveyor's measuring tape}} *{{annotated link|Vernier calipers}} *{{annotated link|Spirit level}} *{{annotated link|Clinometer}} *{{annotated link|Compass}}
===Use of basic hand tools=== *Hacksaws *Hammers *Cold chisels *Pliers *levers, wedges and crowbars *Screwdrivers and wrenches *Pipecutters and bolt cutters
==Underwater inspection == Inspection of underwater structures, installations, and sites is a common diving activity, applicable to planning, installation, and maintenance phases, but the required skills are often specific to the application. Much use is made of video and still photographic evidence, and live video to allow direction of the inspection work by the supervisor and topside specialists. Inspections may also involve surface preparation, often by cleaning, and non-destructive testing. Tactile inspection may be appropriate where visibility is poor.<ref name="Bayliss et al 1988" /><ref name="SM&I" /><ref name="Kelly 1999" /> {{expand section|date=January 2021}}
==Typed of underwater work and the related specialist occupations== thumb|Underwater oxy-arc cutting thumb|Underwater fillet weld in a training pool *Erecting formwork (shuttering) and reinforcing steel for casting concrete. (civils) *Underwater concrete placement using a tremie, concrete pump, skip, bagwork or toggle bags (civils) *Oxy-arc cutting (salvage, ships husbandry, offshore) *Underwater welding (salvage, ships husbandry, offshore) *Use of pneumatic and hydraulic power tools (ships husbandry, civils, offshore, salvage} *High pressure jetting (ships husbandry, civils, offshore) *Hydraulic bolt-tensioning (offshore oil and gas) *Fitting and maintenance of wellhead components (offshore oil and gas) *Hull cleaning and inspection (ships husbandry) *Mooring inspection and maintenance (ships husbandry, offshore) *Pipeline inspection (offshore oil and gas) *Propeller polishing (ships husbandry) *Inspection and replacement of cathodic protection anodes (ships husbandry, offshore) *Underwater demolition (clearance, civils) *Bomb disposal (military, public safety) *Archaeological excavation (archaeology) *Search and recovery (public safety) *Forensic evidence collection and preservation (police) *Search and rescue (public safety, police) *Site surveys and mapping (scientific, archaeology) *Biological sampling and tagging (scientific) *Geological and chemical sampling and specimen collection (scientific). *Core drilling (scientific) *Setting up and recovery of instrumentation (scientific) *Transect and quadrat surveys (scientific) * Photography and videography (media, scientific, archaeology, inspection)
== Gallery == <gallery mode="packed" > File:970216-N-3093M-002 Underwater Construction Training.jpg|Underwater construction training File:Arbeitstaucher bei Industrietaucharbeiten.jpg|Industrial inspection File:Buceador en hélice.jpg|Inspecting a thruster grating File:Coral-drilling hg.jpg|Core-drilling coral File:Buzos con globos de elevación.JPG|Lifting bags File:Buzos con cemento.jpg|Placing concrete underwater File:Buzo junto toma de aspiración del buque.jpg|Inspecting an intake grating File:ROV working on a subsea structure.jpg|ROV working on a subsea structure File:US Navy 011105-N-3093M-011 Navy deep sea diver.jpg|Salvage work File:Ultrasonidos.jpg|Ultrasonic testing File:Inspeccion mediante corrientes.jpg|Non-destructive testing by measuring electrical current File:US Navy 080624-N-5329L-290 U.S. Army Staff Sergeant David Gills, assigned to the 86th Engineering Dive Team, attaches a line on a wire rope that is attached to the sunken former Soviet submarine Juliett 484.jpg|Rigging File:US Navy 051206-N-0879R-005 A U.S. Navy diver uses a scrubber to clean the hull of