diving under special conditions n.
Skip this Video
Loading SlideShow in 5 Seconds..
Diving Under Special Conditions PowerPoint Presentation
Download Presentation
Diving Under Special Conditions

Diving Under Special Conditions

239 Vues Download Presentation
Télécharger la présentation

Diving Under Special Conditions

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Diving Under Special Conditions

  2. References • Guide to Polar Diving. 1976. Office of Naval Research. • Heine, J.N. 1996. Cold Water Diving: A Guide to Ice Diving. Best Publishing Co, Flagstaff, AZ. • Heine, J.N. 1999. Scientific Diving Techniques. Best Publishing Company, Flagstaff, AZ. • Haddock, S.D.H., Heine, J.N. 2005. Scientific Blue-Water Diving. California Sea Grant Publ. No. T-057. • Joiner, J.T. 2001. NOAA Diving Manual: Diving for Science and Technology. Best Publishing Co. Flagstaff, AZ.

  3. Objectives • Upon completion of this module, the participant will be able to: • Describe the general diving conditions to be expected in the various geographic areas of the US • Discuss the aspects of diving from shore • Discuss the aspects of diving from a stationary platform • Discuss the aspects of diving from a small boat • Describe diving in freshwater, especially in the Great Lakes • Discuss the unique aspects of open-ocean diving and the techniques used • Discuss the aspects of diving on coral reefs, and in fast currents • Discuss the aspects of diving from shore

  4. Objectives (cont) • Upon completion of this module, the participant will be able to: • Discuss the special training and equipment required for cave diving • Discuss the special training and equipment required for cold water diving and diving under ice • Discuss the special training and equipment required for kelp, wreck, and night diving • Discuss the unique aspects of diving in dams and reservoirs, and the techniques used • Discuss the unique aspects of diving in rivers • Discuss the unique aspects of diving from a ship • Discuss the unique aspects of diving on pinnacles and seamounts • Discuss the unique aspects of diving in remote locations and coasts with difficult access • Discuss the unique aspects of diving in low and zero visibility • Discuss the unique aspects of diving in other unusual situations

  5. Geographic Regions • The diving conditions of the following coastal areas of the US and other areas will be described: • Northeast Coast • Mid-Atlantic Coast • Southeast Coast • Gulf of Mexico coast • Northwest Coast • Mid-Pacific Coast • Southwest Coast • Central Pacific Ocean • Polar • Tropics

  6. Northeast Coast • This area encompasses the coast from Maine to Rhode Island • Best diving occurs from June through October • During spring and summer, water temperatures range from 50-700F (10-210C), with a significant thermocline. Temperatures at 100 ft (30 m) range from 48-540F (9-120C) • During winter, the temperature in the water column is homogeneous, with temperatures reaching as low as 28.50F (-20C) and very cold air temperatures • Water visibility can range from 50-80 ft (15-24m) during calm seas. During summer, red tide conditions may lower visibility to less than 1 foot (0.3 m) • Coastal waters in the Gulf of Maine have an average visibility of 10 ft (3 m), while south of Cape Cod it averages 10-15 ft (3-4.5 m)

  7. Northeast Coast (cont) • Several species of brown kelp are common, but do not form a surface canopy • Currents are generally tidal-driven • Surf is modest, but can be important along rocky shores such as the coast of Maine • Hazardous marine animals are not common • Sharks have been seen, but are generally not of concern to divers • Torpedo rays and stingrays are found off southern New England • Goose-fish and wolffish may bite if startled • Green sea urchins may be locally abundant

  8. Mid-Atlantic Coast • This area encompasses the coast from Rhode Island to Cape Hatteras • Water generally has low visibility and cold bottom temperatures • Shipwrecks abundant off New York-New Jersey coasts and off Cape Hatteras • During summer, surface water temperatures range from 72-750F (22-240C), with a significant thermocline, and bottom temperatures range from 40-600F (4-160C) • The Gulf Stream can bring warm water nearshore at Cape Hatteras • Underwater visibility is best from September-October • Visibility is typically low near estuaries, such as the Hudson and Chesapeake

  9. Mid-Atlantic Coast • Strong tidal currents can be expected in the Chesapeake Bay, parts of the New York Bight, off the Outer Banks of NC, and in Long Island Sound • The surf is generally moderate • Sharks are abundant, but there have been few encounters with divers • Goosefish common in the north • Stinging jellyfish can be abundant in summer

  10. Southeast Coast • This area encompasses the coast from Cape Hatteras to Florida • In northern parts, summer surface water temperatures are about 700F (210C), and winter temperatures drop to 500F (100C) • In the south temperatures of 75-800F (22-270C) are common, and winter temperatures drop to 65-700F (18-210C) • Visibility in the north averages 20-25 ft (6-8 m) • Visibility in the south is very good offshore, but drops to 25-30 (8-9.5 m) in harbors and bays • Care should be taken when diving near boundary currents such as the Gulf Stream • Shark attacks, while still very rare, are relatively high in Florida

