Category — Rebreathers

As many of you know the NOAA buoys have be been removed from the Saint Lawrence Sea Way.  This decision by the government to save money has left an information vacuum around the river’s status.  Well, a friend of the river and the technical diving community, Andrew Driver, has stepped in to record and publish the water temperature along with river conditions.  He is making Saint Lawrence River water temperature data available through his web site http://www.bluefootdiving.com.

Blue Foot Diving offers technical dive training and guided diving through the summer and into the fall from Alexandria Bay.  Andrew Driver is one of the most experienced instructors in the area and has the resources to manage the logistics for almost any group.  Blue Foot Diving offers shore diving, wreck diving, trimix diving and instruction from Alexandria Bay.

I did my training with Andrew and dive with him at least once a month in the spring, summer and fall.   One of my favorite aspects of diving with him is the speed of the dive boat.  We are able to get on station quickly and back for lunch quickly.  The groups are always very small and the diving is customized for the group.  He is committed to having fun while maintaining the safety of the group.

Hopefully, I will see you up there and we can do some diving together.

Well, it has been almost a month since I last did some diving.  I was hopeful about getting out this weekend, however the apartment search and getting settled took priority.  I started to collect up my gear for this weekend and about half way through I realized that I just couldn’t get my head into it. Even if I could find everything I needed and I could find the time, I am pretty sure I wouldn’t be emotionally prepared to get up at 4:30AM and trek to the boat.  On top of that it was blowing like hell all weekend and cold!  If I can get myself into an apartment this week, I will start to seriously consider getting out this weekend.

I was browsing my normal array of forums today and found a link to, “Task Loading Tips For Underwater Photographers & Videographers” by Becky Kagan.  It is a quick read and has some nice photos.  My experience aligns with Beckey’s. She writes,

“Task loading can come in many forms and it’s different for everyone day to day. Task loading can be anything physical to mental or a combination of both. It could be pushing an over weighted camera with lights in a strong current while trying to set up shots, positioning a model, dealing with sea sickness, a broken fin strap, and a depth and time limitation. All of these little problems can build up into one larger problem so it’s important to recognize when you’re overwhelmed and when to call the dive before it becomes dangerous.”

A month and a half ago, I was relining a silty side mount passage.  I had recently switched from the stock fin straps on my Avante Pros to spring straps.  The springs were a little loose and would slip off the heal sometimes.  When they slipped off the heal, they would unclip themselves from the fin and the fin would work its way off.  Well, the first time it happened I thought it was an odd occurrence and a one off.  The second time it happened I got pissed and then promptly forgot about it.  The third time I was in a low wide silty pristine sidemount passage with my reel in my hand.  The passage was small enough that I would not be able to reach my fin and if it came off, I might not find it.  And since I was 2000ft from the entrance I really wanted to keep both fins.  On top of the fin issue, there was nothing for me to tie the reel off to, there was no where for me to put it down and there was nothing I could get a hold of.   And I couldn’t make forward progress because the loose fin was precariously perched on my foot.

Immediately, a wave of stress washed over me.  I wasn’t sure how I was going to solve this problem without trashing the cave.  I tried to reach my foot a couple of times with my reel in hand.  That was a non-starter.  I didn’t want to pull the line off the last tie-off.  And I didn’t want to get entangled.   I did a little twister practice, but the passage just wasn’t tall enough for me to get my lef forward.  After some more struggle, I started to get frustrated and a little upset.  I wasn’t sure what to do.  I was task loaded and a little stressed.

I decided to stop and take inventory of the situation.  The first step was to just take a couple of breathes.  I had two nearly full tanks on and a stage waiting for me at the end of the line.  I had plenty of time.   I thought about the reel and tried to figure out what to do with it.  I needed to get both hands involved in the self-rescue.  I dogged the reel down and clipped it to my chest d-ring.  I got the line a little taught to keep for getting it involved with my other gear.  Then I stopped again.  How was I going to get my fin and stay neutrally buoyant and not trash the cave.  Hmmm……  I decided to give up on being neutrally buoyant.  The cave had a hard rock ceiling so I inflated my BC until the overpressure valve vented.  I pinned myself to the ceiling.   Now I had two problems solved, no reel and no hovering, plus I gave myself some more room to work.  This is where there was some acrobatics.   I pulled my leg up gingerly and reached down and grabbed the fin.  I reattached the spring to the fin.  I pulled my leg up again and replaced the fin.  I pulled the spring over the hell and used my other hell to work it up the back of my leg.  I felt relieved when the fin went back on.

I slowly let gas out of the BC until I neutralized, unclipped and undogged the reel and finished my relining and survey.  It was a pretty cool experience, the kind that comes from diving.  I managed my task loading by identifying the problems and solving them one by one.  I was able to accomplish the solution without trashing the cave and without burning a significant amount of gas.

