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How GUE’s Approach to Rebreather Diving Compares to My Previous Courses
No one will be surprised to learn that GUE’s got its own somewhat contrarian approach to rebreather diving. Scottish wrecker, Andy Pilley, contrasts GUE’s CCR Diver Level 1 course to what he learned in other rebreather courses.

By Andy Pilley
Header photo by Marcus Rose.
At the beginning of March 2020, I completed Global Underwater Explorers’ (GUE) Closed Circuit Rebreather Diver Level 1 (CCR1) course with Rich Walker. Taking this course had been a long term goal since I began diving under the GUE framework. By way of an introduction, even though I had been curious about GUE for a couple of years, my focus had been on training to use a CCR so that I could extend my diving and undertake more challenging dives. At this point, taking a ‘step back’ to participate in a Fundamentals course, the first step in the GUE education system, was not high on my agenda, and I pushed ahead with a 60 m/196 ft normoxic trimix and Cave CCR.

Photo by Owen Flowers.
In May 2018, I had joined a trip to Molnar Janos in Budapest, where we did some relatively deep dives to the 60m/196 ft section of the cave. During one of the dives I realized that if something were to happen at this point (deepest phase and farthest point from the entrance), the likelihood that any of the divers I was with would be able to effectively assist me in an emergency, was slim to none. After returning from this trip, I completed my “Fundies” with Marcus Rose, and made the decision to pack away my JJ-CCR and dive with the growing GUE community we now have in Scotland. My end objective was to get back on to my CCR, but only when I was ready and could be an effective and vigilant teammate.
Since completing Fundies, I have built up experience, worked on my core skills to develop my capacity as a teammate, and undertaken more serious dives. Following up on this, I completed GUE’s DPV1 and Tech 1 courses in order to develop my abilities with mixed gas diving.
We’re very fortunate in Scotland that there is such a wealth of maritime history around our coastlines, and divers can find wrecks to suit any level of depth and ability. The east coast of the town of Eyemouth provides access to a huge range of wrecks, which include HMS Pathfinder, U-12, the British submarines HMS K4 and HMS K17, as well as the NJ Fjord passenger liner. Many of these wrecks were on my list to dive; but, I wanted to do them with a team that I trusted, so it made sense to proceed with my training in the appropriate manner.

A huge problem in Scotland is that helium prices are astronomically expensive, and a fill of Trimix 21/35 can cost in the region of £180/US $219 if filled from empty cylinders. This of course restricted the frequency of when we could carry out these dives. In addition to this, there are a number of very remote sites that we have dived in the recent past, and gas logistics became the biggest problem in being able to carry out these trips. We would often load up with two twinsets and two stage cylinders each for a weekend, and the cost of these fills soon adds up. As I’m sure you can imagine, the ease of logistics that is made available by using a CCR became appealing very quickly.
Diving Into The Course

What struck me about the course with Rich Walker was the level of detail that went into every aspect of using these machines. In my previous CCR courses, we had carried out checklists for pre-dive assembly and breathing checks. But, these were done as a group of individuals rather than as a team. Prior to this there had never been a sense of accountability toward my teammates, as it was very much a solo diving mindset.
For example, with the GUE class, the pre-build checklist sticker, recording individual measurements of cell linearity, and cell manufacture dates contained a new level of detail that I hadn’t experienced before. That is not to say they weren’t discussed in my previous training, but cell linearity went only as far as, “If the cells sit between 46-54mv (millivolts) they’ll be ok,” and, “remember to change your cells every 12 months.” It was left to us as individual divers to maintain our own equipment without any real accountability to those we were diving with. Needless to say, looking back on this from a GUE view point, I was shocked that I had once been prepared to accept that level of risk.
From the start of the GUE CCR1 course, the point was made that rebreathers are meant to facilitate dives that are infeasible on open circuit due to gas logistics. When you are venturing into these remote and hostile places, why would you be willing to expose yourself to an intolerable level of risk? Especially when something as simple as a checklist could identify faults and prevent a potential failure that could result in an aborted dive for you and your teammates. Teamwork requires that each member be accountable to the others. Something as simple as a completed checklist confirms that you are thinking with the end in mind, and providing reassurance that you have physically checked each element of your unit.
My previous CCR training had no prerequisites in terms of skill level prior to enrolling in the course; the only requirement was a minimum number of dives. I managed to complete Module 1 without too much difficulty; however, Module 2 was a different story.

