Underwater work is work done underwater, generally by divers during diving operations, but includes work done underwater by remotely operated vehicles and crewed submersibles.

Skills commonly used by all professional diving occupations

Underwater 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. *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. *Use of a guide line or jackstay. A

guide line A distance line, penetration line, cave line or guide line is an item of diving equipment used by Scuba diving, scuba divers as a means of returning to a safe starting point in conditions of low visibility, water currents or where pilotage is di ...

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

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 A submersible is a small watercraft designed to operate underwater. The term "submersible" is often used to differentiate from other underwater vessels known as submarines, in that a submarine is a fully self-sufficient craft, capable of ind ...

remotely operated underwater vehicle A remotely operated underwater vehicle (technically ROUV or just ROV) is a tethered underwater mobile device, commonly called ''underwater robot''. Definition This meaning is different from remote control vehicles operating on land or in the a ...

s, or

autonomous underwater vehicle An autonomous underwater vehicle (AUV) is a robot that travels underwater without requiring input from an operator. AUVs constitute part of a larger group of undersea systems known as unmanned underwater vehicles, a classification that includ ...

s, or from the surface by other agents, including surface vessels, aircraft and cadaver dogs. 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. *Diver searches: **

Circular search 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, manned submersibles, remotely operated underwater vehicles, or autonomous ...

** Pendulum search ** Jackstay searches *** Snag-line search ** Compass searches ***Spiral box search ***Compass grid search ***Ladder search ***Swim-line search ** Directed search **Towed search **Searches using hand held submersible sonar transponders **Current drift search **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

*Basic

ropework Ropework or marlinespike seamanship are traditional umbrella terms for a skillset spanning the use, maintenance, and repair of rope. Included are tying knots, splicing, making lashings, whippings, and proper use and storage of rope. While t ...

knot A knot is an intentional complication in cordage which may be practical or decorative, or both. Practical knots are classified by function, including hitches, bends, loop knots, and splices: a ''hitch'' fastens a rope to another object; a ...

s and splices, tackle *

Rigging Rigging comprises the system of ropes, cables and chains, which support a sailing ship or sail boat's masts—''standing rigging'', including shrouds and stays—and which adjust the position of the vessel's sails and spars to which they ar ...

slings

cargo net A cargo net is a type of net. It is usually square or rectangle, but sometimes round, made of thick rope, with cinch ropes extending from the corners, and in some designs, the edges. It is named for its use in transferring cargo to and from shi ...

s and spreaders,

lifting hook A lifting hook is a device for grabbing and lifting loads by means of a device such as a hoist or crane. A lifting hook is usually equipped with a safety latch to prevent the disengagement of the lifting wire rope sling, chain or rope to which th ...

s and

shackle A shackle (or shacklebolt), also known as a gyve, is a U-shaped piece of metal secured with a clevis pin or bolt across the opening, or a hinged metal loop secured with a quick-release locking pin mechanism. The term also applies to handcuff ...

s * Lifting bags * Chain blocks, tirfors and pullers

Inspection, measuring and recording

* *

Use of basic hand tools

Hacksaw A hacksaw is a fine-toothed saw, originally and mainly made for cutting metal. The equivalent saw for cutting wood is usually called a bow saw. Most hacksaws are hand saws with a C-shaped walking frame that holds a blade under tension. Suc ...

s *

Hammer A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nails into wood, to shape metal (as wi ...

s *

Cold chisel Cold Chisel are an Australian pub rock band, which formed in Adelaide in 1973 by mainstay members Ian Moss on guitar and vocals, Steve Prestwich on drums and Don Walker on piano and keyboards. They were soon joined by Jimmy Barnes (at the ...

s *

Pliers Pliers are a hand tool used to hold objects firmly, possibly developed from tongs used to handle hot metal in Bronze Age Europe. They are also useful for bending and physically compressing a wide range of materials. Generally, pliers consist ...

lever A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or '' fulcrum''. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, load and effort, the lever is d ...

wedge A wedge is a triangular shaped tool, and is a portable inclined plane, and one of the six simple machines. It can be used to separate two objects or portions of an object, lift up an object, or hold an object in place. It functions by converti ...