That night when I got home I resolved to fix my fins.  I drilled 4 holes in each fin, one in the post and one next to it.   I put the springs on and then pass a zip-tie through the two holes.  The zip-tie captures the spring bracket and holds it in place.  Since I made this minor modification, I haven’t had anymore problems with those fins.  I was very satisfied with the whole situation.

So, if you become task loaded don’t get frustrated or overwhelmed.  Stop what you are doing and take a couple of deep breathes.  Then look at your gauges to confirm your gases and the time you have to solve the problem.  Take inventory of what is causing you trouble and consider solutions.  Then act on a solution, don’t move forward until you have fixed the friction point.   Methodically address each issue until you can move forward with a mind like water.  Remember, there is no hurry and there is very little chance things will improve if you do hurry.

Great write-up Hans. Welcome back to NJ. Drop me a line and we can go out on my buddy’s dive boat some time. I’m heading to Florida in 3 weeks for CCR cave and CCR trimix training.
I have one question about your mixes. You didn’t say what you used, but doesn’t picking a lighter mix for bottom bailout put you at risk for ICD? Not to mention the narcosis causing a significant pucker factor.
Ken

To answer your question, the fraction of He only dropped by 10% when I switched from CC to OC.  That is not enough to create ICD friendly conditions.  A much larger change in the gradient is theorized to be necessary to promote ICD.  Consider this, if I were to go OC all the way to the surface the first gas change would have a 30% change in  the fraction of HE, the second would have another 30% change in HE content.  These changes do not throw an ICD warning in V-Planner (Which is arbitrary by Ross’ own admission.) and according to the principles I was taught in Trimix class should be ok.  So ICD isn’t a big concern here.

On the other hand, the Narcosis is a concern and that is one of the reasons I executed the drill.  I wanted to confirm I could still function under stress with that END.  The results of the test indicated that I was more impaired then I anticipated though not impaired enough to switch to a richer B/O gas for that depth and those conditions.

This provides a segue into another poignant topic; I never dove open circuit Trimix.  Therefore, I do not have any experience at depth on open circuit beyond bailing out.  This presented an interesting revelation to me; being at 280ft on OC is a fundamentally different experience then doing it on CC, which is something that Patrick Widmann warned me about more then once.

Watching my pressure gauge move noticeably with each breath adds a new sense of urgency and compounds the narcotic effect.  I now believe it is worthwhile to execute a number of OC Trimix dives to get a feel for gas consumption at 10ATA or more; if for no other reason then to learn the confidence and gain the experience to bail out in a calm and collected manner.

I can’t think of any worse set of conditions then to have to go off my unit, for a real emergency, and then to worry about my OC gas consumption and how it will play into my mental state.

I have tested and calculated my SAC rate many times, and it is very predictable.  However, knowing it intellectually and the pencil and paper jockeying wasn’t able to reproduce the feeling of watching the gauge fall.  It is one thing to know on the surface that your tank will be dry in 10 minutes; it is an entirely different feeling to experience it running down that quickly.  My experience is that the intellectual pursuit and mental preparation doesn’t substitute for experience and the only way to gain experience is to go out there and try it.  This is something Steve Bogaerts repeatedly hammered home for me and it was at his urging that Patrick and I both made the investment to execute these training dives.  Patrick had numerous sub-100M dives under his belt on open circuit, so his experience was different then mine.  I had no sub-65M dives on open circuit and I am new to Trimix diving, so I experienced something very different.  By both of our admissions, bailing out was a very beneficial, if costly, drill and was worthwhile.

I have observed the following; any uncertainty, doubt or fear will be magnified in an exponential way when the lizard brain appears on stage.   Therefore, it is advisable to train to mitigate as many of these primal fears as possible thereby freeing your mind to deal the real issue at hand with a “mind like water” focus.  Fear, doubt, and uncertainty cause me to react in disproportionate ways, causing more difficulty, inhibiting a calm collected solution.  The solution or at least the way to mitigate this is to train.

For example, NASA trains their astronauts for years prior to each mission.  This is to mitigate the response of the lizard brain and to ensure they have experienced, not read about, every possible contingency they can create here on earth prior to the mission.  This same approach needs to be taken into diving, especially as I reach further into inner space.  Deep diving with exotic gases in an overhead environment with relatively experimental technology is a highly risky endeavor.

