文章

Technical Diving Resources

by Jon Kieren:
tdi divers researching

Books – The texts listed are all excellent resources for any active technical diver, or anyone who is interested in beginning their technical diver training. Some of the titles are instructional manuals, while others are non-fiction stories of exploration.

  1. Advanced Wreck Diving Guide – Gary Gentile
  2. Basic Decompression Theory and Application 3rd Edition – Bruce R. Wienke
  3. Basics of Rebreather Diving, The – Jill Heinerth
  4. Beyond the Deep: Deadly Descent into the World’s Most Treacherous Cave – William Stone, Barbara A.M. Ende, Monte Paulsen
  5. Blueprint For Survival – Sheck Exley
  6. Cave Divers, The – Robert Burgess
  7. Caverns Measureless to Man – Sheck Exley
  8. CCR Cave “Almost Simplified” – Dr. Mel Clark
  9. CCR Trimix Simplified – Dr. Mel Clark
  10. Deco for Divers – Mark Powell
  11. Deep Descent: Adventure and Death Diving the Andrea Doria – Kevin F. McMurray
  12. Deeper into Diving, 2nd Edition – John Lippmann and Dr. Simon Mitchell
  13. Diving in Darkness: Beneath Rock, Under Ice, Into Wrecks – Martyn Farr
  14. Diving into Darkness: A True Story of Death and Survival – Phillip Finch
  15. Diving Physics with Bubble Mechanics and Decompression Theory in Depth – Bruce R. Weinke
  16. Diving Physiology in Plain English – Jolie Bookspan
  17. Essentials of Cave Diving – Jill Heinerth
  18. Fatally Flawed – The Quest to be Deepest – Verna an Schaik
  19. Introduction to Technical Diving – Rob Palmer
  20. Last Dive: A Father and Son’s Fatal Descent into the Ocean’s Depths, The – Bernie Chowhury
  21. Mastering Rebreathers – Jeffrey E. Bozanic
  22. Mixed Gas Diving: The Ultimate Challenge for Technical Diving – Tom Mount and Brett Gilliam
  23. Physiology and Medicine of Diving, 5th Edition – Alf Brubakk and Tom Neuman
  24. Rebreathers Simplified – Dr. Mel Clark
  25. Shadow Divers – Robert Kurson
  26. Shipwreck Hunter: Deep, Dark & Deadly in the Great Lakes – Gerry Volgenau
  27. Sidemount Profiles – Brian Kakuk and Jill Heinerth
  28. Six Skills and Other Discussions: Creative Solutions for Technical Divers, The – Steve Lewis
  29. Staying Alive: Risk Management Techniques for Advanced Scuba Diving – Steve Lewis
  30. Technical Diving from the Bottom Up – Kevin Gurr
  31. Technical Diving in Depth – Bruce R. Wienke
  32. Technical Diving Handbook – Gary Gentile
  33. US NAVY Diving Manual
  34. Wookey Hole: 75 Years of Cave Diving & Exploration – Jim Hanwell, Duncan Price, Richard Witcombe

Websites

  1. TDISDI.com
    • The SDI/TDI/ERDI website provides student divers direct contact with their local TDI facilities and Instructors via the Dive Center/Instructor Search Tool. You can also search hundreds of articles about technical diving on the TDI Blog. The Course Description Page gives potential students access to complete descriptions as well as the Standards and Procedures of almost all TDI courses offered.
  2. Rubicon Foundation: http://archive.rubicon-foundation.org/
    • The Rubicon Foundation Research Repository is a free digital archive of over 8500 searchable references on topics ranging from Diving Accidents and Fatalities, Decompression Sickness, Hyperbaric Drug Interactions, In-water Recompression, Oxygen Toxicity, and much more! This is by far the largest collection of diving references, and the foundation actively undertakes projects that:
      • Contribute to the interdependent dynamic between research, exploration, science and education;
      • Improve the available resources for students, professionals and the general public; and
      • Preserve the valuable natural resources that are vital to future endeavors.
    • The Rubicon Foundation is a non-profit organization, they accept donations to help support their projects HERE.

Forums – Forums and discussion boards can be an excellent source of information from active technical divers and instructors. It is important to use caution whenever you are taking advice from someone on the internet, however.

