Tri-mix Diver
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Tri-Mix Diver: The NAUI Trimix program trains technical divers in the use of oxygen/helium/nitrogen gas mixtures while allowing them to gain supervised experience in the protocols of deep and extended range diving. The program also accentuates the logic behind the choices between different EANx, trimix, and oxygen decompression gases and it thoroughly introduces students to the most contemporary decompression theories and tables available, particularly the Reduced Gradient Bubble Model.
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Classroom work emphasizes advanced decompression theory and management, gas mixing, diving physics and physiology, oxygen exposure management and dive planning. Practical sessions include rigorous cultivation of proper equipment selection and configuration and technical diver skill execution. Finally, the program is very experience oriented and stresses the practical application of deep diving on mixed gases.
The NAUI curriculum includes three helium-based mixed-gas courses: helitrox, Trimix I, and Trimix II. Helitrox is a special trimix composed of helium and nitrox where the oxygen content exceeds 21 percent. It is designed for diving between 90 and 150 fsw on a helium-based gas resulting in low PO2 and PN2. Helitrox diving is also covered in the NAUI Trimix I course along with traditional trimix diving with oxygen content less than 21 percent in the bottom mix. The Trimix I course trains divers to utilize helium-based gas mixes to depths up to 200 fsw. NAUI Trimix II training extends the maximum training depth to 250 fsw and encompasses the additional planning and skill refinement required for this level of diving.
ACADEMIC REQUIREMENTS
Classroom work emphasizes decompression theory and management, diving physics and physiology, oxygen exposure management, equipment, dive planning and emergency procedures. The NAUI Trimix course includes a full two to three days of classroom work, one to two days of equipment configuration work and skill drills in confined water, and six to eight or more progressively deeper dives.
Topics covered include the following: Introduction to Mixed Gases, Mixed Gas,Gas Properties, Specific Heat Capacity, Thermal Conductivity, Core Temperature, Suit Insulation, Ideal Versus Real Gas Behavior, Determining Best Trimix, Trimix Blending, Mixed Gas Decompression, Helium versus Nitrogen, Saturation/Desaturation, Halftime Comparisons, Equivalent/Effective Depth Formulas, Dissolved Gas Models, Free Gas Phase Models, Schedule Comparisons, Gas Selection, Normoxic Ranges; Decompression Mixes, Gas Switching Problems, Oxygen Window, Decompression Time, Mixed Gas Physiology, Human Responses to PO2, RMV and VO2; Metabolic Oxygen Consumption, Personal Limitations, Environmental Considerations, Physiological Problems, Dive Planning, Time Terminology, Descent/Ascent Rates, Dive Planning, Gas Utilization Calculations, Contingency Plans, Equipment, Procedures, Team members and Players, Surface Support, Agency Protocols, Accident Analysis, Rescue Responses, Emergency Responses, Omitted Decompression, DCS Signs and Symptoms, Neurological DCS, Desktop Decompression, Skills and Techniques.
SCOPE OF COURSE
SKILL REQUIREMENTS
EQUIPMENT REQUIREMENTS
NAUI Technical Equipment Configuration Requirements
PREREQUISITES FOR ENTERING THE COURSE
Age: Minimum is 18 years.
Certification: NAUI Technical Diver or equivalent level. These requirements can be modified or amended during pre-course interview and/or screening dive.
Additional requirements include:
Policies applying to all NAUI SCUBA Courses can be found here
The NAUI curriculum includes three helium-based mixed-gas courses: helitrox, Trimix I, and Trimix II. Helitrox is a special trimix composed of helium and nitrox where the oxygen content exceeds 21 percent. It is designed for diving between 90 and 150 fsw on a helium-based gas resulting in low PO2 and PN2. Helitrox diving is also covered in the NAUI Trimix I course along with traditional trimix diving with oxygen content less than 21 percent in the bottom mix. The Trimix I course trains divers to utilize helium-based gas mixes to depths up to 200 fsw. NAUI Trimix II training extends the maximum training depth to 250 fsw and encompasses the additional planning and skill refinement required for this level of diving.