The risk is so great because there is a disproportionately high probability that the unit will completely fail leading to death; known in gaming theory as ruin.  Therefore, with such a great threat to life possible on every dive, it is incumbent on the diver to train all the situations, including total system failure in situations as close to real life as possible..  Sometimes it is easy for me to assume I will react the right way, I had trained bailing out in 40ft, 100ft, and 240ft many times.  However, the training in 240ft only lasted a couple of minutes and didn’t involve a vigorous horizontal swim; which, upon reflection, presented a substantially different set of environmental, psychological and physical conditions.  It is important to realize that subtle changes in the situation can result in dramatic changes in the outcome and experience.  The threat is that we believe that a similar situation is applicable and overlook the fundamental changes in the environment.  A prime example is people assuming that experience and skill wreck diving will translate into cave diving and vice versa.  More then one diver has died making this false and fatal assumption.

What I learned was that when I move to the next section of cave which drops to 350ft (105m) and presents significant environmental challenges, I will want a richer HE gas.  I also learned that I want to train bailing out and perform an orderly exit in the conditions I expect to be diving in.  I think before I go for Jill’s Chamber, I had better be comfortable exiting from Wakulla Room on OC.

I hope that answers your question.

When should I get a rebreather?

Is it best to get some good caving experience before I go rebreather or is it preferred to get on RB as soon as you can? I know that I will definitely go RB one day, but I want to make sure I am not going too fast down that path.

I am Intro to Cave right now with 20 cave dives/ 250 total dives. — khacken, Cave Divers Forum

I saw this question on Cave Divers Forum today and started to write a short response that turned into a long response ad now it is a Blog post.

This is a pretty interesting question.  I learned to cave dive on OC back mount.  Then I learned how to dive CCR and did a bunch of CCR wreck dives.  Then I moved to Mexico and started CCR Cave diving.  Then I learned sidemount and found myself doing 80% of my dives, even in big cave in sidemount.  I have a couple of observations I would like to offer:

1. It is very easy to go beyond your limits with a CCR and not know it.  If you are only CCR diving, you have to calculate/guesstimate how long your bailout will last you in a very dynamic situation.  If you underestimate, you drown.  I think it is worth while to have dived many of those situations open circuit to see how the environment and situation will change your gas consumption.  This is in the same vein as swimming before scootering discussion.

2. Many many many situations in cave diving are not optimally handled on CCR.  Therefore, it is beneficial to have a broad set of options to solve your problem.  Is the cave small?  Go sidemount.  Is it unexplored?  Go with some 40’s to check it out.  Are tanks and sorb available?  Use double 80’s or go sidemount.  Is your CCR broken or too expensive for the dive?  Use OC.  Do you really want to spend your time setting up/breaking down your CCR for every dive?  NO!  Is the cave deep? Use CCR.There is one big caveat to this point, you need to analyze your diving and determine if you dive frequently enough to switch between OC and CCR and maintain two skill sets.  OC and CCR are different beasts and require different muscle memory.  If you dive sporadically, I suggest you dive only one system and you dive it in forgiving environments.  If you dive often, then you might be able to practice both often enough to be good at both, but this is very tough.  Sometimes when I am off the CCR for a month or more, I find it challenging for a dive or two.

3. Lets look at a side-by-side comparison of cost for diving.Typical shallow 3 hour cave dive cost the following for consumables.  The figures are USD.

Typical OC Cave Dive
Entrance: $10.00
Fuel: $10.00
Fills: $12.00 (3 Single 80’s with Fill)
Total: $32.00

Typical CCR Cave Dive
Entrance: $10.00
Fuel: $10.00
B/O Fills: $8.00 (2 Single 80’s with Fill)
O2: $12.00 (12cuft)
Dil: $3.00 (19cuft)
Sorb: $30.00
Total: $73.00

Add to the financial cost there is a time cost. First it takes me 30-40 minutes to setup the CCR and then it takes 20-40 minutes to break down the CCR. When I am on site, I need to check the unit and pre-breath it on top of my normal S drill. This doesn’t include the costs for O2 sensors or flying the CCR around or fixing it when you drop it. I also didn’t include the cost of servicing the regulators, because you need the same number or more with CCR. Remember with CCR, you need Dil, O2 and B/O regulators.

I am sure there are more reasons to choose one approach or another.  I can tell you that Patrick and I both own Megalodons and only dive them deep (>60ft).  Therefore, 80% of our diving is open circuit.

I think it is prudent to really consider where you are going to dive and the specific situations you will find yourself in.  If you cannot do that because of lack of experience, you need to seek the best possible training and gain the broadest experience possible.  Because you are already an Intro to Cave Diver, become a Cave Diver and make some dives.  Gain some experience.  Then start to layer on more technology, such as rebreather, scooter and stages.

So much of technical diving is about planning and choosing the right equipment and procedures.  Whether to dive OC or CCR, is one of those choices.

