Tec50

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Instructor Guide Section SIx: Tec50

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Six: Tec 50 Standards and Course Content

The Tec 50 subcourse of the DSAT Tec Diver course introduces Tec 45 divers to the first stages of full technical deep decompression diving. Certified Tec 50 divers are qualified to make multistop decompression dives using air, EANx and oxygen with up to two gases for accelerated decompression.

The Tec 45 diver comes to the course with a strong knowledge and skill base. The Tec 50 course extends these, expanding existing skills and with an added emphasis on mission planning and execution.

Program SequenceThe Tec 50 course consists of two knowledge development sections, three practical applica-

tions sessions and four training dives. You will find these in the Knowledge Development, Practical Application and Training Dive subsections, each with content/presentation outlines and related standards.

The fully integrated instructional sequence for the Tec 50 course is:Tec 50 Knowledge Development OneTec 50 Practical Application OneTec 50 Training Dive OneTec 50 Knowledge Development TwoTec 50 ExamTec 50 Practical Application TwoTec 50 Training Dive TwoTec 50 Practical Application ThreeTec 50 Training Dive ThreeTec 50 Training Dive Four

The Tec 50 course provides flexibility in scheduling knowledge development, practical applications and training dives. You may rearrange the sequence and combine knowledge development and practical applications sessions, provided that you maintain the required instructional sequencing. The requirements are:

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Section SIx: Tec50 Instructor Guide

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• 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 completed before that practical application.

• Any knowledge development section that precedes another knowledge development section must be successfully completed first.

For example, the following sequences would be acceptable:Tec 50 Knowledge Development OneTec50 Knowledge Development TwoTec 50 Practical Application OneTec 50 ExamTec 50 Practical Application TwoTec 50 Training Dive OneTec 50 Training Dive TwoTec 50 Practical Application ThreeTec 50 Training Dive ThreeTec 50 Training Dive Four

Tec 50 Knowledge Development OneTec 50 Knowledge Development TwoTec 50 Practical Application OneTec 50 Training Dive OneTec 50 ExamTec 50 Practical Application TwoTec 50 Training Dive TwoTec 50 Practical Application ThreeTec 50 Training Dive ThreeTec 50 Training Dive Four

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Tec 50 Key StandardsParticipant prerequisites: Certified as a Tec 45 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 45 metres/145 feet using air, EANx and oxygen using open circuit scuba equipment. 18 years old, 100 logged dives (20 deeper than 18 metres/60 feet us-ing EANx, at least 15 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 50 or higher level TecRec diver

Training Dive One Environment: Confined water or limited open water with ready access to water shallow enough in which to stand. Depths: Minimum: 2.4 metres/8 feet Maximum 10 metres/30 feet Decompression: No stop only, five stop simulated decompression Gases: Air or EANx, recommended that all blends be breathable at maximum dive depth Ratios: 6:1, 8:1 with one or more certified assistants

Training Dive Two Environment: Open water Depths: Minimum: 12 metres/40 feet Maximum: 24 metres/80 feet Decompression: No stop only, 30 minutes simulated decompression Gases: Air or EANx, recommended that all blends be breathable to maximum dive depth Ratios: 4:1, 6:1 with one or more certified assistants

Training Dive Three Environment: Open Water Depths: Minimum: 30 metres/100 feet Maximum: 50 metres/165 feet Decompression: Decompression dive with two decompression gases Gases: Air, Air, EANx or oxygen Ratios: 3:1, 4:1 with one or more certified assistants

Training Dive Four Environment: Open water Depths: Minimum: 40 metres/130 feet Maximum: 50 metres/165 feet Decompression: Decompression dive with two decompression gases Gases: Air, EANx or oxygen. Trimix permitted within limited conditions. Ratios: 3:1, 4:1 with one or more certified assistants

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Tec 50 Knowledge Development

Knowledge PreassessmentThe Tec 50 course builds upon and extends the knowledge development estab-

lished in the Tec 45 course. A lack of understanding or familiarity with the fundamental knowledge required of a Tec 45 diver can substantially impede learning at the Tec 50 level, and in some cases, raise safety concerns. Therefore, it is important to verify and assess prerequisite knowledge before beginning Tec 50 level knowledge development. Apply these standards:

1. Students who enter the course with a qualifying prerequisite certification (not DSAT Tec 45 certification) must complete all the Tec 40 and Tec 45 Knowledge Reviews and the Tec 45 Exam. It is recommended that you have these students com-plete the reading assignments first. Check over the Knowledge Reviews and score the exam, providing remediation to achieve mastery as necessary.

2. Students who enter the course as DSAT Tec 45 divers (not a qualifying certification from another organization) who you did not personally certify, and/or who completed certification more than six months prior to the start of the course, must retake the Tec 45 exam. Score the exam, providing remediation to achieve mas-tery as necessary.

3. As appropriate, it’s recommended that you preassess potential students’ skill and knowledge in a confined water session and/or interviews. You can combine remedi-ation with preassessment, refreshing student capabilities to mastery prior to beginning the course.

4. Students who you certified as DSAT Tec 45 divers (not a qualifying certifica-tion from another organization) within six months of starting the course do not have any particular assessment requirements. It is recommended that you check their training records for any areas that may have had difficulty and conduct informal assessments by asking questions, etc.

The following knowledge development outlines provide the course content in presentation 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 is recommended that you cover knowledge development through student independent study with the manual and handouts, with presentations that review/remediate what they studied.

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The content outlines note manual supported content and other delivery content. The manual supported content includes a list of reading, exercise and Knowledge Review assignments (repeated in list form in the Appendix for your convenience) based upon the Tec Deep Diver Manual. The other delivery content covers material that is not in the Tec Deep Diver Manual. You may simply deliver this material in verbal presentations using the Tec Diver Lesson Guides on PowerPointTM, or (recommended) you can copy those outline sections 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 involve staff introductions, paperwork, logistics, scheduling etc., do not have independent study materials.

Tec 50 students do not use the Knowledge Reviews in the Tec Deep Diver Manual. Instead, copy the blank Tec 50 Knowledge Reviews in the Appendix for their use. You will also find the answer keys there. Students have not completed a Knowledge Development section until they have completed the corresponding Knowledge Review correctly, accurately and completely.

The final step in completing Tec 50 Knowledge Development is the Tec 50 Exam. Tec 50 students complete the exam after successfully completing Knowledge Development Three. To be successful, the student diver must score 80% or higher and review each question missed with the instructor until mastery on all questions is achieved. Students who score less than 80% must repeat the exam (version B) after ample time to remediate. It is recommended that you administer the exam after Tec 50 Knowledge Development Two.

All material in the Knowledge Development content outline is required and must be covered, studied and otherwise remediated until the student demonstrates mastery.

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Tec 50 Knowledge Development One[The voice in these presentations addresses students. Notes to the instructor appear in brackets.]

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 50 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 50 Knowledge Review One].a. [Review answers to assess mastery so you can tailor your presenta-

tions accordingly.]B. Course Goals

1. The goals of the Tec 50 course are:a. To qualify you to make limited decompression dives using air,

enriched air and oxygen to a depth of 50 metres/165 feet or less.• Certification as a Tec 50 diver qualifies you to use two

decompression gases of EANx and 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 50 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 50 limits.

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e. To lay the foundation continuing your training in the Tec Trimix 65 and Tec Trimix Diver courses.• If your instructor is a DSAT Tec Trimix Instructor,

you may, at your instructor’s discretion, have the option of using trimix during Tec 50 Training Dive Four.

C. Your Obligations and Responsibilities1. During the Tec 45 course, you have these obligations and responsi-

bilities: 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 maintain adequate physical and mental health, and to alert the instructor to any problems you have with them.

d. 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 consequences:a. In the worst case, you could be injured, disabled or killed.b. You will have failed to demonstrate the attitude and maturi-

ty required for tec diving, and will not qualify for certifica-tion.

D. Course Overview, Schedule & Logistics, Administration, Assignments and Study1. 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. Administrationa. Course costs [Explain and collect, as appropriate, all costs

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associated with the course.]b. Equipment and material requirements [Explain what’s

required for the course, and of that, what students must pro-vide and what you will provide.]

c. [Confirm course prerequisites:• Students may confirm these with certification cards,

log entries, signed affidavits, etc. 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 speci-fied 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 50 Training Dive One, the student must have a physician’s approval and signa-ture 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 stu-dents in the DSAT Tec 50 course to have dive accident insurance, 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 most of it.

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• Read the assigned handouts, sections and exercises.b. You will use the manual to complete knowledge reviews pro-

vided 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 50 Exam before the final three training dives of the course.

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II. Emergencies

Manual Supported ContentStudy assignment: Tec Deep Diver Manual, pg 230, Equipment V, Tec Exercise 5.3

Learning ObjectivesBy the end of this section, you should be able to answer this question:1. What is the priority and how do you respond to an unresponsive diver at depth during a decompression dive?

A. As you’ve learned in previous training regarding an underwater convulsion, an unresponsive diver at depth is one of the most serious emergencies you face. Having required decompression makes a rescue complicated.

[Remind student divers of the discussion you had previously about a team mate convulsing at depth -- the same considerations apply.]

B. As a technical diver, you accept the risk and responsibility that something could cause you to become unresponsive, and that decompression require-ments and the distance from the surface may make it difficult or impossible to effect a rescue before you drown.

C. If a team mate becomes unresponsive:1. The priority is getting the victim to the surface (but remember recom-

mendation regarding waiting for the fit to end with diver having a convulsion).

2. Hold the regulator in if it is in and the victim is breathing. If you need to tow the victim underwater to an appropriate ascent area to make a rescue possible (due to current, proximity of surface support, etc.):a. Make the victim neutrally buoyant.b. Hold the mouthpiece in while towing.

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3. Ascend the victim to the surface.a. Take the diver up yourself, if possible, based on your decompres-

sion situation. It’s recommended that you do not drop your or the diver’s weights until reaching the surface (unless necessary), so you don’t risk harm to yourself by losing control of the ascent. As much as possible, keep the victim’s head in a neutral position that allows expanding gas to escape from the victim’s lungs.

b. Signal surface support divers if available.c. Divers completing or almost complete with their decompression

may be able to take over the rescue with minimal DCS risk.4. Whether to risk DCS yourself is a difficult call but one you may have to

make.a. If you owe relatively little decompression, the victim is breathing

and has the regulator in, and there’s assistance at the surface, the probability of the victim surviving is high and the probability of severe DCS is low.

b. If you have a lot of decompression due, the victim is not breathing and is unresponsive, and has been for some time, and there’s little or no surface support, the DCS risk is high and the probability of bringing the victim back is low.

c. There are no hard rules -- you can only make the best decision you can, given the circumstances. Remember that you shouldn’t take unreasonable risks yourself to help the victim -- if you’re in trou-ble, you can’t help anyone else.

