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  1. 1. Instructor Guide Section fIve: Tec45five: Tec 45 Standards andCourse Content The Tec 45 subcourse of the DSAT Tec Diver course introduces Tec 40 divers to the firststages of full, technical deep decompression diving. Certified Tec 45 divers are qualified to makemultistop decompression dives that employ EANx and oxygen for accelerated decompression. The expectation is that a Tec 45 diver intends to continue on in technical diving.Accordingly, the course not only develops the knowledge and skills to make open circuit technicaldives as deep as 45 metres/145 feet, but also begins developing the knowledge and skills the diverwill need at the Tec 50 level and beyond.Program Sequence The Tec 45 course consists of three knowledge development sections, three practical appli-cations sessions and four training dives. You will find these in the Knowledge Development,Practical Application and Training Dive subsections, each with content/presentation outlines andrelated standards. The fully integrated instructional sequence for the Tec 45 course is: Tec 45 Knowledge Development One Tec 45 Practical Application One Tec 45 Training Dive One Tec 45 Knowledge Development Two Tec 45 Practical Application Two Tec 45 Training Dive Two Tec 45 Knowledge Development Three Tec 45 Practical Application Three Tec 45 Exam Tec 45 Training Dive Three Tec 45 Training Dive Four The Tec 45 course provides flexibility in scheduling knowledge development, practicalapplications and training dives. You may rearrange the sequence and combine knowledgedevelopment and practical applications sessions, provided that you maintain the requiredinstructional sequencing. The requirements are: PADI ®padi.com 5-1
  2. 2. Section fIve: Tec45 Instructor Guide • Any knowledge development sections, practical applications or training dives that precede a training dive in the integrated sequence must be successfully completed before that training dive. • Any knowledge development sections or practical applications that precede a practical application in the integrated sequence must be successfully complet- ed before that practical application. • Any knowledge development section that precedes another knowledge devel- opment section must be successfully completed before that knowledge devel- opment section. For example, the following sequences would be acceptable: Tec 45 Knowledge Development One Tec 45 Knowledge Development Two Tec 45 Practical Application One Tec 45 Practical Application Two Tec 45 Training Dive One Tec 45 Training Dive Two Tec 45 Knowledge Development Three Tec 45 Practical Application Three Tec 45 Exam Tec 45 Training Dive Three Tec 45 Training Dive Four Tec 45 Knowledge Development One Tec 45 Knowledge Development Two Tec 45 Knowledge Development Three Tec 45 Practical Application One Tec 45 Training Dive One Tec 45 Practical Application Two Tec 45 Training Dive Two Tec 45 Exam Tec 45 Practical Application Three Tec 45 Training Dive Three Tec 45 Training Dive FourPADI ® 5-2 padi.com
  3. 3. Instructor Guide Section fIve: Tec45Tec 45 Key StandardsParticipant prerequisites: • Certified as a Tec 40 diver or qualifying certification from another training organization. For the purposes of this level, a qualifying technical certification is one that qualifies the student to make decompression dives to 40 metres/130 feet using air and EANx using open circuit scuba equipment. 18 years old, 50 logged dives (12 deeper than 18 metres/60 feet using EANx, at least 6 deeper than 30 metres/100 feet (with or without EANx). • Instructor qualification: Teaching status, insured (where required) Tec Deep Instructor • Assistant qualification: renewed, insured (where required) PADI Divemaster or higher certified as a Tec 45 or higher level TecRec diverTraining Dive One Environment: Confined water or limited open water with ready access to water shallow enoughin which to stand. Depths: Minimum: 2.4 metres/8 feet Maximum 10 metres/30 feet Decompression: No stop only Gases: Air or EANx, recommended that all blends be breathable at maximum dive depth Ratios: 6:1, 8:1 with one or more certified assistantsTraining Dive Two Environment: Open water Depths: Minimum: 12 metres/40 feet Maximum: 18 metres/60 feet Decompression: No stop only Gases: Air or EANx, recommended that all blends be breathable to maximum dive depth Ratios: 4:1, 6:1 with one or more certified assistantsTraining Dive Three Environment: Open Water Depths: Minimum: 18 metres/60 feet Maximum: 30 metres/100 feet Decompression: No stop only Gases: Air, Air, EANx or oxygen Ratios: 4:1, 6:1 with one or more certified assistantsTraining Dive four Environment: Open Water Depths: Minimum: 27 metres/90 feet Maximum: 45 metres/145 feet Decompression: Single gas decompression, gas switch for conservatism, Gases: Air, EANx or oxygen Ratios: 3:1, 4:1 with one or more certified assistants PADI ® padi.com 5-3
  4. 4. Section fIve: Tec45 Instructor GuideTec 45 Knowledge DevelopmentKnowledge Preassessment The Tec 45 course builds upon and extends the knowledge development estab-lished in the Tec 40 course. A lack of understanding or familiarity with the fundamentalknowledge required of a Tec 40 diver can substantially impede learning at the Tec 45level, and in some cases, raise safety concerns. Therefore, it is important to verify andassess prerequisite knowledge before beginning Tec 45 level knowledge development.Apply these standards: 1. Students who enter the course with a qualifying prerequisite certification(not DSAT Tec 40 certification) must complete all the Tec 40 Knowledge Reviewsand the Tec 40 Exam. It is recommended that you have these students complete thereading assignments first. Check over the Knowledge Reviews and score the exam, pro-viding remediation to achieve mastery as necessary. 2. Students who enter the course as DSAT Tec 40 divers (not a qualifyingcertification from another organization) who you did not personally certify, and/orwho completed certification more than six months prior to the start of the course,must retake the Tec 40 exam. Score the exam, providing remediation to achieve mas-tery as necessary. 3. As appropriate, it’s recommended that you preassess potential students’ skilland knowledge in a confined water session and/or interviews. You can combine remedi-ation with preassessment, refreshing student capabilities to mastery prior to beginningthe course. 4. Students who you certified as DSAT Tec 40 divers (not a qualifying certifica-tion from another organization) within six months of starting the course do not have anyparticular assessment requirements. It is recommended that you check their trainingrecords for any areas that may have had difficulty and conduct informal assessments byasking questions, etc. The following knowledge development outlines provide the course content inpresentation form. If the Tec Deep Diver Manual is not available in a language the stu-dent understands, you may use the outline to present all course content. Otherwise, it isrecommended that you cover knowledge development through student independentstudy with the manual and handouts, with presentations that review/remediate what theystudied. PADI ® 5-4 padi.com
  5. 5. Instructor Guide Section fIve: Tec45 The content outlines note manual supported content and other delivery content.The manual supported content includes a list of reading, exercise and Knowledge Reviewassignments (repeated in list form in the Appendix for your convenience) based upon theTec Deep Diver Manual. The other delivery content covers material that is not in the TecDeep Diver Manual. You may simply deliver this material in verbal presentations using theTec Diver Lesson Guides on PowerPointTM, or (recommended) you can copy those outlinesections for students to study independently along with their assignments in the manual.These sections are in the Appendix ready for copy and handout. Presentations that involvestaff introductions, paperwork, logistics, scheduling etc., do not have independent studymaterials. Tec 45 students do not use the Knowledge Reviews in the Tec Deep Diver Manual.Instead, copy the blank Tec 45 Knowledge Reviews in the Appendix of this guide for theiruse. You will also find the answer keys there. Students have not completed a KnowledgeDevelopment until they have completed the corresponding Knowledge Review cor-rectly, accurately and completely. The final step in completing Tec 45 Knowledge Development is the Tec 45 Exam.Tec 45 students complete the exam after successfully completing KnowledgeDevelopment Three. To be successful, the student diver must score 80% or higher andreview each question missed with the instructor until mastery on all questions isachieved. Students who score less than 80% must repeat the exam (version B) afterample time to remediate. It is recommended that you administer the exam after Tec 45Practical Application Three. All material in the Knowledge Development content outline is required andmust be covered, studied and otherwise remediated until the student demonstratesmastery. PADI ®padi.com 5-5
