Category — Cave Course

JJ CCRs take over Mexico!!!!!

Some time ago I was lucky to have the possibility to do a cross over training to the JJ CCR. My Instructor was Sami who is teaching on the unit since quit some time and already performed some very deep dives in the cold mines of Finland.
We started off by taking the unit completely apart even the sensor harness and the solenoid as well as running through the functions of the Shearwater Predator. The first thing that comes to mind is SIMPLICITY. The unit is extremely easy dis- and assembled and I LOVE the possibility to open/clean the solenoid as well as to change the wiring of the cells with no tools out in the field. This makes the unit especially interesting for people that travel a lot or do projects in remote areas.
The Predator has the OLED display that I am already a big fan off due to my Liquivision X1 and same as the X1 the menu is so incredible easy that even a 5 year old could use it.

The unit is very solid built and due to the back mounted counter lungs is very clean in the front. It has a manual O2 button that can be swiveled around and therefore be used as an off board gas intake. With the metal stand you can easily park the unit even on uneven ground without having to constantly worry that it will dip over. The can is made in a way that almost any tank seize will fit and there would be also the possibility to dis-invert the cylinders if wanted!

Right after that we went to the Cenote Chikin Ha for some confined water training. Already gearing up was nice due to the back mounted counter lungs which makes it very similar to putting on a set of doubles (minus the weight of course =)
Under water the unit performed flawless and some of the things I liked right away was the work of breathing, the single hand set and how easy and fast it is to flush the unit.
We worked ourselves though the standard exercises including Hyperoxia, Hypercapnia and Hypoxia as well as Boom scenario and different computer settings and options. One thing that the JJ has that I like on any CCR is the possibility to perform a diluent flush while being off loop with no mayor changes in buoyancy.

Some of the things I didn’t like was first and foremost the very sensitive automatic diluent valve which basically fired each time I was lowering my head a little, although I have heard that this got corrected some time ago and there is the option to switch it off and use a manual add button (similar to the oxygen one) only.. In my opinion diving with minimum loop volume is very important for good buoyancy control and steady PO2.
Also I felt the unit to be quit butt heavy even though I was diving in a dry suit which again though is the same with almost all units on the market. Other things that bothered me a little were the water trap on the exhale side which simply doesn’t keep the water in the lung when you are diving in a horizontal trim and the bail out valve that constantly free flows when you are on the surface which can easily be fixed with a shut off.

The next day we went down south of Tulum to dive Kaan Luum which was really cool and a great experience. We ran through all of the emergency drills while swimming around in this huge sinkhole in absolutely green water.
Thank you Sami again for a great course and some awesome dives!!!

After that I started a CCR cave crossover with Mia who came also with her JJ from Finland.

She did her Cave One last year with me on OC and now was back for more. We had an amazing five days full of incredible long cave dives filled with drills and exercises. This is definitely one of the most demanding courses we teach here and divers need to have their units fully under control if they want to use them here in the cave environment. Many of the local caves are shallow and due their no/low flow nature are filled with fine grained sediments which once disturbed can stay disbursed in the water column for hours. Diving these caves asks for a super streamlined gear configuration, precise buoyancy control, fine tuned propulsion techniques and expert skills in dealing with zero visibility situations. The key skill is to deal with potential problems without creating new ones while in the process.
It was definitely not a walk in the park but Mia was on top of her game and was very focused and concentrated through out the course and therefore successfully completed it which made me very proud!

Congrats Mia, good job!!!!

I hope to soon get some more JJ divers here for some more CCR cave diving fun.

When planning to take a ccr (closed circuit rebreather) cave diver training program, when planning to take a ccr into the cave environment a number of diver, training, drill and skill performance needs to be considered. The ccr cave diver training program is one of the hardest and most complex training programs there is.

We have to be able to do all ccr related emergency drills and skills in the cave such as hypercapnia, hyperoxia, hypoxia, partially flooded loop, complete flooded loop recovery, boom scenario and electronics failure in the cave environment while doing o/c bailouts over larger distances, running the rebreather manually simulating failed open or closed solenoids in a horizontal position not losing sight of the line, not bumping into the ceiling and not bumping into the floor causing a silt out and creating potentially zero visibility, increasing the stress factor and the potential need of embarking on a lost line scenario. You get the idea what I mean with complex activity.

As we plan to dive our rebreather in the cave we need to learn all about the cave diving skills such as diving horizontal, good buoyancy, anti silt propulsion techniques, good line laying technique in terms of getting from the openwater to the beginning of the permanent cave guideline and doing jumps or multiple jumps in complex navigation dives as well as the cave diving related survival drills such as primary light failure and backup light exit, sharing gas with a buddy providing o/c bailout gas from our bailout tank, handing over bailout tanks, touch contact in zero visibility, lost line scenarios is zero visibility, searching for a lost dive partner potentially in zero visibility just to name a few. On top of that we need to dive our rebreather.

In order to be able to learn, conduct and participate actively in the above ccr cave training scenarios the ccr diver needs to have good buoyancy and trim skills as well as having a thorough understanding of his or her particular rebreather model to be able to still manipulate and control the ccr in adverse conditions when stress might be high and visibility low. Over time skills get rusty and get lost. It is important to rehearse and hone these skills in order to be ready to receive the ccr cave diver training. If you are not ready but rusty you will be in for a very frustrating experience.

An important step to prepare for a planned and upcoming ccr cave diver training program is to work hard on buoyancy and trim skills. It is a fact that a cave diver has to dive horizontally and it is a fact that a cave diver has to stay away from the silt on the floor and the ceiling, besides not to damage the fragile cave environment. What’s the use if we like to cave dive but fuck up the cave in the process.

During a pre training program period buoyancy and trim should be especially worked on and practiced. Best to do it in very shallow water, a pool or confined water area with a max depth of 20 – 30 feet / 6 – 9 meters. I know it’s not easy but this is the point exactly. The skills to work on are the skills you need in order to dive in the cave environment safely, and all skill should be performed in a horizontally position not touching the floor or ground and neither the water surface as these both signify the cave floor and ceiling. All drills should be practiced in a way that you do not swim in circles but can do them stationary. All drills should be practiced in full cave diving gear including the bailout tank or tanks, lights, hood, primary light, backup lights, reels. The whole nine yards.

First get your diver skills up. Practice buoyancy, horizontal trim and proper weighting. Most cave environments are in fresh water so check out the weight you carry. Practice propulsion techniques out of the cave diver leg up position such as modified flutter, frog, shuffle and reverse kick. The reverse kick is super important as it lets you stop and back up without the use of your hand which could stir up sediments. Once you have these skills down practice ccr related skills. Being able to turn on a dime with the helicopter turn will prevent you from going in circles and loose direction and orientation.

Once you have your diver level skills sorted and you are able to stop, backup, do helicopter turns, hover motionless and be comfortable move on to the ccr related skills such as hypercapnia, hyperoxia, hypoxia, partially flooded loop and complete flooded loop recovery, simulate electronics failure and solenoid failure in the open and closed while diving your e-ccr manually. Practice boom scenarios. As you go through all these drills remember you are planning to participate in a ccr cave course, meaning you have to do all these drills hovering, horizontally, legs up, not touching the water surface or bottom in your pool or confined water area.

Once you have honed your diver level skills and ccr diver skills as outlined above I would consider you ready to embark on a ccr cave diver training program without being overly frustrated as you have the basics down and be ready to receive ccr cave diver training to go finally cave diving. Enjoy Matt