ACADEMIC REQUIREMENTS
Classroom work emphasizes decompression theory and management, diving physics and physiology, oxygen exposure management, equipment, dive planning and emergency procedures. The NAUI Trimix course includes a full two to three days of classroom work, one to two days of equipment configuration work and skill drills in confined water, and six to eight or more progressively deeper dives.
Topics covered include the following: Introduction to Mixed Gases, Mixed Gas,Gas Properties, Specific Heat Capacity, Thermal Conductivity, Core Temperature, Suit Insulation, Ideal Versus Real Gas Behavior, Determining Best Trimix, Trimix Blending, Mixed Gas Decompression, Helium versus Nitrogen, Saturation/Desaturation, Halftime Comparisons, Equivalent/Effective Depth Formulas, Dissolved Gas Models, Free Gas Phase Models, Schedule Comparisons, Gas Selection, Normoxic Ranges; Decompression Mixes, Gas Switching Problems, Oxygen Window, Decompression Time, Mixed Gas Physiology, Human Responses to PO2, RMV and VO2; Metabolic Oxygen Consumption, Personal Limitations, Environmental Considerations, Physiological Problems, Dive Planning, Time Terminology, Descent/Ascent Rates, Dive Planning, Gas Utilization Calculations, Contingency Plans, Equipment, Procedures, Team members and Players, Surface Support, Agency Protocols, Accident Analysis, Rescue Responses, Emergency Responses, Omitted Decompression, DCS Signs and Symptoms, Neurological DCS, Desktop Decompression, Skills and Techniques.
SCOPE OF COURSE
- The training depths for these dives are 100-200 fsw for Level I. Maximum PO2 is 1.4 atm for working portions of the dives and 1.6 atm for decompression.
- No dives may exceed an equivalent narcosis depth of 130 fsw; an END of 100 fsw or less is generally employed on the training dives.
- The in-water instructor to student ratio will never exceed 3 to 1 for any portion of training.
SKILL REQUIREMENTS
- For each dive students will define oxygen limits based on PO2 of 1.4 atm or less for the working portion of the dive and 1.6 atm or less for decompression stops.
- For each dive students will analyze all gas mixtures and label each accordingly with mix and MOD.
- For each dive students will complete a Technical Diver Plan and a Team Planner
- Set up personal scuba systems for each dive satisfying all training, environmental, and physiological constraints.
- Establish safety and emergency procedures, contingency strategies, abort and bailout plans.
- Demonstrate proper buoyancy control and trim during dives and deco stops.
- Turn around or begin the ascent at the predetermined back gas pressure or bottom time.
- Demonstrate proper underwater communications.
- Shut down failed regulator and isolate for catastrophic gas loss (< 15 sec).
- Shutoff and switch over to redundant regulator.
- Gas sharing, simulate out-of-gas scenario over a distance of 100 feet.
- Remove/replace stage/Deco bottles in timely fashion while maintaining proper trim and buoyancy.
- Conduct planned gas switches.
- Lost visibility - maintain contact with team and continuous line to the surface.
- Equipment failure management drills.
- Demonstrate team cooperation skills.
- Missing diver search procedures.
- Rescue skills.
- Ascend with reel and lift bag and execute drift decompression.
- Execute staged decompression stops.
- Demonstrate mastery of emergency procedures (abort plan, omitted deco protocols, emergency first aid).
- Demonstrate proper descent and ascent rates and depth, time, and gas management.
EQUIPMENT REQUIREMENTS
NAUI Technical Equipment Configuration Requirements
PREREQUISITES FOR ENTERING THE COURSE
Age: Minimum is 18 years.
Certification: NAUI Technical Diver or equivalent level. These requirements can be modified or amended during pre-course interview and/or screening dive.
Additional requirements include:
- Medical clearance and physically fit (nonsmoker)
- Minimum of 100 logged dives with at least 20 decompression dives (beyond certification) as a Technical Diver.
- Must be able to swim 400 meters under 14 minutes and perform breath hold swim for 20 meters
Policies applying to all NAUI SCUBA Courses can be found here