  6. 6. Section fIve: Tec45 Instructor GuideTec 45 Knowledge Development One[The voice in these presentations addresses students. Notes to the instructor appear inbrackets.]I. Introductory SessionLearning ObjectivesBy the end of this section, you should be able to answer these questions:1. What are the goals of the Tec 45 course?2. What are your obligations and responsibilities in taking this course?3. What are consequences of failing to meet these obligations and responsibilities?A. Introductions [Encourage a relaxed atmosphere that promotes teamwork.] 1. [Introduce yourself, staff and anyone else involved in the course. Provide a little bit of background and personal information about everyone so students become acquainted.] 2. [Have students introduce themselves and tell something about themselves, diving interests, etc.] 3. [Collect and review Tec 45 Knowledge Review One]. a. [Review the answers to assess mastery so you can tailor your presen- tations accordingly.]B. Course Goals 1. The goals of the Tec 45 course are a. To qualify you to make limited decompression dives using air, enriched air and oxygen to a depth of 45 metres/145 feet or less. • Certification as a Tec 45 diver qualifies you to use a single decompression gas of up to 100 percent oxygen to make your decompression more conservative or to accelerate your decompression. b. To train you in the knowledge, procedures and motor skills required for decompression diving within the limitations of the Tec 45 certifi- cation. c. To assure you understand and acknowledge the hazards and risks associated with this level of tec diving, and tec diving in general. d. To train you to prepare for and respond to reasonably foreseeable emergencies that may occur within Tec 45 limits. PADI ® 5-6 padi.com
  7. 7. Instructor Guide Section fIve: Tec45 e. To lay the foundation continuing your training in the Tec 50, Tec Trimix 65 and Tec Trimix Diver courses.C. Your Obligations and Responsibilities 1. During the Tec 45 course, you have these obligations and responsibilities: a. To follow the instructor’s directions and dive plans strictly, and to not separate from the instructor or your dive team. b. To take all aspects of what you’re learning seriously, and to display an attitude and conduct that is consistent with that expected of a team-oriented technical diver. c. To refrain from tec diving outside this course until you’re fully quali- fied and certified. d. To maintain adequate physical and mental health, and to alert the instructor to any problems you have with them. e. To accept the risk for this type of diving, and for specific risks unique to each dive environment, and to immediately notify the instructor if this risk becomes intolerable for you. 2. Failing to meet these obligations and responsibilities can have these conse- quences: a. In the worst case, you could be 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.D. Course Overview, Schedule & Logistics, Administration, Assignments and Study 1. Schedule and logistics [Explain anything that you have yet to cover: the course schedule, required reading and assignment due dates, sessions, and training dives. It’s recommended that you have this printed out and go over it with students when they enroll in the course.] 2. Administration a. Course costs [Explain and collect, as appropriate, all costs associated with the course, 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. [Confirm course prerequisites:] • Students may confirm these with certification cards, log entries, signed affidavits, etc. PADI ®padi.com 5-7
  8. 8. Section fIve: Tec45 Instructor Guide d. Students sign the Tec Diver Statement of Understanding and Learning Agreement [Discuss what the agreement does not cover, such as how you will handle missed sessions/dives, assignments not completed, etc.] e. [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.] f. [Have student divers read, complete and sign the PADI Medical Statement. Prior to Tec 45 Training Dive One, the student must have a physician’s approval and signature on the Medical Statement. If the student received a physician’s approval and signature on a Medical Statement for another course within 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.] g. [Diver insurance – It’s recommended that you require students in the DSAT Tec 45 course to have dive accident insurance such as offered by the Divers Alert Network, , if available in your area.] 3. Assignments and Study [Brief the class on the following points as appropriate for how you will handle knowledge development.] a. You will study independently with the Tec Deep Diver Manual and provided handouts. • The manual supports the entire Tec Diver course as well – Tec 40 through Tec 50. You should have already read much of it. • Read the assigned handouts, sections and exercises. b. You will use the manual to complete knowledge reviews provid- ed to you. Do not use the knowledge reviews in the manual. c. We will review the material and help with anything you don’t understand [state where/when: class sessions, practical applica- tions, predive sessions, etc.] d. You will complete the Tec 45 Exam before the last two training dives of the course.PADI ® 5-8 padi.com
  9. 9. Instructor Guide Section fIve: Tec45II. equipment[Note to instructor: Students who took the Tec 40 course in the standardized techni-cal rig (or sidemount) will have already completed this section. At your discretion,they do not have to repeat it. Students who took the Tec 40 course using the basicTec 40 configuration do need to complete this section.]Manual Supported Content Study assignment: Tec Deep Diver Manual, pgs 10-33, Equipment I, Tec Exercise 1.2, pgs 80-87, Equipment II, Tec Exercise 2.1, pgs 142-145, Equipment III, Tec Exercise 3.1 Watch the TecRec Equipment Setup and Key Skills video.Learning ObjectivesBy the end of this section, you should be able to answer these questions:1. What is meant by “standardized technical rig,” and why do technical divers needto apply it?2. What guidelines apply to selecting masks, fins and snorkels for technical diving?3. What characteristics should you look for in a cylinder valve or manifold used fordeep technical diving?4. What is the minimum number of fully independent regulators, per diver, and howdo you configure each?5. What three characteristics should you look for in a BCD, and what five character-istics should you look for in a harness, for a deep technical diving rig?6. How do you choose an appropriate exposure suit for a deep technical dive, andhow may your choice affect your BCD choice?7. What are your options regarding a weight system, and what are the advantagesand disadvantages of each?8. What instrumentation do technical divers generally carry, and why do they gener-ally avoid consoles?9. What are the three types of computers you can use for technical deep diving withair and enriched air, and what are the advantages and disadvantages of each?10. What types of cutting tools are appropriate for deep technical diving, and at leasthow many should you have with you?11. What are six general guidelines regarding pockets, accessories and clips youmight need when technical diving?12. What is the difference between a stage bottle and a decompression cylinder?13. How do you set up a stage/deco cylinder? PADI ®padi.com 5-9
  10. 10. Section fIve: Tec45 Instructor Guide14. What is the advantage of a stage/deco cylinder connection you can cut?15. Why would you need a lift bag/DSMB and reel?16. What are suitable lift bags/DSMBs and reels, and where do you secure them onyour rig?17. What makes a suitable spare mask for tec diving?18. What are the issues and recommendations relating to equipment and oxygencompatibility?19. What are four recommendations regarding equipment maintenance?20. What are three reasons that technical divers consider a slate standard equip-ment?21. What is a “jon line,” and how do you use it?22. What benefits does a multigas computer offer you?23. What are the options regarding urination for long technical dives?You should also be able to:17. Describe the layout, arrangement and configuration of the basic rig and equip-ment, head to toe, as worn for a technical deep dive.A. The technical community has evolved a standardized technical rig that mini- mizes and streamlines your gear so that nothing dangles, everything is easily accessible and so you eliminate the unnecessary. 1. With the extensive equipment needs in technical diving, you must apply the standardized rig philosophy to minimize confusion and pro- cedural error due to equipment task loading, and to assure streamlin- ing, which avoids entanglements and reduces wasted energy due to drag. 2. Gear rigging may vary with the type of technical diving and still be consistent with the standardized technical rig philosophy. In this course, you’ll learn the basic technical diving setup most widely accepted in the technical diving community.B. Mask, fins and snorkel. 1. Choose a compact mask to maximize streamlining and to minimize having it jostled loose by current. PADI ® 5-10 padi.com
