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  • III. Knowledge Development Presentation One [This section address the Tec Trimix Diver student. Notes to the instructor appear in brackets.] A. Introductions [Encourage a relaxed atmosphere and begin interaction that will be the basis for teamwork.] 1. [Introduce yourself, staff and anyone else involved in the course. Provide a bit of your background, including some things that don’t involve diving. Have your staff do the same.] 2. [Have students introduce themselves. Ask them to tell everyone how they got into tec diving, and then one thing about themselves not related to diving that everyone probably wouldn’t know. This is usually a good ice breaker.] 3. [Collect Knowledge Reviews from Section One of the DSAT Tec Trimix Diver Manual . For students who’ve qualified for the course with a prerequisite certification other than DSAT Tec Deep Diver, collect all the Knowledge Reviews from the Tec Deep Diver Manual as well. You’ll review the Knowledge Reviews to assess mastery and tailor your subsequent presentation accordingly. You can do this during a break or while students complete paperwork, etc.]
  • B. Course Goals and Your Responsibilities 1. The goals of the Tec Trimix Diver course are: a. To qualify you to plan and make dives with open circuit scuba using various trimix blends, air, enriched air and oxygen, using the technical diving equipment and procedures required to manage the risks involved. b. To train you in the cognitive and motor skills required for technical trimix diving. c. To assure you acknowledge and understand the hazards and risks of technical diving in general and trimix diving in particular, as well as the limits of training received in the course. d. To train you to prepare for and respond to reasonably foreseeable emergencies that may occur in this type of technical diving. e. To provide skills applicable to further training and experience in technical diving.
  • 2. While taking the Tec Trimix Diver course, you have these obligations and responsibilities: a. Follow the instructor’s directions and dive plans strictly, and to not separate from the instructor or your dive team. b. To maintain adequate physical and mental health, and to alert the instructor to any problems you have with either. c. To accept the risk of technical and trimix diving, and for specific risks unique to each dive environment, and to immediately notify the instructor if this risk becomes unacceptable to you. 3. Failing to meet these obligations and responsibilities can have these consequences: a. In the worst case, you can be seriously injured, disabled or killed. b. You will have failed to demonstrate the attitude and maturity required for tec diving, and will not qualify for certification.
  • C. Course Overview, Logistics and Administration 1. Schedule [Explain anything that you have not previously covered with respect to course scheduling, including study assignments and due dates, sessions and training dives. It’s recommended you have these printed out and go over them with students when they enroll in the course.] 2. Students sign the Tec Trimix Diver Statement of Understanding and Learning Agreement. [Discuss what the agreement doesn’t cover, such as your policies regarding make ups for missed assignments or dives, etc.] 3. Certification a. Upon successfully completing all course requirements, you’ll receive the DSAT Tec Trimix Diver certification. b. Certification as a DSAT Tec Trimix Diver will mean that you’re qualified to: Plan and make decompression stop dives using trimix as a bottom gas and trimix, enriched air and oxygen as decompression gases within the limits of your training and experience. Purchase trimix and purchase/rent equipment required for diving with trimix. c. Certification as a DSAT Tec Trimix Diver also means that you assume all the risks and consequences of technical diving, trimix diving and diving in general.
  • 4. Class Requirements a. Course costs [Explain all costs associated with the course. Collect outstanding funds due as appropriate, explain refund policies, etc.] b. Equipment and material requirements [Explain what’s required for the course, and of that, what students must provide and what you will provide.] c. Course prerequisites [Confirm the prerequisites in Section Two if these were not handled during course registration or as otherwise necessary.] d. If you’ve qualified to participate in the Tec Trimix Diver course through a qualifying certification other than the DSAT Tec Deep Diver certification, you must read the entire Tec Deep Diver Manual and complete the Knowledge Reviews prior to beginning the Tec Trimix Diver course. [This isn’t required if the Tec Deep Diver Manual isn’t available in a language the student can understand, but the student must still complete the Knowledge Reviews, receiving remedial instruction as necessary.]
  • 5. Administration a. [Have student divers read, complete and sign the Liability Release and Express Assumption of Risk for Technical Diving (or the technical diving release specified by your PADI Office for your local area). The release must be signed before any inwater training. b. Prior to any inwater training the student must have physician’s approval and signature on the Medical Statement, even if the student answered “no” to all medical conditions listed on the form. If the student received a physician’s approval and signature on a Medical Statement for another course in the last year and has had no medical condition change, and if you have that Medical Statement on file, then the student does not need to see a physician again. c. Diver insurance [It’s recommended that you require students in the DSAT Tec Trimix Diver course to have diver insurance such as the PADI Diver Protection Program, Platinum or equivalent as available in your area.] [Note: This is a good place for a break prior to getting into the actual course material.]
  • D. Trimix Diving Risks Learning Objectives: By the end of this section, you should be able to answer these questions: 1. What ten risks and hazards does technical diving with trimix present that either don’t exist or aren’t as severe in recreational diving and air/enriched air technical diving? 2. What are the limits of your training as a Tec Trimix Diver? 3. What risks do you face if you exceed these limits? 4. How do you responsibly extend your limits with trimix diving? [!] 1. In the Tec Deep Diver course, you learned risks and hazards that tec diving presents that either don’t exist or aren’t as severe in recreational diving. There are also risks specific to diving with trimix. a. Helium differs from nitrogen in its properties. It is less forgiving of some procedural errors, such as ascending above stop depth. Anecdotal sources indicate a slightly higher DCS rate for diving with helium; this is currently debated and unclear, but nonetheless a risk you must accept. b. More risk of the unknown than air/enriched air diving. There’s a growing field experience, but every trimix dive is somewhat experimental because there’s been little formal testing of it, and therefore more unknown risk. c. If you deplete, lose or have a failure in your decompression gases, you’re unlikely to be able to decompress adequately with your bottom trimix. d. Gas blend inaccuracy leading to DCS due to decompression calculation error. Traditionally, trimix is analyzed based on the oxygen component; blending procedures must be followed carefully to assure an accurate blend. Not a widespread problem, but the risk is present. (Note: The recent introduction of helium analyzers reduces this concern.) e. Vestibular DCS (inner ear DCS) is rare, but most commonly associated with deep dives using helium. Usually occurs with dive depths deeper than typical trimix diving, but the risk is there. Can also occur, but even more rarely, with air/enriched air.
  • f. Hypothermia – primarily a risk if forced to use trimix in your dry suit because helium carries away heat (more about this later); longer deco times are also an issue, especially if your suit leaks. g. Hypoxia – deeper dives using trimix may require using bottom mixes that have too little oxygen at the surface. Breathing such a mix at the surface or too shallow can cause unconsciousness, followed by drowning, without warning. h. Hyperoxia – Due to depth and gases, trimix deco times tend to be longer than air/enriched air diving with higher oxygen exposure, posing more risk of CNS and/or pulmonary oxygen toxicity. Middle ear oxygen exposure during and following decompression can cause a middle ear squeeze (prevented by being aware and gently equalizing periodically, even when remaining at a constant depth). i. Isobaric counterdiffusion – DCS caused by switching to a light gas following breathing a heavy gas. The risk also involves potentially severe skin DCS from using trimix in your dry suit. (More about this later.) j. Difficult or impossible to be rescued – deeper dives and longer decompressions common to trimix diving greatly complicate attempts to rescue a diver. In some circumstances, team mates or your instructor may not be able to even attempt a rescue without unreasonable risk of personal harm, due to low gas or decompression requirements. This is a risk you must accept both in this course and after as a certified trimix diver.
  • 2. Limits of Tec Trimix Diver training a. The Tec Trimix Diver certification qualifies you to initially dive to a maximum of 75 metres/245 feet or the maximum depth at which you trained (whichever is shallower) using open circuit technical diving equipment with trimix as a bottom gas, and trimix, enriched air and oxygen for decompression. b. Stay within the limits of your experience and training. Initial dives after certification should be well within these. Plan simple dives to gain experience.
  • c. Extending your limits responsibly with trimix (depth, duration, complexity) requires many dives. Build experience gradually and conservatively. Dive with more experienced teammates. [! icon]
  • d. Failure to stay within the limits of your training and experience poses risk of permanent injury or death to you and/or teammates!
  • E. Introduction to Trimix Diving Learning Objectives: By the end of this section, you should be able to answer these questions: 1. What is trimix? 2. What is the nomenclature for identifying a trimix? 3. What is meant by “normoxic” trimix? 4. What are three benefits of diving with trimix? 5. What are three general drawbacks of diving with trimix? 6. What are the generally accepted ranges for trimix? 7. How is trimix made? 8. How do you analyze trimix?
  • 1. Trimix is a blend of oxygen, helium and nitrogen used for deep technical diving.
  • a. Nomenclature: “Trimix” followed by the number for the oxygen percentage, then the helium percentage. Abbreviated “TMx” b. E.g. TMx 18/50 = 18 percent oxygen, 50 percent helium, balance nitrogen
  • c. Trimix with 21 percent oxygen is called “normoxic” trimix because it has the same (normal) oxygen fraction as air does. d. Trimix has also been made with gases other than helium (e.g. neon), but for this course and your qualification, trimix is oxygen, helium and nitrogen. e. Fractions of helium and oxygen vary depending on dive requirements. You’ll learn about determining these as part of this course.
  • 2. Benefits of diving with trimix: these are the three primary reasons divers use trimix for deep diving. a. Reduced narcosis (helium is non narcotic). b. Reduced oxygen toxicity (gas blended to have less than 21 percent oxygen when going deeper than 55 metres/185 feet). c. Less dense for reduced breathing resistance at depth.
  • 3. General drawbacks of diving with trimix: In addition to risks listed earlier, trimix has a few drawbacks. a. Expense. Trimix costs considerably more than air and enriched air because helium costs more. b. Longer decompression times. For the depths and durations involved in tec diving, trimix dives typically require longer decompression than the same dive with air/enriched air nitrox. c. More complex logistics and planning. Diving with trimix may have more complexity, require more hardware, planning and preparation.
  • 4. There are differing opinions as to how deep you can go before trimix is considered required. Broadly: a. Air/enriched air are considered acceptable for open water diving, with a simple dive objective and in good conditions to 50 metres/165 feet. b. Below 40 metres/130 feet, trimix is the broad community standard for overhead environments or complex objectives. The more challenging the environment, the more appropriate it is to use trimix. [Note: Some divers apply these guidelines beginning at 30 metres/100 feet.] c. Below 50 metres/165 feet, trimix is considered the broad community standard for all diving. [Note: Some dive communities accept air/enriched air diving to 55 metres/185 feet in optimum, open water conditions.] d. The maximum depth for trimix has yet to be fully established. Typical range for new, beginning trimix divers is to 75 metres/245 feet, or the maximum depth experienced during training. Experienced trimix divers sometimes use trimix as deep 90 metres/300 feet. Dives between 90 metres/300 feet and 120 metres/400 feet are not unusual for very experienced trimix divers. The maximum depth for this course is 75 metres/245 feet. Qualifying to dive deeper requires time and experience. You’ll learn more about this later.
  • 5. Trimix Blending [Note: This is a brief overview. If student divers have qualified as trimix gas blenders and have already completed their training, you may omit this topic.] a. Trimix is made by blending helium, air/enriched air and/or oxygen. b. Partial pressure blending: Based on the required mix, blender adds required helium, oxygen and air in steps to a cylinder. [Demonstrate blender software if available.] Oxygen is analyzed at each step to control final blend. c. Partial pressure blending with enriched air: Blender mixes premixed enriched air nitrox with helium in cylinder. d. Membrane blending/continuous flow with partial pressure: Blender fills cylinders with required helium, then tops to full pressure with EANx required for final blend from membrane or continuous flow source. e. Continuous flow with helium, oxygen and air: Gases flow into mix chamber in the right proportion, then into compressor for pumping into cylinders. Requires helium analyzer as well as oxygen analyzer.
  • 6. Analyzing trimix a. You analyze trimix using an oxygen analyzer the same way you analyze enriched air nitrox. [Note: Demonstrate with trimix using standard oxygen analyzer.] b. The blender analyzes oxygen at each stage when blending after allowing adequate time for gases to mix. If each step has the correct oxygen, the final blend can be determined accurate by oxygen analysis alone. c. If oxygen is off by more than one percent, adjust your dive computer or dive tables accordingly, or have the cylinders reblended with the correct mix. [! icon] d. Helium analyzers are expensive but available. If available, you use it in addition to the oxygen analyzer. You always analyze the oxygen content of every cylinder you will use. [Note: If available, demonstrate use of helium analyzer.] Note that without a helium analyzer, you must know what the target blend was to analyze the final mix. Blending trimix in cylinders partially filled with trimix (to save helium) tends to compound minor blending errors unless you have a helium analyzer. This is why the practice without a helium analyzer is to completely drain trimix cylinders and blend in empty cylinders when using only an oxygen analyzer is available. (Depending on mix gases available, a single “top up” is sometimes considered acceptable.) e. You’ll practice analyzing trimix beginning in Practical Application Two.