the Los Angeles-class fast attack submarine USS Key West (SSN 722).jpg|Hull scrubbing File:US Navy 080724-N-3093M-019 Senior Chief Diver Billy Gilbert, assigned to Mobile Diving and Salvage Unit (MDSU) 2, uses a pipe wrench to remove a damaged propeller on a small patrol boat.jpg|Removing a small propeller File:US Navy 110520-N-VF350-023 Navy Diver 2nd Class Joshua Westman sucks sand off the bottom of the ocean during a Joint POW-MIA Accounting Command (JP.jpg|Removing sediment with a suction pump File:US Navy 110608-N-XD935-079 Navy Diver 2nd Class Justin McMillen holds the lift line as Ordinary Seaman Romando Thomas fills air into a lift bag.jpg|Filling a lift bag </gallery>
== References == <references> <ref name="Bayliss et al 1988" >{{cite book |title=Underwater Inspection |first1=Mel |last1=Bayliss |first2=David |last2=Short |first3=Mary |last3=Bax |isbn=9780419135401 |publisher=Taylor and Francis |date=17 March 1988 |pages=229 }}</ref>
<ref name="CMAS-ISA 3-star" >{{cite book |last=Scully |first=Reg |title=CMAS-ISA Three Star Diver Theoretical Manual |edition=1st |date=April 2013 |chapter=Topic 7: Underwater Navigation |publisher=CMAS-Instructors South Africa |location=Pretoria |isbn=978-0-620-57025-1 }}</ref>
<ref name="Forensicmag 2015">{{cite web |url=https://www.forensicmag.com/news/2015/09/cadaver-dogs-locate-underwater-corpses |date=16 September 2015 |last=University of Huddersfield staff |website=www.forensicmag.com |title=Cadaver Dogs Locate Underwater Corpses |access-date=11 September 2017 |archive-date=11 September 2017 |archive-url=https://web.archive.org/web/20170911205123/https://www.forensicmag.com/news/2015/09/cadaver-dogs-locate-underwater-corpses |url-status=live }}</ref>
<ref name="Hanekom and Truter 2007">{{cite book|last1=Hanekom|first1=Paul|last2=Truter|first2=Pieter|title=Diver Training Handbook|edition=3rd|date=February 2007|publisher=Research Diving Unit, University of Cape Town|location=Cape Town, South Africa |chapter=Section 17: Seabed searches}}</ref>
<ref name="Kelly 1999" >{{cite book |title=Underwater Inspection Criteria |first=Shawn W. |last=Kelly |publisher=Naval Facilities Engineering Service Center |location=Port Hueneme, California |date=March 1999 }}</ref>
<ref name="Salvage manual 040" >{{cite book |url=https://www.navsea.navy.mil/Portals/103/Documents/SUPSALV/Salvage%20Docs/Salvage%20Manual%20Vol%204.pdf |title=U.S. Navy Salvage Manual |volume=4: Deep Ocean Operations S0300-A6-MAN-040 0910-LP-252-3200 |chapter=2: Underwater Search and Recovery Techniques |publisher=United States. Navy Department. Supervisor of Salvage and Diving. |date=1 August 1993 |access-date=11 April 2023 |archive-date=5 April 2023 |archive-url=https://web.archive.org/web/20230405102915/https://www.navsea.navy.mil/Portals/103/Documents/SUPSALV/Salvage%20Docs/Salvage%20Manual%20Vol%204.pdf |url-status=live }} <!--{{PD-notice}}--></ref>
<ref name="SM&I" >{{cite book |url=https://dot.ca.gov/-/media/dot-media/programs/maintenance/documents/f0009172-uwi-procedures-a11y.pdf |title=SM&I Inspection Procedures Manual |chapter=5.4 Underwater Inspection Procedures |publisher=SM&I |date=August 2018 }}</ref>
<ref name="UKDivers" >{{cite web |url=http://www.ukdivers.net/diving/uwnav.htm |title=Underwater Navigation |last=UK Divers |date=October 16, 2007 |website=UKDivers.net |access-date=16 May 2016 |quote=Navigation by reference to terrain features, both natural and artificial, usually with the aid of an appropriate chart. |url-status=dead |archive-url=https://web.archive.org/web/20160313082610/http://www.ukdivers.net/diving/uwnav.htm |archive-date=13 March 2016 }}</ref> </references>
{{Underwater diving|prodiv}}
Category:Underwater work