Category — Naharon

The advantages of a closed circuit rebreather in a shallow cave.

I have to admit that I recently neglected rebreather diving and instead spend most of my time off sidemounting. I pretty much used my rebreather for deep diving only. But recently that changed, I finished crossover training on the Poseidon Cis Luna Mk6 and right after that was with Howard, aka Scubadadmiami for a week of CCR Cave diving. And I am hooked on CCRs again.

The Mk6 exceeded my expectations but this is not what this article is about. What I want to share here is my recent experience diving Ponderosa, Taj Maha, Nohoch Nah Chich, Grand Cenote, Carwash and Naharon. Generally all the dive sites have an average depth of about 30ft and Nohoch even being shallower with Naharon being the exception at 60ft.

In many posts on CCR forums, the Mexican caves are described as CCR “unfriendly” and honestly I do not understand why? Our recent experience illustrated that CCRs can be used effectively in these caves and enabled us to get to know whole sections of systems in only one dive.

Normally when I guide people open circuit I choose a cenote and then guide two dives to the most famous or pretty parts of the system. The dives are usually turned either on time or gas which results in returning to open water. The option to recalculate thirds does exist, however, my opinion is that it should be reserved for experienced divers with experience in the particular system. When divers elect to recalculate thirds, eventually the gas reserve becomes to small to be safe.

The advantage of the CCR is that you have a bail out radius which enables you to spend as much time as the scrubber will allow, normally about 3 hours which is a huge opportunity here in the Riviera Maya.

The cave systems here are like Swiss cheese with many different side tunnels and passages. They are also very shallow. These two characteristics combine to create a situation where divers have a very long range on an 80cuft cylinder. Depending on you gas consumption while bailing out and conservatism factor you want to build in you will have a radius of at least 40min in most places. There are other benefits worth mentioning:

1. Once you come of the frequent traveled passages you will often encounter quiet significant amount of percolation that can seriously affect the visibility.
2. Thinking about the lost line or lost diver scenario, imagine how your chance of survival or the chance of finding your dive partner will increase with an hours long supply of breathing gas.
3. How many accident reports have we seen that speak about people drowning only minutes away from an exit, what would have happened if they would have been on a rebreather.
4. Taking pictures on the way, on a CCR you penetration distance is not going to change because you stop at a place to take some pictures or simply take a brake.
5. Think about a reverse block way back in a cave, how much more relaxed are you going to be, knowing you can stay there fro hours.
6. No time or gas pressure to go to a certain part in the cave and therefore reduced chance of pushing limits due to being goal oriented.
7. And many more

Of course this is a double edged sword and there are as well some negative aspects:

1. Buoyancy is definitely more difficult.
2. It is the perfect tool to bring people that where before limited by their air consumption far into the overhead environment and by that outside of their comfort and experience zone.
3. With most units together with the bail out your overall size in the water column is bigger and therefore you need more effort to travel.
4. Many ups and downs consume Oxygen and Diluent volume.
5. Getting overconfident due to the feeling of having unlimited gas supply.
6. Proper bail out gas and volume is never an issue until it becomes an issue.
7. And many more

To have a real advantage with the CCR we have to change the way we dive in the cave. Instead of using it to go for that record braking long distance penetration why not stay closer to the entrance but get to know all the lines that are in that area.

For example, at Naharon we dove up the main line and did the Jump towards the double domes. We swam up that line until we reached 40min, or bail out distance. On the way we stopped several times to take pictures and simply stopped the timer while we did not go further in the cave. On the way we marked the double set of line arrows that mark the jump towards south western sac be. On our return we arrived back at the arrows and new that from this point on we had 30min for further penetration so now we did the jump and enjoyed the really unreal beautiful sac be section.

On the way there we pass yet another set of double arrows marking the jump that lead down towards Cenote Mayan Blue and again marked it. We continued in the sac be tunnel until we had reached 30min from the jump and turned our dive. On the way back we stopped again a couple of times to take pictures. We didn’t even have to take care about the time since we were well inside our bail out range.

As we arrived back at the Arrows we decided to make yet another jump and check out the line that leads towards Mayan Blue. After some time we turned from there and now did the entire return trip back to Cenote Naharon.

