As a dive destination, Indonesia needs no introduction. An archipelago made up of over 17,000 islands, the country boasts dive spots that regularly top ‘must-see’ lists, including Raja Ampat and Komodo. Due to challenging conditions, these are suitable to deeper and longer dives.

Reason 1: A growing community offering high quality training

Competent technical divers learn from highly qualified and experienced instructors. Over the past few years, the tech diving community on islands like Bali and the Gilis near Lombok has grown and both areas have become the home base for technical dive shops, as well as instructors and instructor trainers offering a wide range of courses from different agencies.

While technical diving is not (yet?) the norm, it’s becoming more widespread and it’s becoming more common to see someone gear up in sidemount gear or pre-breathe a CCR. This is partly due to dive professionals discovering another kind of diving for themselves and spreading their enthusiasm to visiting divers. More demand has led to more supply, and so the community continues to grow.

Reason 2: Exciting dive sites to keep you coming back

Developing skills as a technical diver means more than completing one level of training after another. Building experience between courses by planning and leading dives with other tech divers or a competent technical diving guide is just as important. Arguably, these dives are more enjoyable when there is something to see. In Indonesia, the islands of the Bunaken Marine Park in North Sulawesi offer deep, sheer walls that drop for several hundred feet in places. Bali and the Gili islands have steep slopes, pinnacle and wall dives that also often exceed the 325-foot (100 m) mark.

The beauty of many of those sites is that they make for a great dive, no matter whether you are heading to 130 feet (40 m) or pushing your limits on deeper dives. The marine life will change with every 30 feet (10 m) of depth, with increasing depth usually also increasing your chances to encounter larger, pelagic species.

Reason 3: Accessible dive sites and short travel times

Indonesia offers both extremely remote diving and relatively easily accessible dive sites. The more remote the location, the more you must be prepared to handle a full-on diving expedition. More on this below, under Reason 5.

On the other hand, you can access depth directly from the shore in other places. Northeast Bali, for example, has drop-offs and sloping walls that start directly from the beach. In some cases, you can conduct technical dives here directly from the shore. It’s easier to do deeper dives with boat support, allowing for a safety diver and drop tank. Bunaken Marine Park relies on boat diving with very few exceptions as currents tend to push divers along its steep walls. Again, however, mind-blowing deep walls with overhangs, ledges, and big marine life are accessible within minutes of resorts.

Another advantage of this topography is divers can often conduct decompression stops on the reef, giving them something to see and pass the time, especially during longer stops.

Obtaining gases and bringing tech equipment requires a degree of planning. Established dive centers will be able to supply oxygen-rich mixes on demand. Depending on where in Indonesia you go, helium may require a bit of advance warning, so it’s a good idea to plan ahead, but, as a technical diver, that should be par for the course.

Standard equipment is widely available but pricey due to import taxes. Specialized equipment, including rebreather diving consumables, may be available in the part of Indonesia you are visiting — again, it’s worth checking with the dive operator you are using. If you are planning major equipment purchases, check prices at home and at your destination to see which option works out better.

Reason 4: Combining technical with recreational diving

With depth being easily accessible often directly from the shore, tech divers traveling with recreational divers may be able to dive with the same operator. Several operators are set up to accommodate both, albeit diving from different day boats or on different trips. This is a good way to accommodate recreational-only friends and family until you can convince them to join the dark side.

Reason 5: Exploration

What tech diver doesn’t dream of discovering dive sites no one has seen before? In Indonesia especially, so much of our ocean remain unexplored, that there is a real chance of being on the frontier of tech diving.

South Sulawesi, for example, recently opened Indonesia’s first cave-diving facility. In North Sulawesi, the search continues for the elusive coelacanth. And even in a place as well-traveled as Bali, only a few divers see the depths of the ocean, and a recent project by Unseen Expeditions is exploring species in depths around 325 feet (100 m). At the same time, divers are still discovering deep reefs around Lombok, including deep cleaning stations.

With more than 17,000 islands, much remains to be explored in Indonesia. In any case, it pays to research your tech diving shop ahead of your trip and check on specific requirements. As a rule of thumb, the more remote your destination, the more the journey there will become part of your tech diving adventure.

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Choosing the Right Agency

Starting tech diving training is often more about finding the right instructor than it is about choosing a specific agency. However, it’s worth looking at the agency side also. Each training agency has a somewhat different philosophy, often influenced by founders and training directors.

This philosophy will be reflected in their training programs and materials. As far as materials go, two areas can make a difference. The first point is access: online learning is convenient, cost effective and environmentally friendly, but not every diver finds it easy to learn this way; some people may prefer books, and some may prefer instructor-led theory classes. It’s worth checking whether your chosen course can accommodate your preferred learning style.

The second difference lies in the timeliness of the material: when was it written? Technical diving is evolving fast. There are regular updates to best practices, not just underwater, but also regarding dive planning, equipment specifications, and more. Online-based materials can accommodate these changes far more easily than printed books.

Course Flexibility and Curriculum

Aside from the material, looking at the degree of flexibility within a course is important. Some agencies prescribe exactly which skills divers must perform during each course dive. Others list all skills required for certification but leave it to the individual instructor to decide which skills to tackle on specific dives. The latter often allows for a more tailored course that accommodates individual learning styles and paces.

Also investigate how an agency’s course progression is structured and how it fits with your diving goals. Some of this is evident in course flow charts and course descriptions, but it’s probably something you should discuss with an instructor.

Many technical diving instructors are affiliated with multiple agencies and therefore can advise you on which curriculum best fits with your preexisting qualifications, experience, diving goals, and the environment you are training in. Based on that, you may well stick with one agency’s training.

Does switching have benefits?

Are there any benefits to switching? Definitely. Mainly, you’ll have the opportunity to compare and better understand which curriculum and teaching style works best for you. Generally, crossing over between agencies at a recreational level is as simple as signing up for a new course. However, as technical diving curriculums are not as streamlined as the entry level courses, you may have to take a step sideways to fit into the other agency’s course flow.

As an example, both IANTD’s and TDI’s Advanced Nitrox courses qualify divers to utilize nitrox mixes up to pure oxygen. However, while the IANTD version of the course covers conducting limited decompression stops, TDI’s Advanced Nitrox course stays within no-stop limits. So, coming from IANTD and wanting to continue within the TDI curriculum, divers still need to complete TDI’s initial decompression diving training course, Decompression Procedures. Even though much of the material is similar and the difference in potential maximum depth is only a few feet apart, Decompression Procedures allows unlimited decompression stops—a major difference between the two.

Crossing Over for Dive Pros

For dive professionals, crossing over is a more structured process. Details vary depending on existing qualifications and teaching experience. The process may range from a shorter version of an instructor course to a simple administrative switch. All depends on the individual agency’s requirements and the instructor’s existing qualifications and teaching experience.

Most agencies will recognize that teaching experience is valuable, even the instructor has been teaching different curriculum. At the end of the day, the instructor has still explained technical diving principles and practices to their students. A crossover usually entails spending some screen time learning about an agency’s history, understanding its teaching philosophy, course structures and—perhaps most importantly —teaching standards.

Underwater, a crossover may include a skills circuit, often conducted as a peer review rather than an exam situation. This means that the instructor crossing over is being assessed in a more workshop-like scenario. However, some crossovers are more like a shorter version of an instructor training course, including academic and underwater skills presentations. There may also be requirements to assist on courses.

So, while moving between diver training agencies is fairly straightforward at diver level, those intending to add professional ratings to their qualifications will find more formal requirements.

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What is technical diving — really?

Considering the potential risks of technical diving is impossible without defining what technical diving actually is. Generally, divers distinguish between recreational and technical diving but, strictly speaking, much technical diving is done for recreation — for fun. It may be a more serious or complex form of recreation, but it is nonetheless recreation.

So, where do we draw the line? For this post, we will consider planned diving beyond no-stop limits as technical diving. This includes both open-ocean diving and overhead-environment diving, such as cave or wreck penetration. Most often, the type of diving dictates the need for additional equipment, possibly including a range of nitrox or trimix gases. All of these are included in our definition of technical diving.

It’s also worth examining the anatomy of a technical dive. Simply put, it falls into two parts: the bottom time and the decompression obligation. When a problem occurs will determine its severity: something going wrong at the beginning of the bottom time generally carries fewer consequences than a problem that occurs towards the end of the bottom time when a diver has incurred the full decompression obligation.

Risks of technical diving

First things first — any dive that does not allow a diver to return directly to the surface at any point carries additional risk. From the beginning of their open-water certification course, divers learn that they should complete a safety stop at the end of each dive, but strictly speaking this is not a mandatory decompression stop. Mandatory decompression stops are just that — a diver must carry them out to return to the surface safely.

