Why We Don’t Color Code

HosesI’ve used yellow hoses for deco bottles.  I’ve also used yellow hoses for stage bottles, and I’ve even used a yellow longhose/primary.  I think I’ve also used green and gray hoses, and of course, black.  One of my stage/deco 2nd stages is yellow, currently on a black hose.  I also have a black 2nd stage currently on a yellow hose.

The hose is designed to allow gas to travel from the 1st stage to the device’s 2nd stage, inflator mechanisms, or spg, and the 2nd stage is designed to deliver gas to the diver at slightly above ambient pressure.  The color of the hose and/or 2nd stage has nothing to do with the purpose they serve, nor do they serve as any kind of identifier.  Let’s look at some of the reasons why:

First, switching to the wrong gas can quickly kill you.  More than one person has died because they were breathing an incorrect gas at depth.  The gas switch is a critical point in a technical dive, and a mistake can quickly become tragic.  Due to the opportunity for severe consequences, we use very specific procedures and protocols for switching from one gas source to another.  This includes identifying the bottle (for more information, see our Deco Bottle Marking Page), confirming its contents, identifying/confirming the regulator attached to the bottle, and verifying current depth.  This is all done in a very specific & logical sequence, and hose & 2nd stage color adds no useful purpose to that process.

Next, a regulator can serve multiple purposes.  It may serve different purposes on different dives on the same day.  For example, my criteria for choosing a deco/stage regulator for a given dive is the length of time I’ll be using that regulator on the dive.  I have a favorite deco/stage regulator, and I prefer to use that regulator on the bottle I’ll be breathing the longest.  On a dive that I’m using both a stage and deco bottle(s), I may use it on the stage that I’ll breathe down.  The next dive, I may use it on my 70′ bottle, and the next dive my O2 bottle.  If hose and 2nd stage color were part of the identification process, that regulator would be inflexibly dedicated to a single specific role, or, I’d have to switch out the hose and/or 2nd stage between dives, if the regulator was changing roles/functions.

Another reason color coding doesn’t work in our diving is we operate on a “next reg up” or “next hose up” method.  Meaning, on technical dives, cave/mine/wreck dives and exploration projects we have extra, backup regulators and hoses in the save-a-dive kit.  If there’s an issue with a reg or hose in the pre-dive check, we simply grab another regulator or hose and go.  Having a regulator dedicated to a specific function according to hose or 2nd stage color doesn’t afford us the flexibility of using a regulator for whatever purpose it’s needed for.  This becomes especially important on projects in remote locations with limited resources.

Looking at the above, there is a real opportunity for color coding to actually cause confusion in our diving. Imagine performing our gas switch protocol, confirming the bottle and 1st stage, but with an incorrect hose color, because the regulator was actually put on a bottle it wasn’t intended for.  In our diving, it makes no difference, as we simply confirm the bottle and regulator.  If hose color played a role, at best we’d now have confusion that we need to sort out, at a point in the dive that needs to be performed and completed efficiently and smoothly.  Is it the correct bottle, with wrong hose, or the correct hose, but on the wrong bottle?  At worst, the diver goes to the wrong gas, because he switched to the gas based on the hose color.  He’s now in jeopardy of DCS, as he’s breathing the wrong decompression gas and not decompressing as intended/believed, or worse, oxygen toxicity, if he’s too deep for the gas he just switched to.

Want more info on our equipment configuration, including deco/stage regulators?  Visit our Equipment Configuration Page.


Personal Skills Dives, Critical Skills Dives, Experience Dives and the Blue Gloves of Death

When talking about our training methods, the “blue gloves of death” (the term given when the instructor initiates a “failure” to the students underwater) inevitably comes up.  While initiating a failures is a large part of our more advanced training courses, and is always good for an entertaining discussion and video debrief, I thought I’d offer a bit of insight into the three types of training dives we conduct…personal skills dives, critical skills dives and experience dives, and the important role they each play in achieving our training goals.

Our ultimate goal is to create a “Thinking Diver” though it could be more accurately described as a “thinking teammate”.  However, like almost all things in diving, it’s a process.  It’s not just something you can create in a single class.  We achieve this through a building block training progression, starting at the bottom, building the foundation, and subsequently building on the foundation.