As you can see, we did in one dive what, in conventional OC cave diving style would need three dives. We had an average depth of close to 60ft with a 180min runtime, me carrying an 80cuf and Howard 2 40cuf bail out tanks.

Another example would be Carwash where we could use Lukes Hope to restart the 40min bail out range and therefore had plenty of time to visit the room of tears and all the different Ts in the back. On the way out we did the jump that leads to the back of the room and stayed there for like 30min just doing pictures and enjoying the decorations.

In Grand cenote we went down to the Cuza Nah Loop and could restart the 40 min each time we past a cenote which was awesome since this gave us the possibility to do the jump at the mid way of the loop and take our time while swimming down that line again taking pictures and having a great time. On the way back we continued the loop on the other way since we were still easy inside our bail out range.
And the same was done in all the other places.

All in all I really enjoyed this week especially the possibility to visit lines I have not been too in a long time. I really love to do complex navigation, see different lines and go back and forth and all around.

Another bonus, so to speak, was to get more experience on the Kiss Classic which I really start to like more and more for its simplicity, the 20min prep in the morning and the 5min tear down in the evening, the free chest, constant O2 flow which facilitates buoyancy and the general possibility to keep the same configuration than with a set of doubles.

For Howard it was great too because he really got to know quiet a bit of each system we dove at, although he only did ONE dive there.

Considering all of the above, I would call the caves here perfectly suited for CCR diving if you bring the right set of skills, a good attitude and some creativity to the table.

Of course there are always people that say OC backmount is the only way to go and others believe that OC sidemount is the best, then there are some that believe in multiple stages or scooters or I don’t know what else; Me, I think it all has its use and its just what you do with it that makes it valuable. Try to get the most advantages out of whatever equipment you use and try to work with the right tool for the job!

Keep the loop closed but your mind open!!!

Patrick

A traverse from Naharon to Mayan Blue on rebreathers.

This past week has been very busy for Patrick and me.  With the arrival of “Slow Season” here in Playa Del Carmen, we have found more time and more opportunities to get ourselves into some serious dives.  We have made two trips to The Pit and one trip to Sistema Naranjal with our Megalodons.  Luckily, the dives at The Pit were relatively excitement free, other then Patrick reaching the restriction at Jill’s Chamber at 105 meters.  However, the dive at Naranjal was anything but boring.

Patrick had finished up a full cave class at Mayan Blue on Sunday.  Unfortunately, the student didn’t complete the A Tunnel / Death Arrow circuit, so we had to retrieve the remaining gear, one spool.  We decided the only reasonable way to do the clean up dive was to traverse from Cenote Cristal (Cenote Naharon) down to the Death Arrow jump, pick up the spool, and swim back.  The swim from Naharon to Mayan Blue typically takes about 2 hours.  We decided to cut the swim a little short by only going to the end of the Death Arrow passage.

When we were planning our bailout gas, I was worried about having enough.  I hadn’t swum this distance and I wasn’t sure of the depths.  Patrick and I agreed to take 2 Aluminum 80’s each.  We ran some calculations and it was enough to get us out if we needed it.  Patrick’s calculations showed that two 80’s would last him 4 hours at this depth.  My SAC is higher, so I didn’t have same cushion.

When it came time to decide on our gas mixes, I asked Patrick what he was taking?  He told me Air.  And then we got into a discussion about bailout.  He very sternly explained to me that the choice of bailout gas didn’t really matter.  He didn’t believe he would ever have to bailout.  However, if he did he would only be punished with deco time.  He explained that he follows a checklist and is meticulous about assembling his unit.  I told him I was going to take 32% regardless of his feelings on the topic and I was going to drop a tank of O2 in the cavern for good measure.  You really never know when something unexpected is going to happen.  Isn’t that the definition of unexpected?   We agreed, or I decided in my head, I can’t remember, that if someone bailed out, they would get the 32% and the Air would be the gas of last resort.  At this point, Patrick’s attitude really concerned me and I decided that I was going to have a sit down with him, but I was going to wait until after our dive, as to not mess with his head.