  11. Gulf of Mexico • This area encompasses the area from the west coast of Florida to Texas • Surface water temperatures in the north range from 550F (130C) to about 850F (300C) seasonally. Thermoclines in spring and summer may have differences between surface and bottom waters of as much as 100F (60C) • Tides are semidiurnal along the west coast of Florida, but become diurnal and mixed to the north and west • Tidal ranges are relatively small, but currents can develop in small passes and inlets • Visibility is highly variable depending upon proximity to river discharges and location

  12. Gulf of Mexico (cont) • Due to wide shelf, short period choppy waves are common • Long and short-spined sea urchins are common • Stinging hydrozoa such as fire coral, and jellyfish are common • Stinging scorpion fish and rays are found

  13. Northwest Coast • This area encompasses the coast from Subarctic Alaska to Oregon 1. Alaska • Summer surface water temperatures are about 45-500F (7-100C), and winter temperatures drop to 34-380F (1-30C) • Visibility varies from 40-80 ft (12-24 m) in the Aleutians, and is usually 15-30 ft (4.5-9 m) in bays and straits • In southeast Alaska, spring blooms can reduce visibility to zero in the upper 30 ft (9 m) of the water column • Large tidal ranges cause high tidal currents • There are relatively few hazardous organisms, other than the usual urchins and jellyfish, and surface kelp canopies • Marine mammals such as killer whales and Steller sea lions may cause divers to keep out of the water

  14. Northwest coast (cont) • Washington and Oregon • Water temperatures of 43-600F (6-160C) are common year-round • Visibility is usually low in coastal waters, ranging from 5-25 ft (1.5-8 m), and from 0-70 ft (0-21 m) in protected Puget Sound waters • Currents can be strong • Surface kelp canopies may be present

  15. Mid-Pacific Coast • This area encompasses the coast of northern and Central California • From San Francisco north, the best diving conditions generally occur from June-September • Summer surface water temperatures are about 48-560F (9-130C) • Underwater visibility varies. In the Fort Bragg area summer visibility ranges between 10-15 ft (3-4.5 m), increasing to 15-25 ft (4.5-7.5 m) in the fall • From San Francisco south to Pt. Conception, good diving conditions may continue through December • Visibility is generally poor between Santa Cruz and San Francisco • In Monterey and Carmel Bays, visibility in fall can reach 100 ft (30 m)

  16. Mid-Pacific Coast (cont) • Surf conditions are important when planning dives • Strong currents can occur around headlands • Kelp forests are extensive throughout the area • Hazardous marine organisms include sea urchins, jellyfish, and rockfish • Shark attacks are not common, but have occurred. Diving is not recommended between Tomales Bay and Ano Nuevo Island

  17. Southwest Coast • This area encompasses the coast from Pt. Conception to the Northern Baja California peninsula • Summer surface water temperatures are about 55-700F (13-210C), and winter temperatures drop to 50-600F (10-160C). There is a considerable thermocline in summer • Visibility ranges from 5-10 ft (1.5-3 m) along the coast to over 100 ft (30 m) around offshore islands. Best conditions are in the late summer through fall • Surf conditions should be evaluated prior to diving • Hazardous organisms include sharks, eels, sea urchins and jellyfish • Diving should be avoided around sewage outfalls

  18. Central Pacific Ocean • This area encompasses the coast around the Hawaiian and Leeward Islands • The average water temperature is 760F (240C) • Underwater visibility ranges from 50-100 ft (15-30 m) • Currents and high surf can be a problem • Hazardous organisms include sharks, eels, sea urchins and coral

  19. Arctic and Antarctic • Polar diving is remote and conditions can be extreme • Water temperatures may be as low as 280F (-20C), but air temperatures with wind chill can be much lower (-400F [-400C]) • Hazardous organisms include killer whales, leopard seals and polar bears

  20. Diving From Shore • Safe entry and exit points must be identified • A dive flag should be displayed as required by law, and in areas of boat traffic. It should be towed if divers are swimming • Surf conditions should be carefully evaluated • All equipment should be donned and in place during surf entries and exits • Rip currents may be used for entries. If swimming towards shore, to get out of a rip current, swim parallel to the beach

  21. Diving From a Stationary Platform • Diving from a pier or platform allows for use of surface-supplied equipment • Ladders should be used where possible. Fins may have to removed for entry and exit • Ladder exits require a one-at-a-time procedure. Do not get near the ladder until the diver is safely onboard platform or boat • Be sure of sufficient water depth before entry