The foundational classes are Open Water, Rec 1Essentials and Essentials of Tech.  In these classes, we focus on the foundational skills of precise buoyancy control, trim, propulsion techniques and the basic 6, with a lighter emphasis on situational awareness and teamwork.  In order to be a good teammate, you must be a good diver, and while there are team elements to these classes, the primary goal is to improve the diver’s personal skills and competency.

To achieve this, all dives in the foundational classes are “personal skills” dives.  Personal skills dives can also be called “safe dives” in that no failures are initiated by the instructor.  The goal of these dives is to teach the mechanics of a new skill and allow the student to perform and practice these skills and form muscle memory.  If the instructor were to initiate a failure during this dive, it wouldn’t accomplish anything, since the diver is still learning the skill.  In fact, it’d be counterproductive, as the student would be overwhelmed by having to recognize, manage and resolve the failure, and the skill being practiced would most likely be compromised in order to focus on the failure.  Therefore, the skill would be performed incorrectly, creating a bad habit from the beginning.

After the student has built the foundational skills, subsequent classes (Rec 2 and Rec 3Tech 1Tech 2 and Overhead Protocols) will include critical skills dives.  Critical skills dives are “failures dives”, where failures are initiated by the instructor, or the “blue hands of death”, in varying and progressive difficulty, to start building the thinking aspect, increase capacity and bandwidth and problem management.  This forces problem recognition, management and resolution.  Failures are also used to target a specific deficiency the instructor wants to address and can also be used to drive a specific learning point.  Critical skills classes also have personal skills dives to allow the student to practice a new skill, “warm up” by practicing skills the diver is already proficient at or simply practice a skill the diver may feel rusty with.

Critical skills, depending on the class, vary in complexity and the level of complexity and compounding of the failures that are initiated, again following a building block progression of starting light and growing progressively more challenging, from recognizing and managing a single, simple failure and moving to multiple, complex failures.  Contrary to popular belief, the failures introduced are not random, nor are they initiated to create chaos.  They may be opportunistic, to drive home a point, or somewhat pre-determined in an overall plan.  They all, however, serve a very specific function for an objective the instructor wants to achieve.

In addition to personal skills dives and critical skills dives, we round out the training with experience dives.  Experience dives allow the students to plan and execute dives at the level they are current training, under the supervision of the instructor.

While experience dives are often viewed as “graduation dives”, they are challenging in their own way…

The experience dives are typically done as the final dives of the class, to give the students the opportunity to apply their new skills and knowledge in a real world setting.  While the instructor is present the entire dive, he merely shadows the students, interceding only if needed or warranted for safety concerns.  The entire planning, execution and problem recognition & management process now becomes very real to the student.  While no failures are introduced by the instructor, the students must adapt and adjust accordingly as the environment dictates, at a more challenging level than they were previously accustomed to.

While this type of training was by no means developed by UTD, it does provide a very solid and well rounded diver/teammate, by allowing the student to learn the mechanics correctly, then build awareness and problem management and round it out with doing the actual divers they’re training to do.

Reasoning for Deco/Stage Bottles on Left

For the past few days, I’ve been creating the training materials for the new UTD Stage/Deco Bottle Mini.  One of the things I tried to accomplish is explaining the “why” and not just the “how”, so I thought I’d take some time to offer some insight into the “why” we wear our stages and deco bottles as we do….on the left.

Before getting into that, I’d like to stress that there are many different schools of thought on how the stages and deco bottles should be worn.  This is not an argument against other methods, but merely an explanation of our methodology.  One aspect of diving is personal choice, and my intent with this blog is merely to provide the diver with more information, so they can make a more informed choice, whatever method they choose.