In my previous CCR training, when I started Module 2, I felt as if I was ready to start undertaking deeper dives. However, my lack of fundamental skills, stability, and buoyancy control became apparent when we started diving with two bailout cylinders and trying to manage these effectively. My buoyancy fluctuated massively, and problems I encountered became progressively worse as new skills and increasing depth were introduced and I became task-loaded.
As with Module 1, I managed to pass the course; however, looking back on my performance at that time, I should never have passed. I should have been sent home to work on my foundational skills since what I was missing was the appropriate skill level.
After completing GUE’s Fundamentals, that solid base became apparent.
Capacity and Configuration
As we moved on to learn new rebreather skills in my CCR1 class, the necessity for solid fundamental skills was clear, as we now had to manage our loop volume in addition to our wing and drysuit buoyancy. As I mentioned previously, prior to undertaking Fundamentals I had perceived this as a ‘step back’ from the point where I thought I was in terms of my own diving. However, I cannot emphasize enough the importance of having a solid skill base from which to build your capacity, and progress in your diving.
The capacity that GUE training instills in divers provides a common baseline for the team. It provides the reassurance that each diver is trained to the same standard, and will respond in the same manner to particular scenarios. In contrast, the skills taught in my original CCR courses varied depending on which instructor taught them. This could lead to a significant variance in an individual’s response in any given scenario without guarantee that the response will be correct, and more importantly safe. The difference led me to consider GUE’s rebreather configuration in particular, and the benefits it offered in comparison to a standard CCR configuration.

The rig, configured GUE style, looked very different from what I had seen previously, but after it was explained to me, and how it fits into the GUE framework, it all made sense. I first saw the setup about four years ago in a video demonstrating how a long hose deployment would work, and my first impression was that it looked very complicated and time consuming. ‘Why would you not just hand over a bailout cylinder and be done with it?’ was my thinking back then. In hindsight, I believe that deploying a long hose is much less risky than giving/receiving a bailout cylinder that may or may not have been analysed by that particular diver. Some of the CCR divers I had dived with prior to coming across GUE, don’t analyze their bailout gas before each dive. [Ed. note: GUE standards mandate analyzing and labeling gas the day of the dive.]
Incorporating a twinset of diluent into the rig reduces the number of external cylinders that must be carried on any given dive. As I alluded to earlier, I was carrying two Ali80’s (11 liter cylinders)—one bailout, one for deco—during my Mod2 course and was overweighted to the point that my wing was fully inflated and impeding my ability to manipulate the valve on my oxygen cylinder during a high PO2 drill.
Maintaining muscle memory from using a twinset allows for a smooth and familiar manipulation of the valves when required, and mounting the O2 bottle farther back removes any risk of the valve being caught by the wing if it’s overinflated. Overall, the rig feels safer to me, particularly when bailing out to open circuit. As mentioned previously, my prior training had been to use an external bailout cylinder and deploy that if the breathing loop was compromised.
I was not taught a set drill for verifying and deploying the bailout reg in my original CCR classes, and in a state of panic, I could very well have switched to a cylinder containing 50%, rather than a deep mix. In the case of the GUE configuration, it’s a case of either switching to a backup reg or using a bailout valve (BOV). Personally, I would prefer to do this, rather than running through a full gas switch procedure, especially if I was hypercapnic for example.

