Gas Planning 101: Continued

Now let’s look at Joe’s situation. His SAC (worked out several years ago) is 0.5 cubic feet per minute. Referring to his logbook he sees that Saturday’s dive is going to have a maximum depth of about 149 feet (yes, Joe has dove the site many times before). His task to work out the ambient pressure is a little more complex than Vlada’s. Working in imperial requires depth to be divided by 33 and then one to be added to bring the figure to an absolute value. Working this out Joe gets (149/33) + 1 = 5.5 atmospheres… that seems to check out with his buddy’s calculation.

On previous dives, Joe has used a DF of 1.8 so he settles on an RMV of 0.5 x 5.5 x 1.8 = 4.95 cubic feet per minute. He does a quick conversion from feet to litres by multiplying his RMV by 28 (the number of litres in a cubic foot) and arrives at a metric equivalent RMV of 138.6 litres, which he rounds up to 140. So far, so good because his figures seem to corroborate Vlada’s, and he would expect his consumption to be higher than hers even though he is diving in familiar territory.

The next step would be to plan around the apex dive based on the available volume of gas in the smallest capacity cylinders in the team. Actually, the guideline for this step reads that the diver carrying the least gas becomes the control for the rest of the team. This is critical and is called gas matching.

A common error in gas planning is for the team to ignore this step. Matching a “gas pig” wearing the biggest tanks made with a light breather carrying much smaller capacity tanks is nuts if no allowance for gas matching is made. If “Big Ted” can empty a set of “regular-sized” cylinders in ten minutes, the temptation is for him to buy the biggest tanks he can carry. That’s fine if everyone has the same sized cylinders but creates a horrible situation if Big Ted’s buddy has tiny tanks (because they are “good on air”) and something goes wrong on a dive. Well, actually, if what goes wrong is that Ted’s buddy needs air, they may be OK. But the spirits that control things going pear-shaped on dives are mischievous little buggers and work the worse possible options. Conceivably, if Big Ted’s massive cylinders go for a Burton, his buddy wearing tiny tanks will not be carrying enough gas to get the two of them safety to the first gas switch… and beyond.

Well, Vlada and Joe have their act together and are not going to make that mistake. They will use Vlada as the controlling diver and work with her gas volume to plan the dive for them both.

Vlada wears the smaller cylinders (double 14 litre) and her local dive shop usually pumps them to a little more than 200 bar. This means when filled she will have 14 litres X 2 (she wears doubles) X 200 bar = 5600 litres. So now Vlada knows that her fully charged double 14 litre cylinders hold about 5600 litres of gas. Since her gas planning skills are basic, she follows basic gas planning rules. The Rule of Thirds is a standard in technical diving and states that one third of starting volume of gas is for the first half of the dive, one third or less for the second half, and one third for your buddy or for you in an emergency.

The Rule of Thirds is a simple way to reserve contingency gas. For hard overhead environments, such as cave diving, it guarantees the body recovery crew will find both divers near the cave entrance. I’ll explain this rather grim conclusion in the chapter dealing with special environments, but for now let’s just say that the rule of thirds should be modified for cave diving. For soft overheads such as decompression dives, especially when there is a three-person team, it works just fine as it is. But Vlada has been correctly trained and knows with a two-person team, she needs to modify the rule of thirds by tucking away some extra reserve gas, just in case.

The simple rule she was taught is for dives with two buddies to 45 metres or less, is to put 400 litres of gas aside before calculating thirds and round down to make the starting volume easily divisible by three.
Following this rule, Vlada’s 5600 starting volume becomes 5200, but 5200 does not divide by three into round figures… but 5100 does! One third of 5100 is 1700 litres which she takes as one third of her starting gas.

Two thirds therefore will be 3400 litres and this is her usable gas volume (UGV). Her total reserve is what would be left of her starting volume after she has consumed her UGV. In this case, 5600 litres minus the 3400 litres the Rule of Thirds allows her to use. This gives her a healthy 2200 litres as a reserve… this is the last third (1700 litres) plus the additional reserve (500 litres) and for the record, belongs to her buddy Joe.
Since Vlada has 3400 litres of useable gas and her estimated RMV for the dive is 121 litres per minute, she can calculate the absolute maximum bottom time she can do in her tanks by dividing one into the other (3400/121). This indicates how many minutes her gas will last at depth. The answer is a maximum of 28 minutes.