  • F. Equipment I – Rigged for Trimix Diving Learning Objectives: By the end of this section, you should be able to answer these questions: 1. Why might you carry more than two stage/deco cylinders on a trimix dive? 2. What are the proper markings on trimix cylinders? 3. What are the two ways you can carry four stage/deco cylinders? 4. Why can’t you inflate your dry suit from your back gas when trimix diving? 5. Why would you put a low pressure inflator hose on a decompression cylinder containing air or enriched air nitrox? 6. How do you set up an independent inflation system, and where do you typically put it? 7. What is the advantage of using argon as a dry suit inflation gas?
  • 1. The standardized technical rig – you’ll be diving with the equipment configuration you learned in the Tec Deep Diver course, which is the emerging general community standard for deep tec diving. [Note: Refer students to the Tec Deep Diver Manual for details.] a. Note that due to depth and rapid gas consumption, trimix dives tend to be made with high capacity double cylinders. b. Due to weight of all cylinders, as well as gas weight in high capacity cylinders, redundant buoyancy control is essential. If a dry suit would not provide adequate backup buoyancy or if using a wet suit, then twin bladder BCD is required. using a wet suit with steel stage/deco cylinders makes a twin bladder BCD essential due to significant negative buoyancy some divers have a low pressure inflator hose on one of their stage/deco cylinders that they can attach to a BCD inflator should they exhaust their back gas in an emergency (as discussed later, it can also be used on a dry suit)
  • 2. Stage/decompression cylinders a. As a Tec Deep Diver, you’ve learned to carry two stage/deco cylinders two cylinders usually more than adequate for volume and range of air/enriched air decompression and extended no stop diving, and for many trimix dives b. As a Tec Trimix Diver, you may be diving with more than two stage/deco cylinders. Trimix dives tend to be deeper, requiring larger deco gas volumes. On longer, deeper dives, three or four different deco gases may be necessary to supply the required volumes, and may reduce deco time by optimizing the fraction of oxygen. Some trimix blends may have very low oxygen content and not be suitable for breathing at shallow depths – you may need a travel gas – a higher oxygen content deco/stage gas you use until reaching the appropriate depth for your back gas. More than two deco cylinders is more typical after you gain experience, and more common in some environments, like cave diving, than in others.
  • c. Wearing four stage/deco cylinders May be worn all left or right and left, as with two cylinders. Essential to have a personal standard: wear cylinders the same way all the time, with same cylinders in same place. All left –Common to stack two and trail two by top hook on hip D-ring. Right/left – typical to stack two each side, or wear one each side and trail other two (one side or both) by top hook on hip D-ring. At times, it’s useful to hook only top clip to shoulder D-ring, esp. if you’ll shortly move the cylinder to trail by top clip on hip D-ring. You’ll practice handling up to four cylinders. However, the majority of intermediate depth trimix dives generally require only two deco gases. Remember to simplify your rig and logistics as much as possible. If two will do the job, use two.
  • d. Deco cylinder types Because they’re light and easy to handle underwater, many divers prefer the “aluminum 80” (11 litre) as the optimum type stage/deco cylinder, especially for trimix dives that require more than two deco cylinders and for all left configuration. Using aluminum 80s, it’s quite feasible to handle four or more stage/deco cylinders, though drag is still an issue, esp. if you must wear them the entire dive. Aluminum 80s or cylinders with comparable buoyancy characteristics are required for all left configuration. In some local areas, only steel cylinders or other substantially negative cylinders are readily available; in these areas, using only two deco gases is the standard practice, even with trimix.
  • 3. Trimix markings a. Cylinders with trimix are clearly marked with a label that says “Trimix.” Color coding for trimix isn’t standardized like enriched air and oxygen, and the practices may vary. Essential to clearly identify “Trimix” in all cases. Cylinders should be kept isolated so that they cannot be used accidentally by unqualified divers. b. Cylinders also marked with analyzed content, maximum depth and diver’s name, all visible to teammates when worn. c. In some locations, formal tank cylinder labels/tape are common for this purpose. In other dive communities, divers simply write the information on gray (duct) tape; and yet other communities may combine these practices. d. The essential point is that to avoid accidents caused by confusing gases, all cylinders need proper markings in accord with local practices.
  • 4. Argon inflation systems a. Because helium conducts heat rapidly, you can’t use trimix in your dry suit. Helium in the dry suit also poses a DCS risk due to isobaric counterdiffusion (more about this in later sections), so an alternative inflation system is used. b. If diving in a dry suit, you use a small separate inflation cylinder, typically mounted on the left doubles cylinder, valve down for access while worn and to reduce entanglement hazard. LP hose routed under harness to eliminate slack. (A few divers wear on right, depending on dry suit valve orientation.)
  • d. Some trimix divers also have a LP hose on an air or enriched air deco cylinder in case they exhaust or have a problem with the argon system.
  • c. Argon is preferred inflation gas because it insulates better than air and has little risk of isobaric counterdiffusion . No second stage on regulator so it cannot be breathed accidentally; regulator should have overpressure relief valve. Cylinder clearly marked with argon decal. One reported study found no difference in the insulating qualities between argon and air, though divers widely report a difference.
  • c. Argon is preferred inflation gas because it insulates better than air and has little risk of isobaric counterdiffusion . No second stage on regulator so it cannot be breathed accidentally; regulator should have overpressure relief valve. Cylinder clearly marked with argon decal. One reported study found no difference in the insulating qualities between argon and air, though divers widely report a difference.
  • G. Techniques and Procedures I Learning Objectives: By the end of this section, you should be able to answer these questions: 1.What is the general recommendation regarding how deep you take a cylinder, and what is the issue in trimix diving with regard to this recommendation? 2. What are the procedures for gas switches with up to four deco cylinders? 3. How precise should a decompression stop be? [Note: This section reviews techniques learned in the Tec Deep Diver course. Remind student divers that they will be practicing and demonstrating the skills they learned in the Tec Deep Diver course during the Training Dives. Refer them to the DSAT Tec Deep Diver Manual for skill descriptions and reminders.]
  • 1. Remember, the general recommendation is to never take a cylinder deeper than you can safely breathe from it (maximum depth). a. This isn’t feasible in many open water environments due to concerns about relocating the cylinders. (It’s essential that you be able to relocate them.) b. If you can follow this guideline without serious risk of losing the cylinders, it minimizes the probability of switching to the wrong gas. c. The issue with this recommendation in trimix diving is that you’re highly unlikely to be able to adequately decompress without your deco cylinders. Therefore, the priority is to not risk losing them.
  • 2. Gas switches a. During the Tec Deep Diver course, you learned that switching to the wrong gas is one of the most common causes of tec diver deaths. b. You learned to use the NO TOX mnemonic to remember the steps for a proper gas switch in the correct order. [Refer students to the Tec Deep Diver Manual and the TecRec Equipment Setup and Key Skills video for details.] c. When switching to or from trimix, you can confirm that you’ve gone on or off of trimix by speaking into your regulator and listening for helium distortion.
  • 3. Handling three or four cylinders worn on both sides. a. Traditional to wear oxygen and next highest oxygen deco on right, lowest oxygen/travel gas left (remember Right - Rich, Left - Lean). You’ll learn more about travel gas later. b. Several handling options popular: Stacking all four, two per side: breathe top left, bottom left, top right, bottom right (common to move top cylinders back to trail on hip D-ring after use). Wearing two and trailing two: breathe worn left, switch with trailed left and breathe, breathe worn right, switch with and breathe trailed right. IMPORTANT: Be consistent, always use the same arrangement and always follow the NO TOX switch procedure.
  • 4. Handling three or four cylinders worn all on left side. a. Most common to wear two and trail two. b. The cylinder you’re breathing is always on top. c. Move cylinders as you switch. d. Preplanning reduces moves. If staging cylinders at deepest depth you can breathe them: wear lowest and second lowest oxygen (lowest may be deco or travel gas), trail oxygen and highest oxygen to easily stage. You switch as you retrieve, shifting used cylinder to trail and wearing cylinder you’re breathing. If not staging (wearing whole dive), one option is to wear lowest and second lowest oxygen cylinders with the lowest (first used) on top, and trail other two. When through with the bottle on top, trail it and switch. After switching, bring up next gas to be used under the cylinder in use (one in use is always on top). If not staging (wearing whole dive) some divers prefer to wear only lowest oxygen cylinder (first used) with all others trailed. Switch to trailed cylinders in order. IMPORTANT: Be consistent and follow NO TOX procedure on every gas switch. e. Remember that carrying only two cylinders simplifies handling and procedures. If you only need two cylinders to provide adequate gas supply with reserve, there’s no reason to use three or four. Especially as a new trimix diver, the majority of your dives will only require two.
  • 5. In both all left and left/right configuration, top hooking to chest D-ring allows you to wear two and breathe from a third (top hooked) if you’ll not be using it long. Commonly used with travel gas that will be staged shortly, and/or using travel gas briefly until switching to a higher oxygen deco gas.
  • 6. Decompression stops a. In the Tec Deep Diver course, you learned that precision is essential when making decompression stops. b. As you’ll see, this is particularly important when diving with trimix. Because it diffuses rapidly, helium is less tolerant of poor depth management during decompression. c. You’ll practice making precision deco stops using buoyancy control for extended periods, with and without a visual reference. You must vary no more than .6 metres/2 feet from the stop depth. aim for no more than half that variation requires constant attention when you don’t have a physical contact must pay attention to gas, times and teammates at same time d. Think of the surface as a deco stop. Before immediately exerting yourself by swimming, climbing, etc., whenever possible rest for five to ten minutes first. Continue breathing high oxygen deco gas.
  • H. Emergency Procedures I Learning Objectives: By the end of this section, you should be able to answer this question: 1. Where can you find descriptions of skills for review? 1. During the course, you’ll be practicing skills you mastered in the Tec Deep Diver course and applying them to the higher complexity of trimix diving. 2. You should be prepared to practice the following skills during the training dives: a. gas sharing with long hose, swimming and stationary, with and without mask b. valve shut down drill c. unconscious diver d. lift bag deployment 3. You can find descriptions of these skills in the Tec Deep Diver Manual if you want to review them. You can also see them in TecRec Equipment Setup and Key Skills video.
  • I. Decompression I Learning Objectives: By the end of this section, you should be able to answer these questions: 1.What are the five reasons that the use of desktop decompression software is standard practice in trimix diving? 2.What are the two main differences between desktop decompression software for air/enriched air/oxygen and for trimix? 3. What are the two basic categories of decompression models found in desktop decompression software? 4. What are the basic attributes of each of the two categories of decompression models?
  • 1. The trend in tec diving is to use desktop decompression software, along with multigas dive computers, to plan and make dives. a. This approach maximizes adaptability to specifics of situation. b. Desktop decompression software allows plans based on known real profiles rather than square profiles -- especially beneficial in caves/wrecks or following topography. c. Divers may increase the conservatism as appropriate for their individual circumstances and risk tolerance. d. Desktop decompression software more accurately reflects what a multigas computer will allow, making it more suitable for planning multigas computer dives and backup tables for multigas computer dives.
  • 2. Virtually all trimix divers use desktop decompression software a. Theoretically, there are hundreds of possible trimix blends. Software lets you write a table for what you’re actually using rather than for a range of possible blends. b. Desktop deco software simplifies gas use calculations and simplifies dive planning by allowing you to quickly compare different possible profiles, including using different gases and gas switch depths. c. Software allows you to add deep stops or use trimixes for decompression; this isn’t as straightforward with preprinted tables. d. Software easily generates contingency tables for the dive, including tables for more or less depth/time combinations, and for decompressing without deco gases (if possible). e. Even using a multigas trimix computer you need desktop deco software for dive planning and generating backup tables, etc. You don’t dive multigas computers blindly – you need to know what to expect ahead of time. The generated tables may prove more efficient, logistically feasible or have a more readily applicable deco schedule than the computer. At this writing, desktop software allows more user choice and model sophistication than most multigas trimix computers – though this may change with time.