  1. www.CCRexplorers.com
  2. www.Rebreatherworld.com
  3. www.thedecostop.com
  4. www.cavediver.net
  5. http://www.scubaboard.com/forums/technical-diving-specialties/
  6. http://www.thediveforum.com/forumdisplay.php?36-Technical-Diving

3 Ways to Improve Your Air Consumption

musa diverby: Jon Kieren

The goal of every avid diver is simple: Spend as much of your life as possible underwater. On open circuit SCUBA, we all have one major limiting factor, the amount of gas we brought down with us (along with no decompression limits, but this article will only address gas supply). Most new divers will have the same reaction when diving with a group, “How does everyone else stay down so much longer than me?” While this quickly fades after just a few dives as the beginner starts to be more comfortable, their breathing will relax a bit, and they are diving just as long as most of the others in the group. However, there are always those exceptions in the group that are able to stay down twice as long as everyone else. What are they doing that’s so different? Do they have gills? Well, no, but some of it is simply physiology. Small people with tiny lungs simply breathe less. Their smaller bodies require less oxygen for metabolism, and it takes far less gas volume to fill their lungs. Much of the rest stems from these three simple tricks.

1. Relax.

This is the hardest part for newer divers. Being underwater is both exciting and also a bit stressful at first. When people are excited, their breathing rate tends to increase. As you breathe faster, you tend to breathe shallower. Fast shallow breaths are very inefficient for gas exchange, and your body starts to build up carbon dioxide (CO2). As CO2 builds up, your body’s natural response is to increase your breathing rate. It’s a vicious cycle that results in a vastly increased air consumption rate and shorter dives. Relax and focus on your breathing, with extra attention on the exhalations. Make sure you are ridding your body of all of the built up CO2, and you will see a drastic improvement in your air consumption.

2. Slow Down.

Scuba diving is not a race. We know it’s exciting and you want to see as much as possible, but you’ll actually see MORE the slower you go. Swimming fast means you’re working harder and breathing harder, which means you’re breathing through your tank faster. If you see something amazing, don’t chase after it, let it come to you. Critters don’t like to be chased around the ocean, and you’re probably not going to be able to catch whatever it is anyway. Slow down and take your time and you’ll be able to stay down significantly longer, and in turn see more.

3. Get yourself weighted properly.

Many divers, both new and experienced alike, have a horrible habit of diving over-weighted. Their thought process is typically “I’d rather have too much weight than not enough, because I can always add more air to my BCD.” While to some extent this is true, and you can become neutrally buoyant by adding more air to your BCD, your air consumption will suffer. This happens for two reasons, both which take a brief physics review to explain. First of all, adding weight to a diver increases the diver’s mass. Even though you have added air to the BCD to counter the gravitational pull by adding buoyancy, the diver’s mass has still increased. Increasing a divers mass also increases his inertia, meaning it requires more force to propel the diver through the water. More force means the diver’s body will need to metabolize more oxygen, creating more CO2, increasing the diver’s breathing rate. Not only does over-weighting increase a diver’s inertia, but it also will have a negative impact on the diver’s trim. When a diver falls out of horizontal trim, they are faced with increased resistance when trying to move through the water. More resistance means it will require more force to move the same distance. Starting to see how diving over-weighted can seriously impact a diver’s air consumption?

Relax, slow down, and get properly weighted and you’re on your way to improving your air consumption. Just like anything, practice makes better, and the only way to truly improve is to get out there and dive as much as possible. Working with an experienced instructor can help get your weighting, trim, and buoyancy control dialed in, while the rest just comes from experience.

Survivor or Statistic… Which One are You?

Knowing that we are going to have some sort of equipment malfunctions, environmental/navigation emergencies, and will just simply make mistakes at some point in our technical diving careers, how do we avoid becoming a diving fatality statistic?

3 Mistakes Most New and Veteran Divers Make

This article will discuss 3 mistakes that are common for new divers, how to avoid them, and how an experienced diver could easily end up making the same mistake..

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?

