Precision Diving

I recently had a conversation with a potential student about how I teach team diving techniques compared to what is taught in traditional diving classes. It occurred to me that many divers do not know the difference between team diving and buddy diving. They feel that if they stay with their buddy and can air share in an emergency, that is team diving. It is not, team diving is much more than sticking with your buddy and helping out in an emergency.

First, let’s define buddy diving as it is taught in traditional diving classes. When people go through these classes, they are taught to stick with your buddy, do air shares, and some basic buddy rescue skills. While these skills are important, it does not take the place of working as a team. Buddy diving, is simply looking after each other. The buddy is just there. It doesn’t do much for the safety of the team nor the objectives of the dive. One of the biggest areas where buddy diving fails is in the pre-dive planning stage. In traditional PADI diving classes, students are normally taught BWRAF as their pre-dive plan. That is an acronym for: BCD, Weights, Releases, Air, Final OK. There is no discussion as to how they will descend, swim around, communicate, when to thumb the dive and ascend. This is where buddy diving breaks down.

So, what is team diving? Let’s use the analogy of a football team. US football, not soccer that is. In football, the team works together to work their way down the field to score a touchdown. Everyone on the field has a job to do in order to ensure success. If one area of the team fails, then the quarterback gets sacked, the running back fumbles the ball, or the team must punt away the ball. If an offensive lineman does not do his job effectively, then the quarterback or running back can, potentially, get hurt. The same is true for team diving. The team must work together to ensure the safety of all members of the team. Next time you watch a NFL game, watch the offensive linemen. They are always pointing to something, shouting at each other, etc. The quarterback reads the defense and may change the play at the line of scrimmage (i.e. call an audible). This is an excellent demonstration of constant team communication. Each member of the team knows where other teammates are at at all times. Just as in diving, we must be able to effectively communicate to let the team know where we are at, what to look out for, etc. We do this with passive and active light communication.

It all Starts in the Beginning

To ensure team success, the entire team must be on the same page. Not just in knowing what is expected, but in skill and experience level. Inexperienced divers can learn a great deal from experienced divers, but they must learn it at their current experience level before moving on to something more aggressive and out of their level. This is one aspect of diving where people get into trouble. They simply try to do dives, or take classes, that are above what they are really capable of handling. The problem is they don’t know when to put the brakes on their diving and say, I need to get better before moving on. They don’t do a honest assessment of their diving skills. I had to learn this the hard way, see here.

As part of the pre-dive plan, the team must get together and determine how the dive will get done. They must determine what the goal of the dive will be, who will lead, what the gas plan is, etc. For shallow reef dives, this can be very simple and take only a few minutes. For complex decompression dives, it can take days.

The Team that Descends Together, Stays Together

The majority of diving problems occur during the initial descent of the dive. As a team, it is important to stay together during the descent. There are multiple team descent techniques that can be employed, depending on the water conditions. This is where you need to have learned team diving from a good instructor to knows team diving protocols, not reading off the internet.

A good number of diving accidents have occurred when diving alone. Now, that doesn’t only mean solo diving. It includes when buddies lose contact and separate from one another. If the team descends together and gets to the target depth, then the leader can communicate to the team the direction to swim. This helps keep the team together and swimming off in the right direction. In other words, everybody starts the dive together.

Lending a Helping Hand, or Two, or Three

When the proverbial crap hits the fan, I want my team members there to help me out. This shouldn’t be confused with being self-sufficient. If I’m having a problem with a gas leak, my teammates can see my valves where I cannot. They can tell me which one to shut down, or just do it for me if I am dealing with another problem. They are there to provide me gas, if for some reason I need it. In other words, my teammates must be on the same page as me so that we can prevent small issues/problems from becoming larger (i.e. the incident pit). When diving as a team, all resources become team resources. This includes equipment, gas, etc. But it also includes that person’s experience. This is where solo diving courses fail because the diver solely relies on their own, possibly limited, experience. When I’m diving with less experienced divers, I’m able to prevent or foresee potential problems they may have based on my past diving experiences. A diver’s education and experience level is a big resource one can bring to the table in the team environment.