  11. 11. Instructor Guide Section fIve: Tec45 2. Choose fins with sufficient blade area and flex for power. Fins suitable for snorkeling or warm water recreational diving may not be suitable for tech- nical diving. 3. Usually you omit the snorkel. They are appropriate standard equipment for recreational diving, but not for tec diving. In tec diving condictions, a snorkel tends to create drag and be an entanglement hazard. a. In rare instances with long swims at the surface in conditions call- ing for a snorkel (before or after a dive), you may choose a snorkel you can detach and stow for the dive. 4. Full face masks are not widely used for open circuit tec diving. However, at least one company manufacturers a model with interchangeable mouth “pods” that permit the diver to easily change gases and use standard sec- ond stages. The use of such a mask may be especially beneficial during decompression with oxygen, because it may reduce drowning risk in the event of a convulsion.C. Cylinders and valves. 1. The basic technical rig usually consists of twin cylinders chosen based on your gas consumption, size and the dive requirements. a. Twin 11-12 litres/71.2-80 cubic foot cylinders are sufficient for many divers going no deeper than 50 metres/165 feet. b. In some instances, a single 18-20 litre/105-120 cubic foot cylinder with an appropriate valve will suffice for the planned dive. 2. For twins, choose a valve with twin regulator posts that can shut down gas to either regulator and still allow the other access to all gas in both cylin- ders (in case of a freeflow malfunction). a. You also want an isolator manifold, which has a valve that sepa- rates the cylinders and saves half the remaining gas in the event of a manifold leak. b. The DIN (Deutche Industrie Norm) system is preferred over the yoke system – considered more reliable because of the threaded connection and captured o-ring (some valves will accept either with an insert adapter.) c. If you train in sidemount, you will have independent twin cylin- ders, and (obviously) no isolator valve. Your instructor will go over sidemount equipment specifics in detail. PADI ®padi.com 5-11
  12. 12. Section fIve: Tec45 Instructor Guide 3. For a single cylinder set up, choose an “H” or “Y” valve, which have twin regulator posts and can shut down gas to either regulator and still allow the other access to all the remaining gas (again, the DIN system is preferred). a. All your training in the Tec 45 course will be in doubles, but you may elect to use a single at times as a certified Tec 45 diver. 4. Cylinder and valve accessories a. A remote-close cable for the isolator manifold is common in a few areas with specialized needs, such as in cold water where thick exposure suits make it difficult to reach the valve. b. Some wreck divers use valve guards to protect against impact inside wrecks; the trend is away from these due to bulk and entanglement, though they’re common in some environments that call for them. 5. Doubles are set up with doubles bands set with the mounting bolts a standardized 28 cm/11 inches apart. Setting up doubles takes some training and practice, so have your PADI Dive Center or Resort handle it for you. a. Sidemount cylinders ride on either side of your body much like stage/deco cylinders. These don’t require a manifold, but they do require special clips and other rigging as well as a specialized harness.D. Regulators 1. In deep technical diving, the minimum is two fully independent regula- tors per diver (this does not include those used on stage or decompres- sion cylinders). 2. Choose top of the line balanced regulators for maximum reliability and performance at depth. 3. Configure the right post (as worn) regulator with a low pressure inflator hose and the second stage on a 1.8 m/7 ft hose. Sidemount will be simi- lar, though you will have an SPG. Its hose and the low pressure inflator hose lengths may differ. 4. Configure the left post regulator with the SPG and the second stage on a standard length (about 80 cm/32 in) hose. PADI ® 5-12 padi.com
  13. 13. Instructor Guide Section fIve: Tec45 5. The left regulator may or may not have a low pressure inflator hose (more about this later). 6. Note: neither regulator needs an extra second stage (one per regulator). 7. Again, the DIN system is preferred (most DIN regulators accept adapters for yoke system use). 8. Sidemount configuration is similar – your instructor will show you the sidemount configuration if you’re completing the course in sidemount.E. BCD and harness 1. The basic deep technical rig calls for a harness that sits on top of an inter- changeable BCD bladder; this attaches to double cylinders via recessed wing nuts that screw down on the band bolts. a. In the case of sidemount, the BCD bladder may or may not be incorporated into a typically fabric harness. There are no bands to mount to with sidemount, however, the harness may have a metal rail system at the bottom and back of the harness, which is used to connect the lower part of cylinders. 2. BCDs –called “wings” (because they let you “fly” doubles or because they resemble stubby wings). a. Size – a wide variety is available; choose based on adequate lift to hold you at the surface wearing all the gear for the planned dive, and with all cylinders full. b. Single bladder (has a single air cell, inflator and deflator) and double bladder (two air cells, inflators and deflators) models are available. c. You need back up buoyancy if your primary BCD fails. Options depend upon your other gear: • Single bladder: when using lighter cylinders with a dry suit • Double (dual bladder): needed for heavy cylinders with a dry suit, or diving a wet suit, so you can still restore posi- tive buoyancy even with a major BCD failure. The heaviest diving rigs may pose too much weight for dry suit back up buoyancy; you may need a double BCD in either a wet or dry suit. This is the generally preferred choice. PADI ®padi.com 5-13
  14. 14. Section fIve: Tec45 Instructor Guide • Unrestrained or “bungeed” BCDs – Bungeed wings have elastic or tubing that constricts the BCD to minimize pro- trusion and reduce the profile for wreck penetration div- ing. o bungeed wings should not be so tight that they would squeeze out all air if you had an exhaust valve failure or hole o some BCD wings have adjustable elastic that you set for the required buoyancy; this will not squeeze out all air; some allow you to release the bungee during the dive 3. Harness – holds the BCD to the cylinders, and the assembly on to you. a. Style – Plate (steel, aluminum or plastic) with standard nylon webbing is simple and holds a lot of weight securely. A soft har- ness is all standard nylon webbing and fabric; it is a bit more ver- satile and comfortable, but not as simple. It also weighs less, which is advantageous for traveling divers. b. Crotch strap – Due to the bulk and buoyancy distribution, you’ll need a crotch strap with most harnesses. c. Shoulder harness adjustable quick release connectors – they are generally not needed, but are convenient. Should you need assis- tance, they simplify getting you out of your gear; without them, they may have to cut your straps to get you out of your rig. d. Adjustable D-rings at the shoulders (two max each side) on straps, standoff (bent out or rigid), are recommended. Custom BCD with “permanently adjusted” D-rings are an option. Rigid D rings on the waist strap at hips (one each side) are essential – you need them located for optimum stage/decompression cylinder car- rying (more about this later in the course). • Fabric “butt plates” can be added to some BCDs. Developed for sidemount, these plates have cylinder attachment rails that some backmount divers prefer for stage/decompression cylinders in place of hip D rings. • Sidemount harnesses will also have two bungees clipped off to the back of the harness and to the front shoulder D-rings. This bungee is placed around the valve of eachPADI ® 5-14 padi.com