Wednesday arrived and we got on our way.  The dive was going according to plan.  We passed the restrictions heading for Mayan Blue.  At the T, I wanted to “drop” a cookie.  As I got my markers out of my pocket, I dropped my safety spool. I reached for the safety and lost control of my buoyancy and started to fall.  I reached for the inflator, but no luck!  I ended up rolling down the windows saving myself from crashing into the mud, but creating some silting.  I could hear Patrick laughing as he watched this comedy of errors.  I finally got my act together, marked the T and proceeded.  I am sure it looked hysterical, you know how things happen in super slow motion, I know I was laughing about it.

We arrived at the spool at 80 minutes.  He retrieved the spool and we rested briefly.  When we finally got going on the return trip I was in the lead.  We were singing into the DSVs and just enjoying the dive.  After about 10 minutes we settled into a decent rhythm and pace.

At about 20 minutes, I saw a quick flash of the light head of me.  I instinctively turned and started to swim to Patrick.  We were about 50feet apart.  It took me a second to process the situation.  What I saw was one of the breathing hoses from the KISS Classic just floating in the water and I saw Patrick deploying a bailout reg.  My first thought was, ‘Oh shit, what do I do?  My bailout regulators are really secured and are not quickly accessible.’  Before I was close enough to help, he got his regulator out.  I arrived and assessed the situation.  The exhale breathing hose had disconnected from the canister.  At Patrick’s request, I reattached the hose.  We thumbed the dive, changed positions and started swimming.  This is when my heart rate finally picked up and I became aware of the gravity of the situation.  This was a real live catastrophic loop failure way back in a cave.  This is the exact type of unexpected situation we train and prepare for.  I knew we had enough gas, but I still got hit with some adrenalin.  I had to stop and think about my breathing and heart rate for a second.  My heart rate really isn’t under my control sometimes.  The base of the brain just reacts.

As we swam, I stayed near to Patrick in case something else went wrong.  I checked my computer and marked the time.  We had 60 minutes of swimming up stream to exit the cave.  Patrick cleaned up his hose routing and attempted to go back on the loop.  As I watched him attempt this, I just kept thinking, “You can’t recover a KISS from a total flood.  Don’t try.”  He found out in short order it was a done deal.  Then I offered him my 32%.  He waved it off, and he started to play with his X1.  Patrick later told me he thought he would be fine on air.  However, a couple of minutes later when we reached the T, he realized he was running out of no stop time and asked me for some 32%.

He asked at the worst time for me.  I was about to pick up my cookie and had too many things going on at once.  I struggled with my tank for a minute and finally told him to start swimming.  It would be easier to make the switch underway instead of hovering.  At this point I made a mistake, I think I was a bit overloaded and my brain was fried.  Instead of doing one thing at a time, I had the tank neck out of the bungee in the left hand.  I reached down to get the cookie with my right.  Now I was swimming with both hands full trying to get my tank completely off.  Ug! What a nightmare!

I finally stopped and stowed the cookie.  Then I passed the tank to Patrick.  He reached down to pull the regulator off the tank and the mouth piece came off!  The irony is that Patrick recently told me it was stupid to put the bungee necklace under the same zip tie as the mouth piece and that the mouth piece would come off at the worst time.  I defended my choice and didn’t change my configuration.  The bungee was wrapped around the tank neck and under the single zip tie.  When he showed me the regulator without the mouth piece, I could hear his voice in my head and I laughed.  I have since changed my configuration for CCR diving.  I removed my 120 degree swivel and the necklace on the bailout regulators.  I want them to be as accessible as possible.  Now, I believe that I will need them at the worst possible time.  He replaced the mouth piece and started to enjoy the joy that is 32% EAN.

Patrick swam off and I struggled with his tank.  This dive taught me my sidemount bungees are too short to be useful in an emergency.  As I struggled with the tank, I swam into the ceiling with my rebreather.  It got a little hung up so I jerked my head down.  I immediately realized my head was way heavy and I was heading for the floor!   A huge rock had broken loose and was on its way to pinning me.  I rolled to the right and the rock fell off my head before I hit the ground.

Again, I laughed.  I couldn’t believe how many things had happened to us on a single dive.  We have been diving for seven months together and all of those dives had been incident free.  A series of walks in the park, including cave dives to 300ffw.  The type of diving that breeds complacency.

I caught up to Patrick and we continued to exit.  We decided to pull our gear.  As I pulled my spool from the jump between Southern Sacbe and Southwestern Sacbe, I created a nasty knot around the main guideline.  I ended up cutting the spool free from the guideline.  It was the last in a row of incidents.  We exited safely with a total run time of 180 minutes.  I estimate the total distance at around 8000 feet.