The bottom line is that divers shouldn’t be fooled by instructors/dive stores who are claiming to teach team diving. Nine times out of ten, they are only talking about buddy diving and not team diving. Do your homework and ask the all important question, “How?”. An instructor who truly teaches team diving will be able to teach more than just the “buddy system” and teach how the team can achieve it’s goals, including teams with more than 2 or 3 people.

I welcome your questions or comments.

Dive Safe,
Duane Johnson
Precision Diving

As part of any technical diving class, the topic of oxygen exposure/tracking must be discussed. For the depths required for decompression diving, technical divers are exposing themselves to elevated partial pressures of oxygen (PPO2). Not only in using oxygen rich mixes to accelerate decompression, but bottom gas mixtures can also have a high PPO2. So tracking our exposure to oxygen is a must to reduce the risk of CNS oxygen toxicity. The goal of this article isn’t to teach you how to track your oxygen exposure. A thorough technical diving class should do that. Also, Steve Lewis has posted some great articles on his blog about managing oxygen exposure, Daily Limits for Oxygen Toxicity and About Oxygen Part One. Instead, this article will discuss how to estimate the CNS % (i.e. CNS Clock) when the software or tables are not readily available.

The Assumptions

First of all, this method of tracking the CNS clock requires the use of standard gases (i.e. 21/35, 18/45, etc.). The reason for this is that the depth range for these standard gases gives us an average PPO2 of 1.2. For technical diving, this level is desired to reduce the risk of oxygen toxicity during the working phases of the dive. We raise the PPO2 to 1.6 during rest at deco.

How it is Calculated

Now the risk of oxygen toxicity isn’t an exact science. To calculate the CSN %, you simply divide the dive time by the maximum allowable PPO2 exposure time. The result is expressed as a percentage. The theory is that the closer a diver comes to 100% or more exposure, the risk of oxygen toxicity increases significantly. To look up the maximum allowable PPO2 exposure time, you will need the NOAA tables. However, if you do not have those handy, there is a quick way to calculate the CNS clock.

According to the NOAA oxygen exposure tables, the maximum single dose limit for a PPO2 of 1.2 is 210 minutes. If we divide 100% by 210 minutes, this gives us the percent exposure for every minute. We use 100% as the maximum as we want to reduce the risk of oxygen toxicity. So for the PPO2 1.2, we get 100%/210 = .48 or just slightly less than 50%. So what does this mean? Well, we can simply divide our bottom time exposure by 2 (i.e. half or 50%) to get our CNS %. Let’s look at an example. We do a dive for 145 minutes at a PPO2 of 1.2, the formula looks like 145/2 = 72.5%. NOAA tables give us a 69%. So we are more conservative (i.e. lowering the risk of oxygen toxicity than NOAA tables) in this calculation.

OK, but how do deco gases and 100% Oxygen work?

Again, we must refer to the standard deco gas of 50% Nitrox. If we use that as our deco gas, it gives us an average PPO2 of 1.2 (i.e. 70 feet to the surface). We simply add our bottom time with our deco time and divide that by 2. This gives us the total CNS % for the dive. If we do a dive to 150 feet on 21/35 with 50% Nitrox for our deco gas for 30 minutes with 30 minutes of deco, calculate the CNS % for the dive. We add our bottom time and our deco time together, giving us 60 total minutes. We can do this as the average PPO2 is 1.2 for both bottom gas and deco gas. We divide that by 2 for a total 30% CNS exposure. Running tables, V-Planner, or Deco Planner will give us 22% CNS. So again, we pad a little conservatism into our O2 exposure by using this estimation procedure.

When we deco on 100% O2, we are at an elevated PPO2 of 1.6. So how does decompressing with 100% O2 work? If we look at the NOAA tables, our single allowable exposure of a 1.6 PPO2 is 45 minutes. If we divide 100% by 45 minutes, this gives us 2.2 or 220%. Since the percentage is higher than 100%, we can multiply our deco time by 2 rather than divide by 2. Multiplying by 2 does put us on the aggressive side. For greater conservatism, we can multiply by 2.5. So if we have 15 minutes at 20 feet on 100% O2, this gives us 30% CNS. So if we were to do a dive to 150 feet on 21/35 with 100% deco gas only for 30 minutes of bottom time with 30 minutes of deco of which 15 minutes on 100% O2, calculate the CNS %. We have our bottom CNS % of 15 (30/2=15) added to our deco CNS % of 30 (15*2=30) we get 45 % Total CNS. Deco Planner and V-Planner give us a total CNS of 57%, so you can see the lack of precision in some scenarios. But if we multiplied our deco exposure by 2.5 instead of 2, we now get 67.5% which is now more conservative than Deco Planner or V-Planner.

