--- English --- The Indonesian Mimic
Octopus, Thaumoctopus mimicus.
This fascinating creature was discovered
in 1998 off the coast of Sulawesi in Indonesia, the mimic octopus is
the first known species to take on the characteristics of multiple
species.
This octopus is able to copy the physical likeness and movement
of more than fifteen different species, including sea snakes, lionfish,
flatfish, brittle stars, giant crabs, sea shells, stingrays, jellyfish,
sea anemones, and mantis shrimp.
This animal is so intelligent that it
is able to discern which dangerous sea creature to impersonate that
will present the greatest threat to its current possible predator.
For
example, scientists observed that when the octopus was attacked by
territorial damselfishes, it mimicked the banded sea snake, a known
predator of damselfishes.
--- Català --- El Pop Mímic indonesi, (
mimicus Thaumoctopus. )
Aquesta fascinant criatura es descobria el 1998
davant la costa de Sulawesi a Indonèsia, el pop mímic és la primera
espècie coneguda per prendre les característiques de múltiples espècies.
Aquest pop pot copiar la semblança física i moviment de més de quinze
espècies diferents, incloent-hi serps de mar, lionfish, flatfish,
estrelles de mar, crancs gegants, petxines de mar, stingrays, meduses,
anèmones de mar, i la galera.
Aquest animal és tan intel•ligent que pot
discernir a quina perillosa criatura de mar imitar per presentar
l'amenaça més gran al seu possible predador actual.
Per exemple, els
científics observaven que quan el pop era atacat per els territorials
damselfishes, imitava a la serp de mar embolcada, un conegut predador
dels damselfishes.
--- Spanish --- El indonesio pulpo mímico, (
Thaumoctopus mimicus.).
Esta fascinante criatura fue descubierta en 1998
frente a las costas de Sulawesi en Indonesia, el pulpo mimo es la
primera especie conocida en asumir las características de múltiples
especies.
Este pulpo es capaz de copiar la imagen física y el movimiento
de más de quince especies diferentes, incluyendo las serpientes de mar,
pez león, peces planos, estrellas de mar, cangrejos gigantes , conchas
de mar, rayas, medusas, anémonas de mar, y la galera.
Este animal es
tan inteligente que es capaz de discernir a que peligrosa criatura del
mar debe suplantar para presentar una mayor amenaza a su actual y
posible depredador.
Por ejemplo, los científicos observaron que cuando
el pulpo es atacado por los territoriales damselfishes, simula a una
serpiente de mar de franjas, un conocido depredador de los damselfishes.
The mimic octopus, Thaumoctopus mimicus, is a species of octopus that has a strong ability to mimic other creatures. It grows up to 60 cm (2 feet) in length. Its normal colouring consists of brown and white stripes or spots.
Living in the tropical seas of Southeast Asia, it was not discovered officially until 1998,[1] off the coast of Sulawesi.
Recently found in the great barrier reef in Northern Queensland in
2010. The octopus mimics the physical likeness and movements of more
than 15 different species, including sea snakes, lionfish, flatfish, brittle stars, giant crabs, sea shells, stingrays, flounders, jellyfish, sea anemones, and mantis shrimp.[2][3] It accomplishes this by contorting its body and arms, and changing colour.
Although all octopuses can change colour and texture, and many can
blend with the sea floor, appearing as rocks, the mimic octopus is the
first octopus species ever observed to impersonate other animals.[3][4]
Based on observation, the mimic octopus may decide which animal to
impersonate depending on local predators. For example, when the octopus
was being attacked by damselfish, the octopus was observed to appear as a banded sea snake,
a damselfish predator. The octopus impersonates the snake by turning
black and yellow, burying six of its arms, and waving its other two arms
in opposite directions.[5]
The mimic octopus is often confused with Wunderpus photogenicus, another recently discovered species.[6]Wunderpus can be distinguished by the pattern of strong, fixed white markings on its body.[7]
The mimic octopus lives exclusively in nutrient-rich estuarine bays
of Indonesia and Malaysia full of potential prey. It uses a jet of water
through its funnel to glide over the sand while searching for prey,
typically small fish, crabs, and worms. It also is prey to other
species. Like other octopuses, the mimic octopus' soft body is made of
nutritious muscle, without spine or armor, and not obviously poisonous,
making it desirable prey for large, deep water carnivores, such as barracuda
and small sharks. Often unable to escape such predators, its mimicry of
different poisonous creatures serves as its best defense. Mimicry also
allows it to prey upon animals that would ordinarily flee an octopus; it
can imitate a crab as an apparent mate, only to devour its deceived
suitor.