  • f. Do not use tables for military or commercial divers. The tec community consensus is that these are not appropriately designed for tec divers and tec diving purposes. The potential risk appears to be higher, which may be appropriate for commercial and military divers with unlimited gas supply and recompression on site, but is not for tec divers.
  • 3. The main differences between desktop decompression software for air/enriched air/oxygen diving and trimix diving are the ability to select trimix in the gas choices, and deeper maximum depth calculations allowed. a. The software you already have can probably be upgraded to trimix either online or over the telephone. b. You may have options in different versions of trimix software (see manufacturer of specific software).
  • 4. Decompression models used in desktop decompression software a. Most common decompression models (a.k.a. algorithms ) are neo-Haldanean – models based on Haldanean dissolved gas concepts. assumes no bubbles form – an assumption we know isn’t entirely correct deco strategy is to get the diver to the shallowest allowable depth for shortest decompression (the shallower the diver, the more rapidly gases dissolve out of the tissue) b. Of these, variations of the Buhlmann model are most common widely used in dive computers conservative versatile – easily modified for different applications has a large base of successful testing and field use
  • c. Some desktop decompression software now uses bubble dynamics models. assumes some subclinical bubbles form, and growth of these bubbles, if not controlled, causes DCS deco strategy is to emphasize deeper and more frequent stops to minimize bubble formation for shortest decompression (once bubbles form, they take longer to eliminate than dissolved gas) characterized by predicting shorter deco times than most Buhlmann models, but also shorter no stop times lacks same level of testing and field experience, but nothing at this writing has suggested that such models aren’t reliable basis for deep stops procedure that has become the norm regardless of deco model being applied (more about this later)
  • d. Desktop deco software and multiple gas trimix computers offer users the choice of Buhlmann models or bubble models (Reduced Gradient Bubble Model [RGBM], Varying Permeability Model [VPM], etc.); some versions offer a choice within the same software or dive computer.
  • J. Gas Planning I Learning Objectives: By the end of this section, you should be able to answer this question: 1.What are the two ways you’ll determine the gas volumes you require, including reserves, for a trimix dive? [Note: This guide and program reference “ata” (atmospheres) as the unit of pressure that’s used most commonly by the dive community when referencing partial pressures. Although not precisely the same as the metric bar, for practical purposes within the scope of this program they may be considered interchangeable.]
  • 1. Gas volume, oxygen exposure planning a. You determine your gas volumes and reserves based on your planned dive schedule and SAC rate, just as you learned in the Tec Deep Diver course, with a few differences. Oxygen exposure limits and emergency procedures are exactly the same as you’ve already learned for air/enriched air diving. Use Trimix Oxygen Management Tables for determining trimix PO2s, CNS percent and OTUs. Use Equivalent Air Depth and Oxygen Management Tables (see the Tec Deep Diver Manual appendix) for determining PO2s, CNS percent, OTUs and EADs for EANx and oxygen.
  • Trimix schedules commonly have multiple deep stops more than 3 metres/10 feet apart. Calculate ascents between these until reaching stops separated by 3 metres/10 feet. At that point, use the add-one-minute-every-third-stop method. Be aware that effective breathing habits have more effect on trimix diving due to the depth. Deviations from normal breathing rhythms can affect your gas plan substantially. Get in the habit of slow, deep breathing that maximizes gas exchange in the lungs. Avoid the tendency to breathe shallow and fast when under stress and working hard – stop what you’re doing and reestablish slow, deep breathing. b. You calculate your oxygen exposure following these guidelines as well. c. Desktop decompression software also calculates these, though you need to determine your SAC bottom (working) rate and deco rates to get accurate volume calculations.
  • 2. To be successful in the Tec Trimix Diver course, you will need to be able to determine volumes, SAC, oxygen exposure, reserves and maximum depths (based on oxygen) much as you learned in the Tec Deep Diver course. a. Tec Trimix Diver course will emphasize using desktop deco software for this, but you will also plan a few dives manually, including on the exam. Manually determining these may be necessary if you have deco schedules available in the field, but no desktop deco software to calculate your personal gas consumption, etc. b. If necessary, you can find the material on these for review and to rework problems in the Tec Deep Diver Manual . [Note: You may wish to work the following sample gas planning problem to review this with students. This sample uses trimix to show that there’s no difference using it in these aspects of planning.]
  • METRIC Example: You’re planning to dive to 55 metres for 20 minutes using TMx 21/35. Your decompression schedule, which has the deep stops precalculated, calls for a 10 mpm ascent rate, with a one minute stop at 33 metres using EANx36, followed by one minute at 21 metres, one minute at 18 metres, one minute at 15 metres, two minutes at 12 metres and five minutes at nine metres with EANx50. The final stops use pure oxygen for two minutes at six metres and 17 minutes at five metres. Your SAC rate is 19 litres per minute for the working part of the dive and 16 lpm when decompressing. Assuming a one third reserve, determine your gas volume requirements, OTUs and CNS clock using the appropriate tables.
  • Depth Time SAC CnFct Vol. Gas PO2 OTU/mins OTUs CNS/min CNS% 55 20 19 6.7 2546 TMx21/35 1.41 1.64 32.8 .83 16.6% 44 (a) 2 19 5.5 209 TMx21/35 1.16 1.25 2.5 .48 .96% 33 1 16 4.3 69 EANx36 1.55 1.85 1.85 2.22 2.22% 27 (a) 1 19 3.7 70 EANx36 1.33 1.53 1.53 .67 .67% 21 1 16 3.1 50 EANx50 1.55 1.85 1.85 2.22 2.22% 18 1 16 2.8 45 EANx50 1.4 1.63 1.63 .67 .67% 15 1+1 16 2.5 80 EANx50 1.25 1.4 2.8 .55 1.1% 12 2 16 2.2 70 EANx50 1.1 1.16 2.32 .42 .84% 9 5 16 1.9 152 EANx50 .95 .92 4.6 .33 1.65% 6 2+1 16 1.6 77 oxygen 1.6 1.92 5.76 2.22 6.6% 5 17 16 1.5 408 oxygen 1.5 1.78 30.26 .83 14.11%
  • Answer: TMx21/35 2755 litres used X 1.5 = 4132 litres required EANx 36 139 litres used X 1.5 = 209 litres required EANx50 397 litres used X 1.5 = 596 litres required Oxygen 485 litres used X 1.5 = 728 litres required OTUs = 87.9 CNS% = 47.6%
  • IMPERIAL Example: You’re planning to dive to 180 feet for 20 minutes using TMx 21/35. Your decompression schedule, which has the deep stops precalculated, calls for a 30 fpm ascent rate, with a one minute stop at 110 feet and one minute at 80 ft using EANx36, followed by one minute at 60 feet, one minute at 50 feet, two minutes at 40 feet and five minutes at 30 feet with EANx50. The final stops use pure oxygen for three minutes at 20 feet and 16 minutes at 15 feet. Your SAC rate is .8 cubic feet per minute for the working part of the dive and .65 cfm when decompressing. Assuming a one third reserve, determine your gas volume requirements, OTUs and CNS clock using the appropriate tables.
  • Depth Time SAC CnFct Vol. Gas PO2 OTU/mins OTUs CNS/min CNS% 180 20 .8 6.5 104 TMx21/35 1.36 1.56 31.2 .67 13.4% 145 (a)2 .8 5.5 8.8 TMx21/35 1.16 1.27 2.54 .48 .96% 110 1 .65 4.3 2.8 EANx36 1.56 1.87 1.87 2.22 2.22% 95 (a) 1 .8 4.0 3.2 EANx36 1.45 1.7 1.7 .83 .83% 80 1 .65 3.4 2.2 EANx36 1.23 1.37 1.37 .55 .55% 60 1 .65 2.8 1.8 EANx50 1.41 1.64 1.64 .83 .83% 50 1+1 .65 2.5 3.3 EANx50 1.26 1.41 2.82 .55 1.1% 40 2 .65 2.2 2.9 EANx50 1.11 1.17 2.34 .48 .96% 30 5 .65 1.9 6.2 EANx50 .95 .92 4.6 .33 1.65% 20 3+1 .65 1.6 4.2 oxygen 1.61 1.93 7.72 2.22 8.88% 15 16 .65 1.5 15.6 oxygen 1.45 1.71 27.36 .83 13.9%
  • Answer: TMx21/35 112.8 cf used X 1.5 = 169.2 cf required EANx 36 8.2 cf used X 1.5 = 12.3 cf required EANx50 14.2 cf used X 1.5 = 21.3 cf required Oxygen 19.8 cf used X 1.5 = 29.7 cf required OTUs = 85.16 CNS% = 45.28%
  • Discussion question (metric & imperial) : Might it be worth recalculating this dive without EANx36 as a deco gas? Why or why not? Is PO2 an issue? [Answer: Since it’s only used a few minutes, you can simplify logistics by eliminating the cylinder. Also, switching that deep raises your PO2 to almost 1.6 ata – which is better to avoid after 20 minutes at 1.4 ata (working PO2 limit). However, there could be a benefit with respect to gas volume and deco time for contingency scenarios, perhaps with switching to EANx36 planned for no deeper than 24 metres/80 feet.]
  • K. Team Diving I Learning Objectives: By the end of this section, you should be able to answer these questions: 1.What are four benefits of team diving, and how does each of these relate to trimix diving? 2. In what ways does trimix increase the importance of compatible gases within a team?
  • 1. During the Tec Deep Diver course, you learned that tec diving is a team effort with four primary benefits, each of which relates to trimix diving. a. Team diving has a higher likelihood of mission success based on detailed dive planning. Trimix diving will increase the complexity of dive planning making team planning even more valuable. b. Team diving fosters preparedness and resources for handling complex emergencies. Potential emergencies in trimix diving can be more logistically complex due to depths and gas demands. Team resources enhance the ability to overcome these complexities. c. Team diving reduces accidents by providing a “backup brain” for each other during predive checks and throughout the dive. Compared to tec diving with air/enriched air, trimix diving often has more equipment, tables and plans to check and confirm. There are more critical steps such as gas switches, deep stops, ascent rates, etc. in a trimix dive with more potential for accident. Teams double check and confirm with each other through these critical steps. d. Team diving provides the camaraderie that comes from facing a challenge together. Trimix dives tend to be longer, deeper and more challenging than air/enriched air tec dives. Therefore, the camaraderie tends to be deeper and more meaningful as well.
  • 2. All team members diving with the same gases is important in trimix diving. a. There’s less flexibility in deco schedules with trimix, so gas compatibility is important for allowing teammates to double check each other’s schedules and NO TOX gas switches. gas switches should be made at the same depths depth changes and stop times should be the same (or very similar) teammates signal each other when making switches b. In an emergency, deco gases may be shared without concern about how it’s affecting the deco schedule. c. Predive, teammates can check each other by matching – each diver has the same gases in the same number of cylinders with the same labeling. d. Because the deco schedule will be the same (or very similar), using the same gases keeps the team together.
  • L. Thinking Like a Trimix Diver I Learning Objectives: By the end of this section, you should be able to answer these questions: 1. When planning a trimix dive, what aspects of the dive should you be thinking about in a Good Diver’s Main Objective Is To Live? 2.What makes simulation an effective training tool for learning to dive with trimix? 3. How might you use simulation as a tool following this course?
  • 1. When planning a trimix dive, you should be thinking about these aspects of A Good Diver’s Main Objective Is To Live. (See the Tec Deep Diver Manual for a review of these dive planning steps.) a. Good – Gas How much gas volume will I need? Is it practical to carry that many cylinders in the environment? Can I accomplish the mission within the gas volumes I can carry? How many dives will it take? How will the mission objective and conditions affect my breathing? Can I maintain my normal breathing pattern? Have I simplified the decompression as much as possible? b. Divers – Decompression Do I have adequate backup decompression information? Would I be able to decompress if I couldn’t relocate staged deco cylinders? How well does a next deeper depth/next longer time schedule stack up against my planned gas volumes? Is trimix the appropriate gas for this dive? c. Main – Mission Is the mission reasonable given the depth and decompression? Is trimix the appropriate gas for this dive? Is the mission worth the dive? Could I be more effective or lower my risk by making two dives instead of one? Is the risk worth the benefit? d. Objective – Oxygen Is the oxygen exposure for planned and contingency dive within accepted limits? Have I looked closely at the accumulating oxygen exposure throughout decompression? e. Is – Inert gas narcosis Will narcosis be a significant factor given the gas being used, the depth, the individuals, the conditions and the mission? Should a higher helium blend be used? Is trimix significantly advantageous? f. To – Thermal Given the exposure protection, water temperature and dive duration, will divers maintain adequate warmth? Is there a backup inflation method if argon system fails/exhausts without putting trimix in a dry suit? Can you reasonably simplify by making the dive in a wet suit? g. Live – Logistics Does the dive require surface support? How much? Are support divers well briefed and prepared to assist with trimix activities? Are all cylinders clearly marked and identified? Will there be deco software available at the dive site? Have all team members agreed on the gas blends to use? Do you have the gases and/or mixing hardware to accomplish all the dives required?
