GUE Tech I

What is it?

GUE’s Technical Diver Level 1 (Tech 1) 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. Tech 1 training focuses on expanding the fundamental skills learned in the GUE Fundamentals course (or elsewhere), and is designed to cultivate, integrate, and expand the essential skills required for safe technical diving. 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.

The class will focus on nitrox and Trimix as breathing gases for dives down to 170 feet/51 meters, and provides an excellent foundation on which divers can build their technical diving experience and prepare for GUE’s Technical Diver 2 course (Tech 2).





  1. Must be a minimum of 18 years of age
  2. Must be GUE Fundamentals qualified with the Tech-rating
  3. Must have a minimum of 100 dives beyond open water qualification
  4. Students participating in a Tech class conducted in a cave must be at least GUE Level 2 Cave divers




The Tech 1 class is normally conducted over a six-day period. It involves a minimum of forty hours of instruction, encompassing both classroom and in-water work.


Course Limits


  1. Maximum depth 170 feet / 51 meters
  2. No overhead diving except by active GUE Cave 2 Level instructors while teaching in the cave environment


Course Content


The GUE Tech 1 course involves a minimum of forty hours of instruction designed to provide a working knowledge of nitrox, normoxic and hyperoxic Trimix and decompression mixtures, including history, physics, physiology, tables, and operational considerations.

Course requirements include ten hours of academics and seven dives, 4 of of which will be critical-skill dives and three will be experience dives. Initial dives will be conducted in shallow water to test diver ability and to fill in any deficits in skill levels. The last three dives are to be Trimix dives at depth for experience.



Required Training Materials


  1. Doing it Right: The Fundamentals of Better Diving
  2. Getting Clear on the Basics: The Fundamentals of Technical Diving


Academic Topics


  1. Physics
  2. Pressure and gas-law review
  3. Equations relevant for planning, mixing, and using enriched air
  4. Physiology
  5. Hypoxia
  6. Hyperoxia
  7. Oxygen toxicity
  8. CNS
  9. Pulmonary toxicity
  10. Tracking multilevel, multi-dive, and multi-day exposures
  11. Inert gas narcosis
  12. Inert gas absorption and elimination
  13. Carbon dioxide toxicity
  14. Carbon monoxide toxicity
  15. Hyperthermia
  16. Hypothermia
  17. Decompression illness
  18. Accelerated and general decompression strategies
  19. Decompression practices on air, enriched air, and Oxygen
  20. Generic tables, computers, and custom tables
  21. Introduction to normoxic and hyperoxic Trimix
  22. Advantages over deep air
  23. Equipment considerations
  24. Stage cylinders
  25. Doubles
  26. Decompression stage cylinders
  27. BC/harness
  28. Regulators, depth gauges, pressure gauges, and hose routing
  29. Manifolds
  30. Surface-marker buoys and spools (for deco platforms)
  31. Computers and bottom timers
  32. Exposure suit appropriate for the environment
  33. Dive planning
  34. Operational planning
  35. Support
  36. Teams
  37. Team planning
  38. Gas matching
  39. Oxygen limits
  40. Nitrogen limits
  41. Emergency procedures
  42. Omitted decompression procedures
  43. Procedures
  44. Bottom and deco gas
  45. Normal operations
  46. Procedures for failure, loss, or inadequate supply
  47. Gas mixing
  48. Analyzing and labeling gas supplies
  49. Line following


Land Drills and Topics


  1. Reel and guideline use
  2. Dive team order and protocols
  3. Touch contact
  4. Manifold operation and failures
  5. Use of safety spools and reels
  6. Basic navigation skills
  7. Pre-dive drills




Required Dive Skills & Drills


  1. Must be able to swim at least 400 yards/375 meters in under fourteen minutes without stopping (This test should be conducted in a swimsuit and, where necessary, appropriate thermal protection)
  2. Must be able to swim a distance of at least 20 yards/18 meters on a breath hold


Equipment Requirements


Each student should have, and be familiar with, all of the following required equipment.


  1. At least one time/depth-measuring device
  2. Decompression tables
  3. Mask and fins: Mask should be low volume; fins should be rigid, non-split
  4. At least one cutting device
  5. Wet Notes
  6. One spool with 100 feet/30 meters line per diver
  7. One primary reel per team, with a minimum of 300 feet/90 meters of line
  8. Exposure suit appropriate for the duration of exposure
  9. At least one surface marker buoy per diver
  10. One wrist compass
  11. One reserve mask


Note: Prior to the commencement of class, students should consult with a GUE representative to verify equipment requirements. Whether or not a piece of equipment fulfills GUE's equipment requirement remains at the discretion of GUE and its instructor representatives. Participants are responsible for providing all equipment or for making provisions to secure all necessary equipment before the start of the course. In general, it is better for the student to learn while using his or her own equipment. However, students should exercise caution before purchasing new equipment to avoid acquiring substandard equipment. Please contact a GUE representative prior to making any purchases. Information about recommended equipment can be obtained from the equipment considerations section of GUE's web site