Patrick and I agreed that we handled all of the situations acceptably.  We did a serious review of the dive and have both made changes to our rigs and attitudes.  As I mentioned, I changed my regulators and I lengthened the sidemount bungee.  Patrick also made some changes to his regulators to ensure they are accessible.  We adjusted our bailout gas attitudes.  And we agreed to take better care to avoid team separation.

Once the stress started to pile on, it made simple tasks like a tank swap more difficult.  A task he and I normally can handle in a minute or less took a couple of minutes.  My overall awareness decreased and we got a good distance apart more then once after the main failure.

I feel it was an excellent dive!  We both returned and no one was hurt.  We tested our abilities as a team, and as individuals in a stressful situation.  We both stayed calm and controlled our breathing.  We reacted instinctively and completed the tasks at hand.  We realized our performance wasn’t perfect but it was acceptable. The whole dive confirmed to me the following idea.  Bailout is for unexpected situations and it does matter.  No matter how bullet proof you might think you are or your procedures, unexpected shit happens and it will happen at the worst time.  And these situations never happen alone, they are always compounded by other events.

Patrick used just over 2000PSI from one Aluminum 80 to exit from 60 minutes into the cave.  I hope you learn a little from this, I know I have learned a lot.

As always, your comments and criticisms are welcome here.  If you want to know more about the incident, leave a comment and one of us will respond.

Saturday morning I got up and went to breakfast with a close friend. I still wasn’t sure where I was going to dive. After breakfast I went to The Gym for a run and an ab workout. While I was at the gym it came to me, a eureka moment! I decided I should go to Naharon with my Megalodon and do a CCR length dive.

I went home and pulled together my bailout and my rebreather and jumped in the car. I discovered it is almost exactly 40 miles from my apartment to the entrance of Cenote Cristal. The drive down was uneventful although a little lonely. That is the biggest drawback and the biggest upside of solo diving. The whole thing is solo. I always think of diving as a social activity. Talking about the dive, anticipating the dive, executing the dive and then taking about how big and scary the conquest was all make good memories. Unfortunately, talking to yourself about all those things might get you committed and is just not that entertaining.

I decided on an AL80 and an AL40 for bailout. I have the 80 plumbed into my manifold, so I can use it as diluent or for my BOV. 120cuft of gas gave me a max penetration time of about 50 minutes at the depths I was expecting. This was enough time to cover the distance and areas I wanted. I started the dive by going up the main line and taking the second jump into the Halocline Room. I counted two arrows after the jump, one to the left and one to the right. I guessed the jump to the right might be the end of the main line. I turned the dive in Chac’s Room. On the map it is marked at 1700’. The clock was about at the 45 minute mark and I was starting to feel a little distance pressure. The little man starts to talk to me, when I think about how far I might have to swim on bailout and as far as I know, there are no emergency exits. The Halo-Line is an excellent swim. The first three times I had been to Naharon, I really didn’t see anything. I was focused on the dive and staying a live. This dive was different, my field view really opened up and I saw so much more. One of the striking features of Naharon are the tiny silk covered stalactites. They are really amazing, and with the CCR I took plenty of time to wonder at them.

I returned to the main line and made a left swimming deeper into the cave. I made it to the end of the Main Line in about 15 minutes. It terminated near Chac’s Room as I had guessed earlier. The Main Line is a bummer compared to the Halo Line. The Main Line is a shortcut to Chac’s Room, I would use it as a transit route in the future to cut about 10 minutes off the swim. I turned the dive and headed back to the first jump off the main line.

When I reached the first jump, I was nearly two hours into the dive. I decided to make the jump and swim 20 minutes or so. I counted 4 arrows on the swim and after the 4th arrow the cave takes a hard left and then a right and then you go up onto a boulder / breakdown. On top of that boulder is a gorgeous garden of formations. I was clearly in a part of the cave which doesn’t get a lot of traffic. Even with no bubbles, I was getting a reasonable amount of percolation just from my pressure wave. I relaxed and enjoyed the view for a while and gave my poor calves a break. Then I headed for home.