  15. 15. Instructor Guide Section fIve: Tec45 cylinder to hold it close to the diver’s body. These should be attached underwater and not used to support the weight of the cylinder out of the water, because the bungee isn’t strong enough. Many divers will use a short loop of nylon cord with a bolt snap that can be easily be looped around the valve out of the water to support the cylinder and allow the diver to enter and exit with them on, if needed. • If using a quick release on the harness shoulder, D-rings should be above the release – this makes adjustment easier, and the stage bottle keeps the rig on you if you release it accidentally (very rare with modern harnesses). e. Waist strap – is usually a standard webbing/buckle on a plate har- ness, or a standard webbing/buckle with a removable “cummer- bund,” foundon many soft harnesses. Avoid harnesses with cum- merbund only (these are not as strong and create gear positioning problems). Many divers prefer a metal buckle to avoid breakage when moving heavy gear. 4. The BCD may or may not be partly integrated to your harness; you will want to choose your BCD and harness as a system. 5. Many avid technical divers have two or three wings, or entirely separate BCDs and harnesses, to match differing dive requirements.F. Exposure suits 1. As in recreational diving, you choose your exposure suit based on the water temperature at depth and the dive duration. a. Exposure protection suitable for short recreational dives may not be sufficient for long technical dives. b. You almost always need more insulation for a technical dive due to duration and decompression/safety stops without much exertion. 2. Dry suits a. For longest durations/coldest water. b. May permit using a single bladder BCD. c. Inflate with argon system for additional insulation. d. Master dry suit use in recreational diving before using one in tech- nical diving. At least 20 dives is a conservative minimum before using your dry suit for tec diving. The PADI Dry Suit Diver course recommended. PADI ®padi.com 5-15
  16. 16. Section fIve: Tec45 Instructor Guide • Note that in recreational diving, you use only the dry suit for buoyancy control underwater. • In a heavy weight technical rig, you may need to use both the suit and your BCD – a more complex skill to master. 3. Wet suits a. For most divers, a full 6 mm 1/4 in. wet suit with hood will suf- fice in water 24°C/75°F or warmer for two to three hour dives. Choose high quality neoprene to withstand the rigors of com- pression and recovery inherent to deep diving. b. Choose a redundant (double bladder) wing BCD, because drop- ping weights (if any) may not give you sufficient buoyancy if your BCD fails, or dropping weights may make you too buoyant to make your decompression stops. c. Note that at depth, wet suit compression may require substantial air in the BCD. d. The advantage of diving in a wet suit is simplicity – you only need to adjust the BCD. A minor tear will not substantially affect your thermal protection.G. Weight systems 1. With aluminum double cylinders, you will probably still need weights. With a heavy weight rig, you may not. 2. The choices are weight belt, integrated weight system and weight har- ness. a. Weight belt • Advantages: simple, readily available when needed. • Disadvantages: must don after putting on rig so it’s not trapped by crotch strap; can be hard to position securely amid other components. Note: Since losing weights on a deco dive can be hazardous (discussed in a moment), some divers intentionally wear their crotch straps over their weight belts, knowing they’ll have to release it in a weight ditching emergency. b. Integrated weight system • Advantages: no need to put on last; prepositioned amid rest of rig PADI ® 5-16 padi.com
  17. 17. Instructor Guide Section fIve: Tec45 • Disadvantages: must have a harness system that accepts one; makes an already heavy rig heavier; may add clutter to the configuration (depends on design) c. Weight harness • Advantages: it is put on before the rig; does not add to rig’s weight; provides key advantages of both weight belt and weight system • Disadvantages: may be awkward to adjust and position so that rig doesn’t interfere with weight ditching; may interfere somewhat with putting rig on d. Combination • Advantages: loss of one weight system doesn’t lose all your weight; may make configuration and donning easier. • Disadvantages: more complicated preparation, one more thing to remember. 3. Loss of weights can be a significant hazard when wearing lightweight rigs (such as twin aluminums), due to out of control ascent and the inability to make required decompression stops. a. Some tec divers use double buckles on weight belts to prevent acci- dental release. b. Another technique for backmounts is to use a metal plate and thread smaller weights into the harness in the shoulder area. Typical plates weigh 2.7 kg/6 lbs. Adding small weights to the harness can provide the diver up to 3.5 – 4.5 kg / 8 – 10 lbs that can’t be accidentally lost. While this may not provide sufficient weight alone, it makes loss of weight less of an issue with the remaining system. c. A third backmount technique is the use of a keel weight. This is a bar weight that fits between the cylinders, generally under the harness.H. Instrumentation 1. Basic deep technical rig instrumentation: SPG, compass, computer or timer/ depth gauge and back up computer or timer/ depth gauge. 2. Technical divers generally prefer arm-mount instruments (generally SPG is not arm-mounted, though it can be) – consoles are bulky and protrude (doesn’t follow the standardized technical rig philosophy) creating drag and PADI ®padi.com 5-17
  18. 18. Section fIve: Tec45 Instructor Guide entanglement hazard. (Note: you can often mount two gauges on a single wrist strap. Some tec divers carry back up instruments clipped inside a pouch or pocket.) 3. SPG (submersible pressure gauge) a. One only (except in sidemount) – there is no back up (it cre- ates two potential high pressure leaks); failure means end the dive immediately b. Mechanical preferred – reliable with no battery concerns c. In sidemount, smaller and lower profile preferred 4. Compass -- Good quality, liquid filled as used in recreational diving. It is commonly carried in a pouch until needed, rather than worn. 5. Timer and depth gauge (integrated or separate) a. May be used in place of computer when diving with tables (though most common “timer-depth gauge” is a dive computer set to gauge mode.) b. May be used to back up a computer (with tables). 6. Dive computers a. State of art in tec diving is the multiple gas computer. b. Modern computers accept as many as 7 different gases that you can switch to “on the fly” (during the dive) to accelerate decompression. Some allow you to add or delete gas blends underwater to handle emergency situations. c. Many also calculate helium dives – useful for diving trimix d. Single gas computers can be used, but at this level, are typical- ly used as timer/depth gauges along with tablesI. Cutting tools 1. You always dive with at least two cutting tools. 2. Carry at least one where you can deploy it with either hand. 3. Common types and locations include: a. Typical dive knife – sharp and in excellent condition; com- monly worn on inside of calf (on the outside is prone to entan- glement and hard to reach with either hand), however, most tec divers have moved away from large, leg knives altogether. b. Small dive knife – sharp, typically worn in sheath near center of waist band. PADI ® 5-18 padi.com
  19. 19. Instructor Guide Section fIve: Tec45 c. Z-knife – a small hook with blade especially suited to cutting fine line. It is worn on a gauge strap, harness or BCD deflation hose. d. EMT shears – heavy duty shears that cut rope (some will even handle cable). These may be worn on the calf, harness or waist. e. Bosun’s knife or other folding knife – very sharp for cutting line, often carried with clip or lanyard in a pocket or under instrument wrist bands f. Multi tools – Leatherman®- type tools, sometimes carried to meet specific dive objectives, usually in a sheath/pouch on the waist band or in a pocket with a clip. 4. Different types of technical diving have different cutting tool concerns (e.g., cave divers never wear large, calf-mounted knives).J. Guidelines for pockets, clips and accessories 1. To minimize confusion and bulk, avoid large pocket pouches on the har- ness; small pockets for back up gear (e.g., spare mask) that are out of the way at the hips are okay. 2. The most useful pocket in tec diving is on the outside of the thigh on the exposure suit (some manufacturers make a strap-on pocket if your expo- sure suit doesn’t have one). Some sidemount divers prefer it on the front of the thigh so they can reach it by lifting a knee. 3. Use brass or stainless steel clips on accessories, SPG, etc. Mount clips on accessories, not on the BCD. 4. Sliding gate clips (a.k.a. “dog clips”) are preferred by most divers to marine snaps (a.k.a. “swinging gate clips”), because they won’t acciden- tally snap on to things by themselves. • Choose clips for the environment– smaller clips that work easily in warm water with thin gloves may be impossible to use in cool water with thick gloves. • You should be able to reach all clips, because all clips can entangle or need your attention. 5. Accessories on a D-ring should be well out of way when stowed, and not dangle or create entanglement potential. If possible, keep accessories in a pocket except when in use, and clip them off only to free hands momen- tarily or to avoid dropping them while using them. If possible, only hang one item per D-ring. PADI ®padi.com 5-19
