Category — Exploration

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.

About a year ago I wrote my original Cave Diving Helmet article.  Since then my diving has rapidly evolved calling for ever more refinement in my helmet.  Following are some photos of two revisions of my helmet.  The photos with the yellow backup lights is what I call revision two.  It was sufficient for sidemount diving.  I used it to do a bunch of survey and 100 sidemount dives.  It was still a little too bulky and presented a lot of drag.

The photos with the single light head holder is revision three.  This came about when I started to scooter deep cave with my CCR and realized I needed the minimum amount of drag and tightest fit to stop the helmet from moving when I was zipping along.  Additionally, I learned that my backup lights interfered with my T pieces on my over the shoulder counter lungs.

The things to notice are:

1. I changed the shape of the helmet by slicing it down the middle and clamshelling it.  It sits very tight to my head now and doesn't move at all.
2. I got rid of the flimsy black PVC and created a nice new holder out of white pvc.  I also created some wedges for adjusting the focus of the light for scootering.  Also, I rounded the edges of the PVC to allow easier insertion of the light head.
3. The teal helmet is the original helmet, I have a backup encase I blunder when cutting.  You can see the difference in fit and shape.  And a serious lack of holes.
4. Like all things in cave diving, my helmet and my needs have gotten very specific.  For CCR, I need one light configuration.  For sidemount/survey/exploration I need a different configuration.  I have not reconciled how I am going to switch back and fourth.  Maybe the teal helmet will fill one role and the purple one the other role.
5. I am migrating away from the SL4 LED lights to the Intova light.  Having 8 C-Cell batteries on your head is heavy.

I think that is all, just wanted to write a quick article.  Enjoy and I look forward to you comments!