Overall it was a very meditative dive. My recent tweaks have really paid off. Carrying two BO bottles is superior in a lot of ways to carrying one. More gas rocks and two bottles are so much more balanced then one. My neutral position is not pulled to one side or the other. And de-inverting the tanks really helped my trim.

There are still some problems with my rig:

• It is too heavy. With two BO bottles, I have to really inflate my wing and it is pressing on my back. This is uncomfortable and inefficient. It wastes a lot of diluent and makes the volume changes that much greater.
• The door handles on the Armadillo Butt Plate suck! They are all wrong for AL tanks. And they make reaching the butt ring very difficult. And they just don’t seem to be in the right place. Donning and doffing tanks can be difficult with them.
• My Dive Rite Two Zipper pocket that is belt mounted is also in the wrong place. It is very difficult to get my wet notes out with the BO on.

Here are my proposed solutions:

• I am going to remove the single tank adapter and strap the tank to the back plate with the hose clamps. That should lower my profile and remove a pound or two of weight.
• I am going to remove the door handles and attach two d-rings to the butt plate. Like the original Nomad butt plate. This should fix the position of the tanks and make it easier to reach the goods on the butt ring.
• I may trim some AL off the back plate. However, this is not going to happen immediately.
• I am going to get a new bellows pocket mounted on my left thigh for wet notes and other spare crap. I want to ditch the Two Zip. Or I will start to hang it from my butt ring, like I do when I am side mounting.

I feel like I have seen some of Naharon. Total run time was 2 hours and 40 minutes. There is at least one circuit I would like to do and a bunch new passage to be inspected. I figure I will need another 10 trips there to feel satisfied.

Dive: 396

On Friday morning our friend Paul flew into town to do some cave diving! It was his first trip after finishing full cave with Protech in November. We planned to do 2 dives a day Friday through Monday. However, the airlines had other plans and his flight was late on Friday, so we were limited to a warm up dive on Friday. First thing we did was to go over to Chac Mool and do a quick gear review. Paul had just gotten a beautiful new Halcyon harness and donut wing. We revised his hose routing a little and tweaked some other minor things. Those minor improvements really made a difference.

The crew was Allie, Paul and myself. Paul and Allie were in backmount and I was in side mount. We got in the water, did our S drill and dropped down. The dive was called immediately on account of Allie not being able to equalize. Unfortunately, she had been suffering a minor cold. There were tears all around and then Paul and I elected to continue the dive. We did a quick S drill and started the dive. Paul did a nice job of running the reel. We made the 30 minute swim down to The Monster. The Monster is the world’s largest underwater stalagetite. It measures 45feet tall and it hangs into a pit that is 90feet deep. It is really stunning the first time you see it. I always want to swim over to it and put my arms around it. We chose to dive Chac Mool becuase it is a realatively easy dive and there is only one T to contend with and that leads to a air doom that is breathable. Most of this dive is pretty ho hum, as you get to The Monster the rooms become more decorated and enjoyable. The return trip was uneventful. When we got back to Playa we decided to go to one of our favorite restaurants, La Cueva Del Chango.

Saturday brought fabulous weather and we headed down to Tulum for some diving. Allie wanted to give her head another day to clear, so Paul and I were on our own. We decided to go to Grand Cenote and do two dives. The first dive was down to the Cuzan Ha Loop. We elected to make this dive a little more complex, so we took the short cut jumping to the left on the first arrow. At the end of the line we jumped back onto the main line and turned left. We gapped at Cenote Ho Tul. The dive was going fantastic. We were making good time and I could tell Paul was in complete sensory overload. When we got to to the jump for the circuit a little miscommunication/confusion occurred. I went to set the spool to close the loop and Paul followed me. When I realized he was behind me, I sent him back and then finished up. We I returned to the main line, we continued the dive. We made it about 3/4 of the way around the circuit and had to turn on thirds. As we exited we cleaned up our gear and took our time. This is a beautiful dive and it is fun. The restriction after Cenote Ho Tul is good fun and I particularly enjoy it.