With this in mind, she suggests to Joe that they need to plan a dive with about 20 minutes of bottom time with 25 minutes as the outside contingency. A dive of 25 minutes is what is called an Apex dive for her at this site with her current cylinder / gear set up.

Joe dives double 130 high-pressure steel cylinders. These carry about 260 cubic feet when charged to their working pressure of 3440 psi. Joe now makes a quick calculation to find out what the usable volume of gas for his dive with Vlada is in psi. This is based on Vlada’s figures of 3400 litres because SHE is the control for the dive. This translates into approximately 121 cubic feet (there are about 28 litres in one cubic foot so 3400/28 gives the conversion).

If I allowed for simple examples in my lectures, Joe would start the dive with fully charged cylinders and his next step would be to convert the controlling volume derived from Vlada’s calculations (121 cubic feet) into psi and everything would be done and dusted. Indeed, Joe would finish the dive with a huge reserve, and there’s nothing wrong with ending a dive with a lot of spare gas. However, let’s make things more interesting
Joe’s doubles are currently filled to 2200 psi with a lean trimix (20/30) left over from a previous weekend’s dive. The mix is useable for the planned depth but he needs to know: “Do I have enough gas for the planned dive?”

For divers who insist in working with imperial units, the process of converting pressure to approximate volume (an inaccurate but ubiquitous norm used by the diving community) is more complex than for divers using metric units. One additional challenge is due to the “sizing” of dive cylinders. While metric use wet volume, US manufacturers quote cylinder sizes in standard cubic feet at the cylinder’s working pressure and specific temperature. Let’s look at the challenge this presents for Joe. At their working pressure of 3442 psi his double 130s hold approximately 260 cubic feet.

For this to be useful information, he needs to know things like how many cubic feet a pressure drop of 100 psi represents and conversely the pressure drop in psi when a cubic foot of gas has been breathed. To find the answer to the first question he has to divide rated volume by working pressure in units of 100 psi. Here’s the calculation: 260/34.42 = 7.5 cubic feet per 100 psi (approximately).

This 7.5 cubic foot figure is called the cylinder baseline. Joe has this written down in his dive notes for easy reference. In fact, Joe has baseline figures for various other sizes of cylinders – doubles and singles. (See the appendix for a comparison table of popular cylinder sizes.)

To answer the second question he flips the values in the equation: 3442/260 = 13.25, which determines the pressure drop for every cubic foot of gas he breathes is 13.25 psi. To sense-check both values, Joe can multiply 13.25 by the cylinder baseline and can expect the answer to be close to 100. It is actually 99.375, and that’s close enough for his purposes. (At this point Vlada is thinking how happy she is to be working in metric but she keeps drinking green tea and resists the temptation to tell her buddy about the superior feeling she’s experiencing.)

With these figures in hand, Joe can now work out how many cubic feet of trimix are in his doubles. He can see how many times 13.25 will divide into 2200 to give him the equivalent value for cubic feet (2200 / 13.25 = 166) or he could multiply 7.5 by 22 (the number of units of 100 psi in 2200 psi), which gives him a figure of 165 cubic feet. He can work with either approximation and either way, he comes up with the same answer: Since he needs 129 to 130 cubic feet PLUS a reserve of about 70 cubic feet to match Vlada’s gas plan, he needs a fill because at the moment he is more than 35 cubic feet short.

Of course, he and Vlada could plan their dive around Joe’s starting volume since it is usual to plan a dive around the buddy with the least volume of gas, but Joe feels that it would be better for him to top off his tanks. Rather than dilute his trimix content radically by blowing his cylinders up to 3442, he opts to add just a little more than required and keep his helium percentage as rich as possible… while still only paying for an air fill. Thirty five cubic feet is 35 X 13.25 psi (about 465 psi) will do the trick and so he arranges to top off his tanks to 2700 psi. When this is done, his doubles will contain a little more than the 200 cubic feet (5600 litres) the planned dive requires.