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Other Delivery Content, Tec 50-1Study assignment: Tec 50 Handout 1

Learning ObjectivesBy the end of this section, you should be able to answer this question:1. What are the options and considerations for long hose gas sharing during the decompression phase of a technical dive?

D. Sharing gas with the long hose is usually a procedure that closes the gap between when the victim loses the gas supply and reaches another independent gas supply or the surface.1. On a deco dive, if there are stops before the first gas switch, it may be

necessary to supply gas to the affected diver on those stops.2. One advantage of a three person team is that it provides two people to

help the one – both divers can provide gas to the victim at various inter-vals so that neither one has a severely depleted supply.

3. At the first gas switch, the victim can usually dive independently through the rest of the dive.a. At the Tec 50 level, air breaks will not usually be needed until

after the second gas switch; the affected diver can usually break on the lower oxygen deco gas.

b. If the first deco gas is EANx50 or higher, however, the diver may need to share gas for air breaks.

c. At the surface after completing decompression, the victim will usually breathe from a deco cylinder while orally inflating the BCD, but it’s a good idea for a team mate to stay ready with the long hose until the victim is out of the water.

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Exercise, Other Delivery Content, Tec 50-11. Considerations and options for long hose gas sharing on a decompression dive include (choose all that apply):o a. the depth at which the victim switches to the first deco gas.o b. whether the victim will need long hose gas sharing for air breaks.o c. whether the long hose is oxygen compatible.o d. being ready to provide assistance at the surface after completing decompression.

How did you do?a, b, d.

III. Thinking Like a Tec Diver

Manual Supported ContentStudy assignment: Tec Deep Diver Manual, pg 231-232, Thinking Like a Tec Diver V, Tec Exercise 5.4.

Learning ObjectivesBy the end of this section, you should be able to answer these questions:1. Professionals involved with rescue sometimes cite the philosophy “Better thee than me.” What does this mean and how does it apply to tec diving?2. How do you plan for “specific” mistakes and emergencies?

A. When to separate from a team mate1. The unresponsive diver underwater discussion, and the PADI Rescue Diver

course, caution that in an emergency, you don’t necessarily help if doing so puts you at unacceptable risk. Professional rescuers sometimes call this “Better thee than me.”a. This sounds uncaring, but actually it is the best choice for you and

the victim -- you can’t help someone if you’re in trouble, too.b. Two divers in trouble splits emergency resources.

2. In team tec diving, a similar situation may arise in which a team mate enters a situation that poses an unacceptable risk for you.

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a. You may have to decide whether to accept the risk to help your team mate manage it, or whether to leave your team mate to man-age solo.

b. As a team member, you accept that you will take some risk (tec diving involves risk) for each other.

c. But, at the extreme it is better to have only one diver hurt or dead than two or three.

d. As with the unresponsive diver, there are no hard rules, only hard decisions. You’ll have to use good judgment and make the best decision you can under the circumstances.

B. Foreseeing the foreseeable1. Training in the Tec Diver course, Tec 40 through Tec 50, prepares you

for common, reasonably foreseeable risks in deep tec diving to 50 metres/ 165 feet.

2. Skilled tec divers learn to look at each dive and plan for reasonably fore-seeable mistakes and emergencies specific to that dive. E.g. In poor visi-bility, how to prevent team separation and what to do if it happens; in current, allowing for higher gas consumption; in cold water, planning for the problems of working your gear with thick gloves and some narcosis.

3. Teach yourself to be specific to the dive when covering A Good Diver’s Main Objective Is To Live. You do this by asking, as you already learned, “What about this can hurt or kill me?” Have a way to handle every rea-sonable answer.

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Learning ObjectivesBy the end of this section, you should be able to answer this question:1. What are three reasons you may want to “tec dive” in a pool or shallow water?

C. Practice, practice, practice1. Tec diving involves a lot of motor procedures. A motor procedure is a

series of motor skills that you carry out in sequence in response to a need of some kind (routine or emergency).

2. Motor skills erode with disuse, but usually refresh quickly with practice.3. New situations may call for creating new motor procedures.4. As a tec diver, you may find it a good idea to practice your tec diving

skills in a pool or other shallow, no stop dive situation for these reasons:a. To refresh your skills – You already know you need to do this as a

recreational diver if you’ve not been active in awhile. Even if you’re active as a tec diver, however, you may want to refresh sel-dom-used emergency skills. These may include long hose drills, send up lift bags/DSMBs, drift decompression, etc. – whatever skills you may need in an emergency, but have not actually prac-ticed in quite a few dives.

b. To extend your skills – You may need to apply what already know in a new situation; practicing first may help. For example, if you may have to don and remove deco cylinders in reduced visibility and heavy surface chop while hanging onto a current line, it may be worth practicing doing this with your face entirely underwater and your eyes closed, while hanging onto a line.

c. To invent mission specific skills – Your dive plan may call for doing something highly specific, such as recovering a lost object. If you don’t know the best way to rig the object for recovery, you may want to invent the procedure using a duplicate of it in shallow water.

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Exercise, Other Delivery Content, Tec 50-21. Reasons you may want to “tec dive” in a pool or shallow water include (choose all that apply):o a. refreshing your skills.o b. teaching yourself to cave dive.o c. to extend your skills to specific situations.o d. to invent mission specific skills.

How did you do?a, c, d.

IV. Mission Planning

Manual Supported ContentStudy assignment: Tec Deep Diver Manual, pg 233-235, Mission Planning, Tec Exercise 5.5.

Learning ObjectivesBy the end of this section, you should be able to answer this question:1. What is your dive “mission” and why do you have one?2. Where does your dive mission “objective” rank in priority with the other aspects of a tec dive?3. What is the most common mistake in mission planning?4. How can you simplify a dive mission?5. How does mission planning usually affect dive planning?

A. “Main” in A Good Diver’s Main Objective Is To Live stands for “mission.”1. Tec dives tend to have missions -- the dive objective, which is usually

more than simply going for a look. Without a mission, you’re nothing more than an underwater gear manager; that accomplishes nothing, and you’ll quickly find it unsatisfying. The whole point of learning to tec dive is so you can do something. Common missions include:a. Checking out new sites to see whether they’re worth further

exploration.b. Mapping (ships, caves, reefs).

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c. Recovering something.d. Photo/video.e. Taking samples/recording observations (science related).f. Evaluating equipment or procedure performance for future

application.g. Team practice for a more complex dive.

2. Your dive has a mission for two primary reasons:a. It helps assure that the dive is worth the time and money

you put into it.b. It coordinates the dive team’s planning and dive execution

by providing a common purpose.B. Although the mission is the “purpose” of the dive, the mission’s priority

ranks last behind all other dive planning considerations. As you learned, everyone returning unharmed is the first priority.

C. Mission planning1. The most common mistake in mission planning, and the most com-

mon reason they fail, is trying to accomplish more than is reason-able in a single dive.

2. Since tec diving is itself complex, missions must be simple and realistic.

3. Sometimes the objective is obviously broad and complex, such as “map an entire shipwreck.”

4. Sometimes an objective is more complex than it sounds, such as “locate and recover a flooded DPV.”

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D. To simplify missions:1. Analyze the objective to determine the subtasks it involves. Example: “Locate and recover a flooded DPV” requires 1) a search,

2) rigging the flooded DPV to lift it and 3) actually bringing it up.2. Subtasks may have subtasks.3. Simplify by planning subtasks as dive missions based on time and

what a team can reasonably accomplish on a single dive. As appropri-ate:a. Divide subtasks among team members, according to qualifica-

tions. b. Divide subtasks among different teams.c. Accomplish the objective through several missions on several

dives.d. When possible, organize so that a team can leave in midtask

and resume (or have another team resume) where they left off.e. Rehearsals also simplify missions -- practice a task on land or

in shallow water before trying at depth.4. Rehearsals also simplify missions -- practice a task on land or in shal-

low water before trying at depth.E. Mission planning amid dive planning

1. A clear mission usually simplifies dive planning because it determines depth, time and location.

2. Dive logistics and daily logistics may change the mission. E.g., When recovering the DPV with two dive teams, you find the visibility half its usual clarity. You assign both to the search instead of one to locate and the other to recover, and plan the recovery for the next day.

3. Beware of task focus instead of dive focus.a. Your/the team’s attention should always be on the dive first,

the mission second.b. The dive ends at the required turn time or turn pressure, no

matter how close or far from accomplishing the mission.

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Tec 50 Knowledge Development Two

Manual Supported ContentStudy assignment: Tec Deep Diver Manual, pgs245-252, Chapter Six, all Tec Exercises.

I. Emergencies

Learning ObjectivesBy the end of this section, you should be able to answer these questions:1. How do you define decompression sickness, arterial gas embolism and decompression illness?2. What are the signs and symptoms of decompression illness?3. What is the first aid for suspected decompression illness?4. How does administering oxygen benefit a patient with decompression illness?5. How you administer a field neurological exam?6. How can having diver accident insurance make treatment for decompression illness more effective?

A. As you learned already, technical divers face new risks, and the same risks to a greater degree, compared to recreational divers. One of these risks is decompres-sion illness.

B. As you learned in the PADI Rescue Diver course:1. Arterial gas embolism (AGE) is the condition in which air bubbles enter

the bloodstream through a lung rupture, usually the result of holding the breath during ascent.

2. Decompression sickness(DCS) is the condition in which inert gas (nitro-gen and/or helium) forms bubbles in the tissues and bloodstream as it comes out of solution due to high supersaturation following ascent.

3. Decompression illness(DCI) is the field term for both DCS and AGE together. The first aid and emergency management for both is identical, so it’s not important -- and sometimes impossible -- to distinguish between DCS and AGE.

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C. Signs and symptoms of DCI include pain in the joints or mid limb, undue fatigue, inability to urinate, blurred vision, blotchy skin rash, tingling in the extremities, swelling, vertigo, hearing or speech impairment, paralysis, numbness, unconsciousness, bloody froth from the mouth, loss of coordi-nation, personality change and respiratory/cardiac arrest.