  22. Diving From a Small Boat • Vessels range from small inflatables, to dinghies, to larger solid-hull vessels. Common features include: • A means for divers to enter and exit the water easily and safely • Seaworthy and capable of holding the load required • Professional crew trained in boat handling and operation • Shelter from the sun, cold, or inclement weather • Ship-to-shore communications • Properly maintained and in good repair • Equipped with diver’s flag, emergency oxygen equipment, first aid kit, and drinking water • Being manned by a trained vessel operator while divers are in the water

  23. Diving From a Small Boat (cont) • Entering the water: • The back-roll method is best if the distance to the water is not greater than about 3-4 ft (0.9-1.2 m)

  24. Diving From a Small Boat (cont) • A ft-first entry, such as the “giant stride”, is generally used from a greater height using an opening in the gunwale • For exiting the water: • If using a dive ladder, equipment can be retained and fins removed and looped over the wrists • Alternatively, cylinders and weight belts can be removed and handed to surface personnel prior to exiting • Some ladders are designed to allow a fully-equipped diver to exit without removing fins • Ladder exits require a one-at-a-time procedure. Do not get near the ladder until the diver is safely onboard platform or boat • Larger vessels may have a “swim-step” off the transom that can be used for entering and exiting the water

  25. Freshwater Diving • Ocean divers must correct depth gauges and adjust buoyancy for freshwater diving • Great Lakes Diving: • In summer the upper layer (epilimnion) temperature ranges between 55-750F (13-240C). Below the thermocline (hypolimnion, typically at a depth of 60 ft [18 m]) temperatures average around 390F (40C) • In winter the water temperature ranges between 320F (00C) near the surface and 390F (40C) on the bottom. Diving under ice requires special training • Underwater visibility ranges from about 100 ft (30 m) in Lake Superior to less than 1 foot (0.3 m) in Lake Erie

  26. Freshwater Diving • Other water bodies: • There are many types of lakes, from clear mountain lakes, to reservoirs, to sediment-laden lakes and glacial lakes • Quarries and springs are also popular for diving • When planning a dive bottom terrain, entanglement hazards, algal blooms, and temperatures should be considered

  27. Open-Ocean Diving • Diving in the open ocean, called blue-water diving, does not have a fixed frame of reference (i.e., bottom), so divers may become easily disoriented • Special techniques have been developed for this type of diving (see Haddock and Heine, California Sea Grant, 2005)

  28. Open-Ocean Diving (cont) • Overview of a blue-water dive, showing downline array. Divers are tethered to a down-line and a safety diver serves as a buddy for each working diver, and controls the dive

  29. Open-Ocean Diving (cont) • The down-line is securely fastened to the vessel, and has depth markers and loops to attach the tether at various depths • Other details include a wave damper, shark billy, and light weight (ca 3 lb/1.5 kg)

  30. Open-Ocean Diving (cont) Trapeze keeps divers connected to the down-line Various designs are shown here: Aluminum bar Polypropylene bar with deep-D stainless steel shackles U-shaped “boom bail” Stainless steel rod hoop Stainless steel rod triangle

  31. Open-Ocean Diving (cont) • Details of diver’s tether and quick-release lines

  32. Coral Reefs and Fringing Reefs • Tidal changes may affect entry and exit points • Currents can be strong in reef passes • Rough seas may appear at the reef edge • Adequate protection from sharp coral should be used

  33. Fast Current • Currents of greater than 1 knot can be difficult for divers to swim against • Drift diving with the current can be useful for surveying large areas • Divers should trail surface floats, which are tended by a maneuvering boat • Divers should also carry surface signaling devices such as flares or a safety sausage

  34. Cave Diving • Limited overhead access, visibility, and confined-spaces in caves require special training and equipment • Special hazards include: • The absence of a direct and immediate ascent route to the surface • The sometimes instantaneous loss of visibility due to silting or failure of diver’s light • The entanglement and impact hazards associated with being in a confined, enclosed space

  35. Cave Diving (cont) Four basic rules for cave-diving safety include: • Always use a continuous guideline to the surface • Save two-thirds of the total air supply for returning to the surface • Carry at least three lights during the dive • Carry a redundant scuba regulator and any other equipment where the direct malfunction of which could cause a fatality Safety reel

  36. Cave Diving (cont) • Standard cave diving life-support systems should include: • Double cylinders • Double manifolds with captured o-rings • Two regulators • Submersible pressure gauge • Buoyancy compensator with power inflator • Depth gauge • Timer (computer) • Decompression tables • Exposure suit • Safety reel and line • Lights • Compass • Slate • Pencil