Turn-Around Pressures
Now that Vlada and Joe have worked out their gas needs and planned to have sufficient gas for their planned 20-minute dive, there’s one last gas matching chore for them to take care of: working out their respective turning pressure.

Turning pressure is literally the halfway point of a diver’s bottom time. It is in fact the reading that a diver’s SPG will show when one half of their usable gas volume (one third of their starting gas volume) has been used.

When a team of divers are all using the same size cylinders charged to exactly the same pressure, working out turn pressures for each member of the team is very straightforward, since everyone has the same starting volume of gas and readings for pressure drop for everyone will be exactly the same. So, if everyone dives exactly the same tanks charged to 220 bar (about 3200 psi) a turn pressure of about 150 bar (roughly 2200 psi) would be universal for all members of the team. Just in case this is all new to you, I arrived at that turn pressure by dividing 220 bar by three… well, I cheated a little because I picked a figure lower than 220 that three went into an whole number of times (no fractions) and opted for 210, and that netted me 70. Then I subtracted 70 from the starting pressure (220), and that gave me 150 bar.

Mandating that everyone will dive similar tanks filled to the same pressure is a great way to simplify team planning and logistics. However, it does not reflect the real-world situation entirely. In the real world divers invest their money in gear that suits them and that fits in with their plans. Sometimes this corresponds exactly with what their dive buddies use but more often, cylinder sizes, brands and capacities vary. No worries. This just means that working out turn pressures is not as simple: even when fill pressures are the same, because different size cylinders return totally different volumes of gas for the same pressure drop.
For example, a five bar pressure drop in a set of double 8 litre cylinders signifies a volume of 80 litres, but in a set of double 16s, five bar represents 160 litres. Of course the same is true in the imperial world. One hundred psi in a set of aluminum 80s is about 5.2 cubic feet, but in a set of 130s, we’ve already calculated that the same pressure drop represents 7.5 cubic feet. In both cases the difference is significant enough to cause a whole heap of grief to the ill informed.

To calculate correct turning pressures for their weekend dive, Vlada and Joe do some simple maths. Both need to know – and note in their dive notebooks – how many bar or psi their spg will show when they have used one third of their starting volume of gas.

Vlada goes first. Her usable gas volume is 3400 litres. This represents about two thirds of her starting volume minus a few extra litres for additional security. Since 3400 is what she can use for her whole bottom time, 1700 litres is what she can use for half her bottom time, which is that same as saying 1700 litres is one third. To find her turning pressure, she simply works out what the pressure drop is for 1700 litres by dividing it by her cylinders baseline… or wet volume in the metric world. This is 1700 litres / 28 litres which is equal to a little more than 60 bar. Her turning pressure then is her starting pressure (200 bar) minus thirds (60 bar) which is 140bar.

Now Joe has two options. He can convert 1800 litres to cubic feet and work out his drop pressure from that converted number or he can do his calculations in pure imperial and sense-check when finished. He opts to work in imperial. From his earlier calculation Joe knows that his usable gas volume is 128.5 cubic feet. He rounds this down to 128. That’s two thirds of his starting volume and all the gas he can use for the whole bottom time. Therefore the turning point of the dive will arrive when he has used 64 cubic feet of gas. The drop pressure in his cylinders for 64 cubic feet will be 64 / 7.5 (tank baseline) X 100 psi, which equals 853 psi. This means that Joe’s turning pressure is 2700 psi minus 853 psi or 1847 psi.

Both Joe and Vlada write their respective turn pressures (and those of their buddy) in their waterproof note books. For them, the gas matching exercise is done.

In essence, this example is way more complex than need be. For instance, buddies rarely work in both metric and imperial and Joe’s calcs for topping off his bigger cylinders was a device to get you thinking correctly about matching starting gas volumes. But the basic steps are the same for all dives using the Rule of Thirds or Modified Rule of Thirds.

