TDI’s Trimix Diver course shows how to minimize the effects of narcosis by adding helium to offset the nitrogen in your breathing gas. While taking the Trimix Diver course your TDI Instructor will teach you how to plan and execute dives utilizing as little as 18 percent oxygen and diving to maximum depth of 60 metres/200 feet with a blend of helium appropriate for the planned depth.

Who this course is for

  • The certified Advanced Nitrox and Decompression Procedures diver looking to:
    • Extend their depth range
    • Reduce narcosis for all deep dives
    • Advance their technical diving education

Course prerequisites

  • Minimum age 18
  • Minimum certification of TDI Advanced Nitrox AND Decompression Procedures Diver, or equivalent
  • Proof of 100 logged dives

Equipment requirements

  • Bottom mix cylinder
    • Cylinder volume appropriate for the planned decompression on bottom mix
    • Dual outlet valve, double manifold or independent doubles
    • Labelled in accordance with TDI standards
  • Suit inflation cylinder (required for Drysuit divers only)
  • Decompression mix cylinder(s)
    • Cylinder volume should contain a minimum of 1.5 times the gas required for the planned decompression
    • Labelled in accordance with TDI standards
  • 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 3 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

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 OUT limits, Isobaric Counter diffusion, volume requirements, etc.
    • 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 finning techniques
  • Management of multiple 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 provided:
    • The diving activities approximate those of training
    • The areas of activities approximate those of training
    • Environmental conditions approximate those of training
  • Ability to enroll in TDI Advanced Wreck and TDI Advanced Trimix courses

TDI Trimix Diver minimum certification requirements

  • Satisfactorily complete the TDI Trimix Diver course written examination
  • Complete all open water requirements safely and efficiently
  • Demonstrate mature, sound judgment concerning dive planning and execution

Course does not include textbook, transportation, accommodation, equipment, or air fills. 

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