This octopus mimics venomous sole, lion fish, sea snakes, sea anemones, and jellyfish.
For example, the mimic is able to imitate a sole by pulling its arms
in, flattening to a leaf-like shape, and increasing speed using a
jet-like propulsion that resembles a sole. When spreading its legs and
lingering on the ocean bottom, its arms trail behind to simulate the
lion fish's fins. By raising all of its arms above its head with each
arm bent in a curved, zig-zag shape to resemble the lethal tentacles of a
fish-eating sea anemone, it deters many fish. It imitates a large
jellyfish by swimming to the surface and then slowly sinking with its
arms spread evenly around its body.
Unlike the vast majority of octopuses, it regularly traverses tunnels
and burrows in the sea floor to search for food and to conceal itself
from predators. It can often be seen surveying its surroundings from one
of these burrows, with only its eyes and head sticking out of the hole.[8]
Feeding
The mimic octopus often feeds by covering an area of sand under a disc
of webs while using the tips of its fine arms to flush small animals
into its suckers. It can probe its arms deep into burrows or holes to
search for prey which it can then pass to its mouth
The colossal octopus: pen and wash drawing by malacologistPierre Dénys de Montfort, 1801, from the descriptions of French sailors reportedly attacked by such a creature off the coast of Angola
In this video Scuba Diver Life
explores the fabulous corals and drift scuba diving that Cozumel has to
offer. We met up with Dive Cooperative who led us through our entire
adventure!
If you want to checkout the new museum at Cancun, Mexico, you will have
to don snorkel gear and take a dive under the sea, for it’s the world’s
largest underwater sculpture museum. The Cancun underwater museum
features a series of concrete sculptures by Jason DeCaires Taylor
placed underwater off the coast of Isla de Mujeres and Cancún, Mexico.
The project began in November 2009 with placement of 100 statues in
shallow waters of the Cancún National Marine Park which had been
previously damaged by storms. A total of 400 sculptures is planned to be
installed by the end of 2010.
The primary purpose of the sculpture garden is environmental. Nearly
300,000 visitors flock to the area each year to explore the white sands
and turquoise Caribbean sea, but they are causing damage to marine life.
The idea is to eventually form artificial corals from the sculptures
that will support a variety of marine life. There’s also hope that the
touristic value of the underwater sculpture garden will draw people away
from the over-visited and severely degraded natural corals of the
nearby West Coast National Park.
Cancun Underwater Museum is a series of sculptures by Jason deCaires Taylor placed underwater off the coast of Isla de Mujeres and Cancún, Mexico. The project began in November 2009 with placement of a hundred statues in shallow waters of the Cancún National Marine Park, which had been previously damaged by storms.[1]
The sculptures are created with pH-neutral marine concrete and are based on members of the local community. The artist planned the sculptures as artificial reefs with fire coral planted in the initial sculptures. A total of 400 sculptures are planned, to be installed by the end of 2010.[2][3]
Snorkeleres, scuba divers, and tourists in glass-bottom boats all visit the underwater installation.
Lake County Divers Supply Inc. began operation in September of 1985.
The main purpose of opening the training facility was and still is, to
provide quality diver training and education; top-notch scuba equipment
at a reasonable price along with offering affordable dive travel to
distant vacation destinations.
Currently, the training facility offers courses through:
Scuba diving is an activity that can be enjoyed around the world.
It’s
an activity that can involve the entire family or be done as your own
personal getaway!
Down here, Things are different.
Others realize it’s the beginning of a life long journey. A journey to
explore and learn about new environments and challenging the elements.
A
journey where diving is a part of their lifestyle.
It’s another world.
Scuba diving takes you to a place far beyond everyday stress and strain.
No phones. No faxes. Everything is new and unique.
The colors and
creatures fill you with an unexpected sense of wonder.
Why would you ever want to go back? Diving..........the ultimate escape.
Scuba Diving is safe, simple, and affordable and like nothing else on
earth.