• Know your SAC and know your buddy’s SAC
• Guesstimate the RMV for the planned dive
• Find the controlling volume for the whole team by finding out who is starting with the least gas (volume NOT PSI or BAR)
• Put aside a sensible reserve before calculating thirds (Modified Thirds)
• Divide remaining volume by three (into thirds)
• Two thirds are for the dive and the remainder is contingency gas
• Work out how many minutes the UGV will last according to the RMV calculations. Use this number to cut tables, plan ascent times and so on
• Work out turning pressure for each team member based on one third of controlling volume
• Write down turn pressure for self and buddy
• Make note of gas volumes actually used on the dive. This will inform you how accurate your Dive Factor (DF) estimates were.
• Adjust for future dives

Now let’s talk about gas choices and drill down a little further into why Joe topped off his trimix with air!


A student’s guide to a technical diving course

Based on a presentation made in the winter of 2000, updated 2009

“Shallow men believe in luck. Strong men believe in cause and effect…”
Ralph Waldo Emerson: American Transcendentalist, 1803 – 1882

Technical diving is about having a whole lot of fun while enjoying an unparalleled, unbeatable opportunity for personal growth and unique experiences. The perception is that technical diving is dangerous and edgy and so it’s got a sexy aura about it. All that may or may not be true, but it definitely can take you to places most people don’t even know exist, plus you can dress like a ninja and not be arrested.

What’s more, technical diving is almost universally accepted to the point it has evolved into a borderline mainstream activity… which essentially translates into, fewer and fewer people think tech divers are crazy risk takers and more and more want to join the party!

I can say this because in a recent survey – conducted by Scuba Diving International and Technical Diving International in the Fall of 2008, almost four out of ten divers indicated they were “diving tech” or they were interested in taking a technical diving program of some sort within 12 months following their participation in the survey. Given the audience these data have a definite bias but they nevertheless tell a story: technical diving is a small portion of the dive industry but it is growing larger and more acceptable.

My personal benchmark is that my maiden aunt Mildred has stopped giving me a hard time about being a cave diver because she’s been able to watch it on TV, and now she “gets it!”

But as popular as “it” has become, technical diving is still troubled by a few mysteries and misconceptions. For example sport divers who are thinking about getting started as technical divers usually have a bunch of questions about the training. These essentially boil down to: “How do I get there from here, and what‘s going to happen to me on the journey.”

If you fall into this “uninformed but an interested consumer” category, you can take some comfort knowing you are not alone. The majority of students enrolled in their first tech-diving course start off Day One sitting in the classroom wondering quietly to themselves: “What’s going to happen over the next few days?”

It’s not a complete mystery. Almost everyone seems to have a grasp of the ethereal… Technical diving courses promise to extend one’s envelope of experience and stretch one’s comfort zone.

But how this “growth” and “stretching” are going to be kick-started; and exactly what new concepts and ideas the instructor is going to attempt to cram into their heads, is often kind of cloudy.

A few arrive thinking they are going to be given a special formula to learn or a magic equation to solve. They have an idea that this new piece of information will be their personal Rossetta stone and will unlock all sorts of secrets making them a better diver overnight. And of course that is not the case. There is no special formula or magic equation or blood-curdling chant to remember.

Well, we do hand out secret decoder rings and teach a special handshake, but when it comes to hard facts and new science, there is nada. A special something that helps new tech divers to decipher the inner meanings of internet postings and poorly written textbooks: No, not on your life. The horrible truth is, most of the stuff in a tech diving class will not be new to anyone who’s not suffering from massive memory loss.

One of the first things I tell students in my classes is this: “I have nothing to teach you about the science of diving that you do not already know or have not discussed with instructors in previous classes. All the physics, chemistry, biology and mathematics you need to know about for this kind of diving were covered in your second year of high school and your open water class…”

Lest they rise up as one and demand a refund, I then swiftly add one of the “new” concepts we will be covering during their class. I say that the most important task facing a technical instructor – regardless of what level of program said instructor is presenting – is to show their students how to think creatively about problems… to recognize what problems are present and likely, how to avoid those problems, and what might work if avoidance is not an option (or if something that was categorized as an unlikely problem happened anyway).