  • 2. Simulation for training. a. Effective diver training begins with degrees of simulation. As an Open Water Diver you simulated running out of air to practice alternate air source use. During the Tec Deep Diver course, you made simulated decompression dives before making actual decompression dives. b. During this course, you’ll be simulating trimix dives before making actual trimix dives. c. Simulation makes an effective training tool for potentially hazardous situations like technical diving. allows you to form habits with procedures before you’re in a critical situation with them with minimal risk, you can make and learn from the same mistakes that would be very hazardous on an actual trimix dive you can respond to emergencies without the actual risk of the emergency you can form automatic responses to situations for faster proper action when needed you can try, retry and practice techniques and procedures without the time or expense of actual trimix dives d. During simulation training, the idea is to do everything as closely as possible to what you would do on an actual trimix dive. e. Obviously, you eventually have to make actual trimix dives. However, simulation allows you to learn and practice much of what you need to know with less risk, cost and time.
  • f. After you’re a certified Tec Trimix Diver, you may find it useful to simulate dives in shallow water for reasons that might include to refresh skills if you’ve not been tec diving in awhile. to try out new procedures, equipment or equipment configurations before trusting them in an actual decompression situation. to rehearse a complex mission. to allow divers to familiarize themselves with each other for subsequent team dives.
  • IV. Practical Application One Practical Application One has three primary purposes: 1) to give you the opportunity to check students’ equipment configurations and make adjustments if necessary, 2) to team build and establish camaraderie among the students, and 3) to get students familiar with the basics of using desktop deco software. To successfully complete this Practical Application, the student will be able to: 1. Working within the student’s assigned team, rig gear, including required stage/deco cylinders, so that it conforms with the standardized technical rigging philosophy covered in the Tec Deep Diver course, plus meets any environment specific equipment requirements specified by the instructor. 2. Given a dive depth, bottom time, trimix blend, two decompression gas blends, a working SAC rate and a deco SAC rate, use desktop decompression software to generate a decompression schedule and contingency decompression schedules, each with gas volume requirements (including reserves), turn pressure, OTUs and CNS clock oxygen exposure. 3. Given a dive depth, bottom time, trimix blend, four decompression gas blends, a working SAC rate and a deco SAC rate, use desktop decompression software to generate a decompression schedule and contingency decompression schedules, each with gas volume requirements (including reserves), OTUs and CNS clock oxygen exposure. A. Divide the class into teams of two to four individuals. Staff members may participate as team members if necessary for logistics and sizing, but they should be cautious to participate as equals rather than as teachers/leaders. B. In teams, have students set up their gear – everything, including mask, fins, gauges, cylinder markings and exposure suit – as if for a tec dive. They’re to rig their gear to meet the standardized technical configuration they learned in the Tec Deep Diver course. 1. If appropriate for logistics, you may use this as equipment set up for the Assessment Dive and/or Training Dive One. 2. Encourage students to work together as a team. They may assist each other with configuration revisions and improvements. 3. This should be pretty routine for student divers at this training level. Students qualifying for the DSAT Tec Trimix Diver course with a certification other than DSAT Tec Deep Diver may have some configuration revisions necessary to meet this requirement. 4. Note any students with significant difficulties or problems. Any such student should have remedial training, as necessary, before continuing in this course. C. Have students work in teams with desktop decompression software. 1. Assign a dive depth, bottom time, trimix blend and two deco blends. 2. Have team determine decompression schedule, OTUs, CNS clock and gas volume requirements (with thirds reserve) and turn pressures for each student based on each student’s working and deco SAC rates, and cylinders used. You may assign SAC rates for student divers who don’t know theirs. a. Although working in a team, each student should take a turn working at the keyboard to enter the data and generate the schedules, volumes, etc. b. Each team should be able to show you a single decompression schedule with the different gas volume requirements for each student. (Three gas volume requirement reports.) c. You may have students use this schedule for the simulated decompression in Training Dive One. 3. Have team determine contingency decompression schedules based on the next deeper depth, next longer time and next deeper depth and longer time, along with gas volume requirements for each student diver. a. Although working in a team, each student should take a turn working at the keyboard to enter the data and generate the schedules, volumes etc. b. Each team should generate three contingency decompression schedules, with the different gas volume requirements: the next deeper depth, the next longer time and the next deeper depth and longer time, for each student. (E.g. a team of three would have the three schedules, plus nine gas volume requirement reports to cover the differing SAC rates of each student.) 4. Assign a dive depth, bottom time, trimix blend and four deco blends. 5. Have team determine decompression schedule, OTUs, CNS clock and gas volume requirements (with thirds reserve) and turn pressures for each student based on each student’s working and deco SAC rates and cylinders used. You may assign SAC rates for students who don’t know theirs. a. Although working in a team, each student diver should take a turn working at the keyboard to enter the data and generate the schedules, volumes, etc. b. Each team should be able to show you a single decompression schedule with the different gas volume and turn pressure requirements for each student. (Three gas volume requirement reports.) c. You may have student divers keep this schedule for use as the simulated trimix dive in Training Dive One. If, due to local practices, each student will only have two deco cylinders in Training Dive Two, then you may also assign a two deco gas dive for them to plan as the simulated trimix dive, but they must still demonstrate the planning of a four gas dive to meet the requirements of this Practical Application. 6. Have team determine contingency decompression schedules based on the next deeper depth, next longer time and next deeper depth and longer time, along with gas volume requirements for each student. a. Although working in a team, each student should take a turn working at the keyboard to enter the data and generate the schedules, volumes, etc. b. Each team should generate three decompression schedules with the different gas volume requirements on all three contingencies for each student. (Nine gas volume requirement reports.) c. You may have students keep these schedules for use in the simulated trimix dive in Training Dive Two. 7. At your discretion, you may have students calculate one or more profiles manually for practice, to simulate not having access to desktop deco software for individual gas supply calculation, and to compare with the software results (which will differ somewhat).
  • V. Assessment Dive [Note to instructor: This assessment dive has the primary goal of letting you assess whether a student diver has the skill level expected of a Tec Deep Diver. Use this dive to observe each student diver, being alert for any who may need remedial training prior to further training.] The Assessment is required for students entering the Tec Trimix Diver course with a qualifying prerequisite certification from another training organization. It is required for Tec Deep Diver certified students who have not made a technical decompression dive requiring a decompression cylinder to 40 metres/130 feet or deeper within the previous six months. You may require Tec Deep Diver certified students to complete this dive in any case for assessment, refresher or other purposes. Some students may request it as well. It is recommended that prior to this dive, you schedule ample time for students entering the Tec Trimix Diver course with a qualifying prerequisite certification to read the Tec Deep Diver Manual and view the TecRec Equipment Setup and Key Skills video. The Assessment Dive is sequenced in the course outline as following Knowledge Development One and Practical Application One. However, you may sequence it prior to either or both of those, provided students have met the course prerequisites, medical requirements, etc. To successfully complete the assessment dive, the student will be able to: 1. Working within the student’s assigned team, rig gear, including stage/deco cylinders, and plan the dive following the A Good Diver’s Main Objective Is To Live procedure, and perform predive checks following the Being Wary Reduces All Failures procedures. 2. Working in a team, perform a bubble check, descent check and S-drill. 3. Respond to a simulated out of gas emergency, as both donor and receiver, with receiver switching to donor’s long hose second stage, then swimming 30 metres/100 feet and maintaining contact with the teammate. 4. Shut down both manifold valves and the isolator valve, switching second stages to maintain a breathing supply, beginning with any valve chosen by the instructor, within 60 seconds. 5. Deploy a lift bag from the bottom in water too deep in which to stand. 6. Tow a simulated, unresponsive breathing diver horizontally 6 metres/20 feet. 7. On the bottom, independently don, remove and redon two stage/deco cylinders. 8. Maintain neutral buoyancy and avoid bottom contact while swimming 60 metres/200 feet wearing two stage/deco cylinders. 9. While simulating an ascent with abbreviated stop times along a bottom, perform gas switches to two worn deco cylinders following the NO TOX procedure. 10. Simulate a four stop decompression ascent along a line switching deco cylinders at each simulated stop following the NO TOX procedure, including a final stop of at least 10 minutes maintained only through buoyancy control (no physical contact), staying within plus/minus 1 metre/3 feet of stop depth during gas switches and within plus/minus .6 metres/2 feet variation after gas switches. 11. Don and remove two stage/deco cylinders at the surface in water too deep to stand in. 12. Demonstrate time, depth and gas supply awareness by recording depth, SPG pressure and time at intervals set before the dive by the instructor. A. Assessment Dive Standards 1. The Assessment Dive is a no stop dive conducted in confined water, limited open water or open water. (See Section Two, Course Standards for definitions of these.) The maximum depth is 18 metres/60 feet. It’s recommended that the site provide ready access to water shallow enough to stand up in. If conducting this dive in open water, the intent is to use conditions well within students’ experience and abilities so that you can clearly observe their skill performance without substantial environmental effects. 2. Ratios – 6 students to 1 instructor, with 2 more students permitted with a certified assistant to a maximum of 8 . (See Section Two for specific requirements necessary to qualify as a certified assistant in this course.) These are maximums – reduce ratios as necessary to accommodate student diver characteristics and environmental/logistical considerations. 3. Students and instructor must be equipped as described in the Tec Deep Diver course, with accommodation for environmental needs. This includes but is not limited to: a. Manifolded double cylinders with dual, independent regulator posts. b. Technical diving BCD, redundant buoyancy device (double bladder BCD, or dry suit if appropriate for weight of gear worn) and harness as described in the equipment requirement section, and following the rigging philosophies described in the Tec Deep Diver course. c. Two stage/decompression cylinders configured as described in the equipment requirement section, and following the rigging philosophies described in the Tec Deep Diver course. 