Summary

So, while calculating the CNS % in this fashion isn’t exact. It will still give the diver a pretty close estimate. This is particularly useful when one does not have access to decompression software or NOAA tables to perform the calculations. This method should also not replace accurate oxygen management and tracking protocols taught in a thorough technical diving class. Instead only act as an estimate when the specific tools are not available.

I welcome your questions and comments.

Dive Safe,
Duane Johnson
Precision Diving

The subject of training, gear choices and the development of diving skills can seem secondary to a new diver. Something to get out of the way so we can get out there and dive. The experience of diving is what it’s really all about, right? The wreck, the cave, the wildlife, shooting film, bagging the lobster. Yeah, we can do all that with so-so skills.

But the true enjoyment and safety of the dive is greatly enhanced by how we dive – how we move through the water, control buoyancy and trim, whether we utilize our equipment efficiently, communicate effectively with our dive buddies, and work as a team. It’s also about how we resolve equipment malfunction, a rolled off valve, a free-flowing reg, a lost mask, or an out-of-air situation.

When was the last time you removed, replaced and cleared your mask underwater? Five years ago, maybe once or twice in your open water class? What if your buddy kicks your mask off on your next dive? How comfortable would you be in replacing and clearing it quickly? How much depth would you lose by the time you got squared away again? Have you now lost your buddy? Maybe you’re now on a runaway ascent to the surface?

This simple scenario can easily happen, and it can lead to a real screwed up dive. The same can be said of any number of other little things gone wrong. Here’s another mask scenario:

What if your buddy loses his mask at depth? How long would it take for you to notice? Can you then take him safely to the surface, with safety stops, both holding your positions and communicating with touch hand signals when to move and when to stop? How about doing this on a free ascent, without an upline to hang on to? Did you think to check his air before the ascent?

Divers are even more vulnerable to these stresses after initial certification. And if the level of initial skills and comfort in the water is not minimally sufficient – if the initial training doesn’t demonstrate what those skills should look like and provide a guide for how to develop those skills through practice and drills going forward – then the student is left to struggle on his or her own, and may never learn the most efficient way to do things. How many instructors demonstrate a high level of skill and refinement to their students – showing them what is possible – how it should be done, and what to strive for? (here’s one I know of).

In the lost mask example above, I can think of several skills that you need to have mastered for this situation to resolve smoothly and safely. First, you need to be acutely aware of your surroundings and your buddy, to notice in the first place that he has an immediate problem. Take your head out of that lobster hole once in awhile and look around. This is not as easy as it seems. Situational awareness is a skill in itself, something we need to consciously work on.

If the mask is gone or not functional, you’ll need to take him up safely. You both need to know the protocol for doing this – so team coordination and contingency planning is important. Next, you need to be able to communicate with touch hand signals – calling the dive, move up. You need to check his air, just in case he’s about to need an air share – you don’t want to add to the stress of the situation by waiting for this surprise, remember he can’t see. You both need to have good, intuitive control of your ascent – nice and slow and smooth. When it’s time for the first safety stop, you need to signal your disabled buddy with the touch signal for leveling off, then up to the next stop. You both must hold your position at each stop exactly – 30 feet, 20 feet, 10 feet. Let’s hope your buddy, and you, know how to fine tune buoyancy control with breathing and know how to vent your drysuits with finesse – remember he can’t see his depth gauge to make gross corrections.

In most situations, you might guide your sightless buddy to an upline or anchor line and work up the line. But if you need to make this unplanned ascent away from the surface vessel, and perhaps if there’s a current, you might need to first deploy your SMB to notify the boat crew of your position. Before beginning your ascent, depending on depth, you would signal your buddy to hold position while you blow the bag. There’s another skill you’ll need – quick, efficient, smooth deployment of your SMB. And you’ll need to reel it up while maintaining touch control of your buddy.