Missing mandatory decompression stops almost certainly leads to decompression sickness. In an open-ocean environment, we talk about a ‘virtual ceiling.’ While there is no physical barrier separating the tech diver from the surface, mandatory stops create a virtual barrier. In overhead environments, divers have a ‘hard ceiling.’ This may be the top of a cave, one of the decks of a wreck on a penetration dive, or a part of a mine, for example.

Therefore, technical divers in an overhead environment must know exactly where and how far away they are from the nearest exit. Even in open ocean or freshwater environments, the simple fact that technical diving often involves being further away from the surface means that there is increased risk.

Technical divers understand and accept those risks, but more importantly, they work hard to mitigate and minimize them. As risk is a part of tech-diving life, so too is mitigation.

Risk analysis and mitigation

Risk analysis and mitigation start on the first day of a technical diving course or possibly even before, when students immerse themselves in the study of the theory part of their chosen course. Understanding which risks are involved in any given dive and how to manage them is key to minimization.

Knowing the risks of a dive often starts with an honest assessment — of the individual diver, of their team, of the conditions expected on the dive, and of potential hazards. Knowing these as well as possible, divers can start thinking about potential solutions.

Often, these solutions will involve carrying additional equipment. Redundancy is a key concept of technical diving, and basically means that divers should carry at least two of each piece of life-support equipment. Then, there is the gas supply. With open-circuit technical dives, a diver carries a minimum of one-third of his gas supply in reserve. In overhead environments it is often substantially more. On CCR rebreather dives, open-circuit bailout gas is calculated based on an equipment failure at the very end of the bottom time.

Crucial diver skills

Apart from equipment and gas, perhaps the most crucial element of risk mitigation lies with divers’ skills which, in this case, refers to both technical and non-technical skills. Technical skills are those we generally consider diving skills — buoyancy control, trim, dealing with equipment failures, handling multiple gases, and following a dive plan are just a few of them.

Non-technical skills are sometimes referred to as soft skills. However, they are just as important, if not even more so. These include the ability to work as a team underwater. While technical divers are trained to be largely self-sufficient, team-oriented diving practices will go far toward minimizing risks and dealing with adverse situations.

Then there are communications. Whether via hand signals, wet notes or ‘talking’ to each other through the breathing loop of a rebreather, complex dives often require more complex communications. Complex does not necessarily mean complicated. However, discussing and agreeing on an adjustment to the dive plan, for example, does require a series of hand signals rather than one or two.

Above all, risk mitigation in technical diving is not something that divers learn in a course once and then never review. It is an ongoing process, which involves regular skills practice, both technical and non-technical, thorough dive briefings, equipment maintenance, and the confidence to talk about things that were not ideal on any given dive. But that is a topic for another post and then some.

Technical divers understand and accept that diving beyond no-stop limits carries additional risks. They also analyze, train, plan, and practice to mitigate and minimize those risks for each dive. With all that in mind, it is perfectly fine to decide that you are not comfortable taking those risks, whether that means sitting out one particular dive or never trying technical diving at all.

The post But Isn’t It Dangerous? Risks of Technical Diving appeared first on Scuba Diver Life.

Why it costs more

Divers considering getting into CCR rebreather diving are, generally speaking, a few years into their diving career. In fact, many of them are technical divers, although you don’t have to be trained to hit great depths and complete long decompression stops to benefit from CCR diving.

With a few years of diving experience under your (weight)belt, you may have noticed that scuba diving is not a cheap hobby. And neither should it be. You are entering an environment that is alien to humans. To spend more time underwater safely requires more equipment. And while we may not always think of it that way, especially in the context of recreational diving, diving equipment is life support equipment.

The more you must rely on that equipment, so too must its quality improve. Technical divers committing to decompression stops arguably rely on their equipment more than recreational divers who could ascend directly, even though safety stops are highly recommended.

It’s about more than money

But even with lots of technical diving equipment, making bubbles and diving open circuit severely limits the time you can spend underwater. On the other hand, rebreathers will simply transform your diving. This is where the real advantage lies and where the argument becomes about more than money.  

Let’s accept that rebreather diving also requires a sizable investment to get started—as do golf, skiing, and many other adventure/extreme sports. In the case of rebreather diving, the investment is in both training and equipment. Granted, you can complete at least the initial training with a rental rebreather.

However, once you decide that CCR is for you and you want to continue, daily rental will become more expensive than owning your own rebreather. Plus, understanding your rebreather will make you a more confident and comfortable CCR diver.

You’re buying time

So, how does CCR diving transform your underwater adventures? Simply put, rebreathers buy you time. Since you are recycling your breathing gas (yes, this is oversimplified), a small amount lasts much longer. If, for example, you are in 65 feet (20 m) of water, watching a group of reef sharks or simply enjoying the reef life, low gas will eventually limit your dive time.

On a rebreather, remaining scrubber time often becomes more of a limiting factor. Depending on the model of rebreather you’re diving, as well as diving conditions, you tend to have three hours or more underwater. Consequently, putting on what looks like a lot of equipment becomes more worthwhile because you are doing it to remain underwater for two or three hours at a time.

Your next limit is no-stop time. As a recreational diver, you probably already know that you can extend your no-decompression limits to a degree by diving nitrox for as long as your depth allows. As a technical diver, you simply plan sufficient decompression gas to cover your mandatory stops, plus a reserve. But—and this is the clever bit—as a CCR diver, you’re loading less nitrogen and therefore racking up less stop time. How is that? Put simply, you are diving a set partial pressure known as set point and generally equaling a PO2 of 1.3. This means your rebreather is supplying you with the best possible gas to either extend your no-stop limits or minimize your decompression obligation. More diving, less penalty.

You’ll save money on helium

Very little technical diving occurs without using helium in different trimixes. No matter where you are in the world, helium is expensive. Rebreather diving means that you use dozens of liters of helium per dive as opposed to thousands of liters needed for an open-circuit, technical dive. Even taking the cost of scrubber material into account, your cost-per-dive for trimix rebreather dives is much, much lower than it would be on open circuit. Assuming your goal is to complete longer, deeper dives, this is a real saving.

If this all sounds a bit abstract, let’s make it more concrete. Take Chuuk Lagoon, for example. Here you’ll find dozens of shipwrecks over 325 feet (100 m) long at depths between 40 to 195 feet (12 to 60 m). Based on current recommendations, it’s prudent to dive anything below 130 feet (40 m) on trimix.

So, you have a huge wreck to explore. Assuming you have booked on a technical diving trip, there is no real limit to your dive time. Practically speaking, two to three hours is possible. The idea would be to complete one morning and one afternoon dive with a long surface interval. Being able to spend two, or even three, hours underwater will really allow you to explore those World War II wrecks. And, even after two weeks of dives—including on some of the deeper wrecks—your helium bill, if you’re diving CCR, will be a few hundred dollars rather than thousands. And that’s in a remote destination with some of the world’s highest helium prices.

Compare that to open circuit, and even when carrying lots of gas, your dive time will be shorter, and your gas bill will be larger.

Marine life interactions

Aside from financial arguments, you should consider marine life interaction. One of the biggest differences between open circuit and rebreather diving is the lack of bubbles and, consequently, the lack of noise. This means marine life comes closer and tends to stay longer. The quality and the quantity of your marine life encounters improves. In fact, many species simply don’t seem to know what to make of CCR divers and come in to take a closer look.

We could go on, but in conclusion, there is not much point in comparing one-hour dives at 65 feet (20 m) on open circuit with the same thing on a rebreather, because as a rebreather diver, you can now complete entirely different dives. Your diving limits will change, and the opportunities for underwater exploration open to you will increase incredibly. It’s worth it.

The post Rebreather Diving Is Expensive…Or Is It? appeared first on Scuba Diver Life.

Let’s first clarify the terminology: open circuit means nothing more than traditional scuba, where a tank delivers the gas and you inhale via a regulator. Your outward breath exhales the into the surrounding water, creating bubbles. It’s a fairly simple system. Closed circuit diving (CCR) means recycling some or all of your gas and re-breathing it, hence the name “rebreather.” There are no bubbles with this system. While simple in principle, the actual equipment setup tends to be more complicated when it comes to CCR diving.

Easier transition

Divers typically learn to dive on single tank open-circuit scuba. Therefore, one argument for starting to tech dive in open-circuit configurations is to create an easier transition to decompression diving and mixed gases. New tech divers can change single tanks to doubles and add stage/deco tanks, but the principal components of equipment — cylinders, buoyancy compensators and regulators — remain the same. With that in mind, student tech divers may find it easier to concentrate on learning new protocols and diving techniques.