For sure there are a few other things that must be covered – the physics, chemistry, biology and other hard science needs revision for example – but a technical diving program is where you will learn about and refine the art of diving not the science. It is artfulness and creativity that one needs mastery of to become a successful technical diver. A student, who grasps this early on, will leave a positive impression on even the most case-hardened instructor.

Now let’s consider what’s on the agenda in slightly less broad terms. There are six skills a student must show some level of ability in if he or she wishes to complete a technical diving course with a passing grade. Indeed, these are things divers will meet again and again in the real world of technical diving.

(Calling them skills is a studied misnomer since coming to terms with each one of these six challenges actually requires an understanding and proficiency in several related skills and techniques.)

These six skills can be divided into two sets of three: one set physical and one set mental.

The physical challenges are about place and time: Buoyancy, Trim, Movement. The mental challenges are about control: Breathing, Awareness and Emotion.

The value of each of these will be evident to most experienced divers, but it may come as a mild surprise that such simple concepts and seemingly straightforward challenges form the fundamental structure of even the most rigorous technical diving program.

Now let’s take a few moments to explore more closely why each of these six concepts is so significant.

Buoyancy is a delicate and dynamic balance between the forces of gravity pulling divers and their equipment towards the bottom of the ocean or floor of a cave, and the upward thrust that overcomes this force and that is delivered by various bits and pieces of gear displacing water… a diver’s wing for instance but everything including the diver in reality.

When these two forces are balanced, diving is like flying: not flying like being in a Boeing but flying like being a bird. Equipment becomes weightless, the diver becomes weightless, and her focus suddenly shifts outside her body and extends into the environment surrounding her. Without buoyancy, diving ceases to be fun and becomes a chore… it may also turn into an extremely dangerous situation. With no control of one’s position in the water column the bulk of a diver’s awareness will be burned up with the task of try to maintain a constant depth. Trim will be impossible to master, breathing will quickly become labored and swimming will be difficult… and as though all that wasn’t enough… the slightest interference will distract the diver and her emotional state will start to creep towards bitchiness or borderline panic. Yes, buoyancy is enormously important.

Trim follows buoyancy because without buoyancy trim is inconsequential. It’s a rare graduate from open water class who understands what trim is. Lots of experienced sport divers believe trim is being perfectly horizontal in the water without being able to achieve it with any degree of comfort (about half of which is gear related). Some beginning technical divers are able to maintain horizontal trim in still water conditions and kick themselves mentally when they drift into a slightly heads-up or heads-down attitude. Experienced technical divers understand intuitively that trim is not about being horizontal. That’s only part of the message.

Trim is about being able to adjust one’s attitude in the water to whatever is optimal for the conditions. Trim is about presenting exactly the correct profile to the water so that in a current or high-flow situation, they can make progress – up or down, left or right, forward or backward – with the least effort and most control. Trim – not trying to get too esoteric or Zen-like – but trim really is about becoming one with the water.

Last of this first trio is movement. Twenty five percent of movement is about fin kicks. This includes how to stay stationary in a current (which is partly trim as well, but you already knew that). But it is also about how to move along slowly or rapidly without leaving a trail when one’s tummy is only a couple of hand breadths above a silt floor. Movement is also about how to rotate “on a dime,” and how to move backwards.

Forty percent of movement is knowing where every piece of gear is located on one’s rig and how to access it fast. This includes valves – and which way turns them off and which way does not – stage bottle clips, backup second stages, light switches, spare masks, whatever. The corollary to this of course is that because the whole team’s gear is similarly configured, all the movements to access a buddy’s gear in an emergency are known, practiced, fast and precise!

Ten percent is knowing how to be perfectly still. How to have a quiet body, quiet hands and feet and how to remain motionless when being motionless is the best approach.

The remainder — twenty five percent by my count — is about being in the right place at the right time: like being at the correct depth for a gas switch at the precise moment it needs to happen.

