CCR cave diver training Part III – Into the inky darkness

Deep sinkhole photo shoot preparation Part III – After preparing the unit for horizontal trim and sorted out propulsion and rebreather emergency drills such as the three H’s (Hypercapnia, Hyperoxia, hypoxia) and the boom drill (internal and external uncontrolled gas release) we are ready for the ccr cave diver training program. It is only now that the student is actually ready to focus on the upcoming and cave specific training sessions.

The ccr cave diver training program is the most complex training program taught to students only topped by ccr Trimix cave diver programs. The complexicity is coming from the complex activity or rebreather diving combined with the complex activity of cave diving.

Before we jump in the water a long review of ccr dive planning practices is done plus the introduction of bailout range calculations including the optimization of bailout gases. The biggest difference between a oc cave diver and ccr cave diver are the bailout range or bailout umbrella. The ccr cave diver can spend quite a long time within bailout range (given he is within 1/3’s of sorb, o2 and diluent) diving down different lines to see a lot more cave then the oc cave diver who is bound to just go in and out of the cave.

The cave diver training program starts in the trees where we talking about laying a line into a cavern or cave, how tie offs are made, what the critical positions and tasks of each team member are. The student, in this case Paul Nicklen, learns how to lay a line and how to follow it in zero visibility feeling the line and tie offs. Touch contact communication is explained and practiced.

An introduction on what to do with the safety spool is given in case we have a lost diver or lost line in zero visibility situation. A full explanation of the drill including a full real time drill on land will be given later in the course before we actually do the drills inside the cave.

After the surface we move into a openwater area of a cenote with a large enough openwater pool. Most if not all Mexico cave diver students will know Cenote Eden or Ponderosa as it was called before. Many may know its nick name the pool of pain due to the pain felt by all students initiating their training here. The drill practiced on the surface are repeated in the openwater including a stress circuit where entanglements may happen in simulated zero visibility conditions. Once that is done to the satisfaction of the instructor we can move on into the cave.

The most difficult part of cave diving is to get from the openwater to the beginning of the permanently installed guideline due to the depth change and connected buoyancy changes that are more profound and difficult to deal with being on a ccr rebreather. Once we are on the permanent line and have tied in our reel we are free to cruise … until we do complex navigation in the form of T’s or jumps. The first day or two are spend with short penetration dives doing the three H’s drills, boom scenario, primary light failure and touch contact drills alone and as a team till survivability levels are reached.

Once the student is proficient in ccr and cave survival drills we move on to deeper penetration with constant and now un-briefed ccr emergency drills who now can and will happen at any time during any dive or situation to heighten the students awareness and hone emergency response time. During this period we go back into the trees on the surface to talk in detail about lost line in zero visibility and lost diver scenarios. Once the concept has been understood and drills have been mastered it is time to conduct the drills in the cave. I am of the opinion that the lost line drill is of utmost importance and must be completed successfully. If that can’t be achived on one dive we have the rest of the course to repeat the drill until mastered successfully and thus building confidence in the student.

As the student is getting more and more aware of its surrounding, developing better trim and propulsion, getting better with communication, has a good response to ccr related emergency drills and cave related emergency drills we move on to complex navigation in terms of T’s and jumps, circuits and traverses. A special lecture is given and back in the trees on the surface a spider web of lines is installed to explain hands on about how to do jumps, how to mark intersections and explain the communication within the team in order to ensure that every team member has seen and understood the jump or T that has been created and is now to be navigated. Failure to do so may have dire consequences when the team is coming out of the cave in a worst case scenario in zero viz, off loop and under high stress finding the intersection has not been marked properly. Marking properly means marking our very own exit to be easily identified under high stress and in zero viz..

Then we come to the heart of ccr cave diver training where we can penetrate the cave to maximum bailout range taking waypoint on the way in to mark jump off point when we are on the return leg of the dive towards the exit. As a ccr cave diver with sorb with 1/3, o2 within 1/3 and diluents within 1/3 we can jump off to side lines penetration to maximum bailout range and return to repeat at an different line closer to the exit. This way you can cover a very large cave area with multiple passages and jumps while staying within bailout range and consumable safe diving parameters. The complex caves of Mexico are extremely well suited for complex dives of this kind.

During these complex dives the repetition of un-briefed ccr related emergencies such as the three H’s and boom scenarios continues honing the students emergency response.

If the student would have entered the ccr cave diver training program without spending the time and effort of changing his AP Diving Evolution Rebreather into a highly efficient cave diving unit and would have not spend the time and effort in the prep program called Essential Diver program the student would not have been ready to receive, absorb and retain the information during the ccr cave diver training program as the struggle with the unit would have been to much.

The unit modification session and prep-program have been conducted out of ProTec Playa. When we moved on to ccr trimix cave diving we moved down to ProTec Tulum to be closer to the deep sinkholes and caves down there.

Stay tuned for Part IV – CCR Normoxic Trimix in the Cave

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