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Several days ago the question of how to properly enter a sump was raised,
below is a section from the NEST manual that addresses this topic. This
inf. in no ways qualifies the reader to try this at home........sumps can be
the most wonderful places on the planet and they can also be the worst if
you are not properly equipped and prepared mentally, and physically. It is
incredibly easy to get over your head in hurry in a sump. The line between
being warm and comfortable and having a really bad day is very fine and not
all that obvious until you cross it and see the elephant.
Safe Diving
JOE KAFFL
SUMP EXPLORATION
Great care must be taken in the exploration of virgin sites, a measured
approach of gradually increased penetrations is the safest. The urge to
lay large amounts of line must be tempered at all times by safety
considerations. It is better to lay a short section, turn the dive and
learn the route back under low visibility conditions then to bite of too big
a chunk at once. The fun level rapidly declines under these circumstances.
The sump will always be there for another dive, you may not if you over
extend yourself.
The difficulty in negotiating a section of passage under poor visibility
conditions is greatly reduced by learning the passage in short sections.
Original exploration dives are best accomplished solo with a backup diver in
support standing by geared up. Conservative planning for gas use is a vital
consideration. Site conditions will play a major role in this decision but
as a general rule the use of no more than � of ones starting gas is a good
guide line.
Sumps have a wide variety of personalities and range from almost crystal
clear bodies of water to those in which the visibility is only one to two
inches. If you are fortunate enough to come across a clear sump entrance
pool the greatest care must be taken to preserve this visibility for as long
as possible. The physical layout of the cave will determine your approach to
entering the sump. All things being equal your first task is to determine
the direction in which the cave passage appears to trend and the direction
of water flow if any. This can sometimes be accomplished with a surface
recognizance.
If you are dealing with a spring flow and there is a stream that exits
from the sump this may be your best entrance point. In a situation of this
nature select two separate bomb proof line tie offs on the surface and
position your line in such a manner that it enters the sump at an angle to
your travel path so that you do not have to swim over your line or cross it.
The placement is based on your best guess of the direction in which an under
water passage may head. If natural tie offs are lacking make use of dog
spikes or other artificial belays. After donning your gear lay in the
stream outflow, put on your fins and conduct a final equipment check, then
slowly crawl forward into the sump. If possible proceed to a point where
you can place your mask under water and shine your primary light around to
determine your direction of travel before committing yourself. Once you
have done so enter head first with as little disturbance of the silt as
possible. If you have a going lead head for it, deploying line as you go,
and execute an under water tie off on a solid belay point before entering
the overhead. These natural tie offs are hard to find in most sumps so you
may have to deploy a dog spike if you have deep sediment or use a drop
weight if this is not an option. The proper placement of your under water
tie off is vital to your safety. It should be positioned so that the line
enters the passage you will be exploring parallel to the passage walls and
does not create a line trap. Place the line for maximum ease on your exit
since chances are that the return trip will be done by feel.
Rapid movements and finning are your biggest enemies to the visibility
when accomplishing these initial tasks. Take it slow and do not be spooked
by the billowing cloud of sediment that your entrance will probably create
into making it worse by finning vigorously in an attempt to get ahead of the
cloud. In entering a low flow spring the sediment will be propelled by the
energy you impart to it, it can not swim upstream by itself. Move slowly
and you impart less energy to it. The silt cloud your entrance creates will
in most cases remain a local phenomena that you can slowly move out of and
into the clear water to your front.
As you move forward visualize the passage and make sure you feel
comfortable with returning through the passage that lies behind you. If at
any time you do not feel comfortable turn and exit. Insure that you
properly place the line to avoid line traps on your exit. When ever possible
try to follow a wall or sediment pile avoiding crossing back and forth
across the passage. Belay the line at regular intervals and if you run out
of natural tie offs and use up your artificial anchors this is a hint that
it is time to head for home. If you are fortunate enough to crack the sump
do a good tie off on the surface before exiting. If you have a support
diver standing by take a cautious breath or two to verify that the air is
good and exit before he comes looking for you. The exploration will have to
wait for a second dive. Take the time to savor the experience, don�t rush
things or the chances of a cluster greatly increase.
If you are dealing with a low flow siphon attempt to gear up out of the
inflow and follow a similar procedure. If you are following a stream
passage to the sump entrance pool you may have to gear up a few hundred feet
above the pool and move rapidly to the the pool before the sediment you have
stirred up reaches this area. Once you enter the pool you may still be able
to stay ahead of the silt cloud by moving carefully at a moderate speed.
Every sump is different so you may have to apply other creative
approaches, the goal is always to minimize your impact on the visibility as
long as possible and to move slowly and deliberately. Take the sump in
comfortable sections and then turn the dive. If it takes more than one dive
to crack the sump don�t be concerned, this is what may be required to do it
right.
--
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