D. First aid and responding to DCI should be part of your predive planning, including how you’ll get the patient into emergency medical care. As you learned in the PADI Rescue Diver course, first aid for DCI includes:1. Keep the patient lying down; on the back is fine for a responsive

patient, left side down (recovery position) for an unresponsive breathing patient.

2. Monitor airway, breathing and circulation (ABCs) and administer CPR as necessary.

3. Administer oxygen to a breathing patient, ideally 100 percent via a demand system.a. A very weak patient may not be able to breathe with a

demand system -- use freeflow oxygen with a nonrebreather mask and reservoir bag set at 15 litres per minute flow rate. Remember to inflate the bag before placing the mask on the patient’s face; if the bag deflates completely when the patient inhales, set the flow at 25 litres per minute.

b. For a nonbreathing patient, use freeflow oxygen while pro-viding rescue breaths through a pocket mask. If the patient resumes breathing, switch to the demand or nonrebreather mask.

c. Continue oxygen until you get the patient into emergency medical care, or until you run out. If you run out of oxygen, as a tec diver you may have EANx80 or other high oxygen blend to use if the patient can breathe through a standard regulator.

d. You may give a fully responsive patient fluids to help main-tain hydration. Keep the patient lying down, with water the preferred fluid. Isotonic fluids and fruit juices are accept-able; avoid anything with caffeine or alcohol.

e. Monitor the oxygen pressure gauge; don’t let the cylinder run empty with the mask still on the patient.

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f. See the PADI Emergency Oxygen Provider Manual if you need to refresh what you learned in that course.

4. Contact emergency medical care and the diver emergency service (DAN) that serves the area and get the patient into emergency medical care, and ultimately a recompression facility, under their direction. Statistics show that the sooner recompression treatment begins, the more probable com-plete resolution of symptoms. Delays, on the other hand, are more prone to leave permanent or extended residual symptoms.

E. Oxygen administration has proved to reduce DCI symptom severity and improve the probability of a successful treatment. The reasons for this appear to be that:1. Breathing pure oxygen helps oxygenate tissues suffering from restricted

blood flow due to bubble formation. This helps protect these tissues until the patient receives recompression.

2. Pure oxygen increases the pressure differential of the excess dissolved inert gas, speeding it out of the body faster (same principle that applies to accelerated decompression). This minimizes and slows further bubble growth, reducing further and worsening symptoms.

3. If you’ll be a long way from emergency medical care, have plenty of oxy-gen (tec divers usually do). You can also add a rebreather emergency oxy-gen system to the conventional emergency oxygen set to extend the dura-tion of the oxygen supply (using this system takes a little extra training).

F. Field neurological examination1. DCI symptoms and signs can be ambiguous. If unsure, a field neurologi-

cal exam looks for possible effects on the nervous system. If you find any irregularities, assume DCI, begin first aid and contact emergency medical care.

2. Field neurological steps:a. Have the patient follow your finger with both eyes. They should

track together.b. Have the patient use both hands to squeeze yours. Weakness on

one side suggests a problem.c. Ask the patient to close both eyes, stretch out the arms and then

bend at the elbows to touch the nose with fingertips. The inability to do this with both or either hand suggests a problem.

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d. The patient should be able to stand on one foot.e. Snap your fingers on either side of the patient’s head. Ask if there’s

any significant difference in loudness. If there is, it may indicate impaired nerve function (but ear barotrauma or even water in the ears may be involved with this test).

G. The role of diver accident insurance1. Because the more quickly a patient begins treatment the more likely a

favorable outcome, especially as a tec diver you want to minimize any-thing that would delay treatment should you ever need it.

2. Delays sometimes occur when there’s doubt about payment for a treat-ment; insurance minimizes these delays by establishing the financial cov-erage.

3. Carrying diver accident insurance that covers tec diving, such as offered by some PADI Offices, reduces or eliminates these delays by establishing financial coverage immediately.

4. Compared to your overall investment in tec diving, diver accident insur-ance costs very little, yet can potentially benefit treatment outcome and the financial picture if you should experience DCI.

5. Some dive sites and charter dive boats require that you carry diver insur-ance.

II. Thinking Like a Tec DiverLearning ObjectivesBy the end of this section, you should be able to answer these questions:1. How do prudent tec divers broaden their abilities and limits within tec diving?2. What quality do you find in tec divers who extend their personal limits at an appropri-ate pace?

A. The Tec Diver course qualifies you to enter the initial ranks of deep tec diving.B. Even before you finish the course, it’s not unusual for many tec divers to be

thinking ahead to their next course and extending beyond the limits this course qualifies you for.

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C. Getting ahead of yourself in tec diving is the recipe for getting hurt or killed. Here’s how prudent tec divers expand their abilities:1. Gain experience. The most important immediate step is to gain experi-

ence within your current qualifications. Experience now forms the foun-dation you need to build on to go forward.

2. Push your comfort zone gently. It’s acceptable to extend your limits a bit as you gain experience -- if it weren’t, there would be no way to grow. Prudent tec divers extend themselves carefully, only slightly beyond their experience, and are always prepared to pull back.

3. Learn from those with experience. Hang out with and dive with experi-enced tec divers, especially teams. You’ll learn a lot and get a lot of guid-ance. Although you typically start as a support diver, as you prove your mettle, gain experience and broaden your qualifications, you’ll find your-self on increasingly exciting dives.

4. Respect the limits. Although you’re extending your limits, you’ve been taught the outside limits to your qualifications. Respect these.

5. Continue training. Experience is crucial for moving on, but so is training. In some types of tec diving, such as cave diving or inside wrecks, learn-ing by experience is extremely hazardous. The way to move past the out-side limits to your qualifications, once you’ve gained experience, is to train for a new set of limits and gain experience within them.

D. The top names and leaders in tec diving, almost as a rule, reached their current status over a period of years and hundreds of dives. They’ve become the fore-front of tec diving because they share a common characteristic: patience.

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III. Introduction to Trimix

Learning ObjectivesBy the end of this section, you should be able to answer these questions:1. What is trimix?2. What are the advantages and disadvantages of diving with trimix?3. What will your qualifications be with respect to diving with trimix as a Tec 50 diver?A. At depths beyond 30 metres/100 feet, trimix is increasingly advantageous.

1. Trimix is a blend of oxygen, helium and nitrogen.a. Much as enriched air nitrox is abbreviated “EANx,” trimix is abbrevi-

ated “TMx.”b. Trimix nomenclature is to label a blend with the oxygen and helium

content. Example: TMx10.5/50 is 10.5 percent oxygen, 50 percent helium, balance nitrogen

2. The prevailing view is that you use trimix for open water dives deeper than 50 metres/165 feet .a. Deeper than 40 metres/130 feet, the prevailing view is that trimix is

required for overhead environments or complex open water environ-ments.

b. Although using air as deep as 50 metres/165 feet for open water diving has a long-standing record of being acceptable, the trend is toward using trimix beginning at shallower depths.

c. However, air/EANx remains a viable option in the 30 metre/100 foot to 50 metre/165 foot range in open water and reasonable conditions.

B. Advantages and disadvantages of trimix1. Advantages

a. Reduced narcosis – Helium is not narcotic, so trimix greatly reduces narcosis. This is particularly important for dives below 50 metres/165 feet, but is useful as shallow as 30 metres/100 feet for complex dives, dealing with poor conditions. It is considered mandatory for overhead environment diving beyond 40 metres/130 feet.

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b. Reduced gas density – Helium is a lighter than oxygen and nitrogen so it is easier to breathe under pressure. This reduction in respiratory load is thought to help reduce carbon dioxide buildup by improving respira-tory exchange, as well by reducing the muscular effort required to breathe.

c. Reduced oxygen exposure – At depths below 50 metres/165 feet, it becomes increasingly important to reduce the oxygen in a breathing gas. Helium is a better choice than nitrogen for reducing the fraction of oxygen for both its non narcotic and its low gas density properties.

2. Disadvantagesa. Decompression times and schedules – Because helium diffuses more

rapidly than nitrogen, you need to use tables or mixed gas dive comput-ers set for the specific trimix you’re using.• All else being equal, within typical tec diving limits, a trimix

dive requires more decompression than an air/EANx dive.• You cannot simply use an air or EANx schedule for trimix, even

if the oxygen content is the same.• Trimix almost always requires accelerated decompression with

higher oxygen deco gases.• Most software and many high end tec diving computers support

trimix, so planning your dives does not differ much from what you do as a Tec 50 diver – but you must plan for helium.

b. Theoretical DCS risk – Because helium diffuses rapidly, in theory DCS is more likely with helium, particularly following a rapid ascent, a poorly executed or omitted decompression stop, or similar error.• Recent examination of data does not find that this is clearly the

case. There may be more risk of DCS Type II (neurological), though this isn’t clearly the case either.

• Some argue that helium’s rapid diffusion makes it more effi-cient during decompression.

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• Until we know more, the prudent practice is to assume it has less error tolerance and higher risk; tight, well executed dive skills and conservative schedules are part of reducing DCS risk regardless of what gases you’re using.

• Although there is some question whether the helium diving has a higher DCS risk, until we know more it is a risk you must accept if you dive trimix.

c. Cost and availability – Helium is expensive, and in some areas, nearly impossible to get.• Using open circuit scuba, the cost of helium can be significant.• In some areas, helium isn’t available even at a high price.• For this reason, in some areas trimix isn’t commonly used, or used

less frequently, for open water dives in the 30 metre/100 foot to 50 metre/165 foot range.

d. Heat loss – Helium absorbs heat rapidly and insulates poorly compared to nitrogen-oxygen. For that reason (among others), you cannot use it in a dry suit. The most common solution is to use a small cylinder with an inflation gas (typically argon) to inflate the dry suit.

3. Note: Using trimix does not make an unsafe dive safe!a. Trimix helps offset some of the disadvantages of air/EANx in deep diving,

but it does not eliminate risk.b. Using trimix does not make it acceptable to dive in poor conditions or situa-

tions beyond your experience and skill level. If the site is unsafe for diving with air within air depth limits, pick another site regardless of what gases you’re using.

C. Trimix and the Tec 50 certification1. If your instructor is a DSAT Tec Trimix instructor, you may have the option of

using trimix on Tec 50 Training Dive Four.2. Realize that this does not certify you or qualify you to dive trimix independently.3. To dive trimix, continue your training with the Tec Trimix 65 course and/or the Tec

Trimix Diver course.