The excitement you feel when you first learn that you can breathe
underwater is a thrill that can only be experienced. Scuba diving
provides you with the opportunity to explore hundreds of exotic diving
destinations or view your local waters from a new vantage point.
You
wont believe what the underwater environment has to offer.
AQUATICS UNDERWATER RECOVERY AND RESCUE INC.
(A NON FOR PROFIT ORGANIZATION)
The Aquatics Unit was formed in 1969 after its founding members
recovered a 3-year old child from a body of water in Highland, IN.
The
experience made it clear that an underwater emergency response team was
needed in Indiana's Lake County area.
The Aquatics are a specially trained unit of experienced scuba divers
with the latest U/W technology and water emergency equipment.
The unit
consists of up to 24 highly qualified and professional divers with
thousands of hours of combined water time.
All members must be Master
Diver Certified when they join the unit.
The Aquatics provide citizens with a highly-trained, properly-equipped,
and disciplined team of experienced U/W Rescue Specialist.
On call 24
hours a day, in times of hardship or emergency, they are dispatched by
the Lake County Police Department and supported by the Sheriff.
As a unit of rare talent in the Midwest, the Aquatics services are not
limited to Lake County alone.
The Aquatics have been called to assist
numerous police and fire departments in a five-state area, locating and
recovering evidence, weapons, victims, and vehicles hidden in lakes,
rivers, and quarries.
In 1977, Dr. Martin J. Nemioff of the University of Michigan Hospital
gave new meaning to the term "Dive Rescue Specialist."
For years,
rescuers and doctors alike assumed that a drowning victim, after four
minutes underwater, could not be revived without brain damage.
So,
unless a rescue diver is immediately available, it was a matter of
recovering a body, not rescuing a victim.
Dr. Memiroff, however, has documented the survival of a significant
number of persons who were submerged, without oxygen, in cold water
(below 70 F) for 4-to-45 minutes.
The cold water reduces the oxygen
needs of the tissues and stimulates the "Mammalian Diving Reflex", which
greatly reduces the blood supply to the skin, muscles, and abdomen, and
reserves the remaining blood oxygen for the brain, heart, and lungs.
The
action of this reflex helps cold-water near-drowning victims to recover
without brain damage or other physical impairment.
Therefore, a rescue diver doesn't give up, even if the victim appears
dead.
The victim may be cold, blue, not breathing, have no detectable
pulse or heartbeat, and have fixed dilated pupils.
But as soon as the
victim is pulled out of the water, CPR should be started and continued
until ambulance personnel arrive to take over.
Credentials
Air Force 319th
Security Police Squadron
Aboite Civil Township F.D.
Addison F.D.
Angola F.D.
Aurora F.D.
Beverly Shores F.D.
Birchwood F.D.
Boston F.D.
Boulder Junction Vol F.D.
Braidwood F.D.
Bremen F.D.
Burgin F.D.
Carroll County F.D. and Sheriff
Channahon F.D.
Coal City F.D.
Chicago Police Marine Unit
Chicago Air Sea Rescue
Danville F.D.
Elburn F.D.
Elgin F.D.
Elk Groove Village F.D.
Ellington Vol.
Flossmore F.D.
Fort Madison Fire and Rescue
Freemount F.D.
Gary F.D.
Godfrey F.D.
Greensbury F.D.
Greenwood F.D.
Hammond F.D.
Hobart F.D.
Homewood F.D.
Indiana Dept. of Natural Resources
Indiana State Police
Jamesville F.D.
Joliet F.D.
Lafayette F.D.
Lake Eliza F.D.
Lansing F.D.
Lake Station F.D.
Lemont F.D.
Lynnwood F.D.
Michigan City F.D.
Minooka F.D.
Mishawaka F.D.
New Carlisle F.D.
Notre Dame F.D.
Orland Park F.D.
Oaklawn F.D.
Portage Police
Pendleton F.D.
Penn North F.D.
Plainfield F.D.
Plymouth Police
Preble County Sheriff
Rolling Meadows F.D.
Romeoville F.D.
Rushville F.D.
South Bend F.D.
South Holland F.D.
St.Charles F.D.
Tinley Park F.D.
Tippecanoe County Sheriff
Warsaw Police
MORE UPON REQUEST
Somebody Come and Play In the Traffic With Me! Earn as You Learn, Grow as You Go!