s and

crowbar A crowbar, also called a wrecking bar, pry bar or prybar, pinch-bar, or occasionally a prise bar or prisebar, colloquially, in Britain and Australia sometimes called a jemmy or jimmy (also called jemmy bar), gooseneck, or pig foot, is a tool ...

s *

Screwdriver A screwdriver is a tool, manual or powered, used for turning screws. A typical simple screwdriver has a handle and a shaft, ending in a tip the user puts into the screw head before turning the handle. This form of the screwdriver has been repla ...

s and

wrench A wrench or spanner is a tool used to provide grip and mechanical advantage in applying torque to turn objects—usually rotary fasteners, such as nuts and bolts—or keep them from turning. In the UK, Ireland, Australia, and New Zeal ...

es * Pipecutters and

bolt cutter A bolt cutter, sometimes called bolt cropper, is a tool used for cutting bolts, chains, padlocks, rebar and wire mesh. It typically has long handles and short blades, with compound hinges to maximize leverage and cutting force. A typical bolt ...

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.

Skills specific to specialist occupations

*Erecting

formwork Formwork is molds into which concrete or similar materials are either precast or cast-in-place. In the context of concrete construction, the falsework supports the shuttering molds. In specialty applications formwork may be permanently i ...

(shuttering) (civils) * Underwater concrete placement using a

tremie A tremie is a watertight pipe, usually of about 250 mm inside diameter (150 to 300 mm), with a conical hopper at its upper end above the water level. It may have a loose plug or a valve at the bottom end. A tremie is used to pour concrete unde ...

or skip (civils) * Oxy-arc cutting (salvage, ships husbandry, offshore) *

Underwater welding Hyperbaric welding is the process of welding at elevated pressures, normally underwater. Hyperbaric welding can either take place ''wet'' in the water itself or ''dry'' inside a specially constructed positive pressure enclosure and hence a ...

(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 A wellhead is the component at the surface of an oil or gas well that provides the structural and pressure-containing interface for the drilling and production equipment. The primary purpose of a wellhead is to provide the suspension point and ...

components (offshore oil and gas) * Hull cleaning and inspection (ships husbandry) *

Mooring A mooring is any permanent structure to which a vessel may be secured. Examples include quays, wharfs, jetties, piers, anchor buoys, and mooring buoys. A ship is secured to a mooring to forestall free movement of the ship on the water. An ''an ...

inspection and maintenance (ships husbandry, offshore) * Pipeline inspection (offshore oil and gas) *

Propeller A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...

polishing (ships husbandry) *Inspection and replacement of

cathodic protection Cathodic protection (CP; ) is a technique used to control the corrosion of a metal surface by making it the cathode of an electrochemical cell. A simple method of protection connects the metal to be protected to a more easily corroded "sacrifi ...

anodes (ships husbandry, offshore) * Explosive demolition (clearance, civils) *

Bomb disposal Bomb disposal is an explosives engineering profession using the process by which hazardous explosive devices are rendered safe. ''Bomb disposal'' is an all-encompassing term to describe the separate, but interrelated functions in the milit ...

(military, public safety) *

Archaeological excavation In archaeology, excavation is the exposure, processing and recording of archaeological remains. An excavation site or "dig" is the area being studied. These locations range from one to several areas at a time during a project and can be condu ...

(archaeology) * Search and recovery (public safety) *

Forensic evidence Forensic identification is the application of forensic science, or "forensics", and technology to identify specific objects from the trace evidence they leave, often at a crime scene or the scene of an accident. Forensic means "for the courts". H ...

collection and preservation (police) *

Search and rescue Search and rescue (SAR) is the search for and provision of aid to people who are in distress or imminent danger. The general field of search and rescue includes many specialty sub-fields, typically determined by the type of terrain the search ...

(public safety, police) *Site surveys and mapping (scientific, archaeology) * Biological sampling and tagging (scientific) * Core drilling (scientific) *Setting up and recovery of instrumentation (scientific) *

Transect A transect is a path along which one counts and records occurrences of the objects of study (e.g. plants). There are several types of transect. Some are more effective than others. It requires an observer to move along a fixed path and to count ...

surveys (scientific)

Gallery

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

References

{{Underwater diving, prodiv