Hogarthian Technical Diver 1

The Hogarthian Technical Diver 1 program is structured to prepare divers for rigors faced while technical diving and to familiarize them with the use of different breathing mixtures. Students will become experienced in the use and failure problems associated with diving double tanks. The Hogarthian Technical Diver 1 students will also become acquainted with the use of nitrox mixtures for accelerated decompression, the use of Helium to minimize narcosis, and the applications of single tank stage diving. The curriculum will focus on enriched air and triox – recreational trimix (Helium enriched gas) as a flexible and beneficial breathing medium for dives in the 12 m to 45 m depth range. This class provides an excellent foundation for divers to build their technical diving experience and prepare for the Hogarthian Technical Diver 2 course.


  1. Must meet Course Prerequisites
  2. Minimum age of 18
  3. All participants must be able to swim at least 300 meters
  4. All participants must be able to swim a distance of at least 15m on a breath hold
  5. At least 50 scuba dives
  6. Completion of Hogarthian basic

Hogarthian Technical Diver 1 training focuses on expanding the basic skills introduced in the Hogarthian Basic course and is designed to cultivate and broaden essential skills required for safe technical diving.

The class is structured around a minimum 21 lessons and 12 dives with minimum of 320 minutes bottom time.

Course Content
Hogarthian Technical Diver 1 program instructs divers in the use/failures of doubles, single stage decompression, enriched air bottom mixtures, triox mixtures decompression mixtures up to 100% oxygen. The course is structured to prepare divers for the rigors of technical diving and to familiarize them with the use of different breathing and decompression mixtures. This will include problem identification and resolution, and building the capacity for progressively more challenging diving. In this class, students will be trained in:

  • a) the use of double tanks/cylinders and in the potential failure problems associated with them;
  • b) the use of Nitrox for accelerated and general decompression strategies;
  • c) the use of Helium to minimize narcosis; and
  • d) the applications of single decompression stage diving with respect to decompression procedures.

Course Limits

  1. All dives are to maintain a working PO2 of no greater than 1.4
  2. No dives are to exceed an equivalent narcotic depth of 30 m

Certification level
Deep Diver, Rescue Diver, Advanced Nitrox Diver

Academic Topics

  1. Physics
  2. Pressure and gas law review
  3. Planning, mixing, and using enriched air
  4. Physiology
  5. Hypoxia / Hyperoxia
  6. Oxygen / Pulmonary toxicity
  7. CNS
  8. Tracking multilevel, multi-dive, and multi-day exposures
  9. Inert gas narcosis
  10. Inert gas absorption and elimination
  11. Carbon dioxide / Carbon monoxide toxicity
  12. Hyperthermia / Hypothermia
  13. Decompression illness
  14. Accelerated and general decompression strategies
  15. Decompression practices on air, enriched air, and Oxygen
  16. Generic tables, computers, and custom tables
  17. Introduction to normoxic and hyperoxic Trimix
  18. Advantages over deep air
  19. Equipment considerations (DIR emphasis)
  20. Singles / Doubles / Decompression stage bottles
  21. Dive / Operational planning
  22. Teams / Team planning
  23. Oxygen / Nitrogen limits
  24. Emergency procedures
  25. Omitted decompression procedures
  26. Bottom and deco gas
  27. Procedures for failure, loss, or inadequate supply
  28. Analyzing and labelling gas supplies
  29. Line following

Equipment Requirements

Each student should have and be familiar with all of the following required equipments:

  1. Tanks/Cylinders: Students are required to use dual tanks/cylinders connected with a dual outlet isolator manifold, which allows for the use of two first stage regulators.
  2. Decompression tank/cylinder
  3. Regulators: Two first-stages, each supplying a single second-stage. One of the second stages must be on a 2 meter hose. One of the first stages must supply a pressure gauge.
  4. Regulator for Decompression tank
  5. Buoyancy Compensators: Back-mounted wings, mated with a harness and a back plate.
  6. Survey compass
  7. Two time keeping devices
  8. At least one depth-measuring device
  9. Decompression tables
  10. Mask and fins (fins must be of the non-split variety)
  11. At least one cutting device
  12. Underwater slate or Wet Notes
  13. One reel/spool, with 30 meters of line per diver
  14. One primary reel per team, with a minimum of 120 meters of line
  15. Primary light and two back-up lights
  16. At least one surface marker buoy per diver
  17. Exposure suit appropriate for the duration of exposure