Somebody Come and Play in "Traffic" with me. If you would like to "Join" A Growing Biz Op! Here is Your Chance to get in an Earn While You Learn to Do "The Thing" with us all here at Traffic Authority.
Someday well be living be living on
and under the oceans. This idea isnt farfetched and if it comes true
then here is the answer to a new type of underwater transportation system.
Somebody Come and Play In the Traffic With Me! Earn as You Learn, Grow as You Go!
Somebody Come and Play in "Traffic" with me. If you would like to "Join" A Growing Biz Op! Here is Your Chance to get in an Earn While You Learn to Do "The Thing" with us all here at Traffic Authority.
Somebody Come and Play in "Traffic" with me. If you would like to "Join" A Growing Biz Op! Here is Your Chance to get in an Earn While You Learn to Do "The Thing" with us all here at Traffic Authority.
Fins come and all shapes and colors some work a little better then others But they all basiclly do the same thing. So if your just starting out. Keep that in Mind as some Fins can get a bit costly.
Dmitry Podolsky and Andrew Chistyakov, have achieved marks of 170 and
201 meters in Dahab in frame of deep dive programm, leading by Andrew
Chistyakov.
It was second dive ( on 200+ ) for Dmitry and 7th for
Andrew - leading technical and cave diver in Russia.
Modern methods, the
huge personal experience of Andrew and his student and friend
-Dmitry have allowed to make these dives safe, as well as to squeeze
deco time : 201 m by 225 min.
Blue Hole is a popular diving location on east Sinai, a few kilometres north of Dahab, Egypt on the coast of the Red Sea.
The Blue Hole is a submarine sinkhole
(a kind of cave), around 130 m deep.
There is a shallow opening around
6 m deep, known as 'the saddle', opening out to the sea, and a 26 m long
tunnel, known as the arch, the top of which lies at a depth of 56 m.
The hole itself and the surrounding area has an abundance of coral and reef fish.
Dangers
The Blue Hole is notorious for the number of diving fatalities which
have occurred there, earning it the sobriquet "World's Most Dangerous
Dive Site" and the nickname "Diver's Cemetery".
The site is signposted
by a sign that says "Blue hole: Easy entry". Accidents are frequently
caused when divers attempt to find the tunnel through the reef (known as
"The Arch") connecting the Blue Hole and open water at about 52 m
depth.
This is beyond the PADI maximum advanced recreational diving
limit of 40 metres and the effect of nitrogen narcosis
is significant at this depth.
Divers who miss the tunnel sometimes
continue descending, hoping to find the tunnel farther down and become
increasingly narced.
Map
The "Arch" is reportedly extremely deceptive in several ways:
It is difficult to detect because of the odd angle between the arch, open water, and the hole itself.
Because of the dim lighting and the fact that most light enters from
outside, it appears shorter than it really is. Divers report that the
Arch appears less than 10 m long but measurements have shown it is 26 m
from one end to the other.
There is frequently a current flowing inward through the arch
towards the Blue Hole, increasing the time it takes to swim through.
The arch continues downward to the seabed which is beyond view and there is therefore no "reference" from below.
Technical diver passing under the Arch.
Divers who resist the temptation of the Arch and remain within their
training and limitations are in no more danger than on any other Red Sea
dive site.
However, the Arch has proved irresistible for many and thus
the dive site is considered unsuitable for beginners and a potential trap
for even experienced divers.
Diving through the arch requires suitable training and equipment, usually including a mixed-gas qualification from a technical diving training agency, technical diving
equipment such as redundant gas supply, redundant large-capacity
buoyancy control device and a breathing gas with reduced nitrogen
content such as trimix.
The Egyptian authorities claim that 40 divers have died at this site
since records began; however, many local dive guides believe that the
authorities are deliberately underestimating the numbers and that there
have actually been at least twice that many fatalities.
A famous (and videotaped) death in the Blue hole is that of Yuri
Lipski, an Israeli-Russian diver who died at 91.6 m below the surface.
Lipski was a victim of inexperience and lack of proper equipment.[citation needed]
Source: Wikipedia.org
Somebody Come and Play In the Traffic With Me! Earn as You Learn, Grow as You Go!
Somebody Come and Play in "Traffic" with me. If you would like to "Join" A Growing Biz Op! Here is Your Chance to get in an Earn While You Learn to Do "The Thing" with us all here at Traffic Authority.