OK, so that covers the physical challenges… what about the mental ones. All three of these, breathing, awareness, emotional control are so totally and completely inter-related that it really is impossible to have one sewn up if the other two are not squared away.

Breathing is the red-headed step-child among general scuba skills and this extends from the sport into the technical sectors. It’s poorly understood and badly described in most diving texts. The common reference is: “Don’t hold your breath” and a passing mention that breathing from a regulator is “just like breathing on the surface,” which you and I know is not the case.

One of the all-round technical diving pioneers is Tom Mount who, among other things, is well known for his focuses on the importance of proper breath control in diving. Mount, a black belt martial artist, was one of the first instructors to insist his students practice yoga or tai chi style breathing exercises. As eccentric as this sounded in the 1980s and early 90s, Mount’s system was validated by the results it returned. This was underscored as more and more performance sports trainers explained the “secret” to several medal performances was breath control. This moved breath control away from the eastern mystic and solidly into the realm of hard-nosed western sports… like technical diving.

And when you consider things logically as we move deeper into the water column or we work against current the opportunity to throw our personal chemistry out of balance with high levels of carbon dioxide greatly increases unless we breathe correctly.

A huge amount of time is spent discussing gear configuration, when to start using helium, and what type of primary light is best for wreck diving — all of which are fine questions to seek answers for — but the same people who ask these questions have given no thought to breath control. Seems odd to me, but then I like breathing more than I like arguing about dive gear or gas mixes.

Focus, foresight, pre-planning all describe the second mental skill: Awareness. This skill begins with self-awareness and sufficient honesty to self-assess before, during and after a dive. At a more advanced level, awareness is a chess player’s skill. It is knowing one’s position in the water column relative to one’s team members all the time. Awareness is knowing exactly how far from one’s fin tips are the bottom, sides and top of the environment being traveled through. Awareness is knowing, not guessing, but knowing to within a few dozen litres (say a cubic foot or two) how much gas is left in your buddy’s cylinders — as well as your own — after a 500-metre swim into a high-flow cave. Awareness is focus and mindfulness, all necessary assets when one’s chosen pastime includes swimming around in water too deep to stand up in wearing almost one’s own weight in dive gear.

And the final skill you need to know about is staying calm and keeping a lid on your emotions when stress levels begin to build… for example when something goes wrong at depth. In truth, staying calm and keeping one’s emotions flat, is only possible when one has “situational awareness” and control of one’s breathing. Calmness comes from being in control and feeling relaxed and ready for whatever happens.

Emotional control does not mean that a diver feels no thrill or rush when their team finally reaches its goal. It simply means that if their primary regulator quits behaving properly at that point, their first reaction is one of calm competence and not rushed panic.

One of my very first instructor-trainers gave me a piece of advice that seems particularly apropos. When something bad happens at depth, focus and calmness can easily mean the difference between an exciting day and a disastrous one.

So, when something breaks or quits working, he told me to imagine the owner of my local dive shop standing in front of me with his credit card machine in hand and a smile on his face (this was back in the day when CCs were swiped!) and to think: “Crap! This is going to cost me money!” The intent of this exercise of course was to help focus the mind back to the real world and to prevent any blind, panicky “OH HELP!!!” sort of reaction. I still use it and teach it to this day.

You may have your own techniques for staying calm and quieting your mind so that nothing can faze you. There are lots of places to borrow them from… martial arts, meditation, yoga. Practicing this skill is as necessary as valve shutdowns… and it can be done anywhere.

Well, those are the skills you need to give some thought to and that you might expect to demonstrate in your first tech class. And now I want to quickly outline a drill that I use and what it teaches me about participants in my classes.

Ostensibly this is a drill to build buoyancy control. It’s called the Static Line + Peg Game. Ordinary plastic clothes pins are loaded onto loops positioned about every two to three metres along a taut drop line. The pins at each “station” are marked to make them unique to that station… these marks might be numbers, colors, or depths. A team of divers enters the water and — as a team or buddy pair — stops at the first station to pick up one clothespin per person.