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Exercise, Other Delivery Content, Tec 50-31. Trimix is a blend of oxygen, helium and nitrogen.o Trueo False2. Advantages of diving with trimix include (choose all that apply):o a. reduced narcosis.o b. that it is a better insulator in your dry suit.o c. it has less density.o d. reduced oxygen exposure3. Disadvantages of diving with trimix include (choose all that apply):o a. theoretical DCS risk.o b. cost and availability.o c. longer decompression times.o d. oxygen toxicity.How did you do?1. True. 2. a, c, d. 3. a, b, c.

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Tec 50 Practical ApplicationOn the surface, the practical applications develop skills with procedures related

to gear rigging, using decompression software and dive planning. However, as in the Tec 40 and Tec 45 courses, the practical applications are also develop the team thinking and spirit appropriate for technical diving. At the Tec 50 level, divers are expected to think and behave in ways that demonstrate a clear orientation toward the team and accomplishing things as a team.

To accomplish this, as in previous course, performance objectives require each team – not just individuals – to meet the requirements before progressing. This encour-ages team mates to support each other and work together. It begins the process of learn-ing that in tec diving, what one person does can affect everyone, for better or worse.

You may rearrange teams if necessary to avoid one individual carrying the entire workload, or to avoid a person with significant difficulties holding back the rest inap-propriately. Otherwise allow teams to develop their own interaction and cooperation in meeting the challenges you present in the practical applications. Pay attention to be sure that each person ultimately meets the required performance objectives, but let team mates help those with difficulty develop their capabilities. Unless necessary for logistics or to assure individuals meet performance requirements, avoid breaking up closely-knit, well functioning teams.

Mission EmphasisAt the Tec 50 level, dive planning that addresses the a Good Diver’s Main

Objective Is To Live elements should already be in place and routine. Practical applica-tions at this level continues the planning, but these elements also should be routine (except, perhaps, having two deco gases and an emphasis on accelerated decompres-sion). The primary new development emphasis in the Tec 50 practical applications is on mission planning and execution. All dives, including Tec 50 Training Dive One (pool or limited open water) should have a mission. Missions may be independent, or all four dives may be small missions contributing to a larger, overall mission. The following standards and recommendations apply to all Tec 50 missions planned in the practical applications and carried out in the training dives:

• Students must plan and attempt a mission on each dive, but succeed-ing at the mission is not a performance requirement. Emphasize that safety is always the overriding mission; in fact, completing the mission at the expense of safety would fail to meet a training dive’s requirements.

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• When possible, allow teams to choose their own missions. Depending upon the dive site, they may do this entirely on their own, based on upon your sug-gestions or choose from a list.

• Teams may choose to interact with each other, each with a mission to carry out that is a subtask for an overall mission.

• When feasible, have teams decide upon their mission for all dives during Tec 50 Practical Application One. They don’t have to plan the details for all the dives, but this allows them to build toward an overall goal, such as mapping parts of a wreck in several steps. It also allows them to use Tec 50 Training Dives One and Two (no stop dives) as rehearsal dives, if appropriate.

• Regardless of the mission types, assess each mission plan according to the following questions, having teams make adjustments as necessary:o Is accomplishing the mission realistic within the context of the

broader dive plan?o Has the team eliminated unnecessary complications?o Does the team have the expertise and equipment to accomplish the

mission?o Does the plan address diver safety first?

The course intention is to use the practical application sessions to plan an immediate-ly following dive or dives. However, if scheduling and logistics will separate the practical applications from the training dives by more than a day or two, you may conduct the practi-cal applications as exercises, and then have teams plan the actual dives when you meet to conduct them.

Tec 50 Practical Application One

Tec 50 students come into the course with either of two backgrounds. First, they may have the Tec 45 certification, or they may have a qualifying certification from another orga-nization.

The first part of the Tec 50 Practical Application One is primarily for you to confirm that everyone is set to go with the standardized technical rig (or sidemount) as required by standards. During this practical application, working as teams, students set up their rigs, including two stage/deco cylinders with simulated deco gases (see Tec 50 Training Dive One) following the guidelines in the Equipment I and Equipment II discussions of the Tec Deep Diver Manual (or comparable sidemount setup).

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The second part of this practical application is dive planning with gas require-ments, oxygen exposure, etc. calculated manually. This confirms understanding and retention from prior learning, and assures that students with other-organization back-grounds understand the processes. This is the last place in the Tec Diver course instruc-tional flow where manual calculation is required. After this, students may use their desk top decompression software to determine requirements, though obviously some manual calculations (turn pressures, for example) will still be needed. You may, at your discre-tion, require teams to manually calculate these requirements in subsequent practical applications and/or dive planning.

To successfully complete this Practical Application, the student should be able to:1. Working within the student’s assigned team, rig gear, including two decompression cyl-inders, so that the equipment of all team members conforms with the standardized techni-cal rigging philosophy previously learned, and with any environment-specific require-ments provided by the instructor.2. Working as a team, plan a hypothetical technical dive with two gas switches made for accelerated decompression and with not fewer than five decompression stops, based on information (gases, depths, times, objective, environment etc.) provided by the instructor, with individual diver gas requirement calculations, turn points, reserves, OTUs, CNS clock, etc. calculated manually (not with deco software) using the TecRec Dive Planning Slate, adequately addressing all points of a Good Divers Main Objective Is To Live plan-ning.3. As a team, compare the resulting calculations with the same dive as calculated by desk top decompression software, find any variations and assess whether these variations reflect minor differences in rounding, etc., or an error in the team’s calculations.4. As a team, plan a mission, simulated mission or practice mission to execute as part of the dive being planned.

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Part One, Conduct1. Divide the class into teams of two to four individuals.2. Review proper rigging with a previously set up kit, including mask, fins,

gauges, exposure suit, two deco cylinders each, etc. If necessary, refer stu-dents to the first three chapters of the Tec Deep Diver Manual, as well as Tec 45 Handout 1.

3. Tell the class that, working as teams, they’re to set up their equipment to the appropriate similar configuration according to your example and what they’ve previously learned.• Depending on logistics, you may give this as an assignment to be com-

pleted by a specific time for your evaluation, or you can conduct this as a session during which all teams work with you and staff supervising.

• Emphasize that they succeed at this exercise as a team or that they go back and try again as a team. If student divers are not working together, you are not accomplishing the team objective.

• Encourage discovery learning and team mates helping each other set up into the appropriate configuration.

4. Be available to answer questions and assist with configuration challenges.5. It is recommended that you have basic clips, tools, labels etc. that students may

need while configuring their gear.6. When complete, students present their kits as teams for you to assess. Note

any discrepancies and have the team correct them and then present their rigs again as a team. It is acceptable to stipulate that no one in the team is done until everyone in the team has successfully set the kit appropriately.

7. Tip: Schedule Tec 50 Practical Application I to immediately precede Tec 50 Training Dive One, with time for remediation and adjustments. This gets every-one’s gear set up for the dive, and assures that team mates are familiar with each other’s gear.

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Part Two, Conduct1. Assign each team a Tec 50 level dive to plan using and adequately

addressing all points of A Good Diver’s Main Objective Is To Live planning, based on information you provide.

• Tell divers that the intent of this exercise is to plan an entire technical deep accelerated decompression dive with two deco cylinders, just as they will as certified Tec 50 divers. Explain that they will be doing this in every practical application session in their training from this point through Tec Trimix Diver.

• It is recommended that you use this session to meet the planning requirements for Tec 50 Training Dive One, with the same teams, equipment, gases (simulated) etc. See Tec 50 Training Dive One for ref-erences to specifics to provide students in planning.

• Give students the dive depth (max 50 metres/165 feet) and time. They should plan the dive as a two deco gas, accelerated decompression dive (it is recommended that you assign EANx70 and oxygen as the deco gases). Run the numbers for the depth/time and gases ahead of time to be sure they are planning a five stop dive within the limits of Tec 50 diver.

• You may provide a decompression schedule, or you may have them generate one using decompression software. However, they must calcu-late everything else by handing using the TecRec Dive Planning Slate. Encourage team mates to help each other, but not do it for each other.

• They should have their working and deco SAC rates. Assign rates if necessary.

• The dive plan should cover all aspects of a Good Diver’s Main Objective Is To Live.

• If divers discover something doesn’t work (e.g., the available cylinders do not hold enough gas to meet the requirements), they should adjust the plan accordingly (for example, by reducing bottom time, using a shallower depth, different gear, etc.). You may need to accept the revised plan, but tell students they will still do the simulated decom-pression in Tec 50 Training Dive One.

• Give ample time for this exercise. Be available to provide guidance and answer questions.

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• When they’re done, review the overall plan and note any additional problems they may not have thought of. Ask them for solutions to these. Different teams may have somewhat different plans – that’s fine, provided they reasonably address all required points.

2. Have students plan a mission as they plan the dive.• The mission may be an actual mission (an actual task they can accomplish), a

practice mission (rehearsal for a later actual mission) or a practice mission (a simulated mission that is not a rehearsal for any other mission).

• It’s recommend that you have teams begin planning a mission(s) for Tec 50 Training Dives Three and/or Four so that they can plan Dives One and/or Two as rehearsal dives, if appropriate.

• Emphasize that mission planning is very important and should be the main point of the dive plan, but that executing the mission is always secondary to returning from the dive safely.

• Depending upon the situation, you may assign missions, give teams choices of missions or allow them to come up with their own missions entirely (subject to your approval).

• Be available for consultation and to provide ideas. Allow extra time for mission planning.

• Encourage teams to discuss mission and dive planning for forthcoming dives on their own, away from class, as part of their preparation.

3. Have students compare their calculations to those of decompression software.• Have teams note and account for any major differences.

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Tec 50 Practical Application Two

To successfully complete this Practical Application, the student should be able to:1. Working as a team, use desk top decompression software to plan a hypothetical technical dive with two gas switches made for accelerated decompression, based on information (gases, depths, times, objective, environment etc.) provided by the instructor, adequately addressing all points of a Good Divers Main Objective Is To Live planning.2. As a team, plan a mission, simulated mission or practice mission to execute as part of the dive being planned.

1. Assign each team a Tec 50 level dive to plan using and adequately addressing all points of A Good Diver’s Main Objective Is To Live planning, based on information you provide.

• Tell divers that the intent of this exercise is to plan an entire technical deep accelerated decompression dive with two deco cylinder just as they will as certified Tec 50 divers. Explain that they will be doing this in every practical application session in their training from this point through Tec Trimix Diver.

• It is recommended that you use this session to meet the planning requirements for Tec 50 Training Dive Two, with the same teams, equipment, gases (simulated) etc. See Tec 50 Training Dive Two for references to specifics to provide students in planning.