All this may sound simple, maybe easy, but it’s really not at first, as I and many of my (even technically trained) dive buddies can attest. To master these skills requires a few things: knowledge of how to execute them correctly; likeminded divers who will practice them with you in a calm, shallow environment; and a desire to practice them over time. No different than if you were to spend a Saturday hitting buckets of balls at the driving range to refine your golfing skills. How much better and more enjoyable will your next game be as a result?

Refined diving skills should not be the domain of the technical or advanced diver alone. They can and should be part of every recreational diver’s abilities. Practicing them with good friends can be fun, and it definitely pays off.

More on how we practice skills and drills on our “workout dives” in my next post. (You work out at the gym don’t you?)

Jim Costopulos is a Chicago-area executive with an industrial products distribution company. He began diving as a teenager in Southern California; around Palos Verdes, San Diego and the Channel Islands, which he desperately misses. Currently, diving in Lake Michigan, Lake Superior and of course local quarries is also great fun. He will post here on a regular basis and welcomes your comments.

A while ago, a dive store manager asked me to try out this new gizmo called a Quick Shot. It is a device that is supposed to help divers inflate SMBs or lift bags easier when wearing deco, stage, pony bottles. I have always been reluctant to try new gear that is advertised as an improvement on something that doesn’t need improved, but I tried it anyway.

The Quick Shot is basically the mechanism of the end of an inflation hose, without the hose, that has the 3/8″ threads. It screws into a low pressure inflation port on the first stage of a regulator. This device is meant to go on a deco/stage bottle, not on tanks on your back. This device can only be used with SMBs or lift bags that have the inflation nipple (like a BCD inflation nipple) for inflation.

Normally, SMBs or lift bags are inflated orally or by using a low pressure inflation hose, such as your BCD or dry suit inflation hose. I have always preferred orally inflating my SMBs. So when I tested this device, I did it in a scientific method. That is, I used my normal way of inflating a SMB as a control and compared how to inflate the SMB using the Quick Shot to my control. Below are my findings.

I first found that the Quick Shot needs to be on “top” of the first stage in order to fit the SMB inflation nipple to the Quick Shot device. So my dive was cut short and I had to head back to the bench to move the device to a different port on the regulator. Once back in the water, I used the Quick Shot to launch SMBs. I found that there were two methods to shoot the SMB. One, I had to wrap up the spool and access SMB material in my left hand then inflate the SMB with the left hand as well. The Quick Shot does inflate rather fast. I found this out the hard way as the SMB took off and I was left searching for the spool. The other thing that went wrong with this method of inflation was that if the SMB is in front of you, when it inflates, the SMB may dislodge your mask due to the fast inflation rate. So I had to be careful to keep the SMB away from my face. My second attempt at shooting the SMB, I kept the spool in my right hand and inflated the SMB with my left hand. This gave me more control over the SMB. Again, I had to make sure that the SMB was away from my face. However, this method didn’t leave me with a free hand. If you read my blog article on how to shoot a bag, it is a team activity. If a member of my team had an emergency and I had both hands full with the SMB, it could lead to even more problems. In order to get more practice at shooting the SMB using the device, I shot a total of 12 SMBs using both methods I just described. I even tried using this device when I was in a near vertical position (one I’m not comfortable in). Still the same results. It became even more difficult when carrying two bottles and the bottle with the Quick Shot device is on the bottom. The SMB and spool wanted to get tangled up in the deco bottles. Plus, I had to remember which bottle the device was on.

In conclusion, my theory is that a diver shouldn’t let equipment replace what can’t be done with skill. This holds true with this device. Shooting a SMB the “old-fashioned” way is more effective in that it 1) doesn’t inflate the SMB too fast. The diver can control how fast he/she blows into the bag. 2) It allows the diver to be in more control of the process and also keep an eye on the team. The MSRP for this device is around $20 USD. So if people buy one and never use, then you aren’t out much money. Heck, we’ve all spent a lot more money on more useless things. My suggestion is, learn how to inflate the SMB the right way and stick with that. It is a process that has been proven to be effective time and again.

FWIW, I did not purchase this device and was not paid to test it out.

I welcome your questions and comments.

Dive Safe,
Duane Johnson
Precision Diving