6 Skills Every Technical Diver Should Master

by Jon Kieren:

Technical diving is inherently dangerous. Diving in environments that restrict your access to the surface requires your foundational scuba diving skills to be second nature so when an emergency arises you can focus on solving the problem and aborting the dive. Whether you are just starting your TDI Intro to Tech Course, or have over 200 Advanced Trimix dives, these six essential skills should be practiced on every dive.

  1. Predive Check, Descent/Bubble Check, and S-Drill – While there are three skill sets listed here, we group them together because the overall objective is the same for all three: start the dive properly equipped and with fully functioning equipment.
    • Predive Check – Once fully dressed for the dive, as a team, each diver runs through their own equipment to verify primary cylinders are full and valves open with turn pressures verified, stage/deco cylinders are full with regulators pressurized but valves turned off, BCD inflates AND holds gas, dive computers/gauges are turned on and functioning properly, mask/fins/weights/etc. are donned and in good condition to dive.
    • Descent/Bubble Check – Depending on conditions and site, either on the surface or on the initial descent, the team inspects each other’s equipment looking for leaks and trapped or entangled equipment.
    • S-Drill – Each team member takes turns conducting the proper gas sharing procedure with another teammate.
    • The dive does not start until all of these checks have been conducted, any complication must be resolved before continuing the descent.
  2. Trim/Buoyancy/Finning – It’s not just for looks. The importance of being able to hold your position in the water column and prevent silting-out an environment cannot be overstated; and everyone can use a little practice. Every dive, try to spend some time focusing on different finning techniques and trim/buoyancy control. Grab the GoPro and let your buddies film you so you can get some valuable feedback on what you actually look like in the water as well.
  3. Valve Drills – On every single dive, you should practice shutting down and re-opening each valve. Make sure do to this with a teammate so they can verify each valve gets re-opened. Depending on your exposure protection and recent diving activity, you may find it more difficult to reach your valves than you remember. It is important to work on this flexibility and muscle memory on a regular basis, because when you really need it is not the time to realize that you cannot reach a valve.
  4. Remove and Replace Stage/Deco Cylinders and Bottle Swapping – It is important to occasionally practice removing and replacing stage/deco cylinders in order to maintain this muscle memory. Even if the dive does not require you to stage a cylinder, practicing this skill often will speed up and smooth out the process on the dives where it is required. Going over your bottom time because you were fumbling with a stage cylinder is both embarrassing and dangerous. You should also practice swapping bottles with teammates. This can be done while decompressing by swapping stages or lean deco gasses that you are finished with between your teammates. This increases team awareness, communication, and equipment familiarity. It is extremely important to check that no hoses or equipment have been trapped by the stage/deco bottle any time you replace one.
  5. Lift Bag/SMB Deployment and Reel Skills – Both deploying a lift bag/SMB and running a reel are skills that deteriorate quickly when not practiced regularly, and sloppy work in these skills can be extremely dangerous. Practice these skills as often as you can, if you don’t use it, you’ll lose it.
  6. Post Dive Briefing – It is extremely important to debrief every single technical dive. Discuss the highs and lows of the dive, where communication was good, where it was bad, and what areas can be improved upon for the next dive. You cannot see yourself in the water, so it is important everyone in the team provides some constructive criticism. This is often done with friendly banter, but it is important to remember that this feedback will help you improve your diving and safety.

While this is not intended to be an all-inclusive list of skills to be practiced for technical diving, these six skills are applicable to most technical diving scenarios, and can be easily practiced on just about every dive. What other skills do you like to practice regularly?

How to Switch your Diving Gas

Don’t Trust Your Gas Blender – Analyze Every Tank

by Jon Kieren

Girl analyzing a nitrox tank

Photo Courtesy of Andy Phillips

People make mistakes, it’s human nature. I make them all the time. I’m sure that even after this article has been edited several times and published someone out there will find at least a couple of typos and call us out on it. A typo is one thing. However, a simple mistake in the blending process can result in a diver breathing a mix with significantly more or less oxygen than they had expected, causing serious injury or death. If we KNOW that people make simple mistakes so often, then why do so many nitrox divers today NOT analyze their gas before diving? There are two primary reasons: either they don’t understand why it’s so important (a topic that is covered in every nitrox course), or they have just become complacent. This article will discuss both scenarios and how to avoid them.

Why is it so important to analyze your breathing gas? Simply, it can kill you if it’s wrong. If the oxygen content is less than the diver had expected, they can end up with unexpected and unknown decompression obligations.

Example – You make a dive to 30 metres/100 feet assuming you’re breathing 32% nitrox. You spend 39 minutes on the bottom and surface with no decompression obligation. Unfortunately, the nitrox tank you were diving was accidentally filled with air (21% oxygen), and in reality you just blew off 26 minutes of decompression. A significant error that is almost sure to result in Decompression Sickness. This situation can be made significantly worse by conducting repeated dives.

What if the oxygen content is HIGHER than you expected? Should be better off then, right? As far as decompression obligations are concerned, yes. However, a far greater risk in diving nitrox is Oxygen Toxicity and can cause severe convulsions (not a good situation underwater).

Example – Using the same dive as above, assuming you were on 32% nitrox at 30 metres/100 feet, your partial pressure of oxygen (PO2) would be close to its upper limit at about 1.3 ata. If that nitrox mix was in fact a 50% nitrox mix, your PO2 would now be over 2.0 ata and would be considered extremely dangerous.

The examples above are not the only concerns of breathing the wrong gas at the wrong depth; a thorough nitrox course will cover the others, as well as how to avoid them. So if you have to be Nitrox certified to dive nitrox, and the risks and proper procedures for avoiding those risks are covered in the course, why do people still end up breathing the wrong gas? The simple answer is: complacency. Over time, divers become complacent with their gas analysis procedures and start to skip it altogether, which means they end up in the water with absolutely no idea what they are breathing. Pretty scary.

Normalization of deviance is a term used by astronaut Mike Mullane (*Mullane 2014) to describe the process of complacency in safety procedures. In brief, it explains how humans have the tendency to take shortcuts due to different factors including time, peer pressure, etc. Once this shortcut is taken and nothing bad happens, the brain will incorrectly assume that the shortcut is “safe”. This shortcut now becomes the norm, and we have completely eliminated a critical step in a procedure. This applies to diving at every level. How many times have you seen divers jump in the water without doing a proper predive check? It is taught and its importance stressed in every open water course, yet it gets skipped every day because so many divers have “gotten away with it” they assume it’s safe to dive without making predive checks and then eliminate it from their procedure. Unfortunately, it also results in emergencies from divers forgetting to turn on their air and inflate their BCDs.

The same happens to nitrox divers. Maybe one day they are in a rush and forget to analyze their gas at the fill station. They get to the dive site and realize that they forgot to analyze but now do not have access to an analyzer. They are left with two choices, either not dive today or dive without analyzing their gas. The diver has been getting fills from that fill station for years and has never gotten the wrong mix, so they decide to dive anyway and assume the fill is correct. Nothing bad happens, so they now believe this shortcut is safe. “If I get my fills from XZY Dive Center, I know that it will be correct and I do not need to analyze my gas”. They have eliminated the most critical step in diving nitrox, and this is now the norm.

We know people make mistakes, and that’s why we have safety procedures in diving. These procedures help us catch the little mistakes before they create catastrophic emergencies. When diving nitrox, analyze every tank before every dive without exception. It could save your life.

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* Mullane, Mike. (March 2014). Stopping Normalization of Deviance.