Diving at Cape Evans Wall 15 miles north of McMurdo Station. Clips and
photos of a trip to acquire sea urchins for scientific study. Thanks to "Amusement Parks On Fire" for the permission to use the sound track with this film.
Ice diving in Antarctica. Check out film blog for more: http://kirkoftheantarctic.wordpress.com/
Here
we see the dive crew cutting holes in the 45cm sea ice and then going
in for a dive to collect scientific samples to help with learning about
global climate change. To see more Antarctic film blogs check out
'extremefilm' channel.
Seems like a lot of work to get wet doesn't It?
Ice diving is a type of penetration diving where the dive takes place under ice.[1][2]
Because diving under ice places the diver in an overhead environment
typically with only a single entry/exit point, it is considered an
advanced type of diving requiring special training (although whether it
constitutes technical diving
is part of a wider debate within the diving community). Ice divers are
generally tethered for safety. This means that the diver wears a special
harness under the scuba unit. A line is secured to this harness, and
the other end of the line is secured above the surface by one of a
number of methods.
The diver also can use a weight harness, integrated weight buoyancy
control device, or a weight belt with two buckles on it so the weights
can not be accidentally released which would cause a run-away ascent
into the ice sheet.
Ice diving is a team diving activity because the divers line requires
a line tender. This person is responsible for paying out and taking in
line so that the diver does not get tangled. Communication to the diver,
or to the surface, is accomplished by pulling on the line. Each series
of tugs means a different thing.
There is a diver suited up and ready to
enter the water at a moment's notice.
This diver is a safety diver, and
has his own tender. His purpose is to assist the primary diver in the
event of a problem.
Divers who do not use a tether require extra training and full redundant scuba systems.[citation needed]
Polar diving experience has shown that buoyancy control is the critical skill affecting safety.[2]
Ice Diving - View from the top
Under the ice - view from below
Monitoring an ice diver conducting studies below the ice.
Equipment
Since diving under the ice takes place in cold climates, there is
typically a large amount of equipment required.
Besides each person's
clothing and exposure-protection requirements, including spare mitts and
socks, there is basic scuba gear, back-up scuba gear, tools to cut a
hole in the ice, snow removal tools, safety gear, some type of shelter,
lines, and refreshments[citation needed] required.
Exposure suits
Because of the water temperature (between 4°C and 0°C in fresh water, approximately -1.9°C for normal salinity sea water), exposure suits are mandatory.[3]
Pre- and post-dive thermal protection is critical for safety and diver function.[2]
Hand thermal protection is important to retain functionality and prevent cold injury.[2]
The diver should be kept warm throughout the dive, but active
rewarming by external heating and heavy exercise should be avoided
directly after the dive, as the effect of cold on risk of decompression
sickness is not fully understood.[2]
Some consider a dry suit
mandatory; however, a thick wetsuit may be sufficient for hardier
divers.
A wetsuit can be pre-heated by pouring warm water into the suit.
A hood and gloves (recommended three-finger mitts or dry gloves with
rings) are necessary, and dry suit divers have the option of using hoods
and gloves that keep their head and hands dry.
Some prefer to use a full face diving mask
to essentially eliminate any contact with the cold water.
The biggest
drawback to using a wet suit is the chilling effect on the diver caused
by the water evaporating from the suit after a dive. This can be reduced
by using a heated shelter.
Cutting a hole in the ice to check the water conditions
Checking water conditions through a small hole in the ice
Cutting the ice hole with chainsaws
Scuba equipment
A diving regulator
suitable for cold-water is used. All regulators have a risk of freezing
and free flowing, but some models fare better than others.[4]
Environmentally sealed regulators avoid contact between the surrounding
water and the moving parts of the first stage by isolating them in an
antifreeze fluid (e.g. Poseidon)[1] or by siting the moving parts behind a diaphragm and transmitting the pressure through a pushrod (e.g. Apeks).
Although there is no universally accepted standard, at least one agency[5]
recommends the use of two non-freezing regulators arranged as follows:
primary first stage with primary second stage, BCD inflation hose, and
submersible pressure gauge (SPG); secondary first stage with secondary
second stage (octopus), dry suit inflation hose, and SPG, although only
one SPG is needed for a single cylinder or manifolded twins.
