Advanced Trimix

Advanced Trimix


The TDI Advanced Trimix Diver Course is the top level of training for open circuit divers wishing to dive to depths as deep as 100 metres/330 feet utilizing hypoxic levels of oxygen (below 17 percent). This course is perhaps one of the most informative and challenging of all of the TDI open circuit courses. Upon completion, you will be among some of the most elite divers, capable of doing and seeing more while diving than any other divers out there.

Who this course is for

  • The TDI Extended Range or Trimix Diver looking to:
    • Extend their depth range
    • Advance their technical diving education

Course prerequisites

  • Minimum age 18
  • Minimum certification of TDI Extended Range or Trimix Diver or equivalent
  • Show proof of 100 logged dives, 25 must be deeper than 30metres/100feet

Equipment requirements

  • Bottom mix cylinder
    • Cylinder volume appropriate for the planned dive and student gas consumption
    • Dual outlet valve, double manifold or independent doubles
    • Labeled in accordance with TDI standards
  • Travel mix cylinder
    • Cylinder volume appropriate for the planned dive and student gas consumption
    • Labeled in accordance with TDI standards
  • Decompression mix cylinder
    • Cylinder volume appropriate for the planned dive and student gas consumption
    • Labeled in accordance with TDI standards
  • Suit inflation cylinder (required for drysuit divers only)
  • Regulators
    • Primary & primary redundant regulators required on all bottom mix cylinders
    • Submersible pressure gauge required on all primary & bottom mix cylinders
    • A contingency use long hose second stage should be designated and appropriately rigged to facilitate air sharing at depth if necessary
    • It is strongly recommended that 4 required regulators be all DIN or all yoke
  • Redundant depth & timing devices
  • Air decompression computers allowed for use as depth & timing devices
  • Buoyancy compensator appropriate for equipment configuration
  • Redundant light system if needed for site conditions
  • Ascent reel with lift bag/surface marker buoy
    • Appropriate for maximum planed depth
    • Lift bag with at least 50 lbs of lift
  • Exposure protection appropriate for local diving condition
  • Slates/wetnotes
  • Helium analyzer
  • Two line-cutting devices
  • Other equipment requirements may apply, check with instructor
  • TDI Advanced Trimix Diver manual

What you can expect to learn

  • Advanced decompression dive planning including:
    • Gas planning based on equivalent narcotic depths, nitrogen and helium absorption and elimination, CNS and OTU limits, isobaric counter diffusion, volume requirements, etc.
    • Use of hypoxic gasses
    • HPNS and isobaric counter diffusion
    • Decompression gas choices
    • Tables vs. personal dive computers
    • Emergency and contingency planning (equipment failure, omitted decompression, etc.)
  • Decompression diving procedures
    • Equipment selection
    • Pre-dive checks and drills
    • Stress analysis and mitigation
    • Following a decompression schedule
    • Gas switching
    • Team awareness and communication
    • SMB/lift bag deployment
  • Proper trim, buoyancy and fining techniques
  • Management of multiple (minimum of 3) decompression/stage cylinders
  • Emergency procedures (equipment failures, catastrophic gas loss, omitted decompression, navigational errors, injured/unconscious diver, etc)
  • Equipment considerations, cylinder labeling, analyzing trimix nitrox and mixes, and gas blending procedures

What’s in it for you

  • Ability to conduct technical diving activities using custom trimix mixtures without direct supervision, so long as the following limits are adhered to:
    • The diving activities approximate those of training
    • The areas of activities approximate those of training
    • Environmental conditions approximate those of training

TDI Advanced Trimix minimum requirements

  • Satisfactorily complete the TDI Advanced Trimix course written examination with a passing score of 80%, followed by 100% remediation by the instructor
  • Complete all open water requirements safely and efficiently
  • Demonstrate mature, sound judgment concerning dive planning and execution

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