Where will diving take you?

Another consideration is where you see your diving in five years’ time. Some tech students are simply curious about what lies beyond no-stop limits and are looking to discover ‘the dark side’ step by step. Others have a clear goal in mind — perhaps expedition diving, wreck exploration or mapping caves. These students already know they will be looking for greater depths, longer dives — and a lot of helium for their trimix. If you fall into the latter category, starting your tech diving journey on CCR might be a better option.

Added complexity

While the idea of recycling your gas supply seems beautifully simple, using an actual rebreather is more complex. For starters, there are two tanks involved. The first one contains oxygen to replenish the oxygen you have metabolized on the dive, and the second contains diluent to ensure you can keep oxygen partial pressures at a safe level, as well as being able to inflate your counter-lungs enough to take a full breath. Another key component is the CO₂ scrubber, which removes carbon dioxide from the diver’s exhaled breath via a chemical reaction.

Consequently, setting up your rebreather takes longer than setting up a single tank. The same is true for cleaning equipment post-dive, although, with practice, divers develop a routine and become more efficient.

This added complexity does extend to the dive itself. While electronic CCRs do a lot of work for the diver, manual CCRs require the diver to be more active during the dive. Both types require divers to become very familiar and highly practiced when it comes to dealing with emergencies. Arguably, this also applies to open-circuit diving, but closed-circuit diving beyond the initial certification level does pose a higher degree of complexity.

Extended time underwater

One of the biggest benefits of rebreather diving is additional time underwater. On open circuit, tech divers tightly calculate their gas. One of their main concerns is whether or not they have something to breathe. On closed-circuit systems, however, the concern changes to ‘am I breathing something safe?’ Rebreather divers learn to check that they are maintaining a safe partial pressure of oxygen at all times to avoid hypoxia as well as oxygen toxicity.

With that in mind, the scrubber duration becomes a major limiting factor. This will vary from manufacturer to manufacturer and depend on scrubber size and design, but three or more hours is not unusual.

Marine life encounters

Diving without bubbles means diving almost silently and simply fitting better into the underwater world. Fish are calmer and tend to get closer to the diver to inspect this strange creature more closely. This is amazing for underwater photography and videography, and it can actually be a bit unnerving to new CCR divers. Divers may also find that their marine life encounters become longer as they are not standing out in the underwater environment as much as open-circuit divers do.

What’s your budget?

Diving is not a cheap hobby, nor should it be. It requires specialized life-support equipment that needs to be well maintained and often involves reasonably complex logistics. Technical diving takes all of that up a notch as divers add redundant equipment, some of which needs to be oxygen-clean, and may also look to dive specific, more expensive gases. Longer tech dives also mean that mixed boats with recreational and technical divers don’t always work well, so you may require a separate boat.

Once you exceed certain depths, you’ll need helium to dive safely and avoid issues such as gas density, narcosis, and oxygen toxicity. In most parts of the world, helium is expensive — and this is where the ability to recycle your gas may help you save money if you are diving closed circuit.

On the other side of this argument is the cost of getting started. Just like recreational training, you’ll learn both open-circuit and closed-circuit technical diving in stages, meaning you’ll need several courses to reach your goals. Then there is the cost of the rebreather itself. Many shops will offer rental units to students, but if you’re planning on sticking with CCR diving, investing in a unit of your own will become inevitable.

Having the ability to recycle your gas, however, will go some way toward offsetting the cost of helium along the way.

So, what should you do?

For many people the answer to that question is a bit of both. Laying open-circuit tech diving foundations, understanding decompression dive planning and gas calculations, and running dives will help a diver’s transition into CCR diving.

In addition, you must back up any CCR dive with a bailout plan, which you’ll calculate using largely the same principles open-circuit tech divers would apply to their contingency planning.

There is no one-size-fits-all answer here but consider how much time and budget you can dedicate to technical diving. How sure you are that this is the way your diving will go will help you decide whether to start with open-circuit training or jump straight into a CCR. And, if you can’t decide, there’s nothing wrong with doing both.

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What exactly is scientific diving?

Scientific diving is the use of diving techniques by scientists working underwater in the direct pursuit of scientific knowledge. Marine biologists often apply the scientific method while searching for new species, through their efforts to protect marine life, and in their quest to further expand our knowledge of the underwater world. Scientific divers also help train astronauts before they go into space.

From Boy Scout to marine biologist and diving instructor 

Joseph Bosquez has been diving for the past 20 years, with much of that time spent as a marine biologist. He’s participated in multiple diving operations, from identifying and cataloging fish species with NOAA in the Gulf of Mexico to six months with the Boy Scouts of America on Catalina Island, collecting fish and invertebrate species for the Emerald Bay Aquarium. It was his experience working as a university faculty member, teaching diving and scientific diving, that laid the foundation Bosquez to become an instructor for Divesoft. He says his “overarching vision is to become a high-impact teacher and advocate for the underwater environment.”

Training astronauts for NASA

Perhaps Bosquez’s most notable diving project was his time spent training astronauts at NASA. He spent most of his time at the Neutral Buoyancy Laboratory, where he instructed astronauts-in-training on maneuverability in microgravity spaces. “We focused on underwater operations, known as “dress rehearsals,” where the astronauts could practice moving in space and preparing for a number of jobs they would be tasked with aboard the International Space Station,” said Bosquez.

Bosquez also spent some time in the mission control back room during spacewalks. From there he could watch his trainees successfully complete the missions that they had worked on together in the pool months before.

Parting words

Bosquez currently works as the dive operations manager for Czech dive company Divesoft. When asked about his ambitions as a dive instructor, Bosquez addressed the importance of growth and progress. “Scuba diving and marine science have so many avenues in which someone can experience continual growth,” he said. “Over the past few years, I have focused on becoming proficient with Divesoft equipment and my next focus is to utilize the equipment for more advanced diving.”

Scientific diving opens the door to many specialized careers. Whether you’re interested in marine biology, wildlife conservation, working hand-in-hand with astronauts, or discovering a new lifeform, scientific diving can help you get there. Even though such tasks may seem daunting at first, Bosquez reminds new divers to stay motivated.

“Struggle is important, but it isn’t about finding yourself or finding your passion,” he says. “It’s about turning yourself into the kind of person you would have looked up to growing up.”

By guest author NikolaValtošová

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Skills training vs. course work

Gaining experience as a tech diver means spending a lot of time underwater, yes, but building skills is not as simple as racking up bottom time — it’s about making those hours count.

As an example: to progress between rebreather diving levels, divers must log 50 hours underwater as well as 50 dives. Why? Because, generally speaking, cruising at a set depth is fairly easy, whereas descents and ascents are the potentially trickier parts of the dive. To progress beyond what you need for certification and to keep up that skill level, you must not only spend time at depth, but also safely negotiate your down and back to the surface.

So, how do you make the underwater hours count? There are plenty of ways to gain meaningful experience and to work on skills while having fun. Choose dive buddies or teammates that are more experienced than you are and — crucially — are happy to share their knowledge. Ask them for feedback. How does your trim look? Do they have any thoughts on your gear configuration? What about your movement underwater?

This is not to suggest that everyone knows better than you do. After all, if you learned from a reputable tech instructor you will, at the very least, have a solid foundation to build upon. However, four eyes see more than two, and it is worth hearing out other points of view. Leading technical divers will tell you that they never stop learning and are always keen to improve something.

Why not take more courses?

So, if you are learning from others, why not simply take more courses? In technical diving, taking another course often means adding complexity to your diving. For example, when you move from TDI’s advanced nitrox and decompression procedures combination to normoxic trimix, you are not only gaining depth, you are also learning to handle a different bottom gas and two deco gases rather than one.

That’s a lot of new material to take in — especially if you are still cementing all the skills you learned during the previous course. There may not be a minimum number of dives between completing the two levels – although the pre-requisite dive numbers are very different – but it’s worth consolidating skills and knowledge of one level before signing up for the next course.

This consolidation is even more important if you haven’t tech dived for a while. Muscle memory fades. Motor skills deteriorate over time. However, the more dialled in they were before your diving break, the easier it is to ‘dust them off’.

Ideally, you hone these skills to avoid losing them. If you are keen for instructor-led diving or professional feedback as part of this process, look for workshops. You don’t need to jump to the next level of tech diving to have professional feedback. In fact, technical fun dives involve planning a full-on dive, reviewing procedures as a team and they often allow for skills practice and review to some degree. These dives, whilst not part of a certification course, still require the same level of preparation and planning as course dives would.