4. Gas requirements. Student divers and staff may use air or enriched air, any suitable blend, in sufficient supply to accomplish the dive objectives, and all breathable to 10 metres/30 feet. If all are the same or similar blends, have students mark the deco cylinders with simulated gases of differing oxygen content and simulated maximum depths. These may be blends such as EANx 32, 36, 50 and oxygen, with students marking cylinders with the real blend and then noting SIM: EANx32, etc . Back gas should be simulated or actual 21 percent oxygen. B. Predive Planning, Briefing and Preparation – suggested sequence 1. Predive briefing a. Group in teams, student divers set up their rigs, analyze gases, but do not yet don exposure suits. Encourage teamwork. Inspect each rig for correct setup, ample gas supply, etc. Pay particular attention to proper cylinder markings written and placed so team can read them while worn. b. Dive site overview Depth, temperature, entry/exit points, noteworthy features. Facilities – parking, lockers, boat dry and wet areas, where to find emergency equipment, etc. c. Dive overview Depth/time limits (limited open water) It’s recommended that you have students write down the dive overview and notes on a slate for reference during the dive, and to have them do this for each dive. Skill overview – describe each skill’s performance requirements. Since these are skills that divers should have already, it’s recommended that you have students plan the dive sequence, demonstrations, etc. This should be well within their capabilities. don stage/deco cylinders at surface in water too deep to stand in bubble check, descent check S-drill: signal, out of gas – use long hose as donor and as receiver, swim horizontally 30 metres/100 feet gas shutdown drill unresponsive diver tow underwater 6 metres/20 feet deploy lift bag simulated decompression ascent (abbreviated stop times acceptable) along bottom performing NO TOX gas switches at each simulated depth simulated decompression ascent along line, with final 10 minute neutral buoyancy stop with gas switch provide students with the four stop schedule they’ll follow remove deco cylinders at the surface in water too deep to stand in Time, depth and gas supply awareness – assigned by instructor. May be depths, times, pressures, turn pressures, etc. Goal is to get divers to constantly monitor time, depth and gases. Staff should not remind divers to do this. Teammates are encouraged to assist each other with this. Students must do this no matter what else is going on, short of a real emergency. Review hand signals, emergency protocols, descent and ascent procedures, final details. Assign each team to complete individual dive plans. d. Teams plan dives and gear up Teams go through A Good Diver’s Main Objective Is To Live and plan dive. Have them plan based on a four stop deco schedule you provide. They should generate an entire plan with deco schedule and gas volume requirements for each diver. You may have them do this by hand or use desktop deco software. Allow ample time for proper planning, which may take an hour or more. The final plans should include gas volume requirements for all divers and may be presented on the TecRec Dive Planning Slate and/or on a computer printout. It’s also recommended that you have students laminate copies of the deco schedule to carry on the dive. The dive should include a mission (measuring, assembling something, figuring out a puzzle, etc.) they can reasonably expect to complete within the bottom time of the simulated dive. Teams gear up and finish their checks with Being Wary Reduces All Failures. Student divers use TecRec Equipment Checklist to confirm each other’s equipment setup. Touch drill while geared up and seated, students reach back and touch (grasp) regulator and isolator valves as if to close/open them. Teammates adjust equipment/assist each other as necessary. C. Assessment Dive -- sequence may vary depending upon the dive plan 1. Entry – appropriate for environment a. Divers check their weight if necessary due to environment or gear change. b. Don stage/deco cylinders in water too deep to stand in . c. Divers bubble check teammates. It’s a good idea to have spare o-rings at hand. 2. Descent to insensitive bottom (limited open water) a. Descent check b. Position class for skills 3. Dive skills – instructor demos (if necessary) and has students perform. a. S-drill : Out of gas drill as donor and receiver – pairs swim horizontally 30 metres/100 feet maintaining contact, then switch roles. Watch for signalling, smooth deployment, hose trapping and other problems that interfere with a seamless drill. b. Gas shut down drill – On bottom, student divers close and reopen both regulator valves and isolator valve, switching second stages to stay with the open valve, within 60 seconds. You may have some students start with secondary regulator and others with primary. This is a skill that tends to deterioritate with disuse; it’s acceptable to allow a student to repeat the drill to meet the requirement, but if unable to do so after two or three times, separate remedial training may be necessary. c. Unresponsive diver tow underwater Diver makes self and “victim” neutrally buoyant, hold reg in victim’s mouth and tows over bottom 6 metres/20 feet. Be prepared to assist if student makes self or “victim” too buoyant. Watch for holding second stage in victim’s mouth. Caution student divers to not overexert or get out of breath – swim at a pace that avoids overexertion. d. Deploy lift bag Student divers practice retrieving bags, reels and sending up bag. In a pool, use deepest water possible. Watch for buoyancy control problems. This is a skill that students without Tec Deep Diver training frequently need remediation on. e. Simulated decompression ascent (abbreviated stop times) along bottom performing NO TOX gas switches at each simulated depth As necessary designate areas that represent the “bottom” and deco stops appropriate for switches to deco gases (as simulated or actual). Working in teams, student divers start at the “bottom” and “ascend” to each “stop” and NO TOX gas switch to each simulated EANx/oxygen mix. After all teammates complete a switch, students wait one minute before ascending to next stop. Full stop duration isn’t being simulated. After final stop, divers replace cylinders to their personal standard starting positions, then descend to “bottom” and repeat drill. Watch closely that students actually follow all NO TOX steps exactly and in order. Have those who fail to repeat the drill until they perform all stops following the procedure correctly. Repeat this drill until all divers handle cylinders and make switches correctly and fluidly. f. Simulated decompression ascent along line, with final 10 minute neutral buoyancy stop with gas switch Deploy a vertical weighted line with buoy as an ascent line. Mark the line (knot, clip, cable tie, etc.) with simulated or actual stops at 12 metres/40 feet, 9 metres/30 feet, 6 metres/20 feet and 5 metres/15 feet. All stops should be far enough off the bottom that students do not make bottom contact. You may mark only one or two stops (depending upon the pool/limited open water depth) and have student descend and reascend to simulate their continued ascent. At each stop, working as a team, students signal and NO TOX switch to the appropriate deco gas and decompress according to the schedule you give them. Student divers should not vary more than 1 metre/3 feet from the stop depth during gas switches nor more than .6 metres/2 feet after completing gas switch. Encourage teammates to help each other maintain depth during switches and decompression. The final stop should include 10 minutes maintained at stop depth by buoyancy control only – no physical contact (visual reference acceptable). This may be difficult for some divers. You may need to repeat this one or more times before progressing to Training Dive One. g. Remove deco cylinders at the surface. Student divers establish positive buoyancy and hand cylinders up to surface personnel, or hang them on a gear line, as they remove them in the water. 4. Exit water (as appropriate for environment). D. Post Dive 1. Performance review. After giving divers some time to rest, get a drink, etc., but while memories remain fresh, have teams identify what happened, what they learned, what worked and what didn’t, etc. Comment and fill in missing information as necessary, but have students critique themselves constructively while you guide the process. 2. Have divers show you their slates with the recorded times/depths/SPG readings assigned prior to the dive. 3. Divers disassemble and stow their gear as appropriate. 4. Student divers log dive for your signature. 5. Divers who do not meet the performance requirements must retrain until they demonstrate mastery before beginning Training Dive One. As appropriate, this can be an extra session (to handle one or two problem skills) or repeating portions, or even all of, the Tec Deep Diver course (to handle multiple problem skills, a failure to follow procedures, etc.).
  • VI. Training Dive One To successfully complete this training dive, the student will be able to: 1. Working within the student’s assigned team, rig gear, including stage/deco cylinders, and plan the dive following the A Good Diver’s Main Objective Is To Live procedure, and perform predive checks following the Being Wary Reduces All Failures procedures. 2. Working in a team, perform a bubble check and descent check. 3. With minimal assistance, remove and replace four stage/deco cylinders on the bottom, and swim 60 metres/200 feet wearing four stage/deco cylinders with adequate buoyancy control to minimize bottom contact or unplanned ascent. 4. Swim at least 18 metres/60 feet sharing gas with the long hose as both a donor with a mask and a receiver without a mask. 5. With minimal assistance, remove and replace four stage/deco cylinders while wearing no mask. 6. As part of a team, respond appropriately to spontaneous drills throughout the dive, including but not limited to freeflowing regulator, failed manifold, teammate switching to wrong gas and failed lift bag. 7. Shut down both manifold valves and the isolator valve, switching second stages to maintain a breathing supply, beginning with any valve chosen by the instructor, within 45 seconds. 8. Deploy a lift bag from the bottom in water too deep in which to stand. 9. Conduct a simulated trimix dive, including simulated midwater decompression stops and gas switches along a line or other vertical reference, not varying more than .6 metres/2 feet from each stop depth. 10. While maintaining stop depth varying no more than 1 metre/3 feet, shut down both manifold valves and the isolator valve, switching second stages to maintain a breathing supply, beginning with any valve chosen by the instructor, with no time limit (gas shutdown drill). 11. At the surface while in full tec gear including at least two stage/deco cylinders, tow a simulated unresponsive, non breathing diver also in full tec gear including at least two stage/deco cylinders, 60 metres/200 feet while removing all equipment from self and towed diver, and giving rescue breaths every five seconds. 12. Demonstrate time, depth and gas supply awareness by recording depth, SPG pressure and time at intervals set before the dive by the instructor. A. Training Dive One Standards 1. Training Dive One is a no stop dive conducted in confined water or limited open water. (See Section Two, Course Standards for definitions of these.) The maximum depth is 10 metres/30 feet. 2. Ratios – 6 students to 1 instructor, with 2 more students permitted with a certified assistant to a maximum of 8 . (See Section Two for specific requirements necessary to qualify as a certified assistant in this course.) These are maximums – reduce ratios as necessary to accommodate student diver characteristics and environmental/logistical considerations. 3. Students and instructor must be equipped as described in the Tec Deep Diver course, with accommodation for environmental needs. This includes but is not limited to: a. Manifolded double cylinders with dual, independent regulator posts. b. Technical diving BCD, redundant buoyancy device (double bladder BCD, or dry suit if appropriate for weight of gear worn) and harness as described in the equipment requirement section, and following the rigging philosophies described in the Tec Deep Diver course. c. Two stage/decompression cylinders configured as described in the equipment requirement section, and following the rigging philosophies described in the Tec Deep Diver course. This dive orients students to handling four cylinders, which is accomplished by having students share cylinders for the skill. You may assign each student four cylinders at your option for the four cylinder handling exercises; if you do so, then aluminum cylinders are recommended. 