  20. 20. Section fIve: Tec45 Instructor Guide 6. Use a breakaway clip on anything you may need to discard or release in an emergency. A simple breakaway: connect a clip to accessory or gauge via a small o-ring or small, thin cable tie. In an emergency, a sharp pull or twist breaks the o-ring/cable tie, releasing the accessory or gauge.K. Basic rig: head-to-toe configuration– how everything fits together. [Note to instructor: The most effective way to demonstrate this is to have a staff member wearing the kit for you to demonstrate.] 1. Regulators and valves a. Short hose regulator on the left post - The SPG goes straight down, the gauge mounts at the left hip D-ring or on chest on an upper left or right D-ring with a break away clip. The second stage goes to the right and then rests on the upper chest held by a bungee or surgical tubing “necklace.” The LP hose goes to the right to the back up BCD inflator (if used), or straight down and in, to the dry suit inflator. If using an argon system and no back up BCD, there is no LP inflator hose. For sidemount, the left regulator is the same, however, the SPG may be on a short hose. It rests on the shoulder of the cylinder or in some cases may route directly out from the first stage to make it easier to see. The LPI hose for the BCD connects directly to the BCD, but will have a small loop that folds up underneath the diver’s arm. b. Long hose regulator on the right post- The LP inflator hose goes from it to the BCD inflator. The second stage hose goes straight down behind the BCD wing, up at the hip, across the chest (held in place by a rigid D ring and the safety reel), behind the neck from the left and around into the mouth. A break away clip is mounted where the hose meets the second stage (not clipped while in use). The reel is normally clipped on the right hip D-ring to hold the hose in place. For sidemount, the long hose routes down along the right cylinder, up around the diver’s neck and into the mouth. The hose is held by a bungee or shock cord around the cylinder. A break away clip is mounted in same loca- tion as on a back mount. Reels are typically clipped to a D-ring located on the back of the harness/BCD. PADI ® 5-20 padi.com
  21. 21. Instructor Guide Section fIve: Tec45 c. Note that all hoses route in or down – never out (except a short hose SPG in sidemount). d. All valves and the isolator are all the way open. Do NOT close back a partial turn. This assures they only turn one direction in a shut- down emergency – closed. 2. BCD and harness a. The primary BCD inflator hose is over left shoulder, retained so it won’t float away. b. The back up BCD inflator is clipped behind the wing or bungeed to the cylinder on the left or right (depends upon how the BCD is laid out) to avoid confusion with the primary. (Note: You never use both BCDs at the same time.) If using a high flow inflator, many divers bungee the low pressure hose in place, but don’t connect it so as to avoid a runaway ascent if the back up low pressure inflator malfunc- tions. In a BCD failure situation, they would use oral inflation if they need to quickly establish buoyancy, then connect the LP hose after stabilizing the situation. Note that sidemount configuration generally requires a specialized bladder or rigging. c. If using a dry suit, you should ideally be able to hold the BCD infla- tor and press the dry suit inflator with the left hand at the same time. d. Pockets (if used) should be small and mounted at the hips, out of the way. (The ideal place for a pocket is on the exposure suit thigh). e. Straps are adjusted/trimmed so there’s no excessive slack dangling from any slide or buckle. f. The height on cylinders is adjusted so you can reach both regulator valves and the isolator (with loosened waist/crotch strap acceptable). 3. Exposure suit a. The argon system (if used) usually is mounted on the left cylinder or side of the harness, inverted, regulator in, so you can open the valve while worn. The LP hose to the inflator is threaded under the har- ness, as necessary, to eliminate protruding slack. There is no second stage on the regulator. The system is mounted with straps you can cut away if necessary. Some divers prefer to wear it on the right. b. Desirable accessories • Thigh pockets • Knee pads PADI ®padi.com 5-21
  22. 22. Section fIve: Tec45 Instructor Guide 4. Instruments a. Arm mounted, either side preferred • mounting all one side makes one arm “clean” for more eas- ily sliding in and out of harness • some types of tec diving (e.g. scootering in a cave) make it important to mount gauges on one arm or the other b. The compass is positioned on the arm so you can center it for accurate navigation (it is frequently stored in a pocket/pouch if use is not expected) c. Two computers, or one computer and one depth gauge/ timer/ tables, or two depth gauge/timers and tables. 5. Mask and fins a. No snorkel in most circumstances b. Spare mask (optional) in an out-of-the-way harness pocket or in a thigh pocket c. Fins are preadjusted and taped or otherwise secured so they can’t slip or dangle (unless they have spring heel straps or are adjustable while being worn). d. Inspect straps frequently – this is one of the most common, but most avoidable gear failure points. 6. Weight system -– weights secure, free and clear for ditching; back up buckle secured (if used) 7. Cutting tools – two, mounted appropriately for type, at least one retriev- able by either hand alone. 8. Some variations on the above rigging suggestions exist, but these are the most common approaches. Agree on any departures with team mates – standardized rigs speed up your reaction time.L. Stage and decompression bottles (stage/deco cylinders) 1. They are worn on the side under the arm, clipped at the waist and on the chest, and are often removed and then later replaced during the course of the dive. 2. Although rigged the same, stage bottles are cylinders used to extend your range (working part of the dive), while decompression (deco) bottles are cylinders with enriched air (higher oxygen content than your bottom gas) or oxygen for decompression. PADI ® 5-22 padi.com
  23. 23. Instructor Guide Section fIve: Tec45 a. In this program, you’ll learn about using stage cylinders for extended no decompression dives, and decompression cylinders for decom- pression dives. b. Handling considerations are the same for either, so exercises and descriptions refer to “stage/deco” cylinders. c. Leaving either type cylinder for later retrieval and use is called “stag- ing,” regardless of whether it is a deco or a stage bottle. d. The terms are used somewhat interchangeably. This actually isn’t confusing in context in most circumstances. 3. Typical configuration [show setup cylinder] a. Nylon rope or strap approximately 46 cm/18 in (more or less to indi- vidual needs), runs under the valve opening from the neck down to a band around the cylinder, with a clip at each end – serves as handling strap underwater, plus provides clips for hip and chest D-rings; you may adjust bottom clip (some divers prefer it under the valve knob) b. Regulator is a second stage and SPG only – hoses tuck under inner tubing, bungee, surgical tubing or other retaining band stretched around cylinder c. The second stage has a clip with a breakaway mount so you don’t pull it out unintentionally d. A short hose SPG, bent up and pull tied to the first stage, is popular with some divers e. Suitable cylinders are those that are nearly neutral for easy handling; those substantially negative are not a good choice • an optional exception is an oxygen cylinder for use at 6 m/20 ft, since the added weight may benefit you if you’re under weighted f. Decompression cylinder second stages may have mouth guards/ blocks g. Properly set up, the stage/deco cylinder should be a compact package that you can handle easily with nothing dangling or dragging 4. Stage/deco bottle clips usually attach to the cylinder via a rope or nylon strap, especially in penetration diving, so you can cut away the cylinder in an PADI ®padi.com 5-23