Workshops are another good option offered by many tech instructors or shops. They tread the line between certification course and fun tech dive by providing more of a structure to the review or training process and often building up to more complex dives. Depending on how many people there are in your workshop, you will have the chance to focus on areas you want to improve on or progress further.

Which way is right for you depends a lot and when, where and how you dive. For those tech divers who tech dive regularly where they live, becoming part of a team of divers or even building that team of divers is realistic. With a regular group of techies it becomes easier to make those dives count and improve whilst you dive.

For those tech divers, who are ‘restricted’ to diving a few times or even only once a year, building time to review skills into their tech diving schedule is key to dive safely.

Simply racking up hours underwater without feedback or structure will lead to experience on paper, but it’s unlikely to help keep skills sharp – and that’s what they need to be in case of an emergency. At the same time, taking course after course without consolidation leads to a high number of certification cards, but not necessarily true, applicable experience.

As is often the case, there is a middle ground – enjoying time tech diving whilst adding skills practice and asking for feedback; improving and perfecting skills before moving to the next certification level will go a long way towards becoming a safe, experienced technical diver.

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We can forgive new divers for never having thought about how they move underwater. After all, propulsion techniques are not part of the standard open water diver curriculum of all agencies. However, when you move on to more challenging dives or want to become a technical diver, mastering different propulsion techniques becomes important.

Propulsion: a fundamental skill

Like buoyancy control and trim, propulsion is one of the foundational diving skills for technical divers. And, just like buoyancy and trim, propulsion does not exist in a vacuum. If you cannot hold a set depth by controlling your buoyancy with a combination of wing and lung volume, you won’t be able to focus on how your fins are moving.

Without horizontal trim, even a perfectly executed backwards kick will either send you up or down. Kicking up or down means having to readjust your buoyancy frequently, causing additional task loading. However, if you can get these three to work together, you are well on your way to managing multiple tanks, gases and tasks.

The frog kick

Most tech divers start with a frog kick. In principle, the frog kick is similar to the movement you make when swimming the breaststroke. The knees and ankles and some degree of leg extension drives the fin blade, but it’s not always necessary to fully extend your legs. This kick is a tech diver’s ‘bread and butter’ kick, which they’ll use for a majority of each dive.

The modified flutter kick

If your legs tire from repetitive movement, but you still need a similar degree of propulsion, the modified flutter kick becomes an option. Technical divers generally want to avoid stirring up silt from the bottom of the sea, wreck or cave they are diving in, so this altered version of the kick works without fully extending your legs. Full extension of the legs would create a draft, pulling up sand or silt. Instead, tech divers extend their ankles and point their fins upward before flexing their ankles to allow the fin blade to push the water behind them. The kick feels very strange initially, but you can actually use it to build up a lot of power and speed to help you move through a current, for example.

Modified frog kick and shuffle kick

On the subject of modified propulsion techniques, there are also both a modified frog kick and a shuffle kick. They are essentially smaller, and often slower, versions of the frog kick and the modified flutter kick. We use both the modified frog kick and shuffle kick for controlled movements in restricted areas. They are essential for cave and penetration wreck dives to zero-visibility situations. For both, movements are largely restricted to the ankles. Knees and legs stay almost motionless and at a 90-degree angle. The ankles create enough movement to drive the fin blade.

These are not fast kicks, and they are not designed to cover large distances. They are all about controlling your movement and are useful outside of overhead environments as well. During photography dives, both of these propulsion techniques are very useful when it comes to nearing marine life without disturbing it. Both kicks are ideal for sneaking up on whatever it is you would like to photograph.

Moving backward

Having moved close to where you need to be, it’s also important to be able to move away — ideally without using your hands to skull. This is where the backward kick comes into play. For some, it’s more or less the Holy Grail of propulsion techniques, having taken dozens of dives to master. For others, it comes naturally. All technical divers must master this kick. When moving forward and encountering an obstacle, for example, you first backward kick is effectively your brakes, stopping the forward movement. Your next few backward kicks then allow you to back away from the obstacle.

It’s also handy to know how to move backward when gas sharing. The out-of-gas diver signals his team and a teammate moves in quickly to supply gas. To avoid crashing into each other (while holding torches, controlling reels, etc.) both divers can simply kick backward to give each other a little space while staying close enough to share gas. In open-water environments, the backward kick is ideal when divers are adjusting their position within a team. Anyone who has ever done a fast drift dive along an undulating wall will appreciate the ability to adjust the way they are facing with a swift and powerful backward kick.

The helicopter turn

The helicopter turn is another way to turn around. The name is a giveaway: this kick allows you to turn around — 360 degrees if necessary — without taking up more space than your own length. While you can push around with one leg only doing a semblance of a frog kick, the helicopter turn is smoother, more efficient and a lot more controlled when both legs fin together. In that case, one leg would perform a motion similar to a backward kick to steer and the other performs a version of a frog kick. Most divers will have a favorite direction in which to turn; what’s important, though, is to master this kick in either direction to complete your toolbox.

Fin choice and propulsion techniques

A word on fins: typical tech diving fins with relatively short, rigid blades will make these kicks easier to master and give the diver much better control underwater. That said, many other fins will work, but may make mastery a bit more difficult. Generally speaking, split fins or long freediving fins will make things harder and, when problems occur on technical dives, additional task loading will make it harder to solve anything.

So, how do you master these propulsion techniques? Practice, practice, practice. Dry practice will help teach your ankles, knees and legs how you want them to move, and this is something any diver can do at home. Then, in-water, apart from a solid demonstration and practice time, getting video feedback also makes a difference. Seeing what you are currently doing goes a long way toward adjusting, and eventually mastering, whichever propulsion technique you find trickiest.

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Planning is everything

Like with technical diving in general, ‘technical traveling’ is nothing without pre-planning. Having a clear idea of the kind of diving you want to do and the equipment and logistics required to make that happen is crucial. To be very clear — neither traveling light nor leaving arrangements to the last moment will work in your favor, so start early. How early is early enough? This will depend on the remoteness of your destination and what supplies you can get there. You must start planning early enough to allow for contingency planning.

If you don’t have a checklist for your equipment, start making one. Every piece of equipment on the list must be in good working order or it will cause problems on your trip. If it’s been a while since your equipment got wet, try to schedule a local dive or join a pool session to test your gear. You may have to allow time for equipment servicing should anything fail. Getting wet not an option? How about arriving at your destination a few days before the boat leaves, for example. While this won’t necessarily help with shopping for replacements it may allow time for last-minute servicing.

Use local supplies

Many tech centers have rental equipment available, especially if they also offer introductory tech courses. Selection, however, tends to be limited. If you are counting on specific items to supplement the gear you’re bringing, you must check that they are available and reserve them.

Why don’t the centers carry more rental equipment? Because most tech divers— once they qualify and decide that tech diving is a good fit — purchase their own gear and personalize it. For example, in order to be comfortable carrying three or more tanks, your harness must fit (near) perfectly. It simply becomes too inconvenient to set up from scratch every time you arrive at a new destination.

On the other hand, if you dive a (fairly) standard 50-pound donut-shaped wing that’s too bulky for your luggage, most tech centers can likely supply it. At the end of the day, the more complex your dives become, the more you’ll want to use your own personal gear.

Know your airlines

Getting to far-flung destinations — think Chuk Lagoon in Micronesia or Solomon Islands — inevitably involves a serious amount of air travel. While low-cost carriers might be a great choice on a short hop between two cities, for tech traveling you need a reliable airline with extensive luggage allowance options.

Rather than looking for the cheapest flight, research individual airlines and their specific baggage policies. Many airlines offer an additional allowance for sports equipment, although not all of them will accept dive gear as sports equipment. Use your clothes as padding for your equipment and plan to add to your holiday wardrobe at your destination. After all, who doesn’t like a new diving t-shirt?

If you’re likely to travel for diving regularly, check out airlines’ loyalty programs. While the upfront cost of the flight may look higher, the benefits may well make up for that and more. Eventually, especially with a serious amount of intercontinental travel, you will collect airmiles which will bring additional benefits.

Apart from the financial aspect, other considerations are the restrictions on what you can carry safely. Take scuba cylinders as an example: airline staff are trained to be vigilant about allowing them on board. You will need to remove the valves and make staff aware that you are checking in tanks. It’s best to be proactive about these things at check-in, explaining to (non-diving!) personnel what you’re checking in and why it is safe to fly.

The same is even more true for traveling with rebreathers. CCRs are life-support equipment that is likely to look strange on the average airport x-ray machine. A short explanation of what the equipment does, accompanied by images of you using it, can work wonders here.