• Give students the dive depth (max 50 metres/165 feet) and time. They should plan the dive as a two deco gas, accelerated decompression dive (it is recommended that you assign enriched air and oxygen as the sim-ulated deco gases). Run the numbers for the depth/time and gases ahead of time to be sure they are planning a five stop dive within the limits of Tec 50 diver.

• You may provide a decompression schedule, or you may have them generate one themselves as they plan using decompression software. Encourage team mates to help each other, but not do it for each other.

• Have students recalculate their working SAC rates based on the data they gathered in Tec 50 Training Dive One. These new data will

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account for wearing two deco cylinders, as well as their growing skill levels.• The dive plan should cover all aspects of a Good Diver’s Main Objective Is To

Live.• If divers discover something doesn’t work (e.g., the available cylinders do not hold

enough gas to meet the requirements), they should adjust the plan accordingly (for example, by reducing bottom time, using a shallower depth, different gear, etc.).



2. Have students plan a mission as they plan the dive.• The mission may be an actual mission (an actual task they can accomplish), a

practice mission (rehearsal for a later actual mission) or a practice mission (a sim-ulated mission that is not a rehearsal for any other mission).

• Remind students that executing the mission is always secondary to returning from the dive safely.



• Encourage teams to discuss mission and dive planning for forthcoming dives on their own, away from class, as part of their preparation.

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Tec 50 Practical Application Three

To successfully complete this Practical Application, the student should be able to:1. Working as a team, use desk top decompression software to plan two actual technical dives with two gas switches made for accelerated decompression or for conservatism, based on infor-mation (gases, depths, times, objective, environment etc.) provided by the instructor, adequately addressing all points of a Good Divers Main Objective Is To Live planning.2. As a team, plan a mission, simulated mission or practice mission to execute as part of both dives being planned.

1. Assign each team two Tec 50 level dives to plan using and adequately addressing all points of A Good Diver’s Main Objective Is To Live planning, based on information you provide.

• Tell divers that the intent of this exercise is to plan two entire technical deep decom-pression dives with two deco cylinders, just as they will as certified Tec 50 divers. Explain that they will be doing this in every practical application session in their train-ing from this point through Tec Trimix Diver.

• It is recommended that you use this session to meet the planning requirements for Tec 50 Training Dives Three and Four, with the same teams, equipment, gases (simulated) etc. See Tec 50 Training Dives Three and Four for references to specifics to provide students in planning.

• Give students the dive depth (max 50 metres/165 feet) and time. They should plan the dive as a two deco gas decompression dive. You may tell them to plan accelerated decompression dives, or gas switches for conservatism, or allow them to choose. Run the numbers for the depth/time and gases ahead of time to be sure they are planning a five stop dive within the limits of Tec 50 diver.

• Have the team generate the required decompression schedule and gas requirements using decompression software. Encourage team mates to help each other, but not do it for each other.

• If either dive will be a repetitive dive, remind students to account for it when planning decompression.

• If Tec 50 Training Dive Four will be made with trimix, review setting the desk top decompression software for trimix with students. See Tec 50 Training Diver Four for specific requirements for this option.

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• The dive plan should cover all aspects of a Good Diver’s Main Objective Is To Live.

• Divers should adjust the plan according to the realities of the dive and the mission plan (for example, by reducing bottom time, using a shal-lower depth, different gear, etc.).



• Review these plans closely, because these will be the actual dives the teams attempt to execute.

2. Have students plan a mission as they plan the dive.• The mission may be an actual mission (an actual task they can accom-

plish), a practice mission (rehearsal for a later actual mission) or a prac-tice mission (a simulated mission that is not a rehearsal for any other mission).

• Remind students that executing the mission is always secondary to returning from the dive safely.



• Encourage teams to discuss mission and dive planning on their own as part of their preparation.

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Tec 50 Training Dives

Tec 50 Training Dive OneTec 50 students come into the course with either of two backgrounds. First, they

may have the Tec 45 certification, or they may have a qualifying certification from another organization.

Tec 50 Training Dive One repeats many of the skills learned at the Tec 45 level, and builds upon them. The purpose of this dive is:

1. To allow you to assess and as necessary, remediate Tec 45 level skills and overall diving ability.

2. To begin developing skills and procedures that students will develop fully in the open water portions of the Tec 50 course.

3. To begin developing mission planning skills that allow students to accomplish meaningful tasks while tec diving.

Tec 50 Training Dive One is a long dive, but it is quite feasible given the shallow depths and large gas supplies used. This dive, as well as Tec 50 Dive Two, are no stop dives and therefore the optimum dives for simulating emergencies and imposing task loads that could cause students to have difficulty maintaining stop depths or have to surface pre-maturely. Therefore, besides practicing existing skills and developing new ones, during this dive and the next, students execute skill integrations that wouldn’t be ideal to rehearse in actual decompression situations. In addition, students must carry out (or attempt to carry out) a team mission.

To successfully complete this training dive, the student must be able to:1. Working in a team, assemble and inspect the standardized technical diving rig (or side-mount) including two stage/deco cylinders following the TecRec rigging philosophies and to meet individual/environmental needs.2. Working in a team, use the a Good Diver’s Main Objective Is To Live steps to plan a simulated accelerated decompression dive with two decompression gases, including a sim-ulate, real or practice mission, based on information (simulated depth, bottom time, gases etc.) provided by the instructor.3. Independently don and remove two stage/deco cylinders at the surface in water too deep in which to stand, , positioning them so they are correctly placed with respect to oxygen content and the dive plan.

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4. Working in a team, conduct a bubble check, descent check and S-drill with little or no prompting or direction from the instructor.5. Working in a team, independently remove, secure and stage two decompression cylin-ders in a single location.6. Perform the gas shutdown drill in 45 seconds (30 seconds for sidemount).7. Working in a team, independently recover and secure two decompression cylinders, locating them correctly with respect to oxygen content and the dive plan.8. Working in a team, with little or no stop to forward motion and while maintaining buoyancy control (on the fly), stage two decompression cylinders in two different loca-tions that simulate their respective staging depths (maximum depths).9. Working in a team, with little or no stop to forward motion and while maintaining buoyancy control (on the fly), recover two decompression cylinders staged at two differ-ent locations that simulate their respective staging depths (maximum depths) and secure them properly with respect to their oxygen content and the dive plan.10. Working within a team, maintain depth within plus or minus .5 metres/1.5 feet during a four stop accelerated decompression that includes a NO TOX gas switch at the first and third stops, and an air break during the final stop.11. Respond properly to a team mate or other diver breathing from a cylinder with simu-lated gas that has too high an oxygen content for the depth.12. As part of a team and while wearing two stage/deco cylinders, swim for at least five minutes at a level depth and at a constant pace recording depth, time and gas consump-tion information for later calculation of a working SAC rate.13. As a team and with priority given to completing a safe dive within planned limits, attempt to execute an actual, simulated or practice mission or mission segment as planned prior to the dive.14. Working in a team, manage a simulated catastrophic gas loss emergency in which the affected teammate must receive gas via long hose through a simulated ascent and , decompression, and on the surface as needed.15. Within a team managing the simulated gas loss emergency in the previous objective, and not varying from stop depth by more than .5 metres/1.5 feet, simulate a five stop, drift decompression with NO TOX gas switches at the second and fourth stops, and an air break at the final stop.16. During the simulated decompression of the previous two objectives, correctly respond to and manage any additional simulated or real emergencies that may occur.

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17. Demonstrate gas, time and depth awareness by signaling the instructor and team mates upon reaching any simulated turn point from the simulated dive plan, upon reach-ing any actual turn point of the actual dive plan (and turning the dive) and by recording the SPG reading of the cylinder the diver is breathing and the depth at each 14 minutes of dive time (team mates may assist each other).

I. Training Dive StandardsA. Tec 50 Training Dive One is 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. It is a no decompression dive. It is recommended that the site provide ready access to water shal-low enough in which to stand, and have an intermediate depth (approx. half the maximum depth) for simulating breathing high oxygen only at a shallow depth.1. Note that this is a long dive with gas sharing and simulated free

flows. Although it is described as a single dive, it may be appropri-ate to break it into two dives.

2. It is recommended that you use as shallow a depth as possible and have fills or extra cylinders available if necessary.

B. Ratios – 6 students to 1 instructor, with 2 more students permitted with a certified assistant to a maximum of 8. (See Section Two for spe-cific requirements necessary to qualify as a certified assistant in this course.) These are maximums – reduce ratios as necessary to accommo-date student characteristics and environmental/logistical variables.

C. Students and instructor must be equipped in standardized technical rig (or sidemount) as worn when making open water technical decom-pression dives with Tec 50 limits in the local environment, including exposure suit and two stage/decompression cylinders. 1. The ideal is for the instructor to wear the same kit as students.2. If a class has sidemount and backmount configurations, for demon-

stration purposes it is recommended that both configurations be represented, with the instructor wearing one and a certified assis-tant wearing the other.

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D. Gas requirements: Students and staff may use air or enriched air, any suitable blend, in sufficient supply to accomplish the dive performance objectives and have free time for experience and practice. It is recom-mended that the stage/deco cylinders have richer EANx blends than the back gas cylinders, but be breathable to the dive’s maximum depth. You will have students simulate using different EANx blends and pure oxygen. For this dive, it is recommended you have them simulate using EANx70 and oxygen because they gases go well with the NO TOX gas switch requirements during the simulated decompressions.

II. Predive Planning, Briefing and Preparation– suggested sequenceA. Predive briefing

1. Students set up their rigs, but do not yet don exposure suits (gear may already be set up from the Practical Application)a. Inspect each rig for correct setup, ample gas, proper cylin-

der labels, etc.b. Have divers work in teams. No one in the team is ready

until everyone in the team is ready.c. Have students mark their decompression cylinders with the

actual content and max depth, and a simulated content/max depth (example:, EANx36, 34 METRES, SIM EANx70, 13 METRES; EANx32, 40 METRES, SIM: OXYGEN, 6 METRES)

d. Tell students that they will simulate deep and shallow areas, and handle their simulated deco gases accordingly. [Explain the areas you’ll use as simulated areas.]

e. Students plan the dive based on information you pro-vide (depth, simulated gases, etc.)• Students should have turn pressures, deco sched-

ules, time limits etc. based on the hypothetical dive.• Tell students they will have to signal you when they

reach any of these limits.• The dive should have a team mission in addition to

the required skills.• This planning may be the plan developed during

Tec 50 Practical Application One (recommended)

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2. Dive site overviewa. Discuss depth, temperature, entry/exit points, noteworthy fea-

tures, etc.b. Facilities – overview parking, lockers, boat dry and wet

areas, where to find emergency equipment, etc.B. Dive overview

1. Depth/time limits (limited open water) – if appropriate, note that the dive may actually be two dives if gas fills are needed to get every-thing done.