  24. 24. Section fIve: Tec45 Instructor Guide emergency. You can’t cut connections that are entirely metal. (Some divers use double ended clips; it’s unlikely that both ends would jam at the same time). 5. Single stage/deco cylinders are worn under either arm, usually the left arm. Multiple cylinders may be worn all on the same side or distributed on either side. a. You will learn to use two cylinders in the Tec 50 course. b. If wearing a second cylinder on the right, be sure it does not trap your long hose – the hose should be routed below a hip D-ring when you clip. c. When scootering, you may choose to wear all cylinders on the left so you can aim the propeller wash under your right arm. d. You can clip cylinders you’re done with by the upper clip to a hip D-ring to get them out of the way.M. Lift bag/Delayed Surface Marker Buoy (DSMB) and reel 1. When diving in open water, you may accidentally find yourself away from the anchor line or planned ascent line or area. 2. In this instance, you deploy a lift bag/DSMB on a line from your emergency reel. a. This gives you a line to ascend along and to use to control your depth and stops. b. It marks your location for the boat and support team. 3. A suitable bag or buoy is brightly colored (yellow is preferred – it provides the best visibility amid white caps and in dim light) with at least 45 kg/100 lbs lift. Write your name on it in big letters for surface support identification. [Show example bag] A bright, elongated DSMB is also ideal, because it pro- trudes high above the water. a. In some areas, divers carry two bags/DSMBs – one of a different color to signal for assistance from surface support. b. Different teams and areas have differing protocols regarding bag/ DSMB colors and uses. 4. A suitable reel is compact, with ample line to reach the surface. Some divers use two reels in tandem in case one jams. [Show reels.] 5. Lift bags are commonly carried rolled up and bungeed to doubles or on the small of the back. Compact DSMBs may fit in a pocket or be clipped with the reel. [Show stowed bag/DSMB on rig.] PADI ® 5-24 padi.com
  25. 25. Instructor Guide Section fIve: Tec45 6. The reel clips to the right hip D ring to help hold the long hose in place. In sidemount, it clips to the back rail or a D ring behind the harness. 7. Lift bags/DSMB and reels are considered mandatory safety equipment in most areas. In some places, ascents with bags/DSMBs are standard operating proce- dures. In others, they are emergency procedures only. You’ll practice such ascents several times in this course.N. Spare mask 1. You have a big problem if you cannot read your tables or computer during a decompression dive, because you can’t tell when to ascend to the next stop, and you can’t surface. Therefore, many technical divers carry a back up mask, though it’s considered optional equipment. (Some computers with audio alarms will alert you when you ascend beyond stop depth, making it another tool in this situation.) 2. A suitable back up is as small as possible. 3. It is typically carried in a compact pocket as far to the rear as possible on the right or left hip of the harness. [Show spare mask and location.]O. Oxygen compatibility review 1. As you recall from your Enriched Air Diver course, using gas blends with more than 21 percent oxygen calls for special equipment considerations to avoid fire and/or explosion hazards. a. As a Tec 45 diver, you will be qualified to use EANx up to and includ- ing 100 percent oxygen – the higher the oxygen content, the more important this issue is. 2. Any equipment (regulator, valve, cylinder) that will be exposed to a gas with more than 40 percent oxygen, or pure oxygen, at any time (including during blending) must be rated for oxygen service. a. It must be oxygen clean – free of contaminants. b. It must be oxygen compatible – made from materials that don’t com- bust easily in oxygen. 3. Follow manufacturer recommendations regarding use with air, enriched air or oxygen. Some manufacturers require oxygen service for any enriched air, and some limit the oxygen percentage. However, you may have to make some compromises. [Provide updated information on the oxygen compatibility issue as available.] [See Note to Students.] 4. If you expose oxygen service equipment to nonoxygen clean gases or other contaminants, the equipment is no longer oxygen clean or oxygen service PADI ® rated.padi.com 5-25
  26. 26. Section fIve: Tec45 Instructor Guide a. Example: Using an oxygen service regulator on a standard air cylinder – the regulator is considered contaminated. b. Example: Filling an oxygen service cylinder from a standard scuba air source – standard scuba air (Grade E) is not oxygen clean, and the cylinder must then be re oxygen cleaned. (In the U.S. you must use Grade E Modified or Grade J). 5. Leave enriched air cylinder tags in place for removal by blender – this allows blender to confirm that the cylinder was not refilled by nonoxygen clean air source. 6. To minimize the heat of compression, open cylinder valves slowly and allow equip- ment to pressurize slowly when using enriched air and oxygen. 7. Protect oxygen service equipment from contamination by keeping it bagged and sealed from the environment until needed. Rinse and stow oxygen service equip- ment as soon as possible after use, and keep it away from areas or exhaust that may have oil or other contamination. 8. The general guideline is to have oxygen service equipment recleaned annually. 9. Violating guidelines regarding oxygen compatibility carries a severe risk of injury and/or property damage caused by fire and/or explosion.Note to Students:[Read this to student divers if the DSAT Tec Deep Diver Manual is not in a language they canunderstand.[You’re learning to use enriched air nitrox with more than 40 percent oxygen and/or pure oxygento extend no stop time and benefit decompression. Their use verges on the essential for decom-pression after long, deep dives. The use of higher oxygen probably lessens the risk of decompres-sion sickness, because it is generally believed that for a given a decompression model, a schedulerequiring shorter stops is more reliable than a schedule requiring longer stops. Without the highoxygen, you’d face impractically long decompression stops. Therefore, when a diver can get out ofthe water quicker (accelerated decompression), it reduces the exposure to other risks as diverse asmarine predators, hypothermia, getting separated from the boat in strong currents, and so on.Technical diving is undoubtedly safer with the use of high oxygen gases than it would be withoutthem, which is why it is a standard practice in the tec diving community. Using hyperoxic gases,however, is not without some risk and controversy. Outside of issues you’ve learned related to cen-tral nervous system and pulmonary oxygen toxicity, the greatest hazard comes from the risk of fire.That’s why, as you’ve learned, any high pressure device coming in contact with a gas with morethan 40 percent oxygen (or less than 40 percent if specified by the manufacturer) must be cleanedand dedicated for use with pure oxygen.That’s easy to say, but not as easily done. PADI ® 5-26 padi.com
  27. 27. Instructor Guide Section fIve: Tec45At this writing, relatively few equipment manufacturers in the dive industry warrant the use ofany of their equipment with pure oxygen. A few do, but others specifically warn against usingtheir equipment with enriched air nitrox mixtures containing greater than 40 percent oxygen.Yet, you will still learn in this course to use proper oxygen service equipment with hyperoxicgases including pure oxygen.Basically it comes down to balancing the risks: the risk of getting seriously hurt or killed dueto decompression sickness against the risk of getting seriously hurt or killed due to fire orexplosion. Most tec divers believe – and accident data support – that provided you’re usingproperly cleaned and compatible equipment, not using oxygen is a far greater risk than usingit. In fact, while plenty of divers have been bent over the years, as of this writing only a hand-ful – perhaps only one or two -- has been seriously injured as a result of an oxygen fire using ahyperoxic gas in a technical scuba diving context. And, that is in the context of tens of thou-sands of dives (at least) made with such mixtures over the past decade.In the end the choice will be yours. If you decide to stick with the strict manufacturer’s guide-lines for your regulators, tanks, valves, and SPGs, you may have to choose decompressiongases with no more than 40 percent oxygen. But if so, you must then be willing to accept therisks attendant to the lengthier decompression times involved.Most of the technical diving community believes that, the manufacturers’ warnings notwith-standing, you are better off in technical diving to use oxygen and other hyperoxic mixes thannot. The risk of fire and explosion is real and is, yet again, another risk you must personallyassume before getting involved in technical diving. To manage and minimize that risk, becertain that any equipment you will use with a gas with more than 40 percent oxygen has beenserviced for that use by a qualified professional.P. Maintenance 1. You rely on your gear for life support. Therefore, maintain your gear according to manufacturer specifications. 2. Have regulators, valves, BCDs and gauges inspected and overhauled at least annually or more frequently for heavy use or as manufacturer specified. 3. Have any equipment that doesn’t appear to function normally inspected and serviced before using. 4. Never dive with gear in anything but top shape. To do otherwise in technical diving raises your risk of injury or death by starting the dive with a potential problem. a. If you start a dive with some equipment in less than ideal working order, you are essentially using your back up from the start of the dive. b. In this case, if your back up has no back up, then you’re diving without back up. That’s what often injures and kills divers in technical diving environments. PADI ®padi.com 5-27