4. Gas requirements. Student divers and staff may use air or enriched air, any suitable blend, in sufficient supply to accomplish the dive objectives, and all breathable to 10 metres/30 feet. If all are the same or similar blends, have students mark the deco cylinders with simulated gases of differing oxygen content and simulated maximum depths. These may be blends such as EANx 32, 36, 50 and oxygen, with students marking cylinders with the real blend and then noting SIM: EANx32, etc . Back gas should be a simulated trimix but actually air or enriched air and marked accordingly. The simulated gas designations should match the gases for the trimix deco schedule students will follow during Training Dive Two. B. Predive Planning, Briefing and Preparation – suggested sequence 1. Predive briefing a. Group in teams, student divers set up their rigs, analyze gases, but do not yet don exposure suits. Encourage teamwork. Inspect each rig for correct setup, ample gas supply, etc. Pay particular attention to proper cylinder markings written and placed so team can read them while worn. b. Dive site overview Depth, temperature, entry/exit points, noteworthy features. Facilities – parking, lockers, boat dry and wet areas, where to find emergency equipment, etc. c. Dive overview (no decompression dive) Depth/time limits (limited open water) It’s recommended that you have students write down the dive overview and notes on a slate for reference during the dive, and to have them do this for each dive. Skill overview – describe each skill, the performance requirement and how you’ll conduct it, including signals, etc. don stage/deco cylinders at surface bubble check and descent check remove stage/deco cylinders on the bottom no mask long hose gas sharing as donor and receiver replace stage/deco cylinders on the bottom, swim 60 metres/200 feet neutrally buoyant no mask remove and replace four stage/deco cylinders gas shutdown drill within 45 seconds lift bag deployment simulated trimix dive with midwater decompression midwater gas shutdown drill unresponsive, non breathing tec diver at the surface Surprise drills including but not limited to free flowing regulator, failed manifold, teammate switching to wrong gas and failed lift bag will take place throughout the dive. Time, depth and gas supply awareness – assigned by instructor. May be depths, times, pressures, turn pressures, etc. Goal is to get divers to constantly monitor time, depth and gases. Instructor will not remind divers to do this. Teammates are encouraged to assist each other with this. Student divers must do this no matter what else is going on, short of a real emergency. This exercise stops after the simulated dive and does not continue through the unresponsive diver at the surface exercise. Review hand signals, emergency protocols, descent and ascent procedures, final details. Assign each team to complete individual dive plans. d. Teams plan dives and gear up Teams go through A Good Diver’s Main Objective Is To Live and plan dive. Have them plan based on a decompression schedule they generate from a depth, trimix and four deco gases (as simulated) that you provide. They should generate an entire plan with deco schedule, contingency schedule, gas volume requirements, turn pressures and oxygen exposure for each diver. You may have them do this by hand or use desktop deco software, or you may have them use the schedule and plans from Practical Application One, if appropriate. Allow ample time for proper planning, which may take an hour or more. The final plans should include gas volume requirements for all divers and may be presented on the TecRec Dive Planning Slate or on a computer printout. It’s also recommended that you have students laminate copies of their tables to carry on the dive. Teams gear up and finish their checks with Being Wary Reduces All Failures. Students use TecRec Equipment Checklist to confirm each other’s equipment setup. Touch drill while geared up and seated, students reach back and touch (grasp) regulator and isolator valves as if to close/open them. Teammates adjust equipment/assist each other as necessary. C. Training Dive One – suggested sequence 1. Entry – appropriate for environment, deep water entry recommended. a. Divers check their weight if necessary due to environment or gear change. b. Divers don stage/deco cylinders at surface with minimal assistance. c. Divers bubble check teammates. It’s a good idea to have spare o-rings at hand. 2. Descent to insensitive bottom (limited open water) a. Descent check b. Position class for skills 3. Dive skills – for each, instructor demos, then has student divers perform. a. Remove stage/deco cylinders on the bottom Students place cylinders in a secure place, checking that the valves are closed. b. Long hose, no mask swim Receiver removes mask and signals “out of gas.” Donor provides long hose, both swim together for 18 metres/60 feet. Repeat until all students conduct drill as both donor and receiver. c. Replace four stage/deco cylinders and swim 60 metres/200 feet. Unless students have four cylinders each, have teammates share cylinders for this and the next skill, then switch. Students don cylinders using all left/right-left, trailed/untrailed cylinder configurations as preferred and/or briefed. For right-left, remind divers “right-rich, left-lean.” Allow students ample time to try different configurations. Remind them they’ll need to settle on one configuration they like and stick with it as a personal standard. After they’re comfortable with configuration, students swim in a circle, line or course, accompanied by teammates and/or staff, 60 metres/200 feet. Goal is to familiarize students with handling four cylinders so they learn to maintain adequate buoyancy control to minimize bottom contact or unplanned ascent. It also introduces them to the drag and complexity of wearing four stage/deco cylinders. d. Remove and replace four stage/deco cylinders with no mask. Student divers remove mask, then remove and replace all cylinders to their correct configuration. Successful performance requires little or no assistance. Allow ample time. e. Gas shutdown drill Student divers should be able to complete in 45 seconds. f. Lift bag deployment Student divers should be able to do this with little difficulty. Have students retrieve and restow lift bags for use during simulated trimix dive. g. Simulated trimix dive Bring divers to the surface in water too deep to stand. They make the dive as though the bottom time starts when they reach the bottom. Start the dive. Divers reach the bottom and conduct their mission. Divers are to deploy a single lift bag per team to ascend along. They should do this following the schedule. If necessary for logistics and time, you can brief students to simulate a longer bottom time than actual. (E.g., for a 20 minute bottom time, tell them to have an actual bottom time of 10 minutes but to simulate decompression for 20 minutes.) After they deploy the lift bag, mark the line (knot, clip, cable tie, etc.) with simulated stops at 12 metres/40 feet, 9 metres/30 feet, 6 metres/20 feet and 5 metres/15 feet. Teammates assist reel diver with depth control. Do not shorten decompression stops. All stops should be far enough off the bottom that student divers cannot make bottom contact. You may mark only one or two stops (depending upon the pool/limited open water depth) and have students descend and reascend to simulate their continued ascent. At each stop, working as a team, student divers NO TOX switch to the appropriate deco gas and decompress according to the schedule you give them. If students are wearing four cylinders, you may have them do four switches and handle cylinders accordingly. Students should not vary more than 1 metre/3 feet from the stop depth during gas switches nor more than .6 metres/2 feet after completing gas switch. Teammates signal and help each other maintain depth during switches and decompression. During the decompression, have each student complete the gas shutdown drill. Students must not vary more than 1 metre/3 feet from stop depth. Teammates may assist depth control. There is no time limit. Divers complete the entire decompression and surface. Watch for stop depth control and proper NO TOX gas switches. 4. During Training Dive One, every team should have to respond correctly to each of the following emergencies at least once: free flowing regulator failed manifold teammate switching to wrong gas failed lift bag a. These may occur at any point, including during the simulated trimix dive (during the simulated trimix dive you may want to avoid problems that would cut the dive short, however). b. Brief students ahead of time how you will assign problems (slate, holding in purge button, etc.). c. You may repeat spontaneous problems and assign additional ones as you see fit. 5. Unresponsive, non breathing diver at the surface a. Explain to students that this is simply a review of what they have already been trained to do as PADI Rescue Divers, but a chance to apply it to a tec diving situation. b. In pairs of rescuers and victims, rescuer initiates as if they have just surfaced together. c. Watch for initial check for breathing, establishing buoyancy, calling for help, two slow initial breaths, breaths every five seconds, and maintaining and protecting an open airway. d. Rescuer removes own and victim’s equipment and tows victim 60 metres/200 feet. Assign gear handlers as appropriate. 6. Exit water (as appropriate for environment). D. Post Dive 1. Performance review. After giving divers some time to rest, get a drink, etc., but while memories remain fresh, have teams identify what happened, what they learned, what worked and what didn’t, etc. Comment and fill in missing information as necessary, but have students critique themselves constructively while you guide the process. 2. Have divers show you their slates with the recorded times/depths/SPG readings assigned prior to the dive. 3. Divers disassemble and stow their gear as appropriate. 4. Students log dive for your signature.
  • Trimix1

    1. 1. DSAT Tec Trimix Diver Course Knowledge Development Presentation One
    2. 2. Welcome <ul><li>Introductions </li></ul><ul><li>Course Goals and Your Responsibilities </li></ul><ul><li>Course Overview, Logistics and Administration </li></ul><ul><li>Trimix Diving Risks </li></ul><ul><li>Introduction to Trimix Diving </li></ul>
    3. 3. Introductions <ul><li>Introduction of staff </li></ul><ul><ul><li>Background </li></ul></ul><ul><ul><ul><li>Diving interests </li></ul></ul></ul><ul><ul><ul><li>Outside of diving interests </li></ul></ul></ul><ul><li>Introduction of candidates </li></ul><ul><ul><li>Background </li></ul></ul><ul><ul><ul><li>Diving interests </li></ul></ul></ul><ul><ul><ul><li>How interest developed for tec diving </li></ul></ul></ul><ul><ul><ul><li>Outside of diving interests </li></ul></ul></ul><ul><li>Collect Knowledge Reviews </li></ul>
    4. 4. Course Goals <ul><li>What are the course goals? </li></ul><ul><ul><li>To qualify you to use open circuit technical diving equipment and procedures to plan and make dives using trimix, EANx, and oxygen </li></ul></ul><ul><ul><li>To learn and use cognitive and motor skills required for technical trimix diving </li></ul></ul><ul><ul><li>To understand hazards and risks associated with trimix diving </li></ul></ul><ul><ul><li>To prepare for and respond to emergencies </li></ul></ul><ul><ul><li>To develop skills for further training </li></ul></ul>
    5. 5. Your Responsibilities <ul><li>What are your obligations and responsibilities? </li></ul><ul><ul><li>Follow direction and dive plans strictly </li></ul></ul><ul><ul><li>Maintain physical and mental health </li></ul></ul><ul><ul><li>Accept the risk and notify if risk is unacceptable </li></ul></ul><ul><li>What are the consequences to failing to meet your obligations and responsibilities? </li></ul><ul><ul><li>Serious injury, disabled or killed </li></ul></ul><ul><ul><li>Not qualify for certification </li></ul></ul>
    6. 6. Course Overview and Logistics <ul><li>Schedule </li></ul><ul><li>Tec Trimix Diver Statement of Understanding and Learning Agreement </li></ul><ul><ul><li>Make-up policies </li></ul></ul><ul><li>Certification </li></ul><ul><ul><li>Receive DSAT Tec Trimix Diver certification </li></ul></ul><ul><ul><li>Qualified to make no-decompression dives using trimix as a bottom gas within limits of your training </li></ul></ul><ul><ul><li>Purchase trimix and purchase/rent equipment for trimix diving </li></ul></ul><ul><li>Certification means you accept risks of trimix diving </li></ul>
    7. 7. Course Overview and Logistics <ul><li>Class requirements </li></ul><ul><ul><li>Course cost </li></ul></ul><ul><ul><li>Teammates </li></ul></ul><ul><ul><li>Equipment & Materials </li></ul></ul><ul><ul><li>Course prerequisites </li></ul></ul>
    8. 8. Administration <ul><li>Liability Release and Express Assumption of Risk for Technical Diving </li></ul><ul><li>Physician's approval and signature on current Medical Statement </li></ul><ul><li>Diver Insurance </li></ul>
    9. 9. Presentation One Overview <ul><li>Trimix Diving Risks </li></ul><ul><li>Introduction to Trimix Diving </li></ul><ul><li>Equipment I </li></ul><ul><li>Techniques and Procedures I </li></ul><ul><li>Emergency Procedures I </li></ul><ul><li>Decompression I </li></ul><ul><li>Gas Planning I </li></ul><ul><li>Team Diving I </li></ul><ul><li>Thinking Like a Trimix Diver I </li></ul><ul><li>Practical Application One </li></ul>
    10. 10. Trimix Diving Risks <ul><li>What ten risks and hazards does technical diving with trimix present that either don’t exist or aren’t as severe in recreational diving and air/enriched air technical diving? </li></ul><ul><ul><li>Helium differs from nitrogen </li></ul></ul><ul><ul><li>More risk of the unknown </li></ul></ul><ul><ul><li>Unlikely to decompress adequately </li></ul></ul><ul><ul><li>Gas blend inaccuracy </li></ul></ul><ul><ul><li>Vestibular DCS continued… </li></ul></ul>