2. It’s recommended that you have students list the dive plan on their slates – times, depths, turn pressures, etc., plus the skills, in order, to consult during the dive. Get them in the habit of doing this for each dive.

3. Skill overview – describe each skill, the performance requirement and how you’ll conduct it, including signals you will use, etc.a. proper weighting – no deco cylindersb. don two stage/deco cylinders at surfacec. bubble checkd. descent into deep water –descent check and S-drille. stage deco cylinders – single location, all cylindersf. gas shutdown drillg. retrieve and don deco cylindersh. stage deco cylinders on the fly – separated locationsi. retrieve deco cylinders on the flyj. ascend to first simulated stop depth, NO TOX switch to

first simulated deco gas, two minute simulated deco stop (limited physical contact permitted); ascend to second simulated stop depth, same gas, three minutes simulated decompression

k. ascend to third simulated stop depth, NO TOX switch to simulated higher oxygen deco gas, two minutes simulated deco stop (limited physical contact permitted); ascend to fourth simulated stop depth, four minutes decompression with air break

l. team mate breathing wrong gas drill

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m. surface, switch to back gas; redescend to “deep” arean. SAC swim at constant deptho. stage deco cylindersp mission execution (with preagreed limits)q. catastrophic gas loss – team exercise through end of

dive• a team member has catastrophic gas loss at

depth• the affected diver goes on long hose• the team swims 30 metres/100 feet, retrieves

stages• team sends up the lift bag/DSMB and emergency

signal lift bag DSMB• team ascends along the line – the affected diver

remains on long hoser. simulated five stop, neutrally buoyant decompression

with NO TOX gas switch and air breakss. air breaks during deco (out of gas diver breaks on simu-

lated lower oxygen deco gas, or breaks by sharing gas with a team mate via the long hose)

t. emergencies – other emergencies may occur during decompression

u. after completing deco and ascent, team removes two stage/deco cylinders in water too deep in which to stand; “out of gas” diver is still out of gas and must use oral inflation for buoyancy etc. as appropriate, with team mates assisting

v. recheck weight with near empty cylindersw. gas/time/depth awareness

4. Review hand signals, emergency protocols, descent and ascent pro-cedures, entry and exit procedures and any final detailsa. Predive check – technical level using checklists.b. It’s recommended that you spot check everyone’s gear after

it is donned.

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III. Tec 50 Training Dive One – suggested sequenceA. Entry – into water shallow enough in which to stand (no deco cylinder at

this point).1. Divers check their weight (no deco cylinders)2. If using heavy rigs, divers may be negative with zero weight –

explain that they’ll recheck at the end with near empty cylinders3. Divers don two stage/deco cylinders at the surface

a. Divers should correctly position cylinders (right-rich, left-lean for two sides, if staging first to stage on top for all left, etc.)

b. Divers need to be cautious not to trap gear, esp. the long hose.

4. Bubble check at surfaceB. Descent to non-sensitive bottom (limited open water)

1. Divers perform a descent check; check each other for loose gear, etc.; and conduct S-drill. This should be routine and require little prompting from the instructor.

2. Position class for skills.C. Dive skills –instructor demos each as necessary, then has students perform

as briefed.1. Stage decompression cylinders – as a team, students stage and

secure all their deco cylinders on the bottom in simulated deep water, confirming hoses are tucked, valves closed, etc.

2. Gas shutdown drill – within 45 seconds (30 seconds in side-mount)

3. Retrieve and don deco cylinders – students replace all cylinders, correctly located with respect to oxygen content (first to stage on top for all-left configuration).

4. Stage and retrieve deco cylinders on the fly – as a team, while continuing to swim and maintaining buoyancy control, students stage their cylinders at simulated maximum depths for the respec-tive blends, then retrieve and don them.

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5. Simulated four stop decompression with NO TOX switches and air breaks – teams ascend to first simulated stop depth. a. The suggested actual stop depth is 1.2 metres/4 feet; in lim-

ited open water, it may be possible to simulate using the last two actual stop depths.

b. Remind students to use neutral buoyancy to remain within .5 metres/1.5 feet of the stop depth.

c. To simulate stop depth changes, have students redescend and then ascend to the “next” stop.

Following schedule recommended:Simulated depth Time12 m/40 ft 2 min – NO TOX to deco gas 19 m/30 ft 3 min6 m/20 ft 2 min – NO TOX to deco gas 25 m/15 ft 4 min – air break at 10 min deco

time6. Team mate breathing wrong gas drill

a. During the simulated decompression, a team mate or staff member switches to the wrong gas.

b. The other team mate should respond by pulling the second stage from the team mate’s mouth while providing the long hose.

c. It is recommended that you secretly assign individual stu-dents/staff to skip the NO TOX steps and go to the wrong gas at the first stop.

7. Teams complete decompression, surface, switch to back gas and redescend to bottom in water too deep in which to stand. a. Teams should remain as teams and execute a proper

descent.b. At the bottom, the team conducts a bubble check, a descent

check and carries out S-drills, with all divers as donor and receiver.

c. Deco cylinders remain on divers.

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8. SAC swim at constant depth with two deco cylindersa. Have divers swim for a least five minutes, in teams, at a

constant depth to gather time/depth/gas use information to determine their SAC rates, while swimming with two stage/deco cylinders.

9. Students stage deco cylinders (optional – may keep in place if more appropriate for mission, such as if practicing an open water mission during which cylinders will remain on).

10. Mission execution – teams attempt to execute their missions within the dive plan limits; completing the mission is not a requirement.

11. Stage cylinders (if not staged prior the mission).12. Catastrophic gas loss team exercise – exercise starts with

instructor designating that a team member is out of gas.a. The affected diver signals out-of-gas; the team mate pro-

vides the long hose.b. The team swims 30 metres/100 feet with long hose sharing

(simulates a return to the ascent area) to retrieve staged cylinders.

c. The team sends up lift bag/DSMB and second emergency signal lift bag/DSMB on same line

d. team ascends line; out of gas diver stays on long hose until able to make first gas switch

13. Simulated five stop, neutrally buoyant decompression with NO TOX gas switch and air breaks – students ascend lift bag/DSMB line, reeling in line to the designated stop deptha. The suggested actual stop depth is 1.2 metres/4 feet; in

limited open water, it may be possible to simulate using the last two actual stop depths.

b. Remind students to use neutral buoyancy to remain within .5 metres/1.5 feet of the stop depth.

c. To simulate stop depth changes, have students redescend and then ascend to “next” stop.

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d. Students make a NO TOX gas switch while maintaining depth; team mates may assist each other.

e. Suggested deco schedule:Simulated depth time15 m/50 ft 1 min12 m/40 ft 2 min – NO TOX to deco gas 19 m/30 ft 3 min6 m/20 ft 6 min – NO TOX to deco gas 25 m/15 ft 10 min – air break at 20 minutes

deco timef. After completing decompression, the team ascends slowly

to the surface in water too deep in which to stand, as they would on a real open water tec dive.

g. The out of gas diver remains “out of gas” through the rest of the dive (unless the diver must use gas for a real emer-gency) – team mates may provide the long hose to assist with gas switches, air breaks and at the surface, as neces-sary.

h. Remind teams that in teams of three, both members with gas may help the affected diver.

14. Other emergencies – tell divers that they should handle any other emergencies that occur and continue to manage them through the rest of the dive, or until signaled that the drill is over.a. Be cautious with added drills – students are already dealing

with a complex emergency situation, as well as the gas/time/depth awareness requirements.

b. Successfully handling added task loads will enhance confi-dence and coolness under pressure, but overwhelming stu-dents will undermine confidence.

15. Divers remove deco cylinders and exit (a deep water exit recom-mended).a. If necessary, before exiting, have students recheck their

weight requirement with near empty cylinders, with no stage/deco cylinders.

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16. Gas/time/depth awareness – assign divers to write down the depth and SPG pressure of whatever cylinders they’re breathing from at each 14 minutes of dive time. Divers should also signal the instruc-tor when the team reaches the turn pressure or time limit that they planned if this were a real decompression dive, as well as the real planned limits.

IV. Post DiveA. Performance review. After a moment to rest, get a drink, etc., but immedi-

ately while all memories are fresh, have teams identify what happened, mistakes, what worked, what didn’t, what they learned, etc. Comment and fill in missing information as necessary, but have students critique them-selves constructively while you guide the process.1. In particular, discuss the mission and the catastrophic gas loss simu-

lations. Ask students to discuss what they learned and what they would do differently.

B. Confirm that all divers have their time/depth/pressure information, and their SAC swim and deco data.

C. Divers disassemble and stow equipment.D. Students log the dive for your signature.E. Remind students of assignments/tasks before the next scheduled meeting

(knowledge development, etc.)

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Tec 50 Training Dive Two

To successfully complete this training dive, the student must be able to:1. Working in a team, use the a Good Diver’s Main Objective Is To Live steps to plan a simulated decompression dive with two deco gas accelerated decompression dive switch-es, based on information (simulated depth, bottom time, gases etc.) provided by the instructor.2. Working in a team, assemble and inspect the standardized technical diving rig (or sidemount), including two stage/deco cylinders following the previously described rig-ging philosophies and to meet individual/environmental needs.3. Independently don and remove two stage/deco cylinders at the surface in water too deep in which to stand, locating them correctly with respect to oxygen content and the dive plan (staging, worn throughout dive, etc.)4. As part of a team, conduct a bubble check at the surface or just below the surface.5. As part of a team, conduct a descent check on the bottom.6. Underwater, properly stage two stage/deco cylinders for later retrieval and use.7. Perform the gas shutdown drill within 40 seconds (30 in sidemount).8. Working as a team, attempt to execute the planned dive mission.9. Respond properly to impromptu emergency drills based on previously learned skills presented by the instructor.10. Underwater, retrieve and don two deco cylinders, placing them correctly with respect to oxygen content and the mission plan.11. As part of team, ascend and complete the planned simulated decompression of at least 30 minutes using a methodology appropriate for the local environment.12. As part of a team, while maintaining stop depth during a simulated decompression (plus or minus 1 metre/3 feet) perform NO TOX gas switches at the appropriate depths per the decompression schedule and the maximum (simulated) depth for each of the gases.13. While neutrally buoyant at a simulated decompression stop, perform the gas shut-down drill while maintaining depth within 1 metre/3 feet of the stop depth.14. After an interval of decompression designated by the instructor, or at 20 minutes of breathing simulated EANx80 or higher oxygen content (whichever is less), conduct an air break, then NO TOX switch back to the deco cylinder and complete the decompression.15. As part of a team, while conducting a simulated decompression, send up an emergen-cy signal lift bag/DSMB in a manner appropriate for the decompression method in use.