Ask for help

Remember, diving is a team sport. Even if you are traveling alone, and especially if you are maneuvering several bags, cases and boxes across an airport, onto a ferry or simply out of a hotel room, there are usually people around who can lend a hand.

In Asia, paying porters a small amount to carry luggage is customary, and you can find them in most places where there’s heavy luggage. While it may look strange to western eyes, it’s a source of income for local people, and it can be vital for divers and traveling divers.

Many airlines have support staff available, as well, which comes in especially handy when you have a lot more luggage than hands to carry it. Don’t be afraid to ask for help.

In conclusion

Tech diving and traveling can be challenging, but the rewards outdo the hassle many times over. Be sure to plan ahead, allow plenty of time on journeys and budget realistically — and tech traveling becomes (almost) as easy as a weekend city break.

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X is for X-over

Though we know the letter designation is a bit of a fudge, crossovers are fairly common in technical diving, both at the instructor and recreational tech-diver level. They can happen between agencies, with a diver going from one agency to another, or when an instructor adds another agency’s curriculum to their array of courses.

There are benefits in both following one agency’s curriculum and crossing over between several. By sticking to one agency, tech divers become familiar with that agency’s materials, the course structures and, eventually, its teaching philosophy. Moving on to further levels of training, they will have a better idea of what to expect from the course.

On the other hand, moving between agencies helps divers understand different approaches to tech diving. For tech instructors, offering courses from several agencies is a way to attract more students, who may want to stick to ‘their’ agency’s courses.

Another relatively common form of crossovers in technical diving occurs between closed-circuit rebreather (CCR) units. CCR training is unit-specific, meaning you only qualify to dive the unit that you trained on. But, if divers change their mind and want to dive another brand of rebreather, they don’t necessarily need to go back to the beginning. Instead, a shortened version of the course, highlighting the differences between the units, is often available. This allows the CCR diver to learn everything they need to know about their new unit.

Y is for Y-valves

Y valves and H valves allow divers to back up their regulator. Shaped like an H or a Y, these valves have two outlets where a diver can attach a first stage.

You may never have seen one, as we don’t commonly use either any more as twinsets/doubles or sidemount configuration have become standard for technical divers, both in training as well as after their courses.

The main drawback is of Y or H valves is that the diver cannot back up any cylinder or valve-related issue by using them. Take, for example, a gas leak between the top of the cylinder’s neck and the actual valve — neither an H nor Y valve would help a diver conserve gas in this scenario. More drastically, a leak from a burst disk of a valve can empty a full tank in well under five minutes.

For those reasons, having more than one tank with one regulator each makes technical divers safer.

Z is for Z-knives

Z-knives, also known as Eezycut or Trilobite cutting devices, are among the most universally useful cutting devices for divers. Their popularity is partly due to their small size and the many options for mounting them. These small, flat cutters fit well on harnesses, computer straps or the outside of utility pockets. In fact, many divers carry more than one.

That said, there are plenty of other options for cutting devices. If there is a trend in this area of equipment, then it is toward smaller tools. How many cutting devices should tech divers carry? At least two, one that’s reachable with both hands, as it’s impossible to predict when and where you may get stuck underwater.

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U is for Understanding your Limits

Technical diving is about expanding your limits underwater. In fact, technical diving for recreational purposes as a subdiscipline (next to sport, commercial and research diving) developed in response to the limits imposed by sport diving. In order to widen access to diving as a hobby, newly created training agencies set depth and time limits to keep divers relatively safe. However, while many divers were happy to explore within those limits, others sought to go further. Consequently, technical diving standards developed alongside tech-diving training agencies.

Technical diving does exceed depth, time and environmental limits, but divers still learn incrementally. As they progress through levels of training, they expand their own comfort zone step by step. Understanding your own limits — in relation to equipment, gases, decompression time, dive skills, knowledge etc. — is a key part of any technical course and one of the main drivers of diver safety.

V is for Valve Drills

Valve or shutdown drills are another key part of technical-diving training. Being able to perform them reliably and fast allows divers to isolate leaks and preserve as much as possible of their gas.

The drills are arguably easier in sidemount configuration, as tank valves are within the diver’s field of vision. This makes it easier to identify the source of a problem. However, when moving on to technical sidemount, divers may find their front somewhat cluttered as tank rigging and equipment familiarity become more important. Successfully repeating valve drills during their course and afterward helps them identify and shut down the current valve.

In backmount configuration, a diver’s ability to perform reliable and speedy shutdown drills is even more important as leaks are happening where a diver cannot see them. Of course, a teammate can help identify the source of the problem, but technical divers learn to be self-sufficient. Thus, being able to reach valves and turn them in the correct direction to stop a leak is vital.

Divers often practice this in two stages during training courses: First, divers start with systematic, repetitive shutdown cycles that train muscle memory. Instructors often refer to stage two as a BOOM drill. In this, the instructor simulates a leak behind the diver who must now go through a series of steps to identify and isolate the leak, both alone and together with a teammate. The aim is to efficiently contain the leak, preserve access to as much gas as possible and start a timely ascent.

Both are much easier if divers initially practice on land. Successful performance depends on repetition, both during the course and afterward.

W is for wetsuits vs. drysuits

Technical dives take divers deeper and last longer than the average recreational dive, so exposure protection is crucial. It’s about more than just comfort: on- and off-gassing are related to circulation which, in turn, is related to body temperature.

During the dive’s decompression phase, divers are generally at rest and therefore more prone to hypothermia. Keeping the body’s temperature normal is key to efficient off-gassing and as movement is limited, the diver’s exposure suit is doing that work. Tropical environments really are the only place where wetsuits are warm enough for tech divers.

However, even in the tropics many techies opt for drysuits as it’s simply the equipment they are used to diving. So-called tropical drysuits limit sweating and overheating before the dive while still allowing the diver to layer undergarments depending on the expected water temperature. Another argument for a full wetsuit or a drysuit is that divers will encounter thermoclines at greater depths.

In overhead environments, protection from scratches and cuts becomes an issue, meaning that even if temperatures allow for a short suit, it’s simply not the best choice. Stay tuned for the final installment of our series, where we’ll cover X, Y and Z.

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Q is for Questions

We generally prepare more thoroughly for technical dives than recreational dives. Part of this preparation is meant to clear up any inconsistencies ahead of time before they lead to confusion. However, even the best preparation and briefing cannot cover everything and that’s why one of the hand signals we use most frequently is the question mark — a diver’s index finger bent into a shape resembling a real question mark. And if hand signals aren’t enough, then we can write in underwater notebooks or on slates. In fact, those planning a complex dive often take the time to develop a set of pre-planned phrases that they can use in a number of situations they are anticipating.

In technical-diving courses, asking questions is key for both the instructor and the student. The instructor will be checking the students’ understanding of what he or she is teaching. Students, on the other hand, must ask questions to ensure they are getting to the bottom of things. Letting things wash over you and hoping to successfully complete the course or any subsequent dives without understanding can be dangerous, so don’t be shy.

R is for Rebreather Diving

Rebreathers allow for bubble-free diving by recycling the diver’s breathing gas. In the process, a scrubber material filters out our carbon dioxide — a byproduct of our respiration — and oxygen metabolized by the diver is replenished.

Closed circuit rebreathers (CCR) maintain a constant partial pressure of oxygen in the breathing mix. That means the diver is basically breathing a different gas at different depths with the aim to minimize decompression obligations. The diver inhales and exhales via a breathing loop into a set of counter-lungs, only producing bubbles on ascent when an expansion of the gas in the loop and counter-lungs would cause a fast ascent.

Semi-closed-circuit rebreathers, on the other hand, deliver the same fraction of gas (air, nitrox or trimix) at any depth. We cannot separate the oxygen from the other gases in the loop and must exhale regularly to make space in the loop for new gas to ensure the oxygen is replenished.

The benefits, especially to CCR divers, are plentiful: silent diving and no bubbles mean closer wildlife encounters. Because we are recycling gas rather than exhaling it, we also get more time underwater. Two-hour dive times are not unusual.

S is for START drill

START is the acronym for pre-dive checks taught by TDI, one of the leading training agencies for technical divers. While other agencies use different acronyms, all of them have a common goal: thoroughly checking equipment, gas supplies and the dive plan one last time before descending.

The S in START stands for a modified safety drill, where divers check that they can donate gas to someone who has lost his gas supply. A bubble check is also part of this, wherein teammates check each other’s equipment for leaks.

T stands for a team equipment check, also known as ‘top-to-toe equipment check.’ Divers check each piece of equipment, its location and function in a systematic manner to ensure that everyone is familiar with each other’s setup.