Diving from #MyBuddysBoat

by Jon Kieren:

buddy's boat

photo by Aldo Ferrucci

#AreYouSureThatisaGoodIdea | #SupportYourLocalDiveCenter

As divers, it’s hard to imagine a better summer day than hanging out on your buddy’s boat, doing a little diving, maybe a little fishing, and just relaxing enjoying the sunshine. When all goes well, it’s the perfect way to spend a day out of the office, but what about when it hits the fan? Do you and your buddies have the equipment and skills required to handle the worst case scenarios? While a day out on your buddy’s boat can be a lot of fun, if you are not properly trained and equipped it is probably a better idea to spend a few bucks and head out with your local dive charter instead. Professional dive charters offer more than just a boat ride; they have trained staff and the necessary equipment to handle emergency situations, and could very well save your life. A few points to consider when deciding whether to head out on your buddy’s boat or dive with a professional dive charter are:

    • Equipment-If you’ve ever been on a dive boat, you’ve probably heard a safety briefing given by the captain or crew. This briefing typically outlines emergency procedures and describes/shows where to find emergency equipment onboard. This briefing is not just for show, this emergency equipment can save your life, and typically includes:
      • PFDs (life jackets)
      • VHF Radio-for hailing coast guard, EMS, other vessels, etc.
      • Fire suppressant devices
      • EPIRB- Emergency Position Indicating Radio Beacon
      • First Aid kit
      • Emergency Oxygen

Not only do dive charters stock this equipment onboard the vessel, the crew is trained in its use. Do you and your buddies have access to this equipment? Are you confident in your ability to use it in a high stress emergency?

    • Crew- Are you and your buddies experienced and qualified mariners and rescue divers? In the event of an emergency in/on the water, you need to have well trained personnel on hand to lend assistance effectively. Are you and your buddies trained and prepared to handle the following situations?
      • Distressed/Unconscious diver in the water
      • Fire on-board the vessel?
      • Weather suddenly turning while divers are in the water
      • Lost/missing divers
      • Decompression sickness and other diving injuries

Dive charters staff professionally trained and experienced crew members to assist and handle these types of scenarios. These crew members are often overlooked, because most of the time their skills are not required. But when there’s a problem, you will be glad they are there to help.

Unless you and your buddies are very experienced mariners and divers, we strongly recommend choosing to dive with a professional dive charter instead of heading out on the water alone. Dive emergencies happen quickly and unexpectedly, and having trained professionals and the proper equipment on site can turn a potential fatality into a minor hiccup in the day’s events. Next time you’re thinking about going diving, let the pros do all the work and head out with your local dive charter. To find an SDI facility in your area, click here.

Is Technical Diving for You?

by Jon Kieren:
intro to tech divers

Don’t knock it ‘til ya try it, right? Well, this also works the other way around when we’re deciding whether to pursue technical diving. Technical diving takes a specific mindset, skill level, and a substantial investment of both time and money; are you willing and able to meet these requirements? If you are unsure, there’s an option available to help you make up your mind before you fully commit yourself. It’s called the TDI Intro to Tech course.

Whether you are unsure of your ability to handle the equipment (there’s a lot of it), if you’re mentally tough enough to handle the stress of not having direct access to the surface, or even if you just want to know more about what is involved with technical diving before you commit, the TDI Intro to Tech course can help answer these questions. You will be introduced to the equipment and skills required for technical diving without the additional stress of a pass/fail situation, and without entering an environment or situation you are not comfortable with (increased depth, wreck or cavern/cave penetration, or decompression). This course will walk you through the special techniques, planning procedures and skills that set technical diving apart from traditional sport diving. It will show you how to improve your dive planning methods, in-water skills, and streamline your existing gear configuration.

The specific skills this course highlights are:

  • Advanced Buoyancy Control
  • Gas Management
  • Situational Awareness
  • Trim
  • Gear Configuration and Selection

After completing Intro to Tech, you will be armed with the information you need to make an educated decision about moving forward into the technical diving realm. To find an instructor near you, visit our dive center locator here. Also, check out our Events page for upcoming TDI sponsored Intro to Tech events in your area.

Choosing the Best Decompression Gas

By Jon Kieren

gas blending room

There are many factors that need to be considered when choosing decompression gasses for a dive. The dive profile, logistics, environment/site conditions, and personal preference all come into play; how do these factors affect our decision? First, we need to take a brief look at why we use different gasses for decompression to begin with, and then how the factors previously listed affect our gas choices. For big dives with extensive decompression obligations, it’s often a balancing act between oxygen exposure and off gassing.

Why switch gas anyway? This takes a brief lesson in decompression theory to explain; we’ll focus mainly on the off gassing portion of the dive. The rate of off gassing is related to the partial pressure within the tissues of the body and the partial pressure of the gas being breathed. When the partial pressure of the inert gas (mainly nitrogen and helium) in the lungs (the gas we are breathing) is LOWER than the partial pressure of the inert gas absorbed in our tissues, the gas will move from the area of high pressure (our tissues) to the area of low pressure (our lungs) and be expelled when we exhale.