  28. 28. Section fIve: Tec45 Instructor GuideQ. Slates 1. Usually a convenience in recreational diving, they are a necessity in most technical diving for several reasons: a. Communication -- understanding between you and your team mates may be crucial; if they don’t understand a signal, you need a slate b. Memory back up -- you can’t rely on memory for crucial infor- mation; use a slate to record back up decompression schedules, turn around times, special procedures, etc. c. You record your time, depth and gas supply throughout the dive. 2. Choose a slate that fits easily in your thigh pocket (or other easily accessed pocket) because you’ll use it frequently. 3. You can use specialized slates for dive planning, surveying (cave/wreck diving) and other plans; multiple page slates are a good choice for lots of writing space.R. Jon line 1. Decompressing in a current on an anchor/mooring line can be tiring, also crowded if several divers reach the same deco stop at same time. 2. A jon line is a short line about a metre/three feet to 3 metres/10 feet long that snugs (via a loop or special hook) around the anchor/ mooring line and clips to your harness. 3. The jon line lets you decompress effortlessly, opens up space at the stop depth and helps you control your depth. Also reduces likelihood of get- ting blown off the line in a very strong current. [Show class jon lines and how to attach them.]S. Multigas computers 1. You can program multigas computers with two or more enriched air blends or oxygen, then tell the computer when you’ve switched gases during the dive. The computer adjusts the decompression limits, required decompression, and oxygen exposure calculations based on the gas you’re actually using. 2. This provides several benefits: a. You can conveniently make gas-switch, extended no stop dives as a way of giving yourself substantial no decompression time. b. You can accelerate your decompression to reduce your hang time. PADI ® 5-28 padi.com
  29. 29. Instructor Guide Section fIve: Tec45 c. You don’t need to calculate oxygen exposure manually as you do when making gas switch dives using a single gas computer. 3. Multigas computers accommodate from three to 10 different gases; some require a PC interface with desktop deco software. 4. More about multigas computers shortly.T. Urination 1. In technical diving, long dives (two or more hours) and the inability to surface makes having to urinate a real issue, especially when wearing a dry suit. 2. There are three options available to males, two of which are available to females. a. Dive in a wet suit and wash the suit thoroughly after each dive. • This is not an option in many environments due to water tem- perature or duration • Urinating in a wet suit feels warm, but actually speeds heat loss by dilating skin capillaries • This is an option for both male and female divers b. Adult diapers in dry suits • Do not require any suit modification. • Have limited capacity -- they only hold so much. • Require that you relieve yourself slowly or it will leak into your suit. • Are an option for both male and female divers. c. Condom catheters in dry suits • Use disposable external urination condoms to route waste out- side the suit through a valve. • Sometimes have valves that can only be opened and used face down to avoid a squeeze. • Many not be suitable for pristine environments that would be sensitive to contamination • Primarily are an option for males – attempts to make such devices for females have had only limited acceptance, though some appear to work. [Show student hardware for dry suit condom catheter, if available] PADI ®padi.com 5-29
  30. 30. Section fIve: Tec45 Instructor GuideOther Delivery Content, Tec 45-1 Study assignment: Tec 45 Handout 1III. equipment Issue Discussions and PhilosophiesLearning ObjectivesBy the end of this section, you should be able to answer these questions:1. Why is the standard practice to use two multigas dive computers on the dive, and toplan with desk top decompression software?2. Why are DSMBs replacing lift bags in many tec diving situations?3. Why has failure of quick releases on harness shoulders proved not to be a seriousissue? What would you do if it were to happen?4. What is perhaps the most common weighting error in tec diving?5. Why is backup buoyancy critical in most open water, open circuit technical diving?6. What are the problems with trying to use a lift bag or DSMB as a backup buoyancysystem? 7. What is the policy of virtually every lift bag and dry suit manufacturer with respect tobackup buoyancy?8. Why is the redundant (double bladder) BCD the most realistic approach to providingbackup buoyancy control?A. The standard of practice in deep decompression tec diving is to use multigas dive computers during the dive, with decompression software for overall planning. You may use a single gas computer and/or depth gauge and timer with tables in this course, but this is the recommended approach. There are several reasons why: 1. Multigas computers now handle up to seven gas mixes (including trimix), and also calculate CCR (closed circuit rebreather) diving, making them suited to your future as well as present tec diving. 2. A multigas computer maximizes your options in an emergency, allowing you, for example, to switch to a lower oxygen gas (even back gas) should you lose or exhaust your primary deco gas. a. Some of the newest models allow you to enter entirely new gases during the dive and recalculate your decompression. This provides more options in an emergency. 3. Many multigas computers have PC interfaces, allowing you to adjust stop PADI ® 5-30 padi.com
  31. 31. Instructor Guide Section fIve: Tec45 depths, conservatism factors, etc. Some let you choose the decompression model you prefer. 4. Multigas computers track your actual dive profile, adjusting your decom- pression requirements based on your actual dive. This makes it easier to adjust to circumstances. Example: You accidentally exceed your planned depth slightly; you leave the bottom sooner based on your computer so that your decompression time is the same as planned, keeping you within your gas plan. 5. With a multigas computer, you can choose to decompress based on a sin- gle gas and switch to a higher oxygen gas for added conservatism (as you learned to do as a Tec 40 diver). Should circumstances require (emergen- cy), however, you can switch to accelerated decompression to get to the surface faster with less gas used. 6. You still use deco software to plan the dive – oxygen exposure, decom- pression and gas requirements. Use the computer within the dive you plan. 7. Multigas computers are more sophisticated than single gas, so they’re more complex to use. But, they are not difficult to use and getting easier.B. DSMBs (Delayed Surface Marker Buoys) are replacing lift bags in many tec div- ing situations. 1. DSMBs stand higher in the water, making them preferred for rough condi- tions. 2. DSMBs are more compact on your rig, making them popular when used as an emergency alert only. 3. DSMBs have no-spill designs (though several lift bags have these, too, now), so accidentally losing tension on the line isn’t likely to result in a spilled buoy. 4. The highest capacity DSMBs are essentially tall, thin lift bags and work well for drift decompression. 5. Several types of DSMBs (and lift bags) have LP inflation ports that allow you to fill them with an LP inflator hose, away from your body or mouth, without using a second stage. This minimizes the chance of regulator freeze, as well as minimizing reel tangle issues. PADI ®padi.com 5-31
  32. 32. Section fIve: Tec45 Instructor GuideC. At one time, some people thought failure of shoulder quick release buckles on tec harnesses would be a serious issue. This hasn’t proven true. 1. Quick release buckles are designed to withstand hundreds of kg/lbs direct stress. This explains why stress failure is virtually unheard of. 2. Were the release to fail, you would only have to pass the lower part of the harness strap through the D-ring on the upper part and tie it.D. Weighting 1. Proper weighting and adequate backup buoyancy remain two areas commonly addressed inadequately in open circuit technical divers. 2. Perhaps the most common weighting error in tec diving is under weighting. a. Proper weighting means you’re able to maintain your final stop depth with nearly empty back cylinders and either no or near- empty deco cylinders – this is what would happen if you had a major problem forcing you into a long deco using your gas reserve, and/or decoing on back gas. b. If you were not weighted for this, you face a high DCS risk, because you would not be able to remain at stops. c. As an example, a properly weighted tec diver wearing high capacity doubles and two deco cylinders will be about 14 kg/30 lbs negatively buoyant at the start of a dive, and 4.5 kg/10 lbs or more negative at the end if dive goes as planned. d. In this example, inadequate weighting would mean that in an emergency situation, besides the original problem, you also have to deal with between 4.5 kg/10lbs and 14 kg/30 lbs positive buoyancy while trying to decompress.E. Backup buoyancy is critical in most open water, open circuit technical diving because a diver is substantially negatively buoyant throughout the dive. 1. Failure of the primary BCD without a backup leaves no alternative but to drop equipment (deco cylinders, weights, etc.). This can make the sit- uation worse if the diver must discard deco gases to attain buoyancy. 2. Discarding gear may result in too much buoyancy. If the diver is already in deco, the ability to decompress effectively becomes compromised, growing worse as the diver consumes gas. PADI ® 5-32 padi.com