A great example is a dive I did with Santiago last week.  We dove the Lins/Walton line at The Pit.  I was diving CCR and Santi was diving OC.  We planned to make a 20 minute dive to 245ft.  When we got to 210ft at 6 minutes we found the end of the line.  I signaled to Santi asking him if I should tie in my reel?  He said yes and we went on.  We immediately found going cave and added 100+ft of line to the system and brought the end of the line to 238ft.  We tied off the newly laid line, installed our arrow and head up.  At 220ft, I found another lead with a nasty silty bottom pinching down.  After some inspection, I decided it was too nasty to attempt in CCR and I made the decision to return in sidemount to check out the lead.   I haven’t returned because I haven’t had the time.  However, because I know both systems, I have the option.

CCR was the perfect choice for the initial dive.  I used about $6 HE, $6 O2, $30 Sorb.  Santi used about $100 HE, $40 O2.  I did my initial exploration on the cheap.  Next time, I will go in sidemount and check out the lead.  It will cost more, but I will have a clear objective and the right tool for the job.  Fortunately, because I have a broad base of experience and more then just a hammer in my tool box, I don’t have to use a hammer on that screw.

I love my rebreather, I think it is an awesome tool that has enabled me to dive many places that few people will.  However, it is not always the right tool for the job and is not a panacea of safety.  Rebreathers fail and so you have to carry bailout.  If you bailout, you had better be sure of how much gas you need, because if you are not, fear will creep into your lizard brain and things will go to shit.  Therefore, if you are technical diving a rebreather and until we have truly fault-tolerate rebreathers or bailout rebreathers are standard issue, you need to have a foundation in open circuit.  The best way to develop that foundation is by diving open circuit.

Patrick and I are happy to announce a HUGE success at The Pit.  After a lot of deliberation yesterday morning and discussions with our partners, we decided to make a single alpine attempt at pushing the end of the line at The Pit.  We came to the conclusion that using the habitat and support was too much of a burden and elected to go to the end of the line with one scooter each, no support, zero VPM-B conservatism and limited bailout.  We decided to not use bailout after we realized that loading 35 tanks into the jungle was more of a risk then the possibility of bailing out.  Additionally, we recently perfected the team skill of CCR buddy breathing.

On Tuesday morning, we packed up our gear and headed to the dive site about noon and were in the water at 1PM.   The decision netted a significant addition to the end of the line.  We are still tabulating our survey data but it looks like we added more then 1500ft of line.  The dive took us about 7.5 hours using 7/70 for diluent.

I want to thank our significant others for supporting our effort and the rest of the team for not standing in the way.  The dive was a huge success and will serve as a model for future dives at The Pit.

If you are interested in learning CCR Buddy Breathing, I can make a video of it available to you directly for $4USD per copy.  In a couple of weeks, we will write a full article on our recent success and we will be posting our raw survey data on line in the name of safety and future dive planning.  We expect Jill’s Chamber and Next Generation Tunnel to be a popular dive site with the launch of the new Mark 6 Technical CCR.

Note: This was an April Fools Day post…..  Your milage may vary.

On Sunday, I flew up to Florida for a little diving vacation.  Andrew Driver had put together a wreck diving trip with plans to dive the Hydro Atlantic, Lowrance and the RB Johnson.  And if the team jelled nicely, we might get to dive some more interesting wrecks.  The cast of characters would include Eric Goldstein, Jim Moore and me.  Luckily, we all arrived on time with all our gear undamaged.  We would be diving on the Avid Diver captained by Oliver.

The first challenge was re-assembling my rebreather and finding the right amount of weight for saltwater and a bit more underwear then I would wear in Florida.  After some struggling to find the requisite lead, the rebreather came together.  The only other challenge was that there were no tanks with the valves in the correct position to de-invert the tanks.  So, once again I had to change my configuration and go valves down.  I find traveling with the rebreather very frustrating.   I loath changing my configuration, especially when I spent so much time dialing the unit in Mexico.  The addition of the weight for saltwater and the changing of the tanks really throws the whole thing out of balance and kills my trim.  I think when I go back to Mexico, I am going to return  to diving with inverted tanks and figure out how to balance the unit that way.  I need to find a way to mitigate this frustration and time spent changing my configuration around based on my location.  Enough of that, now on to the diving.

On Monday, we visited the Hydro Atlantic.  The Hydro Atlantic sits in 170ft of water.  It is a real wreck, not an artificial reef.  It was originally a cable laying ship.

The plan was to hot drop on the wreck.  It would be the first time that either Eric or I had done a hot drop and the current was really ripping.  The first attempt we missed the wreck. Visibility was about 25ft, I think we may have just drifted by the wreck as it lies south/north and the same direction of the current.  We surfaced and starting looking for the solo diver that went ahead of us. We he turned up we retrieved him.  Once we had him in the boat, we made a second drop and did a 25min BT.  It was a very cool dive.  RT was about 50 minutes.  Our max depth was 160ft on the second dive.