The depth of this first stop should be around three metres or ten feet. This exercise is repeated for each station (usually at least five stops) and then at the bottom, diver’s pair off and execute an air-sharing drill and reverse their progress replacing the pins as they go. Lost pins, pins replaced at the incorrect station, and complete Muppetry is rewarded with a “lost life” — my students start out with nine and the goal is to have them finish the course with at least one intact. However, I’m a soft touch and in most circumstances a lost life may be purchased back with a round of coffee or tea (or frozen custard!) for the whole group during the debriefing!

Good buoyancy means being able to perform this skill without drifting all over the place, and without having to put your hand in your pocket at Dunkin’ Donuts.

But this drill is about more than buoyancy. To perform correctly, it is also necessary to have control of one’s movement (especially staying still), trim must be perfect (adopting the attitude that gives best control during descent and ascent), breathing, awareness and emotions need to be under control… (These three skills are as easy to observe as the previous three. You‘d be surprised how many divers tense up and hold their breath when they concentrate on a little task like collecting a clothes pin from a loop of cave line.) One of the first things to understand about the drill is that working as a team makes it run much more smoothly, and keeping a regular cadence and a calm demeanor are crucial.

I think we already established that there are no guarantees in technical diving, but with these six challenges met and managed, there is nothing a diver cannot accomplish.

If you understand this and understand that these skills can be acquired and developed through the repetition of drills – both physical and mental – over a period of time, you’ll be a great diver.

How much time is the usual question. This is a variable but years seems about right to become expert.

But of course, a technical diving class does not go on for years… so what does an instructor expect from his students in order for them to earn their certification? Progress is the short answer.

The longer answer is that no instructor expects perfection from a student at the onset of a course. This doesn’t mean it’s OK to show up for a course totally unprepared, but don’t be too flipped out if you have not perfected a seriously powerful back fin kick. There are other, more important, things than that.

So you will be fine with your instructor if you are not perfect in the water when your course starts, and if they are realists, they will not expect perfection by the time you end it. The best possible outcome is a discernible improvement and some indication that the student understands the challenge, is able to perform an drill appropriate to the challenge, and that they appreciate the value of working towards acquiring the necessary skill.

Now, we have to admit right now that nobody can speak for every instructor because each has his or her idea of where a passing grade sits on a continuum that joins inept to perfect. I can tell you what I look for though. Something I’ve found useful in quantifying the progress of students is the Dreyfus Model of Skills Acquisition. The Dreyfus model suggests that in the acquisition and development of a skill, a student passes through five levels of proficiency: novice, advanced beginner, competent, proficient, and expert.

Briefly, a novice is a beginner with no experience and no context for any of the tasks he is being asked to perform. Novices need rules to function. “Just tell me what I need to do and I will get it done.” For example, a novice will perform a valve shutdown exactly as it was demonstrated to them. Their performance will be slow and they will behave inappropriately to a curve ball thrown at them… a simulated gas emergency for example. They have no concept of primacy – what MUST be considered and dealt with first regardless of less important issues. Other challenges, such as buoyancy go to hell in a hand basket.

An advanced beginner is able to perform drills reasonably well, and is beginning to recognize and note the principles that matter. During debriefings they might say something like: “I think I’m beginning to understand why we do it this way.” This student will understand that there is a logical response to a “simulated gas emergency” but will forget primacy or hesitate when given a second concurrent issue to deal with. They will also most likely lose awareness of their surroundings, their equipment or a team member… a situation their instructor will use to provide an in-situ object lesson!

A competent student relies less on “rules” and more on context. Their reaction to a challenge follows a conscious, deliberate plan that they have thought out beforehand, and organized through some analytical perspective. This person has moved away from blind reliance on rules and abstract principles as acceptable paradigms and towards reactions based on past concrete experience. They can deal with a “simulated gas emergency,” maintain primacy and are not surprised when presented with a simultaneous issue. However, they can still be knocked off kilter and lose control of breathing, awareness or emotion, but will have the capacity to fight back and regain composure.