It’s also important to remember that a primary aspect our mindset is consistency.  This includes consistency in equipment, training, protocols and team.  As mentioned above, our equipment configuration places all stage and deco bottles on the left side of the diver.  I’ve listed the reasons why below:

  1. Allows for clean longhose deployment – With the stage/deco bottle on the left side, there is no possibility of the bottle “trapping” the longhose, which is routed on the right side
  2. Ease of scootering – the dpv (diver propulsion vehicle, or scooter) is typically operated with the right hand.  Having the right side clear of bottles allows for more freedom of movement of the right arm to control the dpv/scooter.
  3. Clutter of the right chest D-ring – The right chest D-ring has many items clipped off to it.  It’s where the longhose is clipped off when not in use, a backup light, an extra double ender and the scooter when stowed
  4. No right hip D-ring – In the UTD gear configuration, there is no right hip D-ring, as that is where the light canister is.  Consequently, there is no hip D-ring to clip a bottle to
  5. Allows for one handed stage/deco valve management – With the bottles on the left, facing “up”, the handwheel is on the left, or “outside”, making it very easy to access with the left hand
  6. Clean and consistent hose routing – All regulator hoses come from the left, behind the diver’s neck, and in to the mouth from the right
  7. Clean donation of reg in diver’s mouth with right hand – Due to point #6, the regulator is always donated with the right hand, since the hose routing is always the same
  8. Easy access to right (utility) pocket – This is a common misconception.  This isn’t about how quickly the diver can get to their pocket in an emergency.  The right pocket is the utility pocket.  In other words, the items in the right pocket may be used throughout the dive.  This means that these items may not only be taken out of the pocket, but also may be put back.  Ease of access to this pocket, since it will be used numerous times throughout the dive, is important.
  9. Consistent gas switching and stowing procedures – With all bottles on the same side, the gas switch and stow procedures are always the same.
  10. Consistent stage/deco bottle rigging – Since the bottles are always on the diver’s left, all bottles are rigged the same way.
  11. Clean canister light cord routing – Since the canister light is on the right, and the bottles are worn left, there’s no issue of the light cord getting tangled or “trapped”
  12. No risk of light switch getting bumped off – Like #11, since the canister is on the right and the bottles are on the left, there is no risk of a deco bottle hitting the light switch and accidentally turning off a functioning light
  13. The scooter is stowed on the right side when not in use

Of course, some items listed above are more “critical” than others.  Should a bottle be rigged for the left side, then mistakenly be put on the right when gearing up, it would be an inconvenience when doing the gas switch, due to the hose being on the inside instead of the outside, but probably not a life threatening situation.  Whereas, inability to donate the longhose, or tangled hoses due to unclean routing can cause for a bad situation.  Since our equipment configuration is based on consistency, the above reasons are why we wear the bottles left.

This affects consistency in equipment, of course, protocols (gas switching, stowing, donation of the reg in the donor’s mouth with the right hand, etc), training (the diver is trained to always have the stages and/or deco bottles on left.  There is no “in this circumstance, the bottle goes on left, and in this circumstance, it goes on right…” or “Donate using left hand in this case and donating using right hand in this case…”) and team, since all members of the team carry their bottles the same way.

There are certainly other configurations, and every diver must choose which method best works for them.  This is simply the reasoning behind why our equipment configuration has the stages on the left.

Misconceptions of UTD Essentials & Intro to Tech

Between the misinformation we’ve seen and heard, and some of the questions we’ve been asked, I thought I’d provide some insight into the Essentials, Essentials of Tech, Rec 2 and our overall teaching philosophy.

While we do teach team-based diving, it’s important to remember that we believe a diver must have solid foundational and personal skills before moving on to team skills.  In other words, if a student can’t perform a modified s-drill (personal skill) without losing their trim or buoyancy (foundational skills), how will they be able to perform a full s-drill with a teammate?   While the “team” aspect is a critical aspect to our approach, that is just one block in the overall structure, and the top block is only as solid as the blocks below supporting it.

This is where some misinformation and inaccurate comparisons exist with the Essentials class.  Essentials is exactly as its name implies.  It teaches the essential skills of safe diving.  It is, by design, a personal skills class first.  While team skills are introduced, primary focus is on the foundational skills of buoyancy, trim, kicks and balance.  We then move to the personal skills of the Basic 6 and smb deployment.  Team skills are introduced and performed, but again, the focus of this class is to develop the skills needed to become a safer diver and, in turn, a better teammate.

For the reasons stated above, Essentials is a very common entry point into our curriculum.  While divers at any level, including instructors, photographers and experienced divers will benefit from the class, it’s designed to provide a diver who has taken their open water class from outside the UTD curriculum a means of learning the skills required for future UTD/FKD classes.