Today, the forecast was calling for 5-7 and building.  We elected to head out and try for the Lowrance.  It was questionable when we arrived, there were some 5-6 rollers though the chop wasn’t too bad.  After some discussion, we decided to dive but curtail our bottom time.

We hot dropped and landed right on the wreck, it was an awesome experience!  I felt like we really had done something pretty cool.  We did about 25min on the wreck.  Run time was about 70minutes.  Our max depth was 190ft.  We had planned on 40min but curtailed it due to weather.  The big bonus was the big, 5-6ft tall, sun fish hanging out on the wheel house at 140ft.  We were 2-3 feet away and he was just hanging out.  The deco went smoothly, Jim sent the bag.  The three of us hovered around him.  When we got out the seas had built a little, but not to anything unmanageable.

I guess that is all for today.  Tomorrow, we are planning to dive the Lowrance again.  I am looking forward to another dive on the wreck.

Today, I followed a link from Cave Divers Forum to a Kayaker’s website to watch his video of hucking a 50ft waterfall.  It was super cool.  From that site, I visited his photographer’s site, Tyler Roemer Photography Blog and spent some time gazing at his photos.  Holy crap they are amazing. Tyler’s photos are of the mountains and young people doing the things you do in the mountains: hiking snowboarding, cycling and climbing.  It really got my heart to go pitter pater.  There is something missing here on the Yucatan, green rolling hills and mountains.   Granted the scrub jungle, the beaches and the caves are beautiful, however they are not lush green mountains and snow.  Lately, I have been thinking about moving to the mountains again.  13 years ago, I lived in Keystone, Colorado.  That is where I met Allie, my wife.  We were snowboard bums working at the resort loading skis onto the gondola.  I hiked in the back country a couple of days a week, in the winter.  And in the summer I mountain biked and fly fished.  It was really a beautiful place.  I left Colorado for two reasons. First, Allie left to go to school and I was lonely.  Second, I didn’t want to snowboard anymore.  I had been skiing every weekend since I was seven years old and I didn’t want to be cold anymore.  I get really nasty headaches when my head is cold.  So one day in the spring I hung my snowboard up and bought a mountain bike.  I have only been snowboarding a handful of times since.  Well, the short of the story is that I have been thinking about the mountains a lot lately.  I am not going anywhere anytime soon I still have work to be done here on the Yucatan.  I guess the grass is always greener on the other side.

On a releated note, recently I have been captured by the awesome beauty we have all around us.  Brain Kakuk has been turning in some amazing photos of the Helictities in Dan’s Cave in Abaco, Bahamas.  You can see some of the photos of the formations here and here.  I am filled with amazement to get to see this stuff, it really enriches my life.  Thank god for the internet!

In a week I am flying to Florida for almost two weeks of diving.  The first week will be deep wrecks out of Ft. Lauderdale with Blue Foot Diving and the second week will be cave diving in north Florida to do my Cave CCR Crossover with Ted McCoy.  As you can imagine, the mad rush is on to get all my work buttoned up and to do some dives in my dry suit.   The wackiest thing is to realize that I am taking vacactions from Playa del Carmen, Mexico.  It has become home and I am ready to travel away from paradise already.

Some of my photos from a mountain bike ride from Teluride, Colorado to Moab, Utah.  It tooks us 7 days.  Awesome ride!

Every once in a while I read about some really cool diving that is going on that reminds me how basic the stuff I am doing is.  Brain Kakuk is continuing to make headway in the Bahamas and has blessed us with a write up about exploration at Dan’s Cave on Abaco Island.   Take five minutes are read about it, it got my juices flowing.

Cave Exploration in Dan’s Cave on Abaco Island, Bahamas.

When you are done reading about the diving, make sure to check out his photo gallery, the formations are stunning!

Now that we have that out of the way, do you ever dream about diving?  Well, I do!  And last night I had the craziest dream.  I thought you might enjoy a retelling, it is ridicules.  So, the dream started in the middle of a dive at The Pit.  Victor, Santiago and myself were working our way into the BMB passage.  (I haven’t been there yet, so I don’t know what it looks like.)  In my dream, the passage narrowed down the width of two people and angled down.  Then the passage continued through a hole in the floor.   The line was run was against the ceiling entering the passage, onto the floor and then against the ceiling through the hole and it was slack.  I was the third man.  When we got to the hole, Victor was looking in trying to figure out how to pass the restriction and kept moving the line back and forth forcing me to keep crossing under the line.  This was all taking place at like 330ft in my rebreather with bailout.  To say the least, it was a little stressful.  After sometime of watching them and getting very upset about having to repeatedly cross under the line and wasting my dive time, I hit my turn time and called my dive.