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16. At the surface in water to deep in which to stand, independently remove two decompres-sion cylinders.15. Demonstrate gas/time/depth awareness throughout the dive by a) signaling the instructor and team mates upon reaching the agreed turn point of simulated dive plan (not actual dive plan) and b) writing the depth, time and SPG reading at each 14 minutes throughout the dive.

I. Training Dive StandardsA. Tec 50 Training Dive Two is conducted in open water. The minimum

depth is 12 metres/40 feet and the maximum depth is 24 metres/80 feet. It is a no decompression dive that simulates a decompression dive with a least 30 minutes simulated decompression time required.

B. Ratios – 4 students to 1 instructor, with 2 more students permitted with a certified assistant to a maximum of 6. (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 charac-teristics and environmental/logistical variables.

C. Students and instructor must be equipped in standardized technical rig (or sidemount) appropriate for the local environment, including exposure suit and two stage/decompression cylinders. 1. The ideal is for the instructor to wear the same kit as students.2. If a class has sidemount and backmount configurations, for demonstra-

tion purposes it is recommended that both configurations be represent-ed, with the instructor wearing one and a certified assistant wearing the other.

D. Gas requirements: Students and staff may use air or enriched air, any suit-able blend, in sufficient supply to accomplish the dive performance objectives and have free time for experience and practice. It is recommended that the stage/deco cylinder have a richer EANx blend than the back gas cylinders, but that all cylinders are breathable to the dive’s maximum depth. It is recom-mended that you have students simulate using EANx and pure oxygen to match the requirements of the simulated decompression schedule.

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II. Predive Planning, Briefing and Preparation– suggested sequence

A. Predive briefing1. Students plan a decompression dive within Tec 50 limits

using EANx/oxygen for accelerated decompression based on information you provide (depth, bottom and deco gases, etc.). Tec 50 Practical Application Two may be the planning session this dive.a. Students should have turn pressures, deco schedules, time

limits etc. based on the hypothetical dive.b. Tell students they will have to signal you when they

reach any of these limits.2. Students set up their rigs, but do not yet don exposure suits (gear

may already be set up from the Practical Application)a. Inspect each rig for correct setup, ample gas, proper cyl-

inder labels, etc.b. Have divers work in teams. No one in the team is ready

until everyone in the team is ready.c. Have students mark their decompression cylinders with

the actual content and max depth, and a simulated con-tent/max depth (example: AIR, 50 METRES, SIM: EANx36, 34 METRES; EANx32, 40 METRES, SIM: EANx40, 30 METRES) based on the simulated dive.

d. Tell students that they will simulate deep and shallow areas, and handle their simulated deco gas accordingly. [Explain the areas or depths you’ll use as simulated deep and shallow areas; during decompression you can use real depths with simulated gases; for example, air simulated as oxygen, divers should not breath deeper than 6 metres/20 feet. If the site allows, it is recommended that simulated bottom depth be 40 metres/130 feet or deeper, then have students decompress at the real stop depths, with a switch to simulated oxygen at 6 metres/20 feet.]

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e. As appropriate, remind students that the actual bot-tom time may be longer than the simulated bottom time (but within no stop limits) if necessary to accomplish all skills.

3. Dive site overviewa. Discuss depth, temperature, entry/exit points, note-

worthy features, etc.b. Facilities – overview parking, lockers, boat dry and

wet areas, where to find emergency equipment, etc.B. Dive overview

1. Depth/time limits – Students planned a simulated dive; establish the real limits for the dive.

2. It’s recommended that you have students list the dive plan on their slates – times, depths, turn pressures, etc., plus the skills, in order, to consult during the dive. Get them in the habit of doing this for each dive.

3. Students will need the simulated decompression schedule on their slates because this is a no stop dive and their dive computers will not provide the schedule.

4. Skill overview – describe each skill, the performance requirement and how you’ll conduct it, including signals you will use, etc.a. don stage/deco cylinders at surfaceb. bubble checkc. descent checkd. stage two deco cylinderse. gas shutdown drillf. missiong. free time as time allows -- surprisesh. retrieve and don deco cylindersi. ascent and decompressionj. neutrally buoyant gas shutdown drill

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k. air breakl. emergency signal to surface support drillm. remove stage/deco cylinders in water too deep in

which to stand n. gas/time/depth awareness

4. Review hand signals, emergency protocols, descent and ascent procedures, entry and exit procedures and any final detailsa. Predive check – technical level using checklists.b. It’s recommended that you spot check everyone’s

gear after it is donned.

III. Tec 50 Training Dive Two – suggested sequenceA. Entry – appropriate for environment (no deco cylinder at this

point).1. Divers check their weight (if necessary, no deco cylinder)2. Don stage/deco cylinders at the surface in water too

deep in which to stand a. Cylinders must be correctly placed with respect to

oxygen content and the dive plan3. Bubble check at surface (just below the surface is accept-

able if conditions require)B. Descent to non-sensitive bottom

1. Students perform descent check; check each other for loose gear, etc.

2. Position class for skills.C. Dive skills –instructor demos if necessary

1. Stage deco cylindersa. The team stages together, confirms valves are

closed and cylinders secured.b. Both their cylinders are left together.

2. Gas shutdown drilla. The drill is conducted one at a time with each stu-

dent for 40 seconds (30 with sidemount).3. Mission

a. Students conduct the mission as planned.

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b. Remind students that completing the mission is not required; they should turn the dive according to planned limits.

4. Free time – surprisesa. Tell students that they will be able to explore the immediate

area as teams (set limits as necessary to maintain control) until reaching the required ascent time or gas pressures (actual).

b. You may signal or use a slate to present problems for them to deal with as they’ve trained – anything they’ve learned is fair game.

5. Retrieve and don deco cylinders6. The team ascends and completes simulated decompression – 30

minutes minimum time.a. Students decompress according to the planned schedule.b. Remind students to stay plus or minus .5 metres/1.5 feet of

the stop depth and generally horizontal, stop depth at chest level.

c. Have students NO TOX switch to their simulated gas at the appropriate depths.

d. Use a decompression method appropriate for the environ-ment (along a line, drifting under a lift bag/DSMB, follow-ing a slope, etc.)

7. Neutrally buoyant gas shutdown drilla. During the simulated decompression, have students conduct

the gas shutdown drill using only buoyancy control to remain within 1 metre/3 feet of the stop depth.

8. Air breaka. Have students practice switching to back gas for two-three

minutes, then practice NO TOX switching back to deco gas after a set interval, using simulated EANx80 or gas with a higher oxygen content.

b. If the decompression does involve at least 20 minutes on simulated EANx80 or higher, have them air break at a given interval.

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c. Remind students that if following a decompression table, break time does not count as deco time.

9. Emergency signal to surface support drilla. Teams send up a lift bag/DSMB to signal surface support

for help.b. Use a technique that is appropriate for the decompression

method in use.10. Remove stage/deco cylinders in water too deep in which to

stand a. After completing the simulated decompression, teams sur-

face together.b. Teams remove stage/deco cylinders and exit the water as

appropriate for the environment.11. Gas/time/depth awareness

a. Have students signal you and team mates when they reach an agreed turn point based on the simulated dive plan.

b. Students record the depth, time and SPG reading at each 14 minutes throughout the dive regardless of what else is going on (other than a real emergency). Team mates may assist each other with this task.


ately while all memories are fresh, have teams identify what happened, mistakes, what worked, what didn’t, what they learned, etc. This should include looking at the mission as well as the dive skills. Comment and fill in missing information as necessary, but have students critique themselves constructively while you guide the process.

B. Confirm that all divers have their time/depth/pressure information.C. Divers disassemble and stow equipment.D. Students log the dive for your signature.E. Remind students of assignments/tasks before the next scheduled meeting


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Tec 50 Training Dive ThreeTo successfully complete this training dive, the student must be able to:1. Working in a team, plan and execute an actual two deco gas decompression dive based on table and/or multigas computer diving following the A Good Diver’s Main Objective Is to Live procedure.2. Working in a team, assemble and inspect the standardized technical diving rig (or side-mount) including a stage/deco cylinder following the previously described rigging philos-ophies and to meet individual/environmental needs.3. As part of a team, conduct a bubble check at the surface or just below the surface.4. As part of a team, conduct a descent check on the bottom.5. Demonstrate gas/time/depth awareness throughout the dive by signaling the instructor and team mates upon reaching an agreed turn point of technical dive plan.6. Working in a team execute the dive’s mission, carrying it out to the team’s ability within the limits of the dive plan.

Reminder: As you know, beginning with Training Dive One, students must demon-strate mastery of all skills in each training dive prior to progressing to the next. Because Dive Three is the first actual decompression dive at this level, there should be no doubt that skills learned and practiced in the previous dives have been mas-tered. Remember, you do not continue instruction into Training Dive Three with any students who have not yet demonstrated mastery of all prior skills and learning.

I. Training Dive StandardsA. Tec 50 Training Dive Three is conducted in open water. The minimum

depth is 30 metres/100 feet and the maximum depth is 50 metres/165 feet. It is a decompression dive with two gas switches to provide added conservatism or to accelerate decompression.

B. Ratios – 3 students to 1 instructor, with 1 more student permitted with a certified assistant to a maximum of 4. (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 characteristics and environmental/logistical variables.

C. Students and instructor must be equipped in standardized technical rig (or sidemount) appropriate for local environment, including exposure suit and two stage/decompression cylinders.

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1. The ideal is for the instructor to wear the same kit as students.2. If a class has sidemount and backmount configurations, for demon-

stration purposes it is recommended that both configurations be represented, with the instructor wearing one and a certified assis-tant wearing the other.

D. Gas requirements: Students and staff may use air, enriched air and/or oxygen, in sufficient supply to accomplish the dive performance objec-tives.