There are two ways we can reduce the partial pressure of the inert gas in our lungs. First, is by ascending and letting Boyle’s law take over. As the gas expands as we ascend due to reduced ambient pressure, the partial pressure of the gas drops. This works but is not the most effective method. If we ascend too far or too fast and the ambient pressure decreases too rapidly, bubbles can form causing decompression sickness. The second method of reducing the partial pressure of the inert gas in our lungs is to reduce the fraction of the inert gas in our breathing mixture. In order to reduce the fraction of inert gas in the mix, we increase the fraction of oxygen. By switching to an oxygen rich gas on the ascent, we reduce the partial pressure of the inert gas in our lungs and increase the rate and efficiency of off gassing. So, more oxygen=less inert gas=faster/more efficient deco. Got it?

Okay, so if a higher fraction of oxygen is better for decompression, why don’t we just use 100% oxygen for the entire ascent? It would sure reduce our decompression times by a significant amount, wouldn’t it? Well, unfortunately we have to be cautious of the pesky oxygen free radicals caused by breathing high partial pressures of oxygen. If these oxygen free radicals are left to cause damage faster than the body can repair it, oxygen toxicity can become a serious concern. In short, the higher the oxygen content in the breathing gas, the shallower it must be breathed. As an example; for sport and technical diving applications, the maximum operating depth of oxygen is 6 metres/20 feet; and the maximum operating depth of 50% nitrox is 21 metres/70 feet. Here’s where we begin our balancing act.

We now need to consider the other factors that will affect our gas choice. First of all is logistics. What gasses are actually available? Many technical dive facilities have their decompression gasses pre-mixed, so you may be limited to what they have available or are willing to blend (gas blending can be a time consuming process). Also, there are many places in the world where 100% oxygen is not available, or can only be filled to roughly 150 bar/ 2000psi, depending on the fill station’s equipment. Once you know what your options are, you need to look a bit closer at the environment you’ll be diving in and how you will conduct your last decompression stop.

Many divers will vary the depth they plan to conduct their final decompression stop based on the environment they will be diving in. In a perfect world, we would always conduct our last stop at 3 metres/10 feet. Unfortunately, this is not a perfect world. Rough seas and overhead environments may make it difficult or impossible to conduct your last stop at 10 ft, so it may need to be conducted a bit deeper at 6 metres/20 feet. Conducting this last stop on 100% oxygen could now be problematic as you will be exposed to a much higher partial pressure of oxygen for the duration of the final decompression stop. Add rough seas to this in open water, and it could be very difficult to remain at a safe depth on oxygen. This is an instance where reducing the oxygen content may be wise. While a lower fraction of oxygen will not be quite as effective as a decompression gas on this final stop, it can significantly reduce the diver’s oxygen exposure. If you are making multiple gas switches in order to maximize the partial pressure gradient for the entire ascent, you will also need to look at the environment to decide what gasses to carry. A good example of this would be a cave dive. If you were planning your dive to switch to 50% at 21 metres/70 feet, but you know that there is a restriction in the cave at 21 metres/70 feet making it difficult to conduct a proper gas switch, you have a few options. First, would be carry the same gas, but decide to switch to it at a shallower depth where there is not a restriction. This would work fine, but would not be as effective for your decompression. You could also choose to bring a different decompression gas. A leaner nitrox mix could be switched to a bit deeper, but would not be as effective for the shallower stops. A richer nitrox mix would be more effective in the shallower stops, but you would not be getting the advantages of a decompression gas until later in the decompression schedule. Using desktop/mobile decompression software makes running these alternative options quick and easy so you can see immediately how your choice will affect your decompression plan.

After looking at all of the scenarios above, sometimes it just comes down to personal/team preference. Many divers and dive teams choose to use a standardized set of decompression gasses. This policy helps keep things simple and consistent. If a diver always carries 50% and oxygen for decompression, then they are always making gas switches at 21 metres/ 70 feet and 6 metres/20 feet. This standardized method streamlines the dive planning considerably, is consistent, and works well for many applications.

While this is not a complete discussion on decompression gas planning, it’s a good example as to what type of considerations we need to take into account when choosing our deco gasses. These points, along with others, are covered in depth in the TDI Decompression Procedures, Extended Range, Trimix, and Advanced Trimix courses and course materials. For more information on these courses, please visit TDI courses section