After calling the dive, the dream skipped right to the point I was out of the water and laying in bed continuing to decompress, at which time I noticed I had forgotten to wear my X1 and I never set my PO2 above .4.  Actually, I realized that I hadn’t ever looked at my PO2.  I decided that I must have followed Santiago’s open circuit schedule and I was freaking out.  (When I woke up my jaw was sore from being clenched.)  I wanted to get out of bed to check how much deco I had omitted, though I didn’t know what set points to use.  And I couldn’t figure out when laying in bed had become part of deco.  I knew I should be bent in the dream and I kept checking my right elbow.  The dream ended with me thinking to myself that it was awesome that I wasn’t bent and that I had gotten lucky.

What a wild dream!  Well, it was for me.  If you have ever had a really crazy diving dream, please post it as a comment.  If it is really long and interesting,  you can email it to me at hans@quietdiver.com and I will post it as an article.

And to tie things off, right before going to sleep last night I watched “Pod Cisnieniem” or “Under Pressure”.  It is a movie (DVD) about an open circuit depth record dive by a Polish team in the Red Sea.  I got the movie from Patrick who was teaching Jacek Szymczak this week.  Jacek is the deep diver in the movie.  Watching the movie really got me amped up and I think it inspired my dream about The Pit.  I love the idea of participating in a big project like that and supporting something extraordinary.  With any luck, I will have the opportunity one day.

Unfortunately, the trailer is in Polish.  However, the DVD is subtitled in English and well worth watching. Here is the trailer for the movie:

In another coincidence, Leigh Cunningham, the deep support diver, was Patrick’s trimix instructor in Egypt.  It was really cool to see his instructor in action.  I hope you enjoy the movie as much as I did!

Last week I wrote about an awesome cave dive to The Wakulla Room at The Pit.  Well, three days later, Saturday, I returned to make another try.

Over the last two weeks, I also wrote about some oxygen sensor trouble, trouble might be overstating the issue.  My 02 sensors had come to the end of their lives and needed replacement.  Unfortunately, after many hours of preparation for my dive on Saturday including staging all my gear in the water and starting my dive, I experienced another sensor failure, or sensor abnormality.

To recount the chain of events, on Saturday, 1/17/09, I went to Vaca Ha to do some cave diving on the unit.  The night before as I prepared my Megalodon, I discovered the number 2 sensor was dead, no voltage.  I didn’t think anything of it, the sensor was old and I hadn’t fired up the unit in three months.  I replaced the sensor with a new one dated July 2008, calibrated the unit and dived it.  During the dive at Vaca Ha, the number three sensor became current limited.  It wasn’t a big problem; I took the appropriate steps and exited the cave.  In preparation for my Pit dive on Wednesday, 1/21/09, I replaced the number three sensor with a new one dated March 2007.  That sensor was pretty old, but I wanted to give it a go.  Maybe it only lasts 6 months, maybe it lasts a year.  It was vacuum packed from the factory.  I calibrated the unit and went for a dive at The Pit.

During my 2 plus hours of deco I noticed the number 2 cell started to read a little lower than the other two sensors.  I checked to see if was current limited and I flushed, both checked out.  I didn’t think much of it. I assumed that the cell had come out of calibration as it baked in during the dive.  I figured, I could recalibrate the unit and all would be well.  The number one and number three sensors agreed.  Since I calibrate before every dive, it would be taken care of in my next pre-dive.

And that brings us to Saturday, 1/24/09.  I had another dive scheduled at The Pit.  Again, the setup and gearing up process went very smoothly.  I was super relaxed and ready for an awesome dive.  I finished my in water meditation and dropped down the deco line to check my staged tanks.  At the surface I had a PO2 of .4.  At the 20ft station I stopped and gave my gear the “In Water Two’s Check.”  My PO2 looked fine.  But for some reason, I decided to watch my primary handset as I descended.  This is not something I normally do, usually I check the handset and my HUD periodically to confirm the PO2, but I don’t watch it.

As I approached the 70ft station to check on my 50%, my number two sensor spiked to 1.97.  The other two sensors were in range at 1.0.  I had been adding diluent (7/71) on the way down.  I stopped and hovered staring at the handset trying to figure out what I was looking at.  I watched the PO2 fall on the number two cell from 1.97 to .8, while the other two sensors held steady at 1.0.

At this point I made a mistake; I didn’t flush the unit and put a known gas in the loop.  I just stared at the numbers trying to figure out if I should go for a dive.  Luckily on at least two separate occasions in the past week, I flushed the loop instinctually.  This time due to some mental twist, it never even crossed my mind. I think because it was so near the beginning of the dive and I thought I knew what should be in the loop.  The truth is I had no idea what was in the loop!  I wrongly assumed that I started the dive at .4, maybe I started the dive closer to 1.0.  I really didn’t know at that point, and what is worse is I didn’t know that I didn’t know.  I thought I knew.