A stands for air, representing breathing gases carried by each diver, and gas matching, where divers ensure that they have enough to help each other in case of an emergency. This is relatively straightforward when everyone dives the same size tanks, but a bit more tricky when divers choose different tank sizes.

R stands for route and objective. Where are we going and what are we planning on doing there? Technical diving is time and cost intensive, so it’s important to use underwater time as efficiently as possible.

The final T stands for time and tables. This is when we compare our dive plan and contingency plans one more time before the dive starts.

Sound complicated? It doesn’t have to be. Experienced divers can complete these checks in less than five minutes.

T is for Turn Pressure

Turn pressure tells divers when it’s time to start heading back to their ascent point. Assuming they’ve planned the dive using the ‘rule of thirds,’ with one-third of gas for the way away from the descent point, another third for the way back, and the last third as a reserve for emergencies, divers will turn their dive around when the first team member has used up one third of their gas.

This ensures that everyone has enough gas to make it back safely, plus a reserve in case of emergencies. Confirming turn pressure is only one part of gas management for technical divers, however.

Those heading into wrecks and caves must also take distance into account. For example, if you are at a depth of 33 feet (10 m), but 650 feet (200 m) into a cave without any other exit points, you will not be able to ascend within a few minutes as you would in open ocean. Instead, it will likely take you 20 to 30 minutes to cover the distance, which also means you’ll have to deal with any problems on the spot and account for that gas for even a relatively shallow dive.

Stay tuned for the next in our alphabet series, where we cover U through W.

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M is for M-value

The M-value is the highest degree of over-pressurization our tissues can withstand without problematic bubbles forming and potentially leading to decompression sickness. What? Ok, let’s take a step back here. On every single dive, our bodies/tissues absorb nitrogen as we descend and stay at depth. On the way up, atmospheric pressure drops, and our tissues off-gas nitrogen. Even after safety and decompression stops this process continues, with tissues containing nitrogen at a higher pressure than the atmosphere surrounding the diver. The M-value dictates how much higher the tissue-pressure can be in relation to the diver’s surroundings. Captain Robert Workman of the U.S. Navy Experimental Diving Unit first coined the term and went on to develop a full decompression model around the concept. While we’ve since superseded the model, the M-value concept remains in use by modern decompression models.

N is for Normoxic

The term normoxic describes a gas with a ‘normal’ content of oxygen. In technical diving, we apply it to trimix, which is a mix of oxygen, nitrogen and helium. Normoxic trimix has a normal content of oxygen, typically between 18 and 21 percent, which we can safely breathe at the surface. We can generally dive normoxic trimixes to 213 feet (65 m), based on their oxygen content. Their helium content will heavily influence the density of the gas as well as the degree of narcosis a diver feels.

Further along the scale, divers planning deeper dives may opt for hypoxic trimix. Cast your mind back to the letter H of this alphabet series, which described the difference between ‘hyperoxia’ — too much oxygen — and ‘hypoxia’ — too little oxygen. Hypoxic trimix is any mix with less than 18 percent of oxygen. Put (overly) simply, the lower the oxygen content, the deeper you can breathe a gas, although not safely at the surface. In those cases, divers utilize travel gas, which they can breathe on the journey to and from depth.

O is for Overhead Environments

Overhead environments are the most challenging places to dive for technical divers. Safely diving here requires specialized training and equipment. Generally speaking, we divide overhead environments between wrecks and caves, with mines somewhere in between. Diving these environments can be incredibly rewarding.

The main difference between these dives and technical dives on reefs or recreational dives is that the diver cannot return directly to the surface as there is a ‘hard ceiling’ above their head. This means the diver must deal with any problems happening inside the wreck or the cave right there and then — at least until they can start exiting. Problem solving takes time, and time requires gas reserves. Overhead divers must plan not just for the depth of their dive but also for the distance they need to travel to their exit point.

Navigation inside wrecks or caves can be tricky as well. The interiors of caves can resemble labyrinths in layout, and a line guiding the diver back to the exit is essential. Silt is another consideration: both wrecks and caves may have a layer of silt which, if a diver stirs it up, can lead to zero-visibility situations.

Wrecks are generally less stable than caves and divers must be extra careful when assessing potential penetration sites. The list of considerations goes on, but one thing is key: divers must thoroughly train and prepare for overhead dives.

P is for Preparation

Technical divers put a huge focus on their dive preparations, which may start days, if not weeks, before the dive. Tech divers must research conditions on the sites, ensure the required gases are available, arrange roles within a dive team, gather equipment, and so much more. Some considerations for dive planning include broader areas like logistics and the distance to the nearest recompression chamber. Others include the minute details of the dive, such as bottom time and individual staged-decompression stops. Tech divers must also consider their exposure to oxygen, especially if they conduct dives on rebreathers with long runtimes. The dive objective is another consideration, as is the level of expected gas narcosis and so much more.

Preparation for dives is a large part of any tech diving course and something that we continue to apply to any subsequent tech dives following certification. Stay tuned for the next article in our series, addressing the letters Q through T.

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I is for Isobaric Counter-Diffusion

Sound complicated? It doesn’t have to be. Isobaric counter-diffusion (ICBD) is an integral part of diving physiology and especially relevant to trimix divers using hypoxic gases. These divers must manage three gases: oxygen, nitrogen and helium. Isobaric counter-diffusion deals with the two inert gases, nitrogen and helium, and describes their movement in and out of our tissues at a constant ambient pressure (= depth) after a change of breathing gas.

Normally, we link the off-gassing process to changes in ambient pressure or depth. But divers trigger the IBCD changes by switching from a gas low in nitrogen and generally high in helium to a gas high in nitrogen. The result can be bubble formation leading to inner-ear decompression sickness. Since we control our balance with the inner ear, symptoms can include extreme nausea and disorientation to the point of divers losing their sense of up and down.

There is no easy way to deal with inner-ear DCS. This is why divers planning for deep trimix dives carefully select breathing gases to minimize potential problems.

J is for Judgment

Technical divers learn to plan for contingencies in case the dive doesn’t go to plan. And while many divers mentally rehearse failure scenarios before a dive, it’s near-impossible to preempt every potential change in water conditions, for example.

On the dive, that means using judgment to deal with unexpected situations. Divers must evaluate what’s happening, what tools they can use to deal with the specific situation, and then make a considered decision on how to end the dive as safely as possible.

Good judgment requires excellent diving skills so that diving becomes second nature and experience built up over numerous dives in varying conditions. You cannot develop good judgement overnight, but thorough debriefs do help the process along. These help divers understand issues that arose on the dive, how the team leader dealt with it and made decisions and, crucially, how they can improve for the next dive.

K is for the Key to tech-diver progression

‘Dive, dive, dive’ is part of the answer to tech-diver progression. However, just accounting for quantity of dives might be too simplistic, as just counting experience doesn’t examine diver’s foundations. We began our tech-diving alphabet with the ABCDs — awareness, buoyancy, communications and discipline — which, alongside other in-water skills, are the foundation for any skilled technical diver.

An introductory technical courses puts many of these foundations in place. If your technical-diving instructor makes you practice hovering, trim and propulsion techniques over and over again, thank them. Without these skills becoming second nature, it’s futile to try decompression dives. You may be able to complete a few successfully, but without strong foundational skills you simply won’t be able to progress to more complex dives.

The same goes for diving theory. Understanding as much as possible what is happening in your body (physiology) and around you (physics) allows you to make informed decisions about decompression plans, for example. Tech-diving theory is constantly evolving and trying to stay current will help you develop your knowledge when you’re not in the water.

With solid foundations in place, then it’s time to dive, dive, dive to build and retain muscle memory.

L is for Logistics

Logistics may not be the first thing on a recreational diver’s mind, but the more you develop your diving the more you’ll have to think about diving logistics. Alternately, pick a dive operator that will do the organizing for you.

Tech diving often requires different gases, additional gear, tanks, regulators and more. Longer runtimes mean you may not always be able to fit in with a regular dive boat schedule unless you want to curtail your dive time.

Then there’s the question of gear transportation. As a tech diver, you’ll become familiar with airlines’ excess-luggage charges. You’ll learn who has the best policies for taking sports equipment and, for CCR divers, how to fly with tanks.

It might not all be fun and games all the time. However, learning these basic terms and skills is all part of the adventure that is technical diving.

