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Thanks for all the emails. Because there were so many I just posted this as
a starter.
The following information was written for other purposes but as you read it
remember that it was written at a beggining level and to avoid any
specifics. Lift bag deployment as a decompression platform is different in
all areas of the world and only you can make the final choice as to the
style and deployment configuration. The specifics will vary based on
visibility, golves vs no gloves, current, surface conditions reel sizes and
bag sizes ect. Read this and you can give me an email back if you like but
make sure you include where you are from and we can make sure that you are
looking at the right concepts and mabye I can put you in touch with someone
in your area that I know.
I wont get into to many specifics here as we all know the ability of
techdiver to twist a basic subject into a scientific project. I am located
in Vancouver BC Canada. The water is about 38 to 48 degrees and vis ranges
from 0 to 40 feet. The most popular system in this area is a standard
diverite primary reel with a 100 lbs lift bag. This is because we do alot
of open water decompression on the coast and around islands. We can never
really know what depth is below us as you drift around the islands. Droping
line below us is not an option due to OUR situation. I have done lots of
diving in Florida where (know that I think about it) this may work but at
the same time, simple practice and repitition with a lift bag will eliminate
about 98% of any reel entanglements you may experience when releasing the
bag. We all fill the bag and release it from depth here, no problems.
EAL !!
by Reg Creighton
Diver Magazine March 1996
Your drifting along the wall and you start paying far more attention to the
fish than you should. Your lack of attention to the dive profile has left
you out of sight from the wall and the bottom is far below. You now find
yourself in mid-water with these fantastic fish you were looking at, with no
reference....what do you do ?
The EAL or Emergency Ascent Line is probably one of scuba diving's best kept
secrets. This simple configuration of equipment is used to assist divers
through a safe, controlled ascent in limited visibility or in openwater
where the bottom cannot be seen. Let's be honest, how well can you control
your ascent in mid-water and can you (if needed) complete a safety stop or
decompression stop with out a reference. The EAL consists of a line reel
that can spool out line at high speeds and a lift bag that can be attached
to the reel (easily). As easy as it sounds, the key to using a safe EAL
system is understanding the basic concepts related to it's design and
deployment.
First, the act of deployment. There are many way to utilize an EAL but
let's start with the basics. Although the details are slightly different in
each area of the world the basic concept is the same.
1. Free Ascent EAL Deployment
During this method of deployment the diver attaches the reel to the lift
bag and sends the lift bag to the surface from depth. As the diver ascends
they reel in the line and slowly travel to the surface. While ascending the
diver can stop for safety or actual decompression stops on the way to
the surface.
This is probably the most popular method of EAL deployment
in areas where there are prevailing currents that make it difficult if not
impossible to stay in one position during ascent. Any time
you are diving a sight with current (and it does not take much) you should
consider taking an EAL system of some kind with you to
assist in your ascent.
By using the Free Ascent EAL you have A) notified anyone on
the surface that you are ascending B) given a visual aid marker that points
directly to you for the duration of the ascent and C) you have supplied a
line of reference in an area of ascent where it can be difficult (if not
impossible) to maintain orientation due to a total lack of reference points
whether it is from poor visibility or it is simply to deep below you to see
the bottom.
This type of deployment also allows you to ride the easy
seat so to speak. The diver will drift with prevailing currents instead of
fighting against them. The end result is a lowering of
diver stress and physical exertion levels as well as slowing heat loss from
having cold water flow around you, allowing you (the diver)
to enjoy the dive "and" the ascent.
The major drawback of this method of deployment is simple.
You have to know you can get back to the boat or shore when you finish
the ascent. Unless you enjoy walking with your equipment on. On safety
stops or decompression dives in current swept waters it is not
unusual to drift a very long distance in a very short time, not to mention
that the current will not always take you to shore. (Then what do you
do ?)
2. Assisted EAL Ascent
Using the Assisted EAL method of deployment the diver releases the lift bag
up to the surface (just as they did with the fee ascent EAL) and
then runs the line reel under a solid piece of wreckage (preferably
something that is "not alive"). The diver then ascends beside the line by
releasing line off of the reel which allows the diver ascend to the
surface. Once the diver reaches the surface the line is cut where it is
attached to the lift bag and the line is reeled in(as long as it is not
caught on the wreck below). This allows the diver to loose very little of
the line that was used on the reel.
This is a type of deployment can be used to A) mark the
surface for any surface support or boat captains and B) allow the diver to
maintain position relative to the dive site. This deployment is usually
done with a much thicker line that will not easily break from the strain of
the ascent or cut from the abrasion of wrapping it on a piece of wreckage.
The increased thickness of line on these systems usually makes
them much larger in size and harder to carry on the dive.
Also, special note should be taken for tide and current changes that may
drastically effect the divers ability to stay in one position for the
entire ascent. A long or short stay in any type of current
can raise diver stress levels and breathing rates as well as chill the
diver thoroughly in cold water.
3. Tied EAL Ascent
In the tied EAL ascent, the diver once again sends the lift bag to the
surface but then ties the line to a piece of wreckage. Once tied, the line
is cut and the reel is stored back on the body to free the
divers hands for the ascent to the surface. When the ascent is complete
the diver will cut the bag off of the line and leave the
rest of the line to decay away naturally over a period of weeks.
A quick reality check will pull up many obvious bad points
related to this system. First, it has to be a special line that will decay
and disappear quickly if left in the water, unfortunately,
if you use this line it will need to be replaced constantly because every
time you dive, it gets wet, kind of a catch 22. Second,
anytime you leave line in the water you place the next diver (not to
mention local sea life) at risk of line entanglement until
the line has actually decayed. Several other points are applicable to this
ascent that include the risk of fighting current and tidal
exchange while stuck in one position in the water column as well as
hypothermic conditions related to cold water current
conditions.
So those are the basics, as usual there are hundreds of
combinations and hundreds of different applications for each system.
Regardless of your choice of Emergency Ascent Line system
deployment it is essential that you get training. Special care should be
taken to develop contingency plans....make sure you ask
yourself....what if ...."before" you deploy any EAL system.
The EAL is a very simple skill to learn and with some
pointers from your local Technical Instructors you can find out what is used
in your area and why. Remember....you can make a
difference in diver safety. Get Trained, stay wet and dive safe.
Reg Creighton
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