After less then 1 minute, I decided to call the dive.  I couldn’t see going for a 4 hour 350ft cave dive with a unit that may or may not be broken.  I decided that when I surfaced, I would replace the number two cell again and try and go for another dive.

When I surfaced four minutes later, I hoisted the unit out of the water and changed the number two sensor with a brand new one.  I fired the unit up to calibrate it and the brand new sensor read 9.4mv.  I stared at it for a minute and realized, I couldn’t remember the proper range for an oxygen sensor.  My sensors had always started above 10mv, and that was my mental low limit.  I asked another CCR diver, Victor an Evolution diver, and he told me 8-13mv was the acceptable range, though I wasn’t sure if that same range applied to the R-22D sensors.  Later, I found out that the sensor was in range.

I decided against diving that day.  It was unfortunate that I couldn’t remember the proper range because I would have been able to continue my diving.  It amazes me how the smallest issue can sometimes put a dead stop to something that took hours and hours to prepare for.  It was a case of not being sure of a fundamental piece of information and paying the price.  In any event, I had hit my limit for the day.  Jorge and I packed up the gear, waved to Santiago and Victor and headed back to Playa for an afternoon on the beach.

The next day I called Patrick Widmann and Andrew Driver to discuss the sensor issue.  The very first thing they both did was give me a good flubbing for not flushing the unit.  The lesson is, know what you are breathing and don’t assume.  It was a good reminder that at any point in the dive, I may need to flush the unit to determine what gas is in it.  It may save my life.  As a result of my discussions, the sensor that spiked has been pulled from service. I am going to take it with me to Florida and put it on a cell checker.   The 9.4mv sensor is going to stay for now; however, I am going to watch it closely.  The bull got me.

A solo trimix CCR cave dive to the back of the Wakulla Room.

After our dives at The Pit in October I was pretty rattled about deep diving and CCR diving.  During those three days at The Pit, I lowered my rebreather into the water with the BOV open, twice.  The first time I know I made a mistake and luckily only suffered a little water in the loop, not enough to cancel the dive.  The second time, I double checked the BOV was closed before I lowered it.  After twenty minutes, I noticed the Megalodon was floating kind of funny.  When I checked it, it was flooded bad.  The bottom of the can was full of water and the sorb was shot.  I called my dive that day due to “technical difficulties” and waited on the surface for Patrick.  When he returned in pain, I got rattled.  The combination of making a very pedestrian error, one which I was taught not to make in basic CCR, twice and then seeing Patrick injured me, just put me off CCR diving and deep diving all together.  I just wasn’t sure I was cut out to play at that level if I am going to make basic mistakes.  I spent some time considering selling the rebreather and just diving open circuit.

I didn’t dive the CCR for a couple of months and concentrated on sidemount/survey diving.  I gave myself some room to rebuild my confidence, see Patrick’s outcome and to get some distance.  Finally, with Patrick back in the water and the season for deep diving returning I thought it was time to get back in the saddle.  I had a choice, I could dive the rebreather or get rid of it.  No reason to have it sitting in the corner depreciating.  I decided to dive it with a renewed focus on checking everything twice.  I started with a couple of dives at Vaca Ha.  Both of those dives went very smoothly and I was really stoked to be back on the machine.

Then Victor & Santiago told me they would be doing a week of deep diving at The Pit and asked me if I wanted to join.  I thought, “This will be good.”  It will be a chance to get back to The Pit and concentrate on myself.  Victor & Santiago would dive as a team and I would dive solo.  Learning from our October experience, I hired a sherpa, Jorge, to do the heavy lifting.  He would be responsible for raising and lowering the tanks and moving them from the truck to the water and back, which was an excellent investment!  The three of us split the cost of the sherpa and it was the best 80 Pesos I have spent in a long time.

The two days before the dive were filled with the typical work: planning, blending, and double-checking gear.  The rebreather needed a new #3 cell so that went in and was calibrated.  The gases were mixed: 10/60 for bottom and 5 different blends for bailout.  Tuesday night was spent poolside doing bubble checks and assembling the gear.  The tanks were loaded into the 4Runner and the rebreather was assembled.   I cut my dive plans and hit the sack calm and ready for my dive.  I was in bed by 11:30.

Jorge arrived at 7AM on the dot and we loaded the remaining gear and Chico, my Black Lab.  We were on the road by 7:30AM.  It is really amazing how much smoother things go without 3 other divers involved.  Normally, it would take us and hour to get loaded and out of Playa.