In other words, most open water students wanting to take Rec 2, which is the “equivalent” of Advanced and Nitrox combined, and also where team skills and light critical skills (failures) are introduced would very quickly be overwhelmed, simply because they haven’t built the foundation needed for that class.  They wouldn’t learn anything from the class because they’d be in over their head from the very beginning.

This isn’t to say that every diver wanting to enter our recreational curriculum must first take Essentials, as we do accept equivalents.  However, Essentials was designed to teach the foundational and personal skills, and introduce team skills, in a non-evaluation environment where the student can focus simply on learning, and not the pressure of passing or failing.

Additionally, there are also only 2 gear requirements for the Essentials class…a 7′ longhose and blade style, non-split fins.  It was important to us to make this class accessible to anyone wanting to take it, without a large investment in gear and equipment.

The UTD Essentials of Tech class, while similar to the Essentials class in several ways, does differ in that it is an evaluation class. Essentials of Tech is a more robust course, where the student is learning the skills needed to enter our Technical Diving curriculum, in a non-critical skills (failure) environment.  To enter the Tech 1 class, where the student will be entering mandatory decompression obligations, the student must first meet the standards of the Essentials of Tech class.  To that end, the Essentials of Tech class is an evaluation class, but the student is still learning the required foundational, personal and team skills required to build that foundation needed for more advanced technical diving.

The Essentials of Tech class is taken in double cylinders and a decompression bottle.  We feel that teaching the mechanics of gas switches, stowing and bottle passing in a non-critical skills environment allows the student to learn properly the first time and also allows them time to go practice their new skills before entering the Tech 1 curriculum, where failures are introduced.

Upon entering the Rec 2 (after Essentials) or Tech 1 (after Essentials of Tech), the focus shifts to team, awareness, problem solving and thinking.  This is because they now have the foundation built, and they can refocus their new extra bandwidth towards those areas, as it is no longer needed for their own skills.

It should be noted that this method is not the only dive instruction philosophy.  It’s simply the training approach of UTD and FKD.

Rock Bottom for Recreational Dives

Proper gas planning & management is critical to safe diving since humans cannot breathe underwater without life support equipment.

Unfortunately, many divers don’t understand what gas planning & management is, and simply use the standard “Back on the boat with 500psi” or the rule of “thirds”.  While those types of plans may work in certain circumstances, they can also be very dangerous, since, in the first example, the diver is planning his gas so he arrives at the surface with a set pressure in his tank.  He’s not planning his gas for what would be needed should an emergency occur underwater, which could be the difference between life and death.

It’s important to remember that an Out Of Gas (OOG) emergency is unacceptable.  Proper gas management and gear maintenance is all that is required to avoid this type of situation.  However, when planning our dive, we plan according to worst case scenarios.

What is Rock Bottom

Rock Bottom is, quite simply, planning for the worst case scenario…the instance where a diver in a 2 person buddy team experiences a catastrophic and complete loss of gas at the deepest part of the dive.  It’s the minimum amount of gas needed for 2 divers to ascend, completing all required stops, sharing air on a single cylinder.


In your open water class you learned about Boyles Law.  Simply put, Boyle’s Law states that at a given temperature as pressure increases, volume decreases.

In salt water, every 33’ is an atmosphere.  At the surface, we are under 1 ata (atmosphere absolute) of pressure.  Therefore, at 33’, we’re under 2 ata’s of pressure (the single atmosphere at the surface, and the 33’ of water above us).  At 66’, we’re under 3 ata’s of pressure.  99’ is 4 ata’s, and so on.

Since every 33’ of saltwater is an atmosphere, to determine the pressure, in ata’s, of any given depth, we simply divide the depth by 33, and add 1 (for the pressure at the surface).  In other words;

Ata = Depth / 33 + 1

Likewise, to determine the depth of any given pressure, we simply subtract 1 (for the pressure at the surface) from the pressure, then multiply by 33.  Also shown as;

Depth = ata – 1 x 33


It’s important that every diver know his/her own consumption rate.  If you don’t know your consumption rate, and would like to learn more, please Contact Us to schedule a FREE Gas Planning & Management Workshop.