With this piece, I thought I would provide an overview of the particular elements of the course rather than a day-by-day account. I hope you’ve found this an interesting account of my experience and reflection on how the course sits in comparison to some other CCR training courses. If your objective is to move to CCR diving in the future, I would thoroughly recommend this course. I look forward to diving more with the GUE community and seeing you all on projects in the future.
Dive Deeper:
GUE CCR1 Course
The Thought Process Behind GUE’s CCR Configuration

Andy Pilley is a Chartered Surveyor, team member of GUE Scotland, passionate wreck & cave diver and Ghost Fishing UK team diver. Andy started diving with the Scottish Sub-Aqua club in 2011 and began diving with GUE in 2018. Andy dives on the east and west coasts of Scotland where there is a rich maritime history and an abundance of wrecks to be explored. He has a passion for project diving and is developing objectives for a number of sites with the GUE Scotland team. He hopes to assist on the Mars Project and with the WKPP in the future.
Community
Why It’s Okay To Make Mistakes
To err is human. To trimix is divine? Instructor evaluator Guy Shockey examines the importance of learning through one’s mistakes, and most important, being willing to admit and share them with others, especially for those in leadership positions. It’s the only way to create ‘psychological safety” within our community and improve our collective diving safety and performance. Wouldn’t that be divine?

By Guy Shockey. Images by Andrea Petersen
A few months back, I read an article about a club where members talked about failure and making mistakes. This club required that members freely discuss their mistakes and failures without fear of judgment. The goal was to destigmatize failure and recognize that we learn by making the very mistakes we are afraid to talk about! Moreover, to become truly high performing and develop unique and creative solutions to problems, the article argued that we needed to be free of the worry of failing—to understand that “to err is human.”
The article went on to mention that for high performing teams to be successful, they needed to operate in an environment of “psychological safety.” This term was originally coined by Harvard professor Amy Edmondson, and Gareth Lock has written about the concept extensively. In his work with The Human Diver, Lock identifies psychological safety as a key component primarily missing in our diving culture. As a full-time diving professional and someone who delivers The Human Diver programs, I couldn’t help but reflect on the failure-destigmatizing club in the context of our diving culture in general and, more specifically, dive training.
Consider the humble Roomba robot vacuum cleaner. The Roomba learns how to clean a room by bumping into nearly everything in the room and, with some nifty software, creates a “map” of all the “vacuumable” space in the room. Then, it goes about its business efficiently and repetitively cleaning the room. The Roomba has learned by making multiple mistakes—much like humans do.
Now imagine being able to transfer that new “map” from one Roomba to another so a new Roomba doesn’t have to repeat the mistakes of the first as it sets out to vacuum the room. Finally, imagine this transfer of data to be less-than-perfect—perhaps, occasionally, the new Roomba will make some mistakes (from which it will learn). But it will make far fewer mistakes than the original Roomba had to make.
I’m sure you can see where I’m going with this. Humans learn the same way Roomba vacuums do (hopefully without running into as many hard surfaces), and we can transfer information between each other. Because the transfer process is less than perfect, we still make some of the same old mistakes. This is particularly interesting because, despite drawing specific and repeated attention to these common errors, students often still make the same errors! One of the most important parts of instructor training is educating future instructors to recognize where these common mistakes will occur and encouraging them to ramp up to being hyper-vigilant rather than regular-vigilant.

