Technical diving pioneer and Dive Rite CEO Lamar Hires
Risk Assessment for CCR diving
My specialty is cave diving so I look at risk factors based on the cave environment. Divers refer to the overhead or ceiling as anything that prevents a direct ascent to the surface. For many divers this is the decompression after a deep wreck dive. For me it’s about the trip home, the cave entrance. Failures in a cave still require an exit before worrying about decompression, so bailout and gas management are calculated differently. We need to carry bailout for the exit, based on penetration, flow, visibility and hazards (restrictions). This is typically more bailout then wreck divers since their concerns are ascent and decompression. In caves we can stage bottles and decompression gas so we don’t think about what we can carry, but rather where to stage it.
How much bailout is enough or when is it overkill? (Click below to continue)
Risk assessment is a personal perception and acceptance of the
risk-to-reward of a dive plan. Some look at the minimalistic approach
while others want to make sure that every contingency is planned for.
Example – Cocklebiddy Cave in Australia was explored by the Aussies
using sleds to carry an abundance of gas to push the cave beyond Toad
Hall. A Frenchman came in with a minimalistic approach using scooters
and pushed the end of the known cave with a small team on one dive,
(camping at Toad Hall); a different approach and different perspective
of risk-to-reward.
We all have a different perspective of risk-to-reward and we need to be
aware of setting parameters based on one’s own standards. Some of the
factors may be health, physical fitness, familiarity with a dive site,
skill level and dive partners. We all approach risk differently and can
look to other sports and activities when we make evaluations. Do you
drive the speed limit or push it to the limit of safety or what you
think is allowable without getting a ticket? Snow skiing is a good
parallel: the trails are rated with level of difficulty, green for
novices, blue for intermediate and black diamonds are for experts. You
can take lessons to increase your skill level before venturing on to
more difficult trails, but you always have to weigh the risk-to-reward
when you venture on to more difficult trails. Just like CCR diving you
need to weigh the risk-to-reward factors.
I hope by now you have a grasp of my risk-to-reward concept. The
following is my opinion on risk-to-reward for CCR cave divers. The
amount of bailout a diver should carry for a dive seems to be the topic
of discussion. What is an adequate amount of bailout for a diver?
Should a dive be planned on a team concept or on individual self rescue
concepts? I have to answer “it depends,” but on what?
First let’s define bailout – “The gas needed to exit the cave in the
event of a total loop failure“. Divers practice and execute exits
during class to affirm this, but a drill is not the real thing. During
a drill all events are controlled; even if the events are spontaneous
it is still just a drill. Many assumptions are made during drills and
there is always the peace of mind that it is just a drill. Breathing
rates are controlled because it is just a drill (you can go back on the
loop if you need gas), we need to factor in the “oh sh#?t” factor to
see what happens to breathing rates and bailout needs for an exit. How
much gas is expended before you determine the loop is “toast”? Now
reality sets in on a number of levels. 1) How long to get out? 2) How
much gas do I have after trying to solve the problem to get back on the
loop? 3) Did I stage enough deco gas for this scenario? 4) How fast can
I get out (further elevating the breathing rate)?
Risk-to-reward evaluation
As a cave diver I believe in redundancy. If I am down one regulator
then I have serious problems and I need to get out of the overhead
situation. This does not sit well with me. I can’t shake the cave diver
mentality. There is safety in numbers or redundancy as we cave divers
refer to it, so I will not set bailout up on a one bottle scenario. My
choice is to carry two bailout bottles in a sidemount configuration for
streamlining and balance out the gas. If I need 80 cu ft of gas, which
is common for most dives above 130 feet, then I carry two 40 cu ft
cylinders. If the dive is deep or long requiring more bailout then I
carry two aluminum 80 cu ft cylinders and/or stage the gas considering
variables like flow, restrictions, DPV and visibility.
I find there are open circuit divers that try to impose their
perspective of risk-to-reward on CCR divers, yet don’t follow the same
rules. For instance, the average cave fill is 300+ cubic feet of gas,
but a solo cave diver is happy with a single aluminum 80 for bailout.
Do the math; this is not 1/3 of the starting gas volume so how can 80
cubic feet be acceptable for open circuit divers when they need to
carry at least 100 cubic feet? The answer is comfort level. Open
circuit divers are comfortable with an aluminum 80. It is perceived as
enough volume to take care of any problem. If a diver has to use this
bailout bottle then he is down to one regulator and serious problems
for the trip home, but the odds of using it are so slim that the risk
is acceptable to most cave divers.
CCR divers don’t have this long history to fall back on. We use open
circuit procedures as guidelines to develop our own risk-to-reward
assessment. As I push farther into the caves on CCR, I weigh and
re-weigh the risk-to-reward element. What works for me today may not be
right for tomorrow. I started with a single bailout bottle, sometimes a
40 cubic foot cylinder in a team management plan and then an 80 for
longer dives. Today, I dive twin 40 cu ft bottles for an average dive
of 1500 to 2000 ft penetrations on dives averaging 100 ft in depth,
then move up to twin 80’s and stages for deeper or longer dives.
Sometimes when the cave is small I use twin 40’s and 80 stages like
diving at Rose. My last big dive in Devil’s Ear was a 4000’ working
dive so it called for twin 80’s bailout. Bailout style is determined by
the mission, a single dive site may require multiple bailout
configurations based on the objectives.
Bailout management plans – The team concept or self sufficient. This
appears to be the argument today. As I stated earlier what I carry is
a mission based plan. I have already heard the comment that a
recreational dive for me may be a push the limits dive for another
diver, so is the difference in bailout requirements. Traveling the
main line in a popular cave system, doing a dive I have done before on
OC is very different from planning a push dive. On the recreational
dives the team concept works very well, I carry the feel good 80 cu ft
of gas but in two aluminum 40 cu ft cylinders. I am self sufficient
for bailout but able to help a buddy in distress since my bailout is in
two cylinders. On longer dives both methods are used. We stage gas in
for bailout but since we aren’t breathing it we stagger the bottles to
give either team member as much gas as possible in the event of a total
loop failure. For instance on a 4000’ push at 130’ we drop a bottle at
1400’ (best location for visibility) another at 2400’ and then we drop
DPV and swim on with 80 cu ft each (in 40 cu ft bottles) because the
cave gets small and we need wiggle room. If it was a three man team
there would be one more 80 cu ft bottle dropped to leave a nice trail
out gas for the team. On long DPV dives with no swimming involved we
would just carry 2 aluminum 80 cu ft cylinders each.
I gauge my bailout needs on my open circuit experience for exiting a
cave and plan accordingly. I suggest that CCR divers look to open
circuit gas management and use their reserves as a meter for bailout
needs. If an open circuit diver is going to do the dive on a set of
high volume doubles, then a couple of 40 cu ft cylinders should be
adequate bailout for a CCR diver. A CCR diver has more options when
problems occur; switching to open circuit bailout is often the last
resort. Planning is critical, but understanding ones needs is very
important to planning. Do not plan a dive on best case scenario, but
rather a realistic worst case scenario. --LaMar Hires