The proficient student understands situations as part of a continuous series of related events rather than disjointed or discordant bits and pieces. They enjoy a “whole world view” in which all possible responses are understood but challenges are met with only relevant responses. If this first level response is blocked or becomes impractical because of a second issue, they fall back onto a Plan B immediately and seamlessly. A “simulated gas emergency” becomes part of the dive and is dealt with efficiently while plans for the rest of the dive are being modified according to the particular circumstances of the emergency. For example, they will be thinking along the lines of: “Is this a situation that requires some secondary action and how does it alter the team dynamic, how does it impact the collective “risk” and what would be the best course of action if such and such a thing happened next.”

The expert student is more like a mentor and potentially a candidate to become an instructor. They read situations intuitively and focus immediately on the critical primary issue with a deep understanding built on a solid foundation of experience. This type of person will be able to perform tasks creatively and can think “on the fly” to come up with unusual but appropriate solutions to challenges. They do not lose control and are completely in the zone throughout a dive. In essence this diver has made a full transition from detached observer to someone involved and engaged by the situation.

And so, this is the scale I find it useful to work from. I rate each student on their “Dreyfus Level” for each of the six challenges — Buoyancy, Trim, Movement, Breathing, Awareness, and Emotion — after our first dive together.

It would be unrealistic to expect students to make it from novice to expert in meeting even one of these challenges during the course of a six day decompression program. I do expect them to fall into the advanced beginner category at least when the course starts. The goal is to have them competent and on their way to proficient by the conclusion.

This sounds way more scientific than it actually is, because there is a percentage of “gut feeling” that enters into any evaluation of a candidate – whether the course is for a diver or and instructor – and I am unable to qualify or quantify that factor.

So where have we ended up? I hope you have a better idea of what skills are going to be expected of you in a technical diving class… there are only six of them and they can all be improved upon with practice. All the book work is secondary to understanding these six skills. If you are maths and science challenged, we can work around that… there are computers to do most of that stuff… but if you are inattentive and distracted, given to rash decisions and incapable of passing within six metres of a silt pile without kicking it up, you have a real challenge ahead of you… and so does your instructor.


A Small Reminder of Joe Steffen

It’s a tiny thing… a small orange piece of plastic shaped like an arrowhead… but it carries a lot of meaning.

This past week, Erik Van Dorn, Jim Clark and I had an opportunity to place a line arrow on the vertical section at the junction of King’s Bypass and King’s Canyon in Jackson Blue Spring, Florida. It used to belong to Joe Steffen… a mate of ours who died while exploring the Bell Island Mine on February 4, 2007. He had personalized it and several others ready for laying new line a couple of days before his final dive. At some point in the confusion of his body recovery our attempts to revive him, and getting him to a medical facility, I ended up with a handful of them in my kit. I seriously cannot remember picking them up or being handed them, but they were in with my dive gear the following day.

I’ve placed those arrows in various spots over the past year and a half as a sort of memorial. As with each of the others, this last one has been put in a spot that is particularly beautiful and a little off the beaten track. The jump off the gold line for King’s Bypass and King’s Canyon is at about the 500 metre mark from the cave entrance (that’s approximately 1500 feet). The bypass itself is a low bedding plane, wide but less than two metres from ceiling to a very silty floor. After about thirty or thirty five metres of of that (100 feet), the line shoots straight up leading  into a vast fissure that looks like a classic steep-sided canyon… hence its name. It is a remarkable spot in a really stunning cave. Joe’s arrow is on that section of the line.

Joe was a popular member of the North American cave diving community and the hope is that from time to time, one of those friends will swim past one of his line arrows and say a silent thank you to someone or something for giving us a mate like Joe.

He left us all with lots of memories. I cannot go to a sushi restaurant without thinking about his habit of ordering at least one of everything on the menu. And he remains one of the few non-Japanese, non-Koreans I’ve met who shares my taste for Uni (which in case you did not know are sea urchin’s gonads… yep).

In any event, it was a pleasure knowing him and truly an honor to be able to remember him in this way.

Thanks for your time.