At the recreational level, we typically plan for a stressed diver to breathe approximately 1cuft per minute (Respiratory Minute Volume, or RMV), at the surface.  Applying Boyle’s Law, from above, if a diver breathes approximately 1cuft per minute at the surface, stressed or working, he’ll breathe 3 cuft per minute at 66’, due to the fact that your 2nd stage regulator must deliver air to you at slightly above the ambient pressure;

1 (RMV) x 3 (ata of 66’) = 3

At 99’ the diver will breathe 4 cuft of gas, when stressed or working;

1 (RMV) x 4 (ata of 99’) = 4

You can certainly increase your planned stressed RMV upwards, for conservatism, if desired or if you know your working RMV to be higher than 1.

Calculating Recreational Rock Bottom

When calculating Rock Bottom, there are certain rules and assumptions that we must apply and consider;

  • Use working RMV (1.0 each if not known, as previously stated)
  • :01 to donate the regulator, assess the situation and initiate the ascent
  • Ascend at 30fpm to first stop (50%)
  • Ascend at 10fpm from 50% to surface

One final rule; never use a Rock Bottom of below 500psi.  If your calculated Rock Bottom is below 500psi, use 500psi.  This is due to the inaccuracy of the spg when reading pressures below 500psi.

When applying the rules and assumptions above, its easiest to visualize the situation in 2 segments; the bottom segment (donation, assessment and initiation of ascent) and the ascent.

Additionally, there are only 3 pieces of information needed to calculate Rock Bottom;

  • How deep (depth)
  • How long (time)
  • Breathing rate (combined RMV for TWO divers, since they will be breathing off a single tank)

Depth and time are both variable.  The deeper the dive, the more that is needed/used in the bottom segment, due to the increased depth.  Likewise, the deeper the dive, the longer the ascent time.

Here’s an example;

RB Vol Ascent

So, in the example above, a buddy team experiencing an OOG emergency at 100’ will need 40cuft of gas to ascend safely, completing all stops.

However, since we work with pressure, and not volume, while underwater, we must convert the volume (40cuft) to pressure, or psi.

To do that, we’ll simply run a quick calculation using tank factors

Tank Factors

Tank factors are simply the amount of cubic feet per 100 psi, for a given tank.  Using tank factors is a very easy way of converting between volume (cuft) and pressure (psi).

To calculate a tank’s tank factor, you simply divide the tank’s rated pressure by the tank’s rated volume, then multiply by 100;

Tank Factor = rated volume / rated pressure x 100

For an al80 (al80’s actually contain 77cuft, not 80), the tank factor would be:

77 / 3000 x 100 = 2.66

This means on an al80, there are 2.66 cuft per 100psi.

To make life simple, we’ll just call it a tank factor of 2.5.

It’s important to remember that you must use the rated pressure and volume.

Now that we know the tank factor of an aluminum 80, we can convert the volume (40cuft) to psi in the above example, using a simple formula.  The diagram below is actually a formula in itself.  If you want to know the volume, you’d simply multiply pressure by the tank factor.  If you want to know the pressure (psi), you’d simply divide the volume by the tank factor.


So, using the formula above, to determine how many psi 40cuft of gas in an al80 is, we simply divide the volume (40) by the tank factor (2.5);

40 / 2.5 = 16 or 1600

Applying this to the above example of a Rock Bottom Ascent, we’d get this:

RB PSI Ascent

1600psi is needed for the 2 divers to ascend from 100’, sharing air on a single al80, completing all required stops.  Since this is based on assumptions, if you’d like to add a buffer of 200 or 300psi, making the Rock Bottom 1800 or 1900, that is perfectly acceptable.  However, you should never lower the Rock Bottom number.

There are other gas plans as well, as Rock Bottom doesn’t work in every scenario (overheads, such as caves or wrecks, where additional gas is needed to get to the ascent point).  But for most everyday recreational dives, Rock Bottom gives you the knowledge that you need to safely execute a dive.

It’s important to understand that Rock Bottom is for a specific depth, and not a specific dive.  In other words, 100’ has a different Rock Bottom than 90’.  For instance, if you hit your Rock Bottom at 100’, and ascend up to 80’, you must ensure that you don’t exceed your Rock Bottom for 80’.