The two first stages are mounted on independently closable valves, as
a first stage freeze free-flow can only be stopped by shutting off the
air supply from the cylinder until the valve has thawed out.
The second
regulator is there to supply the remaining gas when the first regulator
is shut off.
A second-stage isolation valve used in conjunction with a
first-stage overpressure relief valve may be effective as a quick method
to manage demand valve free-flow.[2]
Regulators should be checked to ensure that they perform effectively at low temperatures before use far from a free surface.[2]
A minimum of two independent regulators is recommended for diving
under ice, as scuba apparatus has a tendency to free-flow under polar
conditions Divers must be competent in change-over procedures, including
shutdown of the free-flowing equipment.[2]
Keeping regulators warm and dry before diving, and limiting
breathing from the regulator before immersion will reduce the risk of
regulator freezing. Purging or any other cause of high flow rate
markedly increases the probability of freezing and should be kept to an
absolute minimum.[2]
Redundant systems usually typically comprise double cylinders with a
primary and alternate regulator.
Each of the 2nd stages is supplied its
own first stage, which can be shut down at the cylinder valve in an
emergency, such as a free flow.
The diver’s bcd is on a different 1st
stage to the drysuit so if there is an issue with one the diver can
still control his buoyancy.
Most divers also use a primary regulator on a 7-foot hose and a
secondary on a necklace, this is especially important when not using
tethers so the divers can swim in a horizontal line.
The reason for the
primary being on a long hose is to ensure the diver who has an issue
will get a known good regulator.
Also there is less chance of the donor
rolling off the regulator that was given to the diver in the emergency
situation.
Buoyancy and weighting
A drysuit should be used with a buoyancy compensator for ice diving
unless the diver exposed to greater risk with a buoyancy compensator
than without one.[2]
A tethered diver, who is deployed to work independently, should
preferably be equipped with full face mask, voice communications to the
surface and redundant air supply. This is often obligatory for
professional divers.[2]
Most divers prefer to be more negative for ice diving than in open
water like in most overhead environments, and learning to disconnect the
low pressure inflator on a BCD or drysuit is a critical skill.
Surface team.
Adequate thermal protection must be provided to tenders and standby divers.[2]
Warm waterproof shoes.
Warm anorak for cold weather.
Warm cap covering the ears.
Sunglasses with a UV filter to protect the eyes in sunny days.
Lip-care stick and cream to protect hands and face against cold and wind.
A device like crampons to aid in traction on ice. especially when cutting the hole or carrying gear
Procedures and precautions
A snow shovel is used to clear the snow and ice from the area.
An ice saw or a chain saw is used to cut a hole in the ice.
A weatherproof area is used for the divers to suit up.
The diver and tender on the surface are connected by a rope
and harness. The harness is typically put on over the dry suit but
under the BC or other buoyancy device so that the diver remains tethered
even if he or she must remove the air cylinder or buoyancy control
device. The harness fits over the shoulders and around the back such
that the tender on the surface can, in an emergency, haul an unconscious
diver back to the hole. The harness should not be able to slide up the
diver's torso when pulled.
Rope signals or voice communications systems must be used.
A roped standby diver is ready on the surface.
One or two divers may dive at the same time from the same hole, each
with his or her own rope. Using two ropes runs little risk of getting
tangled together, but using three significantly increases this risk.[citation needed]
If the regulator free-flows and freezes, the diver should close it down and switch to the backup, and terminate the dive.
When diving in pack ice, the surface team must constantly monitor ice movement to ensure that the exit is not compromised.[2]
The diver must ensure that there is always a positive indication of
the route to the exit area. A tether to a surface tender is usually
preferable as it can be used to communicate,[2] but if this is not practicable a reel and distance line is an alternative.
The risk of attack by predators should be considered. Polar bear and leopard seal may be hazards in some areas.
Deployment of a single tethered scuba diver is a reasonable and safe
alternative to free-swimming buddy team diving. The tethered scuba
diver is equipped with a full-face mask with voice communications, high
capacity scuba air supply, and an independent emergency air supply. A
lifeline with communications cable is secured to a body harness on the
diver and is handled by a surface tender who is in constant voice
communication with the diver. A similarly equipped standby diver is
available on the surface.[6]
A guide line can be used as a reference for the divers to find the
hole after the dive or in an emergency in a similar way to cave diving
or wreck penetration.