    11. 11. Trimix Diving Risks <ul><li>More risks and hazards of technical diving with trimix </li></ul><ul><ul><li>Hypothermia </li></ul></ul><ul><ul><li>Hypoxia </li></ul></ul><ul><ul><li>Hyperoxia </li></ul></ul><ul><ul><li>Isobaric counterdiffusion </li></ul></ul><ul><ul><li>Rescue difficult or impossible </li></ul></ul>
    12. 12. Limits of Tec Trimix Diver <ul><li>What are the limits of your training as a Tec Trimix Diver? </li></ul><ul><ul><li>A maximum of 75 metres/245 feet or maximum training depth </li></ul></ul><ul><ul><li>Use open circuit technical diving equipment with trimix as a bottom gas, and trimix, enriched air and oxygen for decompression </li></ul></ul><ul><ul><li>Stay within limits of your experience </li></ul></ul>
    13. 13. Limits of Tec Trimix Diver <ul><li>What risks do you face if you exceed these limits? </li></ul><ul><ul><li>Serious Injury </li></ul></ul><ul><ul><li>Death </li></ul></ul>
    14. 14. Limits of Tec Trimix Diver <ul><li>How do you responsibly extend your limits with trimix diving? </li></ul><ul><ul><li>Extend limits progressively </li></ul></ul><ul><ul><li>Dive with divers with more experience </li></ul></ul>
    15. 15. Introduction to Trimix Diving <ul><li>Trimix </li></ul><ul><li>Benefits </li></ul><ul><li>Drawbacks </li></ul><ul><li>Ranges for Trimix </li></ul><ul><li>Blending Trimix </li></ul><ul><li>Analyzing Trimix </li></ul>
    16. 16. Introduction to Trimix Diving <ul><li>What is trimix? </li></ul><ul><ul><li>Trimix is a blend of oxygen, helium and nitrogen used for deep technical diving </li></ul></ul>
    17. 17. Trimix <ul><li>What is the nomenclature for identifying a trimix? </li></ul><ul><ul><li>Nomenclature – Trimix followed by the oxygen percentage, then the helium percentage </li></ul></ul><ul><ul><li>TMx 18/50 </li></ul></ul>Oxygen Percentage Helium Percentage Trimix Abbreviation
    18. 18. Trimix <ul><li>What is meant by “normoxic” trimix? </li></ul><ul><ul><li>Trimix with 21% oxygen is called “normoxic” </li></ul></ul><ul><ul><li>Helium percentage may vary </li></ul></ul>
    19. 19. Benefits <ul><li>What are three benefits of diving with trimix? </li></ul><ul><ul><li>Reduced narcosis </li></ul></ul><ul><ul><li>Reduced oxygen toxicity </li></ul></ul><ul><ul><li>Less dense for reduced breathing resistance at depth </li></ul></ul>
    20. 20. Drawbacks <ul><li>What are three drawbacks of diving with trimix? </li></ul><ul><ul><li>Expense </li></ul></ul><ul><ul><li>Longer decompression times </li></ul></ul><ul><ul><li>More complex logistics and planning </li></ul></ul>
    21. 21. Ranges for Trimix <ul><li>What are the generally accepted ranges for trimix? </li></ul><ul><ul><li>There are differing opinions as to how deep you can go before trimix is considered required. Broadly accepted ranges include: </li></ul></ul><ul><ul><ul><li>Air/enriched air to 50 metres/165 feet </li></ul></ul></ul><ul><ul><ul><li>Below 40 metres/130 feet, trimix used for overhead environments or complex objectives </li></ul></ul></ul><ul><ul><ul><li>Below 50 metres/165 feet, trimix for all diving </li></ul></ul></ul><ul><ul><ul><li>Maximum depth has yet to be established </li></ul></ul></ul>
    22. 22. Blending Trimix <ul><li>How is trimix made? </li></ul><ul><ul><li>Blending </li></ul></ul><ul><ul><ul><li>Partial pressure blending </li></ul></ul></ul><ul><ul><ul><li>Partial pressure blending with enriched air </li></ul></ul></ul><ul><ul><ul><li>Membrane blending/continuous flow with partial pressure </li></ul></ul></ul><ul><ul><ul><li>Continuous flow with helium, oxygen and air </li></ul></ul></ul>
    23. 23. Analyzing Trimix <ul><li>How do you analyze trimix? </li></ul><ul><ul><li>Analyzing </li></ul></ul><ul><ul><ul><li>Oxygen analyzer as with enriched air nitrox </li></ul></ul></ul><ul><ul><ul><li>Oxygen is analyzed at each stage </li></ul></ul></ul><ul><ul><ul><li>Helium analyzers </li></ul></ul></ul>
    24. 24. Equipment I <ul><li>Standardized Technical Rig </li></ul><ul><li>Stage/Decompression Cylinders </li></ul><ul><li>Trimix Markings </li></ul><ul><li>Argon Inflation Systems </li></ul>
    25. 25. Standardized Technical Rig <ul><li>The standardized technical rig—you’ll be diving the same equipment configuration as a Tec Deep Diver </li></ul><ul><ul><li>High capacity double cylinders </li></ul></ul><ul><ul><li>Redundant buoyancy control is essential </li></ul></ul>
    26. 26. Equipment Requirements
    27. 27. Equipment Requirements
    28. 28. Equipment Requirements
    29. 29. Equipment Requirements
    30. 30. Equipment Requirements
    31. 31. Stage/Decompression Cylinders <ul><li>Why might you carry more than two stage/deco cylinders on a trimix dive? </li></ul><ul><ul><li>Tec Deep Divers use two stage/deco cylinders </li></ul></ul><ul><ul><li>Trimix Divers may use more than two stage/deco cylinders </li></ul></ul><ul><ul><ul><li>Trimix dives require larger deco gas volumes </li></ul></ul></ul><ul><ul><ul><li>Three or four different deco gases may be necessary </li></ul></ul></ul><ul><ul><ul><li>May need travel gas </li></ul></ul></ul>
    32. 32. Stage/Decompression Cylinders <ul><li>What are the two ways you can carry four stage/deco cylinders? </li></ul><ul><ul><li>Worn all left or right and left </li></ul></ul><ul><ul><li>Develop a personal standard </li></ul></ul><ul><ul><li>Wear cylinders the same way every dive </li></ul></ul><ul><ul><li>All left – stack two, trail two </li></ul></ul><ul><ul><li>Right/left – stack two each side or wear one each side and trail two </li></ul></ul><ul><ul><li>Simplify rig and logistics </li></ul></ul>
    33. 33. Stage/Decompression Cylinders <ul><li>Deco cylinder types </li></ul><ul><ul><li>Aluminum 80s – preferred if diving with more than two cylinders </li></ul></ul><ul><ul><li>Aluminum 80s for all left configuration </li></ul></ul><ul><ul><li>Steel cylinders - use two </li></ul></ul>
    34. 34. Trimix Markings <ul><li>What are the proper markings on trimix cylinders? </li></ul><ul><ul><li>Clearly mark with a label indicating “Trimix” </li></ul></ul><ul><ul><ul><li>No standardized label </li></ul></ul></ul><ul><ul><ul><li>Keep isolated </li></ul></ul></ul><ul><ul><li>Mark with analyzed content, maximum depth and diver’s name </li></ul></ul><ul><ul><li>Avoid accidents caused by confusing gasses </li></ul></ul>
    35. 35. Argon Inflation Systems <ul><li>Why can’t you inflate your dry suit from your back gas when trimix diving? </li></ul><ul><ul><li>Can’t use helium in a dry suit </li></ul></ul><ul><ul><ul><li>Conducts heat </li></ul></ul></ul><ul><ul><ul><li>DCS risk due to isobaric counterdiffusion </li></ul></ul></ul><ul><ul><li>Small separate inflation cylinder </li></ul></ul><ul><ul><ul><li>Typically mounted on the left doubles cylinder </li></ul></ul></ul><ul><ul><ul><li>Valve down for access </li></ul></ul></ul>
    36. 36. Argon Inflation Systems <ul><li>Why would you put a low pressure inflator hose on a decompression cylinder filled with air or enriched air? </li></ul><ul><ul><li>Some trimix divers have low pressure hose on the regulator attached to deco cylinder as back up in case they exhaust or have a problem with the argon inflation system </li></ul></ul>
    37. 37. Argon Inflation Systems <ul><li>How do you set up an independent inflation system, and where do you typically put it? </li></ul><ul><ul><li>Argon is preferred inflation gas </li></ul></ul><ul><ul><ul><li>No second stage only LP hose </li></ul></ul></ul><ul><ul><ul><li>“Mini” SPG & overpressure relief valve </li></ul></ul></ul><ul><ul><ul><li>recommended on first stage </li></ul></ul></ul>
    38. 38. Argon Inflation Systems <ul><li>What is the advantage of using argon as a dry suit inflation gas? </li></ul><ul><ul><li>Argon insulates better </li></ul></ul><ul><ul><li>Little risk of isobaric counterdiffusion </li></ul></ul>
    39. 39. Techniques and Procedures I <ul><li>General Recommendations </li></ul><ul><li>Gas Switches </li></ul><ul><li>Cylinders Worn on Both Sides </li></ul><ul><li>Cylinders Worn all Left </li></ul><ul><li>D-ring </li></ul><ul><li>Decompression Stops </li></ul>
    40. 40. General Recommendations <ul><li>What is the general recommendation regarding how deep you take a cylinder, and what is the issue in trimix diving with regard to this recommendation? </li></ul><ul><ul><li>Never take a cylinder deeper than you can safely breathe from it </li></ul></ul><ul><ul><ul><li>Relocate cylinders to adequately decompress </li></ul></ul></ul><ul><ul><ul><li>Minimizes switching to wrong gas </li></ul></ul></ul><ul><ul><ul><li>You’re highly unlikely to decompress without your deco cylinder, the priority is to not risk losing them </li></ul></ul></ul>
    41. 41. Gas Switches <ul><li>Gas switch recommendation: </li></ul><ul><ul><li>Switching to wrong gas is a common cause of tec diver deaths </li></ul></ul><ul><ul><li>Use NO TOX mnemonic </li></ul></ul><ul><ul><li>Confirm switch </li></ul></ul>
    42. 42. Cylinders Worn on Both Sides <ul><li>What are the procedures for gas switches with up to four deco cylinders? </li></ul><ul><ul><li>Common to wear oxygen and next highest oxygen deco on right, lowest oxygen/travel gas left </li></ul></ul><ul><ul><li>Several handling options </li></ul></ul><ul><ul><ul><li>Stack all four, two per side: breathe top left, bottom left, top right, bottom right </li></ul></ul></ul><ul><ul><ul><li>Wear two and trail two: breathe worn left, switch with trailed left and breathe worn right, switch with and breathe trailed right </li></ul></ul></ul><ul><ul><ul><li>IMPORTANT: Be consistent </li></ul></ul></ul>
    43. 43. Cylinders Worn all Left <ul><li>Procedures for gas switches handling three or four cylinders all on left: </li></ul><ul><ul><li>Common to wear two and trail two </li></ul></ul><ul><ul><li>Cylinder you’re breathing is on top </li></ul></ul><ul><ul><li>Move cylinders as you switch </li></ul></ul><ul><ul><li>Preplanning reduces moves </li></ul></ul><ul><ul><ul><li>Several handling options </li></ul></ul></ul><ul><ul><ul><li>Be consistent and follow NO TOX procedure </li></ul></ul></ul><ul><ul><li>Two cylinders simplifies handling </li></ul></ul>
    44. 44. D-ring <ul><li>In both left and left/right configurations: </li></ul><ul><ul><li>Top hooking to chest D-ring allows you to wear two and breathe from a third (top hooked) if you’ll not be using it long </li></ul></ul><ul><ul><li>Commonly used with travel gas </li></ul></ul>
    45. 45. Decompression Stops <ul><li>How precise should a decompression stop be? </li></ul><ul><ul><li>Precision is essential </li></ul></ul><ul><ul><li>Helium less tolerant </li></ul></ul><ul><ul><li>Decompression stops vary no more than .6 metres/2 feet from stop depth </li></ul></ul><ul><ul><li>Think of the surface as a decompression stop </li></ul></ul>
    46. 46. Emergency Procedures I <ul><li>Where can you find descriptions of skills for review? </li></ul><ul><ul><li>During the course you’ll practice skills you mastered in the Tec Deep course and apply them to the higher complexity of trimix diving </li></ul></ul><ul><ul><ul><li>Long hose drills </li></ul></ul></ul><ul><ul><ul><li>Valve shut down drill </li></ul></ul></ul><ul><ul><ul><li>Unconscious diver </li></ul></ul></ul><ul><ul><ul><li>Lift bag deployment </li></ul></ul></ul><ul><ul><li>Consult the DSAT Tec Deep Diver Manual and Key Skills Video </li></ul></ul>
    47. 47. Decompression I <ul><li>Desktop Decompression Software </li></ul><ul><li>Standard Practice </li></ul><ul><li>Differences Between Air/Enriched Air/Oxygen for Trimix Diving </li></ul><ul><li>Decompression Models </li></ul>
    48. 48. Desktop Decompression Software <ul><li>What are the five reasons that the use of desktop software is a standard practice in trimix diving? </li></ul><ul><ul><li>Maximizes adaptability </li></ul></ul><ul><ul><li>Allows plans based on known real profiles rather than square profiles </li></ul></ul><ul><ul><li>Can increase conservatism for individual risk tolerance </li></ul></ul><ul><ul><li>More accurately reflects what a multigas computer will allow </li></ul></ul><ul><ul><li>Can produce contingency tables </li></ul></ul>
    49. 49. Desktop Decompression Software <ul><ul><li>Virtually all trimix divers use desktop decompression software because: </li></ul></ul><ul><ul><ul><li>The software can write a table for the trimix blend you’re using </li></ul></ul></ul><ul><ul><ul><li>You can quickly compare different possible profiles, different gasses and gas switch depths </li></ul></ul></ul><ul><ul><ul><li>Allows the addition of deep stops or use trimixes for decompression </li></ul></ul></ul><ul><ul><ul><li>Generates contingency tables for the dive </li></ul></ul></ul><ul><ul><ul><li>Software may have a more readily applicable deco schedule than a computer </li></ul></ul></ul>
    50. 50. Standard Practice <ul><li>Standard Practice for using Desktop software: </li></ul><ul><ul><li>Use software even if using multigas computers </li></ul></ul><ul><ul><li>Do not use for military or commercial diving </li></ul></ul>
    51. 51. Differences <ul><li>What are two main differences between desktop deco software for air/enriched air and for trimix? </li></ul><ul><ul><li>The ability to select trimix in the gas choices </li></ul></ul><ul><ul><li>Deeper maximum depth calculations are allowed </li></ul></ul>