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E is for Equipment       

Out of all technical-diving aspects, equipment needs and choices can be the most intimidating. Technical divers carry far more equipment than recreational divers. This is largely because technical dives often involve going deeper and breathing more gas due to the increased ambient pressure. Consequently, tech divers use doubles/twinsets or sidemount tanks, plus additional tanks to complete their decompression stops. Each of these requires its own first and second stage regulator, SPG and possibly other accessories. This is in accordance with the principle of redundancy, which requires each diver to carry a back-up of any life support equipment.

Life support includes more items than you may initially think, including tanks, gas and regulators, of course, but also a back-up mask and cutting devices. You’ll also likely want to purchase a computer designed specifically for technical diving.

Equipment quality is also crucial. Diving deep or entering overhead environments puts a strain on gear, so high-performance equipment is a must. Additionally, the regulators you use for high-oxygen decompression gases must be oxygen-clean. All told, technical divers simply face more detailed considerations than their recreational colleagues.

F is for your First Time Leading a tech dive

Most students in technical-diving courses come from a recreational-diving background and are often used to following a dive guide. In fact, they may never have been in a situation where they led a whole dive. Dive professionals ‘going tech’ have a bit of an advantage here, because leading dives is already part of their everyday life.

During technical courses, instructors train their students to deal with equipment failures, plan a dive and follow that plan — and they will expect their students to lead dives. Why? Because after certification, the instructor is no longer there to lead the way.

All this training stretches a student’s comfort zone. And often, that first time ‘being out front’ has a bigger impact on the diver’s performance than all the previous failure drills. Picking the right pace for a dive and ensuring the team is on track when it comes to executing the dive plan can be tricky at first. Having said that, once a diver becomes comfortable leading dives, their general confidence underwater grows.

G is for Gradient Factors

Gradient factors have become a staple of decompression-dive planning. Modern decompression-planning algorithms largely fall into modified/neo-Haldanean types, basing their predictions on tissue compartments and dual-phase bubble models that try to control the size and number of nitrogen bubbles forming in the diver’s body on ascent.

Gradient factors have become a popular tweak, which we apply to tissue-compartment models, allowing divers to personalize their ascent. Divers can determine how deep their decompression stops start as well as how much over-pressurization they want to allow in their tissues on ascent.

With each ascent from a dive, recreational or technical, divers search for the perfect balance between on-gassing and off-gassing. For recreational divers, this means staying within no-stop limits and conducting a three-minute safety stop at 15 feet (5 m). Technical divers, on the other hand, deliberately exceed their no-stop limits, heading closer to tissue saturation. On ascent, they must often complete several decompression stops of varying lengths. Where these stops start and how long they last can change based on the gradient we allow between ambient pressure surrounding the diver and remaining tissue pressure, thus determining the speed of ascent from a technical dive.

H is for Hypoxia and Hyperoxia 

When it comes to diving, we must ensure that the oxygen in our gas mixture is just right, breathing not too much and not too little.

Divers face hyperoxia, or oxygen toxicity, when they breathe too much oxygen. This is not only a concern for technical divers, but also nitrox divers who must stay within their maximum operating depths, or MOD. Technical divers utilize high-oxygen gases to accelerate their decompression stops. Put very simply, they try to maximize time at depth while minimizing time spent on decompression stops. Using these gases efficiently means switching to them as soon as safely possible. This is a crucial part of any technical dive, as dropping deeper at this point means risking hyperoxia.

Hypoxia, the opposite of hyperoxia, refers to too little oxygen. This is mostly a concern for closed-circuit rebreather divers (CCR) ascending from a dive. As ambient pressure around the diver drops, so does the partial pressure of the gas they are breathing. At that point, CCR divers must make sure they’re breathing a sufficient amount of oxygen.

Hypoxic trimix divers deliberately choose a gas mix with low enough oxygen content to avoid hyperoxia at depth. They must also carry a gas that has enough oxygen to be breathable from the surface to a depth where they can switch to their bottom mix. As with many aspects of diving, it’s all about finding the right balance to dive safely.

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The basics

As a recreational diver, you may already own a set of regulators. Generally, this consists of a first stage, two second stages — one of which is mounted on a longer hose — a high-pressure hose for your submersible pressure gauge (SPG) and maybe a console plus one or two low-pressure inflator hoses for your BCD and your drysuit, if you’re diving in cold waters.

As an open-circuit technical diver, you will be carrying more than one tank, and consequently, you will be using more than one set of regulators. Each set has slightly different components depending on its purpose, but all will consist of a first stage, a second stage and a high-pressure hose with SPG — with one exception we’ll get to later in this post.

Which components are part of your individual regulators depends on when you are planning to use them on the dive. Roughly speaking, you can divide tech dives into three phases: the bottom part, travel to and from the bottom part, and the decompression phase.

Bottom or back-gas regulators

Bottom, or ‘back-gas,’ regulators attach to your twinset or your main sidemount tanks. While the term bottom gas is pretty self-explanatory, ‘back-gas’ refers to the fact that the twinset containing this gas is usually on your back.

Whether you are diving air, nitrox or trimix, these are the regulators that you will be using during the deepest phase of your dive, when your breathing gas is most dense and therefore hardest to breathe. That means you are looking for high-performance regulators that can deliver a lot of gas to allow you to breathe as easily as possible. Your choice of gas obviously influences breathing ease, but your regs have a role to play as well.

Regulator configuration

If you are diving twinsets, you need a first stage each for your left and right tank, also called left and right post. While there are some variations, most tech divers will have a second stage with a 7-foot (2 m) hose on the right as well as their inflator hose leading to their wing. The long hose connects to the second stage that tech divers generally breathe from. The hose is longer to allow divers to share gas and exit a restriction while swimming behind each other.

The left tank typically holds a second stage on a short regulator hose with a ‘necklace’ made from bungee cord or surgical tubing, as well as a high-pressure hose and an SPG. There may also be another inflator hose here for a drysuit or the second bladder of the BCD if it has one. The necklace allows the diver to easily reach their second stage in case they need to donate their long hose.

Did you notice there is no SPG on the right post? When diving manifolded (connected) twinset tanks, the diver accesses gas from both tanks through one regulator as long as the manifold isolator valve is open. This means that as long as there is no equipment failure, one SPG is enough.

Sidemount setups

Sidemount setups can vary more as the configuration in general is more individual. One common option, however, is to rig the right tank with a first stage, a second stage on a long hose, and an SPG on a short high-pressure hose, usually about 6 inches (15 cm) long. There may also be an inflator hose for a drysuit or a second BCD bladder here.

On the left tank is a first stage with a second stage attached to a short hose and again equipped with a necklace. Often, there is an angled ‘elbow’ piece between the second stage and the hose, allowing divers to easily identify which tank they are breathing from. Additionally, there is a short high-pressure hose with an SPG and an inflator hose connecting to the sidemount harness and wing.

Many sidemount divers run their inflator across their body rather than over their shoulder. This means that suitable regulators often have a fifth low-pressure port at a right angle to the other ports. It’s also easier to streamline a sidemount setup by using first stages that have the capacity to swivel and therefore allow cleaner hose routing.

Some manufacturers have started offering dedicated twinset and sidemount regulator sets. This is a good way to purchase all the bits and pieces in one go. In the case of twinset regulators for example, they might have low-pressure ports pointing downward at an angle for better hose routing. Sidemount sets will have swiveling first stages with five low-pressure ports, one of which is at a right angle.

Deco regulators

Regulators for the decompression phase of the dive generally feature a first stage, second stage on a somewhat longer hose (octopus length) and an SPG on a short high-pressure hose.

Tech divers use these regulators with oxygen-rich nitrox mixes to help accelerate decompression and, therefore, the units must be suitable for use with oxygen. In practice, this means choosing a regulator that is made of a material with a high flash-point – titanium, for example. The regulator must also be cleaned for oxygen use, and any O-rings and greases used in the process must be oxygen-compatible. Not every regulator will be suitable fresh out of the factory, so it’s important to check on this when you are buying your deco regs.

As we generally use these regulators on shallower parts of the dive, we can use unbalanced first stages. However, this is still life-saving equipment, so the general recommendation to buy the highest quality possible while remaining practical.

Travel gas regulators

Trimix divers usually use ‘travel gas,’ a breathing gas that does not contain enough oxygen to sustain life on land. Their components will often resemble deco regulators, although they may not need to be oxygen-clean depending on the gases the diver uses.

If all that sounds daunting, consider this: you can usually rent equipment for your tech courses from the instructor or shop that is conducting the course. Most budding tech divers qualify initially to dive a twinset or sidemount tanks for the bottom part of the dive and one deco gas, so that’s ‘only’ three regulators. Additionally, you may be able to reconfigure some of the components you already own.

