Diving Under Special
Conditions
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.
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
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
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
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 (10210C), 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)
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
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
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
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
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
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
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
Northwest coast (cont)
2. Washington and Oregon
•
•
•
•
Water temperatures of 43-600F (6-160C) are common yearround
Visibility is usually low in coastal waters, ranging from 525 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
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)
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
Southwest Coast
• This area encompasses the coast from Pt. Conception to
the Northern Baja California peninsula
• Summer surface water temperatures are about 55-700F (13210C), 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
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
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
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
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
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
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 (0.91.2 m)
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
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
Freshwater Diving
• Other water bodies:
– There are many types of lakes, from clear
mountain lakes, to reservoirs, to sedimentladen 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
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)
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
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)
Open-Ocean Diving (cont)
Trapeze keeps divers connected to the
down-line
Various designs are shown here:
A. Aluminum bar
B. Polypropylene bar with deep-D
stainless steel shackles
C. U-shaped “boom bail”
D. Stainless steel rod hoop
E. Stainless steel rod triangle
Open-Ocean Diving (cont)
• Details of diver’s
tether and quickrelease lines
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
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
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
Cave Diving (cont)
Four basic rules for cave-diving safety include:
1. Always use a continuous guideline to the surface
2. Save two-thirds of the total air supply for returning
to the surface
3. Carry at least three lights during the dive
4. Carry a redundant scuba regulator and any other
equipment where the direct malfunction of which
could cause a fatality
Safety reel
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
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
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
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
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
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
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
Night Diving (cont)
Predive
1.
2.
3.
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
1.
2.
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
1.
Safety- For decompression diving, a lighted decompression line is
essential. Adequate thermal protection should be available for divers
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:
1.
2.
3.
4.
Depth
Water temperature
Visibility
Flow velocities
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
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
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
River Diving (cont)
• A “creeper” device can be used to move
across the bottom in swift currents:
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
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
Diving from a Ship (cont)
• Diving While Underway
– Divers may be required to make underwater observations on
towed equipment or instruments
– The small boat can maneuver the divers into position to enter in
front of the towed system
– Special care must be taken to avoid entanglement, entrapment,
and being forced against bottom obstructions. Divers must
always carry a sharp knife
– Jellyfish may pose a particular hazard when diving on trawls
– Towed speeds of over 3 knots (1.5 m/s) preclude divers from
holding onto nets, and may cause mouthpieces and/or face
masks to become dislodged
– Wireless communications should be considered. Color-coded
float balls can be used to signal the surface
Pinnacle and Seamount Diving
• Pinnacles often have relatively flat tops and
steep sides, and may have significant currents
• In oceanic conditions, divers should be tended
from a small boat
• A downline marked with depths may be used
• Sharks may be present, and divers should carry
a shark billy
Diving in Remote Locations and
on Coasts of Difficult Access
• Emergency evacuation of an injured diver must be
thoroughly planned for
• Boats should have flares, dye markers, compass, survival
packs, drinking water, satellite phone, and GPS
• An emergency safety vessel should be considered
• A DMT and emergency medical supplies should be onhand
• Medical, rescue, and recompression facilities may not be
available. Extra safety measures should be used
Diving in Low and Zero
Visibility
• The ability to navigate accurately is reduced
• Other marine hazards, such as entanglement, dangerous
marine organisms, and injuries from work-related tools
may be more likely
• A standby diver should be available
• Conservative planning relative to depth, underwater
time, and air consumption should be considered
• Lifelines should be used, if appropriate
• Other equipment to be carried include a sharp knife and
lights
Other Unusual Situations
• Noxious gas in bottom water
– Gases such as hydrogen sulfide, ammonia,
and methane can occur in anoxic waters
around fish cages and mussel rafts
– Drysuits and positive-pressure face masks
should be considered
• Fish tanks, cages, farms, floating systems
– Diving in enclosures has the potential for
entanglement and trapping
Other Unusual Situations (cont)
• Diving around enclosures
– Larger mesh netting can be especially dangerous for
entanglement
– Predators may be associated with fish cages
• Diving within enclosures
– Small enclosures may only allow one diver, so a fullydressed standby diver should be ready
– A diver safety line, and/or weighted shot line should
be used
Other Unusual Situations (cont)
• Oceanographic engineering
– Equipment may need to be placed, monitored, or operated by
divers
– Heavy equipment may be managed by using lift bags
Diving Modes Requiring Specialized
Training and Authorization
• The following modes of diving may require
further specialized training before being utilized:
–
–
–
–
–
Nitrox diving
Mixed gas diving
Surface supplied diving
Hookah diving
Staged decompression diving
Blue water diving
Ice and polar diving
Saturation diving
Overhead environments (cave, wreck penetration)
Study Questions
• Use the following study questions to
review some of the information presented
in this self study module. When you are
finished you can print out your study
questions results.
Self-study Questions
Which of these coasts encompass the
area of Maine to Rhode Island?
a.
b.
c.
d.