It’s a good idea to make note of your Rock Bottom in 10’ increments, from 60’ to the maximum depth you dive to.  An easy way of doing this is to keep them in your wetnotes.  If you know the volume, you need only use the tank factor to adjust it for the tank you are using.

If you’re interested in learning more about Gas Planning & Management, please Contact Us to schedule a free Gas Planning & Management Workshop.

Practical Application of Ratio Deco

I’d like to take a few moments to illustrate how standard gases and ratio deco have effected my diving recently.

I posted a trip report of our attempt to dive the SS Governor here.

Here, I’d like to talk about the flexibility the UTD standard gases and decompression strategies. Keep in mind that ratio deco isn’t a decompression theory, it’s simply a strategy using existing models and research to help shape an ascent profile.

On our attempt on the Governor, we used 15/55 for backgas and EAN50 and O2 for deco. This allowed us a range of depths, generally in the 200’ to 240’ range. That afforded quite a bit of flexibility to explore the wreck, which was especially useful in this case as the wreck is sitting upright where the mudline is at 240’ and the deck is at ~ 200’…quite a variance in depths.

Our plan, however, was to try to keep max depth at 230’, and spend most of our time on the deck at 200’ to keep our average depth at 220’ or shallower, to keep our deco time manageable.

Unfortunately, due to vessel traffic delaying our splash time, we weren’t able to do the Governor. We instead decided to do the Al-Ind-Esk-A-Sea, another large wreck that sank in 1982 after a fire broke out and numerous explosions occurred. Dan Warter has a great article on the Al on his website, DCS Films.

Though the profile of the “Al” is similar to the profile of the Governor, it really made me think about what would happen if we were to do another wreck with a completely different profile. In other words, what if we planned to do a wreck that was 240’, but due to conditions, we were forced to do a dive in 200’?

Well, for starters, we’d have to make sure our backgas was compatible with the profile of that dive. We had 15/55 in our tanks, which would allow us to go as deep as 240’, and would certainly work for 200’. Now that we know our backgas is ok, we need to figure out our decompression. There’s quite a difference in the deco obligation/profile for a 240’ dive and a 200’ dive. If we simply used the same profile for the 200’ dive as we do for the 240’ dive, our first stop will be much deeper than necessary and our deco time will be much longer than necessary. We could bring out the laptop if we brought it and cut new tables, but we’d also have to print them and laminate them. We could just run our computers as well, which is fine, but if everyone has different computers running different algorithms, that can create some confusion as well.

This is what I like about Ratio Deco…”deco on the fly”, or “tailgate deco” as I sometimes call it, allows me to calculate an entirely new deco schedule in 2 minutes time on scratch paper. Instead of hurrying to pump out a new set of tables, or doing much more deco than necessary because I don’t have any other tables than the ones I made for the original profile, I just grab a pen, a napkin, scroll out my new schedule as a general plan, then relax and prepare mentally for the dive.

How can I do this? Standard gases all have the same deco shape. Sure, we may add extra deco gases, but the shape is the same. No new numbers to remember, no tables to cut every dive. The shape is always the same whether its an mdl dive, Tech 1 dive, Tech 2 dive or a Trimix dive. This makes it very easy to remember and calculate.

How about the reverse? Had we a chosen a mix specific to the depth we planned to go to (or “best mix”), rather than a range and ended up going to a wreck deeper than the one we had originally planned, we wouldn’t be diving at all that day. All that time and effort preparing, the cost of the charter and the gas, and we can’t even dive!

While there’s more benefits to standard gases and ratio deco, these are 2 that I really appreciate and have really positively effected my diving. They allow me to actually explore. We can do our dive, with plenty of flexibility to adjust our profile as needed, then, when our dive is over, we can figure out our deco.

On our dive on the Al-Ind-Esk-A-Sea, we had no tables or deco schedules…nothing written on a wrist slate or in our wetnotes. We did our dive…then, when our dive was done and we were ready to ascend, we figured out our deco. One quick signal of “average depth, 210’” and we both knew what the rest of our profile would look like.

The next 65 minutes we spent decompressing, both of us knowing what the rest of the ascent would look like.