  33. 33. Instructor Guide Section fIve: Tec45 3. There is a high likelihood of surfacing with omitted decompression if the diver cannot maintain stop depths, or lacks the required decompression gases, or both. 4. A dry suit may work as a backup buoyancy device. a. This is primarily an option when the dive will be relatively short and shallow, with short decompression – the gas requirement is low, so the diver is not substantially negatively buoyant (such as when using aluminum cylinders). b. Limited option – most dry suits will not hold more than small amount of excess gas. Beyond a certain point, it escapes through neck/wrist seals. c. Several manufacturers caution against inflating their dry suits to gain large amounts of buoyancy because of zipper failure issues. d. A large volume of expanding gas is harder to control in a dry suit. e. With deeper/longer tec dives, backup buoyancy control other than the dry suit is generally necessary. 5. Some have advocated using a lift bag or DSMB as a backup buoyancy device. This has several problems: a. DSMBs and lift bags are not designed as buoyancy devices and are difficult to control in that role. • They are even more difficult to control while trying to per- form gas switches, handle a gas shutdown, etc. • Even if learned and practiced, it is not a skill one would expect a diver to perform reliably in a real failed BCD emer- gency over the course of a real decompression. If it has not been practiced at all, it would be especially difficult. • DSMBs/lift bags do not provide a realistic buoyancy system for positive buoyancy at the surface after completing decom- pression. • Using a DSMB/lift bag as back up buoyancy would require the diver to hold on to the bag while dealing with other tasks, or it would have to be clipped to the harness. Either would compromise safety. PADI ®padi.com 5-33
  34. 34. Section fIve: Tec45 Instructor Guide b. If the DSMB/lift bag is used for backup buoyancy, then it is not available to send to the surface. c. Sending the DSMB/bag to the surface and hanging on the line for buoyancy is not a good option either. • In all but flat seas, this will cause the diver to rise and fall, compromising the quality of the decompression. • Once sent up, there is no way to adjust the bag’s buoyan- cy. • It is not a technique that transfers well to other environ- ments. • Stress on the line and reel is a major issue. For this to be reliable, the diver would need to carry much heavier line and a larger reel than most tec divers prefer. d. Trying to use a lift bag or DSMB as a backup buoyancy system unnecessarily complicates an emergency situation, and provides inadequate benefit. 6. It’s worth noting that no dry suit manufacturer and no lift bag manufac- turer sanctions the use of their products as tec diving backup buoyancy devices. Some specifically warn against it. 7. The redundant (double bladder) BCD is the most realistic approach to providing backup buoyancy control. a. They are designed for the job and endorsed by the manufactur- ers. b. They are used the same way as your primary BCD – a well prac- ticed skill you use on every dive, exactly what you want in an emergency situation. c. They are applicable to virtually all dive environments. d. Other than a slightly higher investment, there are no meaningful drawbacks. e. They are the only real option for open water tec diving in a wet suit.PADI ® 5-34 padi.com
  35. 35. Instructor Guide Section fIve: Tec45exercise, Other Delivery Content, Tec 45-11. Multigas computers have become the standard of practice in tec diving because (choose all thatapply)q a. they handle multiple gases and CCR diving.q b. they maximize your options in an emergency.q c. their decompression models are newer than those in single gas computers.q d. they are smaller than single gas computers.2. DSMBs are replacing lift bags in many tec diving situations because (choose all that apply)o a. they don’t stick so far up into the wind.q b. they are more compact on your rig.q c. they have no-spill designs.q d. some have special inflation systems.3. It is unlikely that a quick release on your harness shoulder would fail, but if it did, you wouldonly need to tie off the loose end.q Trueq False4. Perhaps the most common weighting error in tec diving isq a. under weighting.q b. over weighting.q c. neutral weighting.q d. None of the above.5. Backup buoyancy control is critical in open water, open circuit tec diving because if you’reproperly weighted and your primary BCD fails, you risk being unable to decompress adequately.q Trueq False6. Problems with trying to use a lift bag or DSMB as a backup buoyancy system include (chooseall that apply)q a. it is a complex skill with low reliability for use under stress after disuse.q b. it is difficult to conduct that skill and other complex skills at the same time.q c. hanging from a floating DSMB/lift bag may compromise the quality of decompression.q d. hanging from a floating DSMB/lift bag requires a heavier line/reel than tec divers like to use. PADI ®padi.com 5-35
  36. 36. Section fIve: Tec45 Instructor Guide7. Several manufacturers endorse the use of the lift bags/DSMBs are emergency backup buoyancydevices.q Trueq False8. The redundant (double bladder) BCD is the most realistic approach to providing backup buoy-ancy control because (choose all that apply)q a. they were designed specifically for this purpose.q b. you use them exactly like you use your primary BCD – a practiced skill.q c. it is applicable to almost all dive environments.q d. other than a slightly higher cost, it has no meaningful drawbacks.How did you do?1. a, b. 2. b, c, d. 3. True. 4. a. 5. True. 6. a, b, c, d. 7. False. 8. a, b, c, d.Iv. Gas PlanningManual Supported Content Study assignment: Tec Deep Diver Manual, pgs 93-97, Determining Gas Supply and Reserve Requirements for Multiple Depths and Decompression Stops pgs 146 -161, Gas Planning III, Tec Exercise 3.2Learning ObjectivesBy the end of this section, you should be able to answer these questions:1. How do you determine your gas supply and reserve requirements for a multiple depth dive(including dives with decompression or safety stops)?2. What is the theoretical cause of gas narcosis?3. How do you account for narcosis in dive planning?4. What depth limits arise from narcosis concerns?5. How do you perform an “air break” and why should you do so?6. How do you determine your OTUs and OTU limits for a given dive profile?7. How do you calculate your “CNS clock” exposure for a given dive profile and determine itslimits?8. How do you include oxygen concerns in determining the ideal enriched air to use at a givendepth? PADI ® 5-36 padi.com
  37. 37. Instructor Guide Section fIve: Tec459. What is the basis of oxygen surface interval credit, and how do you apply it?You should also be able to:10. Calculate the gas supply requirements and oxygen exposurefor a decompression dive based on a single gas computer using enriched air and/or oxygenduring decompression for conservatism.A. As a Tec 40 diver, you learned to use desk top decompression software to plan your gas requirements and oxygen exposure. This is the state of practice, but as a Tec 45 diver, you should understand more specifically what the software does for you. We’ll start with a review of what you learned already.B. Determining gas supply and reserve requirements for multiple depths and decom- pression stops. 1. To determine the gas you need for a given depth, you multiply your SAC by the number of minutes at that depth and by the conversion factor for that depth: gas required = SAC X min X conversion factor a. You get the conversion factor from the SAC Conversion Factor Table in the Appendix of the Tec Deep Diver Manual. (Round up to the next depth if the exact depth isn’t shown.) b. The conversion factor is simply the absolute pressure in atmo- spheres: Metric: (D in metres + 10) / 10 Imperial: (D in feet + 33) / 33 Metric Example: If your SAC is 24 l/min, how much gas would you consume in 15 minutes at 30 metres? Answer: 24l/min X 15 min X 4.0 = 1440 litres Imperial Example: If your SAC is .7 cf/min, how much gas would you consume in 15 minutes at 100 feet? Answer: .7 cf/min X 15 min X 4.0 = 42 cubic feet PADI ®padi.com 5-37