Southeast Coast
Northeast Coast
Gulf of Mexico Coast
Mid-Atlantic Coast
Self-study Questions
Which of these coasts encompass the
area of Maine to Rhode Island?
a.
b.
c.
d.
Southeast Coast
Northeast Coast
Gulf of Mexico Coast
Mid-Atlantic Coast
Self-study Questions
In the Northeast Coast during the
spring and summer water
temperatures at _____ range from 4854 degrees Fahrenheit (9-21 C).
a. 50 feet
b. 75 feet
c. 100 feet
d. 125 feet
Self-study Questions
In the Northeast Coast during the
spring and summer water
temperatures at _____ range from 4854 degrees Fahrenheit (9-21 C).
a. 50 feet
b. 75 feet
c. 100 feet
d. 125 feet
Self-study Questions
During what months is underwater
visibility best in the Mid-Atlantic
Coast?
a.
b.
c.
d.
September-November
August-October
September-October
August-November
Self-study Questions
During what months is underwater
visibility best in the Mid-Atlantic
Coast?
a.
b.
c.
d.
September-November
August-October
September-October
August-November
Self-study Questions
The fish common to the Gulf of Mexico
with the worst reputation for biting is
the _____.
a.
b.
c.
d.
Grey triggerfish
Great barracuda
Sand tiger shark
toadfish
Self-study Questions
The fish common to the Gulf of Mexico
with the worst reputation for biting is
the _____.
a.
b.
c.
d.
Grey triggerfish
Great barracuda
Sand tiger shark
toadfish
Self-study Questions
What is the highest temperature that is
normally reached in the Northwest
Coast during summer?
a.
b.
c.
d.
34 degrees Fahrenheit
38 degrees Fahrenheit
45 degrees Fahrenheit
50 degrees Fahrenheit
Self-study Questions
What is the highest temperature that is
normally reached in the Northwest
Coast during summer?
a.
b.
c.
d.
34 degrees Fahrenheit
38 degrees Fahrenheit
45 degrees Fahrenheit
50 degrees Fahrenheit
Self-study Questions
The mid-Pacific costal region includes the waters of
Northern and Central California. From San Francisco
north, the best diving conditions in terms of water
temperature and visibility generally occur from June
through September. From San Francisco south to Point
Conception, good diving conditions may continue
through _____.
a. November
b. December
c. January
d. February
Self-study Questions
The mid-Pacific costal region includes the waters of
Northern and Central California. From San Francisco
north, the best diving conditions in terms of water
temperature and visibility generally occur from June
through September. From San Francisco south to Point
Conception, good diving conditions may continue
through _____.
a. November
b. December
c. January
d. February
Self-study Questions
The average water temperature around
the major islands in the Central
Pacific Ocean is _____.
a.
b.
c.
d.
74 degrees Fahrenheit
75 degrees Fahrenheit
76 degrees Fahrenheit
77 degrees Fahrenheit
Self-study Questions
The average water temperature around
the major islands in the Central
Pacific Ocean is _____.
a.
b.
c.
d.
74 degrees Fahrenheit
75 degrees Fahrenheit
76 degrees Fahrenheit
77 degrees Fahrenheit
Self-study Questions
Jellyfish abound in the Tropics.
a. True
b. False
Self-study Questions
Jellyfish abound in the Tropics.
a. True
b. False
Self-study Questions
A boat used as a diving platform should be:
(select all that apply)
a. equipped with a means for divers to enter and exit the water
easily and safely
b. seaworthy and not loaded beyond the capacity recommended by
the manufacturer for the expected conditions
c. equipped with ship-to-shore communications
d. maintained properly and in good repair
e. carrying a diver's flag, oxygen kit, first aid equipment, and
drinking water
f. Manned by a trained vessel operator while divers are in the
water
g. All of the above
Self-study Questions
A boat used as a diving platform should
be: (select all that apply)
a. equipped with a means for divers to enter and exit the water
easily and safely
b. seaworthy and not loaded beyond the capacity recommended by
the manufacturer for the expected conditions
c. equipped with ship-to-shore communications
d. maintained properly and in good repair
e. carrying a diver's flag, oxygen kit, first aid equipment, and
drinking water
f. Manned by a trained vessel operator while divers are in the
water
g. All of the above
Self-study Questions
In the Great Lakes, the water below the
thermocline approach the
temperature of maximum density for
freshwater, ___.
a.
b.
c.
d.
39 degrees Fahrenheit
32 degrees Fahrenheit
55 degrees Fahrenheit
75 degrees Fahrenheit
Self-study Questions
In the Great Lakes, the water below the
thermocline approach the
temperature of maximum density for
freshwater, ___.
a.
b.
c.
d.
39 degrees Fahrenheit
32 degrees Fahrenheit
55 degrees Fahrenheit
75 degrees Fahrenheit
Self-study Questions
Most open-ocean divers carry shark
billies.
a. True
b. False
Self-study Questions
Most open-ocean divers carry shark
billies.
a. True
b. False
Self-study Questions
Currents of 1 knot are considered the
common limit for divers to be able to
swim against.