    52. 52. Neo-Haldanean Models <ul><li>What are the basic attributes of each of the two categories of decompression models? </li></ul><ul><ul><li>First category - Haldanean model: </li></ul></ul><ul><ul><ul><li>Assumes no bubble formation (questionable) </li></ul></ul></ul><ul><ul><ul><li>Decompression strategy is to get diver to shallowest allowable depth for shortest decompression </li></ul></ul></ul><ul><ul><li>Of these Buhlmann model most common </li></ul></ul><ul><ul><ul><li>Widely used in dive computers </li></ul></ul></ul><ul><ul><ul><li>Conservative and versatile </li></ul></ul></ul><ul><ul><ul><li>Large base of field testing continued… </li></ul></ul></ul>
    53. 53. Bubble Dynamics Model <ul><li>Basic attributes </li></ul><ul><ul><li>Second category of decompression models - Bubble dynamics models: </li></ul></ul><ul><ul><ul><li>RGBM - reduced gradient bubble model </li></ul></ul></ul><ul><ul><ul><li>VPM - varying permeability model </li></ul></ul></ul><ul><ul><ul><ul><li>Assumes some subclinical bubbles form </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Emphasizes deeper and more frequent stops </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Characterized by predicting shorter deco times and shorter no stop times </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Lacks same level of field testing </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Basis for deep stop procedures </li></ul></ul></ul></ul>
    54. 54. Decompression Models <ul><li>Two categories of decompression models found in desktop software </li></ul><ul><ul><li>Desktop software and multi gas trimix computers offer users the choice of Buhlmann models or bubble models (Reduced Gradient Bubble Model [RGBM], Varying Permeability Model [VPM], etc.); some versions offer a choice within the same software or dive computer </li></ul></ul>
    55. 55. Gas Planning I <ul><li>Gas Volume, Oxygen Exposure Planning </li></ul><ul><li>Volumes, SAC, Oxygen Exposure, Reserves and Maximum Depths (based on oxygen) </li></ul><ul><li>Example </li></ul><ul><li>Discussion Question </li></ul>
    56. 56. Gas Volume, Oxygen Exposure Planning <ul><li>What are the two ways you’ll determine the gas volumes you require, including reserves, for a trimix dive? </li></ul><ul><ul><li>Tables </li></ul></ul><ul><ul><ul><li>Use Trimix Oxygen Management Tables for determining PO 2s, CNS percent, and OTUs </li></ul></ul></ul><ul><ul><ul><li>Use Equivalent Air Depth and Oxygen Tables </li></ul></ul></ul><ul><ul><ul><li>for determining PO 2 , CNS percent, OTUs </li></ul></ul></ul><ul><ul><ul><li>and EADs for EANx and oxygen continued… </li></ul></ul></ul>
    57. 57. Multiple Deep Stops <ul><li>Determining the gas volumes and reserves for a trimix dive </li></ul><ul><ul><li>Tables continued… </li></ul></ul><ul><ul><ul><li>Trimix schedules commonly have multiple deep stops more than 3 metres/10 feet apart. Calculate ascents between deep stops until reaching stops separated by 3 metres/10 feet. At that point, use the add-one-minute-every-third-stop method. </li></ul></ul></ul><ul><ul><li>Use desktop decompression software to determine oxygen exposure and the dive profile </li></ul></ul>
    58. 58. The Numbers <ul><li>Dive Planning Exercise </li></ul><ul><ul><li>You need to determine volumes, SAC, oxygen exposure, reserves and maximum depths (based on oxygen) </li></ul></ul><ul><ul><ul><li>Use desktop deco software when possible </li></ul></ul></ul><ul><ul><ul><li>Manually determine these numbers if desk top deco software is not available </li></ul></ul></ul><ul><ul><ul><li>Review materials in the DSAT Tec Deep Diver Manual </li></ul></ul></ul>Metric Question Imperial Question Discussion Question Next
    59. 59. Metric Question <ul><li>55 metres for 20 minutes using TMx 21/35 </li></ul><ul><li>Deco schedule calls for a 10 mpm ascent rate </li></ul><ul><ul><li>1 min. stop at 33 metres using EANx36 </li></ul></ul><ul><ul><li>1 min. at 21 metres using EANx50 </li></ul></ul><ul><ul><li>1 min. at 18 metres using EANx50 </li></ul></ul><ul><ul><li>1 min. at 15 metres using EANx50 </li></ul></ul><ul><ul><li>2 min. at 12 metres using EANx50 </li></ul></ul><ul><ul><li>5 min. at 9 metres using EANx50 continued… </li></ul></ul>
    60. 60. Metric Question <ul><li>Final stops use pure oxygen </li></ul><ul><ul><li>2 min. at 6 metres </li></ul></ul><ul><ul><li>17 min. at 5 metres </li></ul></ul><ul><li>SAC rate is 19 litres per minute (lpm) for the working part of the dive and 16 lpm when decompressing </li></ul><ul><li>Assuming a 1/3 reserve determine </li></ul><ul><ul><li>Gas volume requirements </li></ul></ul><ul><ul><li>OTUs </li></ul></ul><ul><ul><li>CNS clock </li></ul></ul>Metric Answer Discussion Question Imperial Question
    61. 61. Metric Answer <ul><li>TMx21/35; 2755 litres used X 1.5 = 4132 litres required </li></ul><ul><li>EANx 36; 139 litres used X 1.5 = 209 litres required </li></ul><ul><li>EANx50; 397 litres used X 1.5 = 596 litres required </li></ul><ul><li>Oxygen; 485 litres used X 1.5 = 728 litres required </li></ul><ul><li>OTUs = 87.9 </li></ul><ul><li>CNS% = 47.6% </li></ul>Metric Question Discussion Question Imperial Question Next
    62. 62. Imperial Question <ul><li>180 feet for 20 minutes using TMx 21/35 </li></ul><ul><li>Deco schedule calls for a 30 fpm ascent rate </li></ul><ul><ul><li>1 min. stop at 110 feet using EANx36 </li></ul></ul><ul><ul><li>1 min. at 80 feet using EANx36 </li></ul></ul><ul><ul><li>1 min. at 60 feet using EANx50 </li></ul></ul><ul><ul><li>1 min. at 50 feet using EANx50 </li></ul></ul><ul><ul><li>2 min. at 40 feet using EANx50 </li></ul></ul><ul><ul><li>5 min. at 30 feet using EANx50 continued… </li></ul></ul>Previous
    63. 63. Imperial Question <ul><li>Final stops use pure oxygen </li></ul><ul><ul><li>3 min. at 20 feet </li></ul></ul><ul><ul><li>16 min. at 15 feet </li></ul></ul><ul><li>SAC rate is .8 cubic feet per minute (cfm) for the working part of the dive and .65 cfm when decompressing </li></ul><ul><li>Assuming a 1/3 reserve determine </li></ul><ul><ul><li>Gas volume requirements </li></ul></ul><ul><ul><li>OTUs </li></ul></ul><ul><ul><li>CNS clock </li></ul></ul>Imperial Answer Discussion Question Metric Question
    64. 64. Imperial Answer <ul><li>TMx21/35; 112.8 cf used X 1.5 = 169.2 cf required </li></ul><ul><li>EANx 36; 8.2 cf used X 1.5 = 12.3 cf required </li></ul><ul><li>EANx50; 14.2 cf used X 1.5 = 21.3 cf required </li></ul><ul><li>Oxygen; 19.8 cf used X 1.5 = 29.7 cf required </li></ul><ul><li>OTUs = 85.16 </li></ul><ul><li>CNS% = 45.28% </li></ul>Metric Question Discussion Question Imperial Question Next
    65. 65. Discussion Question <ul><li>Question </li></ul><ul><ul><li>Might it be worth recalculating this dive without EANx36 as a deco gas? Why or why not? Is PO2 an issue? </li></ul></ul><ul><li>Answer </li></ul><ul><ul><li>Simplify logistics – eliminate a cylinder </li></ul></ul><ul><ul><li>Switching that deep raises your PO2 to almost 1.6 ata which is better to avoid after 20 minutes at 1.4 ata (working PO2 limit) </li></ul></ul>Previous
    66. 66. Team Diving I <ul><li>A Team Effort </li></ul><ul><li>Compatible Gasses within a Team </li></ul>Previous
    67. 67. A Team Effort <ul><li>What are four benefits of team diving, and how does each relate to trimix diving? </li></ul><ul><ul><li>Higher likelihood of mission success </li></ul></ul><ul><ul><li>Fosters preparedness and resources for handling complex emergencies </li></ul></ul><ul><ul><li>More critical steps such as gas switches, deep stops, ascents, etc. makes a “backup brain” essential </li></ul></ul><ul><ul><li>Camaraderie is greater because of the complexity of the challenge </li></ul></ul>
    68. 68. Compatible Gasses within a Team <ul><li>In what ways does trimix increase the importance of compatible gases within a team? </li></ul><ul><ul><li>Allows teammates to double check schedules and NO TOX gas switches </li></ul></ul><ul><ul><li>In an emergency deco gasses can be shared </li></ul></ul><ul><ul><li>Double check each other by matching – same gasses, same number of cylinders, same labels </li></ul></ul><ul><ul><li>Using the same gases keeps the team together </li></ul></ul>
    69. 69. Thinking Like a Trimix Diver I <ul><li>Good Diver’s Main Objective Is To Live </li></ul><ul><li>Simulation as an Effective Training Tool During and After Training </li></ul>
    70. 70. Good Diver’s Main Objective Is To Live <ul><li>When planning a trimix dive, what aspects of the dive should you be thinking about in a Good Diver’s Main Objective Is To Live? </li></ul><ul><ul><li>G ood – G as </li></ul></ul><ul><ul><li>D iver’s – D ecompression </li></ul></ul><ul><ul><li>M ain – M ission </li></ul></ul><ul><ul><li>O bjective – O xygen </li></ul></ul><ul><ul><li>I s – I nert gas narcosis </li></ul></ul><ul><ul><li>T o – T hermal </li></ul></ul><ul><ul><li>L ive - L ogistics </li></ul></ul>
    71. 71. Simulation <ul><li>What makes simulation an effective training tool for learning to dive with trimix? </li></ul><ul><li>Simulation for training </li></ul><ul><ul><li>Allows you to form habits with procedures </li></ul></ul><ul><ul><li>With minimal risk, you can make and learn from mistakes that would be hazardous on an actual trimix dive </li></ul></ul><ul><ul><li>Can respond to an emergency without the risk </li></ul></ul><ul><ul><li>Form automatic responses to situations </li></ul></ul><ul><ul><li>Try, retry, and practice techniques </li></ul></ul>
    72. 72. Simulation <ul><li>How might you use simulation as a tool following this course? </li></ul><ul><ul><li>Simulation after certification </li></ul></ul><ul><ul><ul><li>Refresh skills </li></ul></ul></ul><ul><ul><ul><li>Try out new procedures, equipment or equipment configurations </li></ul></ul></ul><ul><ul><ul><li>Rehearse complex missions </li></ul></ul></ul><ul><ul><ul><li>Familiarize yourself with new teammates </li></ul></ul></ul>
    73. 73. Practical Application One - Objectives <ul><li>Rig gear, including required stage/deco cylinders </li></ul><ul><ul><li>Standardized technical rigging philosophy </li></ul></ul><ul><ul><li>Environment specific equipment requirements </li></ul></ul><ul><li>Given a dive depth, bottom time, trimix blend, two (then four) decompression gas blends, a working SAC rate and a deco SAC rate </li></ul><ul><ul><li>Use desktop decompression software to generate a decompression schedule and contingency decompression schedules, each with gas volume requirements (including reserves), turn pressure, OTUs and CNS clock oxygen exposure. </li></ul></ul>
    74. 74. Presentation One Review <ul><li>Trimix Diving Risks </li></ul><ul><li>Equipment I – Rigged for Trimix Diving </li></ul><ul><li>Techniques and Procedures I </li></ul><ul><li>Emergency Procedures I </li></ul><ul><li>Decompression I </li></ul><ul><li>Gas Planning I </li></ul><ul><li>Team Diving I </li></ul><ul><li>Thinking Like a Trimix Diver I </li></ul><ul><li>Practical Application One </li></ul>
    75. 75. Let’s Go Diving <ul><li>Assessment Dive - Objectives </li></ul><ul><li>Training Dive One - Objectives </li></ul>
    76. 76. Assessment Dive - Objectives <ul><li>Working within a team </li></ul><ul><ul><li>Rig gear </li></ul></ul><ul><ul><li>A G ood D iver’s M ain O bjective I s T o L ive </li></ul></ul><ul><ul><li>B eing W ary R educes A ll F ailures </li></ul></ul><ul><ul><li>Bubble check, descent check and s-drill </li></ul></ul><ul><li>Simulated out of gas emergency </li></ul><ul><li>Shut down and switch second stages </li></ul><ul><li>Deploy lift bag </li></ul><ul><li>Tow a simulated, unresponsive breathing diver continued… </li></ul>
    77. 77. Assessment Dive – Objectives <ul><li>On the bottom, don, remove, and redon two stage/deco cylinders </li></ul><ul><li>Neutral buoyancy and swimming with two stage/deco cylinders </li></ul><ul><li>Simulated ascent with abbreviated stop times </li></ul><ul><li>Simulated four stop decompression ascent </li></ul><ul><li>Don and remove two stage/deco cylinders at the surface </li></ul><ul><li>Time, depth, and gas supply awareness </li></ul>
    78. 78. Training Dive One - Objectives <ul><li>Working within a team </li></ul><ul><ul><li>Rig gear </li></ul></ul><ul><ul><li>A Good Diver’s Main Objective Is To Live </li></ul></ul><ul><ul><li>Being Wary Reduces All Failures </li></ul></ul><ul><ul><li>Bubble check, descent check and s-drill </li></ul></ul><ul><li>Remove and replace four stage/deco cylinders on the bottom and swim </li></ul><ul><li>Sharing gas </li></ul><ul><li>Remove and replace four stage/deco cylinders while wearing no mask continued… </li></ul>
    79. 79. Training Dive One – Objectives <ul><li>Respond to spontaneous drills </li></ul><ul><li>Shut down and switch second stages </li></ul><ul><li>Deploy lift bag </li></ul><ul><li>Simulated trimix dive </li></ul><ul><li>While maintaining stop depth shut down and switch second stages </li></ul><ul><li>Tow a simulated unresponsive, non breathing diver </li></ul><ul><li>Time, depth, and gas supply awareness </li></ul>
    80. 80. DSAT Tec Trimix Diver Course Knowledge Development Presentation One End Show

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