Learning Through Mistakes
One way we learn is by making mistakes, talking about them, and sharing the experience in the hopes that future divers don’t have to make the same ones. At its core, this is the very essence of learning. Incidentally, this is also what makes experience such an important characteristic of a good teacher. The more experience the educator has, the more mistakes they’ve made and, consequently, the more information they can transfer. Fear of owning our mistakes keeps us from learning from them; perhaps more importantly, it means that others will miss out on these important lessons.
Yet, in diving culture, we (for the most part) shy away from discussing the mistakes and errors we (hopefully) learned from for fear of being considered a less than capable diver. When divers in influential or leadership roles do this, it is a tremendous loss for the diving community in general—it robs future groups of divers of the opportunity to learn. Sadly, because this commonly happens at the leadership level, it is hardly surprising that other divers further down the line copy that behavior, and we ultimately end up with a diving culture that emulates the example of the leadership.
I advocate for taking the opposite approach. In my teaching, I am very open about the mistakes or errors I have made while diving. I recognize that I am basically a smart Roomba, and I learn by making mistakes. Thus, it would be disingenuous to pretend that I don’t make mistakes—I had to learn somewhere! I believe this approach lends authenticity to my instruction and starts to create psychological safety in my classes. Ultimately, my goal is to encourage students to recognize that, “If the instructor can admit they make mistakes, then it is okay to talk about the ones our team made during the training dive.”
I have found that there is a remarkable change in the relationship between student and instructor when this happens. Learning becomes more of a collegial activity, and stress and performance anxiety significantly decrease. This leads to more successful learning outcomes and happier students. I am a firm believer that, while training can be serious, it should also be fun!
Creating Psychological Safety
Creating psychological safety in our diving culture is a daunting task, but every flood begins with a single raindrop. The first thing that needs to happen—at all levels—is an acknowledgement of failures and mistakes among those in positions of influence and leadership. Sadly, this is not as easy as it sounds, and there is frequent pushback. Ego is one of the most dangerous aspects of a personality and it frequently causes people to overreach, crippling growth and learning. The irony here is that every single one of us has made a mistake. We all understand that no one is perfect, yet many in leadership positions cling to the view that vulnerability is weakness—that demonstrating imperfection will cause others to stop trusting them (or revering them).
I propose that the opposite is true. I should also note that I believe every dive professional is acting in a leadership role. This means that, while creating psychological safety can best be started by those in senior leadership roles, it must also be encouraged at all levels of leadership, including anyone in supervisory or teaching roles. In a perfect world, every diver would embrace this approach and enable psychological safety within their team.
There are a few things you can do to help develop psychological safety. First, facilitate a debrief at the end of the dive and begin with “something that I as the leader did wrong or could have done better was…” This immediately creates fertile soil for psychological safety to flourish. When the leader is the first person to say, “I made a mistake,” it establishes that this is a safe place to discuss mistakes and errors with the intention of learning from them. This opens the door to follow-up discussions.
On the subject of transparency, in any organization it is often the voice of dissent—a contrary position—that is the most valuable. This voice causes the group to reflect on original assumptions and decisions and offer a perspective that “groupthink” does not. This means that we need to be open to different solutions to problems lest we be blinded by our own cognitive biases—ones that have been developed over thousands of years of evolution in order to make us more efficient Roombas.
We are essentially fighting against our own brains, and it takes a significant amount of effort to think outside the box. We are hard-wired to think in terms of “evolutionary” rather than “revolutionary” ideas, and we need to make a conscious effort to consider the voice of dissent and understand why it is so hard to do so.

In Conclusion
In psychologically safe environments, we experience a significant increase in “discretionary effort,” or shifts on the “need to do” and the “want to do” curves. If a team has a high degree of psychological safety, they are motivated to perform higher than the minimum standard. If you create a high degree of psychological safety, your team will perform better as a result.
This is where it all comes full circle. We want our dive teams to perform at a high level. We want them to have a high degree of discretionary effort. We want them to embrace our “commitment to excellence.” Therefore, we must be the ones to create the psychological safety necessary to facilitate this growth.
One of the most effective things you can do as a leader is to be open and willing to share that, in the end, you are human too. You make mistakes, you admit to them, you learn from them, and you share them with others so they can learn too.
One of the most effective things you can do as a leader is to be open and willing to share that, in the end, you are human too. You make mistakes, you admit to them, you learn from them, and you share them with others so they can learn too.
DIVE DEEPER
Other stories by Guy Shockey:
InDEPTH: Reflections on Twenty Years of Excellence: Holding The Line (2019)
InDEPTH: Situational Awareness and Decision Making in Diving (2020)
InDEPTH: The Flexibility of Standard Operating Procedures (2021)
InDEPTH: How to Become an Explorer: Passion, Partnership, and Exploration (2022)
InDEPTH: Errors In Diving Can Be Useful For Learning— ‘Human Error’ Is Not! by Gareth Lock
InDEPTH: Learning from Others’ Mistakes: The Power of Context-Rich “Second” Stories by Gareth Lock

Guy Shockey is a GUE instructor and instructor trainer who is actively involved in mentoring the next generation of GUE divers. He started diving in 1982 in a cold mountain lake in Alberta, Canada. Since then, he has logged somewhere close to 8,000 dives in most of the world’s oceans. He is a passionate technical diver with a particular interest in deeper ocean wreck diving. He is a former military officer and professional hunter with both bachelor’s and master’s degrees in political science. He is also an entrepreneur with several successful startup companies to his credit.