A. True
B. False
Self-study Questions
Currents of 1 knot are considered the
common limit for divers to be able to
swim against.
A. True
B. False
Self-study Questions
Which of these is NOT a special hazard
normally associated with cave diving?
A.The absence of a direct and immediate ascent route to
the surface
B. The sometimes instantaneous loss of visibility because of
silting or failure of the diver’s light
C. The entanglement and impact hazards associated with
being in a confined, enclosed space
D.Being dragged to the surface while deploying a lift-bag
for a marker buoy
Self-study Questions
Which of these is NOT a special hazard
normally associated with cave diving?
A.The absence of a direct and immediate ascent route to
the surface
B. The sometimes instantaneous loss of visibility because of
silting or failure of the diver’s light
C. The entanglement and impact hazards associated with
being in a confined, enclosed space
D.Being dragged to the surface while deploying a lift-bag
for a marker buoy
Self-study Questions
Every cave diver must carry at least _____
lights during a dive.
a.Two
b.Three
c. Four
d.five
Self-study Questions
Every cave diver must carry at least _____
lights during a dive.
a.Two
b.Three
c. Four
d.five
Self-study Questions
Diving in cold water and at or near freezing
temperatures presents potential equipment
problems such as regulator freeze-up and freeflow. In an attempt to avoid cold related
equipment problems, divers can/should: (select
all that apply)
A.
B.
C.
D.
E.
select regulator models designed to resist freezing
submerge before breathing from or purging the regulator.
Avoid rapid or prolonged inflation of dry suit or buoyancy compensator.
Pre-chill the regulator before the dive
Pay attention to early signs of a potential regulator freeze-up such as ice
crystals on the tongue and abort the dive should these signs occur.
Self-study Questions
Diving in cold water and at or near freezing temperatures
presents potential equipment problems such as regulator
freeze-up and free-flow. In an attempt to avoid cold
related equipment problems, divers can/should: (select
all that apply)
A. select regulator models designed to resist freezing
B. submerge before breathing from or purging the regulator.
C. Avoid rapid or prolonged inflation of dry suit or buoyancy
compensator.
D. Pre-chill the regulator before the dive
E. Pay attention to early signs of a potential regulator freeze-up such as
ice crystals on the tongue and abort the dive should these signs
occur.
Self-study Questions
Penetration wreck diving, like cave diving,
requires special training and equipment. Select
the true statements concerning wreck diving.
A.Most intact wrecks are at depths in excess of 80 ft. (24.4
m).
B. Few intact wrecks can be found within divable depth
ranges.
C. Entanglements are a real concern.
D.Visibility can be limited.
E. The use of a safety reel is mandatory.
F. A single scuba cylinder equipped with a J-valve is the
recommended configuration for wreck diving.
Self-study Questions
Penetration wreck diving, like cave diving,
requires special training and equipment. Select
the true statements concerning wreck diving.
A.Most intact wrecks are at depths in excess of 80 ft. (24.4
m).
B. Few intact wrecks can be found within divable depth
ranges.
C. Entanglements are a real concern.
D.Visibility can be limited.
E. The use of a safety reel is mandatory.
F. A single scuba cylinder equipped with a J-valve is the
recommended configuration for wreck diving.
Self-study Questions
Aside from the need for diver carried lights,
there are few concerns to consider when
night diving.
A.True
B.False
Self-study Questions
Aside from the need for diver carried lights,
there are few concerns to consider when
night diving.
A.True
B.False
Self-study Questions
Which of these is NOT one of the four major
conditions to be considered when
planning dives at dams?
A.Depth
B. Water temperature
C. Visibility
D.Flow velocities
E. Current direction
Self-study Questions
Which of these is NOT one of the four major
conditions to be considered when
planning dives at dams?
A.Depth
B. Water temperature
C. Visibility
D.Flow velocities
E. Current direction
Self-study Questions
Towed speeds of over _____ preclude divers
from holding onto nets, and may cause
mouthpieces and/or face masks to
become dislodged.
A.2 Knots
B.3 Knots
C.4 Knots
D.5 Knots
Self-study Questions
Towed speeds of over _____ preclude divers
from holding onto nets, and may cause
mouthpieces and/or face masks to
become dislodged.
A.2 Knots
B.3 Knots
C.4 Knots
D.5 Knots
Self-study Questions
Noxious gasses such as _____ commonly occur in anoxic
halos from concentrations of fecal matter under fish
cages and mussel rafts, as well as in areas of sewage
settlement or low water flow. (Select all that apply)
A.Methane
B. Ammonia
C. Hydrogen Sulfide
D.All the above
Self-study Questions
Noxious gasses such as _____ commonly occur in anoxic
halos from concentrations of fecal matter under fish
cages and mussel rafts, as well as in areas of sewage
settlement or low water flow. (Select all that apply)
A.Methane
B. Ammonia
C. Hydrogen Sulfide
D.All the above