II. Predive Planning, Briefing and Preparation– suggested se-quence

A. Predive briefing1. Students plan a decompression dive within Tec 50 limits using

EANx or oxygen. Tec 50 Practical Application Three may be the planning session this dive.a. Students should have turn pressures, deco schedules, time

limits etc. for the dive.b. Tell students this is an actual decompression dive that

should be planned and conducted as appropriate and realis-tic for the local environment.

c. There is no minimum or maximum decompression time requirements, other than being within the normal gas vol-ume, oxygen exposure, etc. Guide students to account for exposure duration.

d. There is no requirement for decompression methodology. It is recommended that students use whatever is standard practice in the local area (drift deco, hanging on a line, deco on the bottom, etc.)

2. Students set up their rigs, but do not yet don exposure suits.a. Inspect each rig for correct setup, ample gas, proper cylin-


until everyone in the team is ready.c. Have students mark their decompression cylinders with the

actual content and max depth.

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3. Dive site overviewa. Discuss depth, temperature, entry/exit points, noteworthy

features, etc.b. Facilities – overview parking, lockers, boat dry and wet

areas, where to find emergency equipment, etc.B. Dive overview

1. Depth/time limits.2. It’s recommended that you have students list the dive plan on their

slates – times, depths, turn pressures, etc., plus the skills, in order, to consult during the dive. Even if diving two multigas computers, carrying a copy of the program-generated deco schedule (or lami-nated table) is advised for emergency uses. Get them in the habit of doing this for each dive.

3. Students will use their dive computers for their decompression schedule. Multigas computers may be used for accelerated decom-pression or divers may decompress with them set for bottom gas and use the gas switches for conservatism.

4. Skill/dive overview – describe each skill, the performance require-ment and how you’ll conduct it, including signals you will use, etc., as needed.a. don stage/deco cylinders at surfaceb. bubble checkc. descent checkd. missione. gas/time/depth awarenessi. ascent and decompression, NO TOX gas switches

4. Review hand signals, emergency protocols, descent and ascent pro-cedures, entry and exit procedures and any final detailsa. Predive check – technical level using checklists.b. It’s recommended that you spot check everyone’s gear after

it is donned.

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III. Tec 50 Training Dive Three – suggested sequenceA. Entry – appropriate for environment

1. Divers check their weight (if necessary, no deco cylinders)2. Don stage/deco cylinders at the surface – as appropriate for envi-

ronment3. Bubble check at surface (just below the surface or combined

with descent check at bottom is acceptable if conditions require)B. Descent

1. Students perform descent check on non-sensitive bottom or midwater, etc.; check each other for loose gear, etc.

C. Dive skills1. Mission – teams execute the planned mission to the best of their

ability within dive plan limits; completing the mission is not required.

2. Gas/time/depth awareness – students should signal you and their team upon reaching any turn point; everyone is expected to remain within the planned limits

3. Ascent and decompressiona. Technique as appropriate for local area.b. Contingency situations handled as planned.c. Remind students to use good decompression technique

4. NO TOX gas switchesa. Students NO TOX switch to a higher oxygen EANx, or

oxygen, as planned, following the NO TOX procedure5. Air breaks

a. Air breaks may not be necessary depending upon the decompression duration.

b. Have students plan and make air breaks if the total decom-pression time exceeds 20 minutes.

c. You may assign more frequent air breaks for practice.d. Remind students that air break time does not count as deco

time when following tables, or to switch to air (or EANx used as break gas) with multigas computers

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6. Remove stage/deco cylinder in water too deep to stand ina. after completing the decompression, teams surface togetherb. remove stage/deco cylinders and exit water as appropriate for

environment


ately while all memories are fresh, have teams identify what happened, mis-takes, what worked, what didn’t, what they learned, etc. Comment and fill in missing information as necessary, but have students critique themselves con-structively while you guide the process.

B. Divers disassemble and stow equipment.C. Students log the dive for your signature.D. Remind students of assignments/tasks before the next scheduled meeting


Tec 50 Training Dive Four

To successfully complete this training dive, the student must be able to:1. Working in a team, plan and execute an actual two deco gas decompression dive based on table and/or multigas computer diving using and adequately addressing all points of a Good Divers Main Objective Is To Live planning.2. Working in a team, assemble and inspect the standardized technical diving rig (or side-mount) including a stage/deco cylinder following the previously described rigging philoso-phies and to meet individual/environmental needs.3. As part of a team, conduct a bubble check at the surface or just below the surface.4. As part of a team, conduct a descent check on the bottom.5. Demonstrate gas/time/depth awareness throughout the dive by signaling the instructor and team mates upon reaching an agreed turn point of technical dive plan.6. Working in a team, execute the dive’s mission, carrying it out to the team’s ability within the limits of the dive plan.

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Reminder: As you know, beginning with Training Dive One, students must demon-strate mastery of all skills in each training dive prior to progressing to the next. Because Dive Three is the first actual decompression dive at this level, there should be no doubt that skills learned and practiced in the previous dives have been mastered. Remember, you do not continue instruction into Training Dive Three with any stu-dents who have not yet demonstrated mastery of all prior skills and learning.

I. Training Dive StandardsA. Tec 50 Training Dive Three is conducted in open water. The minimum

depth is 40 metres/130 feet and the maximum depth is 50 metres/165 feet. It is a decompression dive with two gas switches to provide added conservatism or to accelerate decompression.

B. Ratios – 3 students to 1 instructor, with 1 more student permitted with a certified assistant to a maximum of 4. (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 characteristics and environmental/logistical variables.

C. Students and instructor must be equipped in standardized technical rig (or sidemount) appropriate for local environment, including exposure suit and two stage/decompression cylinders. 1. The ideal is for the instructor to wear the same kit as students.2. If a class has sidemount and backmount configurations, for demon-

stration purposes it is recommended that both configurations be rep-resented, with the instructor wearing one and a certified assistant wearing the other.

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D. Gas requirements: Students and staff may use air, enriched air and/or oxy-gen, in sufficient supply to accomplish the dive performance objectives.1. This dive may be conducted with trimix within Tec 50 and all

other limits, provided:a. The instructor is a Tec Trimix Instructor.b. Certified assistants (other than those functioning as shallow

water support divers) must be certified as Tec Trimix Divers in addition to meeting other requirements for assisting in the Tec 50 course.

b. The trimix is a blend with 21 percent or more oxygen.c. All divers (students and staff) use the same trimix and com-

patible deco gases.d. The decompression schedules must be specifically for the

trimix used.

II. Predive Planning, Briefing and Preparation– suggested sequence

A. Predive briefing1. Students plan a decompression dive with Tec 50 limits using EANx

or oxygen. Tec 50 Practical Application Three may be the planning session this dive.a. Students should have turn pressures, deco schedules, time lim-

its etc. for the dive.b. Tell students this is an actual decompression dive that should

be planned and conducted as appropriate and realistic for the local environment.

c. There are no minimum or maximum decompression time requirements, other than being within the normal gas volume, oxygen exposure, etc. Guide students to account for exposure duration.

d. There is no requirement for decompression methodology. It is recommended that students use whatever is standard practice in the local area (drift deco, hanging on a line, deco on the bot-tom, etc.)

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2. Students set up their rigs, but do not yet don exposure suits.a. Inspect each rig for correct setup, ample gas, proper cylin-


until everyone in the team is ready.c. Have students mark their decompression cylinders with

the actual content and max depth.3. Dive site overview

a. Discuss depth, temperature, entry/exit points, noteworthy features, etc.

b. Facilities – overview parking, lockers, boat dry and wet areas, where to find emergency equipment, etc.

B. Dive overview1. Depth/time limits.2. It’s recommended that you have students list the dive plan on their

slates – times, depths, turn pressures, etc., plus the skills, in order, to consult during the dive. Even if diving two multigas computers, carrying a copy of the program-generated deco schedule (or lami-nated table) is advised for emergency uses. Get them in the habit of doing this for each dive.

3. Students will use their dive computers for their decompression schedule. Multigas computers may be used for accelerated decom-pression or divers may decompress with them set for bottom gas and use the gas switches for conservatism.

4. Skill/dive overview – describe each skill, the performance requirement and how you’ll conduct it, including signals you will use, etc., as needed.a. don stage/deco cylinders at surfaceb. bubble checkc. descent checkd. missione. gas/time/depth awarenessi. ascent and decompression, NO TOX gas switches

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4. Review hand signals, emergency protocols, descent and ascent procedures, entry and exit procedures and any final detailsa. Predive check – technical level using checklists.b. It’s recommended that you spot check everyone’s

gear after it is donned.

III. Tec 50 Training Dive Four – suggested sequenceA. Entry – appropriate for environment

1. Divers check their weight (if necessary, no deco cylinders).2. Don stage/deco cylinders at the surface – as appropriate for

the environment.3. Bubble check at the surface (just below the surface or

combined with descent check at the bottom is acceptable if conditions require).

B. Descent 1. Students perform descent check on non-sensitive bottom

or midwater, etc.; check each other for loose gear, etc.C. Dive skills

1. Mission – teams execute the planned mission to the best of their ability within dive plan limits; completing the mission is not required.

2. Gas/time/depth awareness – students should signal you and their team upon reaching any turn point; everyone is expected to remain within the planned limits.

3. Ascent and decompressiona. Use atechnique appropriate for the local area.b. Contingency situations should be handled as

planned.c. Remind students to use good decompression tech-

nique.4. NO TOX gas switches

a. Students NO TOX switch to a higher oxygen EANx, or oxygen, as planned, following the NO TOX pro-cedure

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5. Air breaksa. Air breaks may not be necessary, depending upon

the decompression duration.b. Have students plan and make air breaks if the total

decompression time exceeds 20 minutes.c. You may assign more frequent air breaks for prac-

tice.d. Remind students that air break time does not count

as deco time when following tables, or to switch to air (or EANx used as break gas) with multigas com-puters.

6. Teams remove their stage/deco cylinders in water too deep in which to stand.a. After completing the decompression, teams surface

together.b. Teams remove stage/deco cylinders and exit the

water as appropriate for the environment.

IV. Post DiveA. Performance review. After a moment to rest, get a drink, etc., but

immediately while all memories are fresh, have teams identify what happened, mistakes, what worked, what didn’t, what they learned, etc. Comment and fill in missing information as necessary, but have students critique themselves constructively while you guide the process.

B. Divers disassemble and stow equipment.C. Students log the dive for your signature.D. Remind students of assignments/tasks before the next scheduled

meeting (knowledge development, etc.)

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