Training
Training includes learning about how ice forms, how to recognize
unsafe ice conditions, dive site preparation, equipment requirements,
and safety drills.
Ice divers should be skilled in the use of drysuits, choice of
thermal insulation, buoyancy control and weighting, and should be
competent and experienced with the specific equipment they will use.[2]
If lifelines are used, both divers and tenders must be competent to use them.[2]
Other skills required by the ice diver include:
How to impact the underside of the surface ice if the diver's weight
belt falls off for any reason and the diver ascends uncontrollably and
rapidly.
How to deal with a frozen air-supply system using a redundant back-up system.
What to do in the event the diver loses contact with the line or the
line tender does not get feedback from the diver in response to signals
given to the diver.
Hazards
Hazards of ice diving include the general hazards of penetration diving, and some hazards that are more specific to the low temperature and overhead environment.
Slipping on ice since scuba gear is heavy outside of the water. Also
the water on the divers exposure suit can quickly freeze reducing
mobility and traction
Regulator freezing
When air expands during pressure reduction in a regulator, the temperature drops and heat is absorbed from the surroundings.[7] There are two possible ways for a regulator to freeze and free-flow.
First stage freeze
Air from the diving cylinder is subjected to a dramatic reduction in
pressure - as much as 220 bar from a full 230 bar cylinder at the
surface - when passing through the regulator first stage.
This lowers
the temperature of the air, and heat is absorbed from the components of
the regulator.
As these components are largely metal and therefore good conductors
of heat energy, the regulator body will cool quickly to a temperature
lower than the surrounding medium.
When immersed in water during a dive,
the water surrounding the regulator is cooled and, if this water is
already very cold, it can freeze.
If the water in direct contact with the pressure transfer mechanism
(diaphragm or piston and the spring balancing the internal pressure) of
the regulator freezes, the mechanism will be locked in the position at
which the freezing takes place, as the ice will prevent the movement
required to close.
Since the cooling takes place during flow through the
regulator, it is common for the freezing to occur when the first stage
valve is open, and this will freeze the valve open, allowing a
continuous flow through the first stage.
This will cause the interstage
pressure to rise until the second stage opens to relieve the excess
pressure, the pressure relief valve on the first stage opens, or a low
pressure hose or fitting bursts.
All of these effects will allow the
flow through the first stage to continue, so the cooling will continue,
and this will keep the ice causing the problem frozen.
To break the
cycle it is necessary to stop the gas flow or expose the ice to a heat
source capable of melting it.
While underwater, it is unlikely to find a
heat source to thaw the ice and stopping the flow is only option.
Clearly the flow will stop when the pressure in the cylinder drops to
ambient, but this is undesirable as it means total loss of the breathing
gas.
The other option is to close the cylinder valve, shutting off the
pressure at the source.
Once this is done, the ice will normally melt as
heat from the surrounding water is absorbed by the slightly colder ice,
and once the ice has melted, the regulator will function again.
This freezing can be avoided by preventing water from coming into
direct contact with cooled moving parts of the regulator mechanism,[1][8] or by increasing the heat flow from the surrounding environment so that freezing does not occur.[9]
Both strategies are used in regulator design.
Second stage freeze
A similar effect occurs with the second stage. Air which has already
expanded and cooled through the first stage expands again and cools
further at the demand valve of the second stage.
This cools the
components of the second stage and water in contact with them may
freeze. Metal components around the moving parts of the valve mechanism
allow heat transfer from the surrounding slightly warmer water, and from
exhaled air from the diver, which is considerably warmer than the
surroundings.
A second stage freeze is also likely to happen with the valve open,
causing a free flow, which may precipitate a first stage freeze if not
immediately stopped.
If the flow through the frozen second stage can be
stopped before the first stage freezes, the process can be halted.
This
may be possible if the second stage is fitted with a shutoff valve, but
if this is done, the first stage must be fitted with an overpressure
valve, as closing the supply to the second stage disables its secondary
function as an overpressure valve.
Source: Wikipedia.org
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The Aquatics Unit was formed in 1969 after its founding members
recovered a 3-year old child from a body of water in Highland, IN.
Lake Eliza F.D.
Pendleton F.D.