We arrived at The Pit by about 8:45.  Jorge and I set to work.  In short order the tanks and rebreather were in the water.  As soon as the rebreather hit the water, I jumped in and checked it.  Everything seemed to be sealed up nice and tight.  About 9:30, I had my wetsuit on and I was in the water.  I kited up and pre-breathed the machine.  I played the dive over in my head a couple of times.  Everything was going so smoothly, I was very happy.  Once everything was on and I was comfortable, I lay back in the water and did my five minute meditation.  I cleared my mind and took nice long deep breathes and listened to my heartbeat.  I could hear it slowing to a nice rhythm.

When the five minutes were up, I waved to Jorge and calmly dropped down the deco line.  At 20ft I stopped and checked the O2 bottle, it had pressure and was off.  Then I dropped down to the 50% and checked it, though I checked it more thoroughly.  I noticed something strange, it only had 2500PSI.  The 50% should be full I thought to myself.  The 02 is the bottle that was short.  Then I looked at the MOD sticker and I realized that I was looking at the O2 bottle.  It was at the wrong depth!  I thought to myself, “Damn it!”  I unclipped the bottle and ascended to the 20ft station.  I swapped the bottles, reconfirming them and then dropped back down to deposit the 50% at the right depth.  All this was handled in the span of a couple of minutes; however the clock had started to run at that point.

I am very glad I checked the tanks before I left.  In the past, we lowered the tanks and assumed they were fine.  It would have been a nasty surprise to arrive at the “50%” and find that I was looking at a bottle of 100%.  Without in water support it would have been especially problematic, because it would have required that I break my ceiling by 50ft to retrieve the 100% while breathing the 30/30.  I know I should have enough gas to deal with the situation, but the fact is it was avoidable and in fact was avoided by double checking the gassed at the deco stations.  During stage class and deco class we are taught to check and recheck the gas we are breathing, the same lesson goes for staging gas on a deco line.  Another lesson learned.
With the gases at the correct depths, I left for my dive.  I started to make up for lost time, though I arrived at the 150ft stage depot a minute late.  By the time I got to the 220ft way point I had slowed my swimming to limit my exertion I let go of the fact that I was late.  I was still a half minute behind.  I arrived at the By-pass and felt great.  The cave is awe inspiring; the scale of it is really remarkable.  The Cardea Passage and Wakulla Room are huge, both wide and tall.

I swam through the By-pass and beyond my previous distance.  This trip I had some time to really enjoy the Wakulla room (Map of The Pit by Nick Toussaint).  I had scheduled 20 minutes for my deepest segment, so I just took my time.  At 15 minutes I arrived at the second T in Wakulla.  I thought for a second trying to remember the way to BMB, I took the left, a moment latter the line drops off towards the BMB.  I had reached my distance goal, but I still had time.  I decided to drop down and try and catch a glimpse of the BMB.  I got down to 317ft at minute 18, two minutes ahead of schedule.  I stopped and peacefully enjoyed the moment.  All of the anxious excitement of my first dive to Wakulla was absent.  By minute 19 I had turned and was heading out, by minute 24 I had exited the By-pass and started my ascent.

The ascent was super peaceful; I was really stoked about my progress and execution.  I had about 2 hours of deco ahead of me and I wasn’t dreading them.

I arrived at my 40ft stop around 11:30AM.  I could see Victor & Santiago getting into their gear.  I was really excited for them; I hoped they would have a great dive.  While I was on my 20ft stop, another team came up from the deep.  After some puzzling, I thought I recognized the diver in doubles, it was Dennis from Aquanauts.  It was nice to see him.  We exchanged glances and hand gestures to pass the time.  At minute 164 my dive was over, I was floating on the surface chatting with Dennis.  It was an awesome dive.

I floated around for 30 minutes just relaxing.  I pulled off my CCR and got it read to lift.  Jorge, with some assistance from Dennis, lifted the CCR and the tanks.  What a luxury to have help.  Jorge and I cleaned up our mess waiting for Victor’s team.  We got them out of the water and squared away.  Jorge, Chico and I headed for home around 3PM.  It was a fabulous day of deep diving.  Almost everything went right and I had a huge amount of fun.  The pay-off was huge for the effort.  With any luck, I will be back there in 4 days to give it another go.

Of course, no dive is executed by only one person.  I want to thank Jorge for his time, he was a life saver.  I want to thank Patrick Widmann from Protec for mixing up some excellent Trimix and loaning me his deep bailout.  I know I need to blend my own.  I want to thank Santiago and Victor for having me a long.  And I want to thank Chico for being the loving attentive friend that he is.

And as a closing treat, a friend forwarded me this video from YouTube.  I thought was great, though unrelated to diving.