The second dive was towards Lithium Sunset. Last time I tried to find the jump off the mainline, I just couldn’t figure out where it was. I guess I wasn’t persistent enough. The picture I had in my mind’s eye was short jump, the reality was it is about 50 feet or so. Maybe less if you make it a straight shot. So we made the jump, went to the second arrow and made the short jump to the left. This is another beautiful dive although it is a little less challenging. If there is a no brainer, this is one of them. Just set the cruise control and enjoy the scenery. Some dives are just easier/less engaging then others. Paul was over joyed at the end of the dive. I was super relaxed and really enjoyed the dive. Grand Cenote is really a wonderful place to dive. The cave is bright white almost blue-ish and is highly decorated.

Sunday Allie decided to join us. We planned to go down past Tulum to Cenote Cristal aka Naharon. I wanted to give Paul the experience of the caves north of Tulum, in Tulum and south of Tulum. My experience is that they offer very distinct dives. And let me tell you, Naharon is no slouch! Naharon is feed by swampy lands to the north and west. Therefore the water in the system is tanic and stains everything. Naharon is about the darkest place I have ever dived and Allie and I find it to be a very psychologically challenging. It literally eats HID light. The darkness makes it very tight and unforgiving. This challenge makes the dive some much more rewarding! Once your field of view starts to open up, you discover the the black silk floors and the black stained formations are amazing. It is really like diving into the belly of a beast. On the main line there is a portal in the rock that looks like the jaws of a shark. As I pass through the formation, I imagine being swallowed by the beast. I guess the Halocline room is the belly.

Naharon is a little deeper then most of the other caves we dive. We plan for a depth of about 70feet and to stay out of deco we use 32% EAN. The plan was to head up to the Halocline Room; which is about a 25 minute swim up the main line. The most striking feature of the Halocline Room is the demarcation on the walls between the fresh water and salter water. The wall below the saltwater is perfectly white. The wall above is tanic stained black. My understanding is that the saltwater eats the black stain. It is really stunning and a worthwhile dive. I really want to get down to Naharon with my CCR or a couple of stages. I can only imagine what treasures hide in the inky blackness.

Dive over, it was time for food! We headed into Tulum for some Chicken! I love the chicken in Tulum. Our favorite place to eat is Pollo Bronco. It is an orange building on a corner on the north bound side of the road. Chicken can be had in the following sizes: quarter, half and whole. There are not really any other options. I think you can get pasta instead of rice. But, I never do.

Lunch over, it was time for diving. We drove over to Car Wash for a little dive. Car Wash is a cenote where the taxi drivers used to wash their cars. The land owner has really made some improvements to this site since that time. There are rest rooms, changing rooms and tables to setup on. They have built a reception area at the Luke’s Hope cenote. It is really nice.

This time of year there is a cloudy layer for the first 10 feet in the cenote then visibility opens up. It is really awesome to drop down through the cloud into clear water and to watch a friend do the same. The visibility reminds me of wreck diving in NJ.

This time it was Paul’s job to run the primary. We setup our primary tie in on a tree a couple of feet from another team’s, then we proceeded in. What we found was an unbelievable spider web of line. The team ahead of us had literally criss crossed the cave at different depths at least three times. Paul was confused and I was livid! Message to all you Muppets out there, “CAVE DOESN’T BELONG TO YOU!” There are other teams in the world, have some common decency. We spent an unreasonable amount of time negotiating the other team’s line. In the end we had two choices: call the dive or install our gear woven through theirs. We choose to install our gear. I helped Paul to take the most respectful path possible. Then we hit another snag, Paul’s primary reel was too short. I loaned him a spare Spool and we gapped to the main line. The lesson here is; confirm how much line you have on your primary reel. Don’t take the manufactures word for it. Unfortunately, the cavern debacle cut our penetration short. I think we made it 15 minutes past Luke’s Hope and Paul turned us on thirds.

When we got back to open water, we recalculated thirds and went for a little exploratory dive down stream. Again we ran into the other team. Again they had taken the entire cave to themselves with their handy reel work. What a headache. Please learn to use your reel!

Monday was going to be a short day for Paul and I. Since he hadn’t been to Minotauro, we went over and did the circuit in two dives. I blundered in my briefing, but nothing severe enough to call the dive. I actually realized it as soon as we submerged on the first dive. We setup the circiut and returned. The second dive we completed the circuit. The only thing notable was that I did the in about 1000PSI. I guess all this working out and concentrating on finning technique is paying off.

Paul’s trip was fantastic and we had a great time. Hopefully he will come back soon and we can do some more diving. There are just too many beautiful places to see!