Last, but not least, consider where you will be diving. If you’re going to be in cold water, make sure your regs are suitable for that. If you will be spending a lot of time in remote areas, some brands will be easier to maintain than others due to the availability of spare parts and service technicians.

The first step when it comes to choosing regulators for technical diving is to speak to your instructor and other tech divers about what they use. Spend some time researching before going on that shopping spree. One thing is for sure — as your tech diving journey continues, your gear bag will only expand.

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Finding the right technical diving instructor

Few budding divers research the instructor for their open-water class. Especially in vacation destinations, it’s often a case of striking up a conversation with an instructor in a particular dive center. You may enjoy the atmosphere and book there. Others choose a dive center because it’s located in their hotel. If you’re learning to dive at home there may only be one operator, so scheduling options might be limited. But most importantly, few open-water students know what questions they would ask of their prospective instructor.

When divers move on to technical diving, they already have a level of experience — of different instructors, dive centers and operators. This puts them in a much better position to ask the right questions and find the technical diving instructor that’s right for them. Here are few criteria that might help you find your ideal tech instructor.

Look for a coach and mentor

Technical diving training can be challenging, and courses sometimes run over the minimum number of dives a training agency requires. Similar to professional-diver training, you are looking for a coach and a mentor who will guide you there rather than someone who creates divers on a production line. Committed tech instructors often have long-standing relationships with their students. Many will come back for further training, join on dives, or simply get a piece of advice on their gear. Make sure your prospective instructor is approachable and available for these kinds of interactions.

Find out how they dive

What is their diving like? This may sound like a rhetorical question but check out whether your instructor still enjoys tech diving for themselves. Teaching, even at the top level of tech-diving training, can become routine. How much tech teaching or fun technical diving does your instructor do? Even the highest-level divers need practice to keep their skills sharp. It’s key for instructors to develop their diving to help them enjoy passing on skills and knowledge to others For example, it will be almost impossible for someone who teaches two tech courses a year and doesn’t practice their skills outside of that to remain in shape.

Explorers vs. educators

TDI published an article on choosing between ‘explorers’ and ‘educators’ when it comes to looking for a technical diving instructor. It’s a great distinction and one that illustrates where your instructor’s interests lie. Arguably, a combination of both is best — as a diver, you will benefit from learning from an explorer, but as a student, you can learn from someone who enjoys passing on knowledge.

So, how do you find out about all of these things? Ask questions. Booking a tech course should involve more than a few emails back and forth, although they may be so detailed that all is clear after a several exchanges. Most tech shops have fairly small instructional teams, so you’re likely talking with one of the people who will train you. Ask about their experience. Check them out on social media and see if there is a profile on the dive shop’s website. Maybe you can meet them before the course at a local dive show.

Where should you learn?

This leads us to the choice of location. There are a few valid approaches to this decision. First, where will you conduct your technical dives after the course? Can you take your initial courses there? Learning in the environment that you will be diving in after the class is a straightforward solution.

However, it’s perfectly possible to take courses in one environment and transition to another. The key is taking the time to adapt to different conditions and environments and getting some local advice. Assuming you took your courses in the tropics in a wetsuit and used aluminum tanks but are now looking at diving the wrecks in the Great Lakes, you’d need to practice buoyancy with steel tanks and become comfortable in a drysuit.

Light systems are another consideration: while even deep reefs in Indonesia, for example, don’t often require strong lights, any dive in the Great Lakes will. Transitioning from cold water to the tropics means that dehydration becomes a larger consideration and aluminum tanks will create additional positive buoyancy toward the end of a dive.

Summing it all up, what is the key to finding the perfect technical diving instructor? Most importantly, ask questions. Find out about your prospective instructor, including their approach to teaching and to their own learning. Inquire about their diving outside of teaching and anything else you would like to know before starting a course. Make sure you feel comfortable with them. Finding the right technical diving instructor can make the transition to this type of diving a little less daunting and a lot more exciting.

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Twinset diving

Twinsets or doubles have been classically associated with technical diving and most technical divers trained with them. Many instructors and training agencies use what we call a ‘Hogarthian set up.’

Named after cave diver William Hogarth, it emulates the DIR — Doing It Right — philosophy of technical diving. That means it’s minimalist while also ensuring that divers have backed up every piece of life-saving equipment.

As you’d expect for a twinset configuration, there are two tanks, often the same size as recreational divers’ tanks. A manifold — a type of bridge valve that allows divers to access gas from both tanks through either side’s regulator — connects the tank valves. Each valve has a first stage attached. On the right, this first stage connects to a 7-foot (2.1 m) hose with a second stage and an LPI inflator for the wing. On the left, the first stage connects to a second stage on a standard-length regulator hose. The diver uses an attached necklace to place the regulator around his neck. There’s also an SPG hose and any inflator hoses for drysuits.

Why the long hoses?

Why is one of the hoses over 6 feet (2 m)? This goes back to overhead-environment diving, where divers may have to exit behind each other in an out-of-gas situation. The diver with gas would donate the long hose to the victim. He’d then switch to the back-up regulator on the necklace for himself. In this way, the divers can exit single file by swimming behind each other.

A wing and harness with backplate holds everything together. Wings come in different shapes and sizes, but most importantly they must provide enough lift for the amount and type of tanks the diver is using. Divers can choose between having a single bladder in their wing or a second one to use in case the first one fails. Classic harnesses consist of a single piece of weight-belt webbing plus a crotch strap. They also offer D-rings to provide attachment points for regulators and other gear.

The goal is to achieve stability, allowing the diver to control the twinset and potential stage tanks underwater, effectively turning the twinset into a platform from which the diver is suspended.

Sidemount diving

Sidemount, on the other hand, is more about flexibility, allowing divers to attach and remove tanks underwater when necessary. This configuration has become hugely popular within technical diving — some even call it a fad. We can trace the origins back to U.K. sump diving, where divers maneuvered through restrictions too small for twinsets, sometimes even small enough that they had to remove their tanks and push them through the restriction ahead of their body. Sidemount is still closely associated with cave diving, although depending on the size of the cave, twinsets may be just as suitable.

For sidemount configuration, divers mount tanks at their side rather than on their back, starting at the armpit and ending below the hips. Tanks connect to the harness with a cam band or jubilee clip attached to the lower part of the tank and equipped with a bolt snap. Tank valves remain in place on the diver’s body with bungee cord, typical for aluminum tanks, or a combination of bungee and clips, more typical for steel tanks.

Twinset and sidemount differences

One of the main differences between sidemount and twinset diving is the degree of standardization. Twinset configurations are highly standardized whereas sidemount configurations are not necessarily. This has to do with sidemount history as a means to an end initially, which gradually developed into a full-fledged diving configuration. Divers in sidemount courses will learn a variety of setups but will have to spend time to perfect their own.

As a consequence of sidemount flexibility, different divers might also set up regulators differently. Most sidemount divers prefer regulators with swiveling first stages to allow flexible hose movement. They usually prefer a fifth low-pressure port as well, allowing them to mount hoses at a 90-degree angle. Sidemount divers can also configure regulators by largely following the twinset configuration described above. This means having a first stage, long hose and second stage with an SPG on the right side and a first stage, short hose, second stage with necklace, inflator hose and SPG on the left side.

Harnesses, hoses and bladders

Many sidemount harnesses invert the corrugated inflator hose. This means that it runs from under the diver’s left arm across the upper body, rather than over the left shoulder. This is to keep as low a profile as possible in order to navigate restrictions. This is where the fifth low-pressure port comes in handy, allowing divers to install a short inflator hose across the body rather than over the shoulder.

Speaking of hoses, divers usually mount sidemount SPGs on 6-inch (15 cm) high-pressure hoses. This is because longer hoses are not practical and can become an entanglement hazard. Inflator hose lengths vary according to diver size and configuration.

Sidemount harnesses and bladders come in many shapes and sizes. Most are adjustable to fit different-sized divers, but some come in size ranges. Which one works best will depend on your size and the type of sidemount diving planned. Just like with twinset wings, it’s important to pick one with sufficient lift for the tanks. For example, those who want to do recreational sidemount dives with no more than two tanks will find a small, super-streamlined harness adequate. Technical dives with more tanks will require more lift capacity.

Most tech divers start their journey in either of these open-circuit configurations. Rebreathers add another option — take a look at this post for the basics. Paramount for safely diving in either configuration is instruction by a qualified teacher. Sidemount especially may not look that different from other configurations, but the devil truly is in the details. If you get it wrong, you’ll compromise comfort, streamlining and trim — some of the main reasons to dive sidemount. Technical-diving configurations may seem intimidating, but with the proper knowledge, they open up a whole new world underwater.

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