  37. Cold Water Diving • Diving in cold water presents potential equipment problems such as regulator freeze-up and free-flow • Several models designed to resist freezing are available • Divers should submerge before breathing from or purging the regulator • Rapid, prolonged inflation of drysuits or buoyancy compensators should also be avoided • Drysuits are commonly used, and special training is required for their usage • Thermal protection, especially of the extremities, is important. Dry gloves can be fitted to drysuit sleeves • Facilities must be available for divers and surface tenders to stay warm • See Heine (1996) for detailed information on cold water diving

  38. Diving Under Ice • Specialized training and equipment are required for diving under ice • Solid ice offers a stable platform with little or no seas, but currents are possible • Ice thickness must be determined by drilling a small hole

  39. Diving Under Ice (cont) • Triangular dive holes allow access for up to three divers at a time • Each diver has a surface tender, and there is at least one standby diver for the group • Divers are tethered to a line securely fastened on the surface • Excursion distances from the entry hole should be kept to a minimum (90 ft or 27 m) • See Heine (1996) for detailed information on diving under ice

  40. Kelp Diving • There are many species of kelp, some forming low-lying bottom canopies, while others grow up and form a thick surface canopy • Holdfasts anchor the plant to the substrate, while hollow floats buoy the long stipes and fronds up to the surface • The surface canopy can be very thick, and care must be taken when entering and exiting • Divers should be sure their equipment is streamlined to reduce snagging and entanglement • Kelp has great tensile strength, but can be broken by bending

  41. Wreck Diving • Penetration of wrecks requires special training and equipment • Most intact wrecks are in deeper water (80 ft or 24 m, or greater) • Twin scuba cylinders and redundant air supply are recommended • Visibility can be limited, and the use of a safety reel is mandatory • Entanglement is a real concern

  42. Night Diving • A properly anchored and lighted vessel must be attended during the dive • Each diver must carry a primary and a backup light • A chemical light can be taped to the snorkel or cylinder valve for underwater and surface visibility • Hand signals should be practiced. They can be made against the diver’s chest while shining the light toward oneself

  43. Night Diving (cont) Predive • Lights- adequate light for surface team. May need lighting for entry/exit point, and vessel • Markers- jackstays or shot-lines should be used where necessary • Briefing- to include tasks, routes to a from the site, entry and exit, and safety procedures Dive • Safety- a lifeline to the surface may be required • Light- there is usually some ambient light at night. Diver’s must carry battery-powered lights and should use chemical light sticks Postdive • Safety- For decompression diving, a lighted decompression line is essential. Adequate thermal protection should be available for divers

  44. Diving in Dams and Reservoirs • Many of the same procedures are used as in cave and wreck diving • Dive planning with site personnel is critical for safe operations • There are four major considerations in dive planning: • Depth • Water temperature • Visibility • Flow velocities

  45. Diving in Dams and Reservoirs (cont) • Depth • Can vary greatly and be quite deep around dams • Water temperatures can vary from 800F (270C) in summer to slightly above freezing in winter • Spring runoff from rivers can produce low visibility. Sediment can also reduce visibility to near zero • Diving in dam gatewells must be carefully coordinated with dam personnel to prevent suction at the orifice • Diving in fish ladders can involve high water flows

  46. Diving in Dams and Reservoirs (cont) • Diving at Water Withdrawal and Pumping Sites • Divers may be required to inspect fish screens • Several types of water-withdrawal sites are common: • A vault-like structure with a screened underwater opening • A pier-like structure set out from the shoreline that supports turbine pumps • A combination pier/vault created by closing in the area under a pier • A simple arrangement of a pump or siphon with a single intake line extending below the low-water level

  47. River Diving • Rivers vary greatly in size, turbidity, terrain, flow and temperature • Hazards such as log jams, submerged rocks, trees, old cars, barbed wire, and fishing lines may be encountered • When working with lines, tethers, or umbilicals in a current should be aware of the drag on them • Ascending and descending in a swift current can be difficult

  48. River Diving (cont) • A “creeper” device can be used to move across the bottom in swift currents:

  49. Diving from a Ship • There are a number of personnel that may be involved in diving operations from a larger vessel. They must communicate and discuss logistics before any diving operation takes place • The ship’s captain has the final decision in any matter pertaining to the vessel and its operation • The divemaster is responsible for all aspects of the diving operation • The science coordinator, in conjunction with the captain and divemaster, ensures that the scientific goals of the diving mission are achieved

  50. Diving from a Ship (cont) • A suitable diving storage locker should be used. It should be equipped with backup diving gear • Air compressors should be positioned with the intake towards the bow of the vessel, and away from any paints, solvents, or other chemicals • If diving in a remote region or far offshore, evacuation plans must be in place • A decompression chamber may be required onboard if decompression, repetitive, or deep diving are planned • Use of a small dive-support vessel is recommended