Deep trimix dives to 65 metres
PADI Tec Trimix 65: trimix course
Course description
PADI Tec Trimix 65 is the first level of trimix training in the PADI TecRec system, the point where helium enters the breathing mix. The course is for technical divers who have completed the Tec Deep Diver path and want to go deeper than air or nitrox allows.
The reason for using helium is practical, not about prestige. Below 50 metres, nitrogen narcosis and breathing gas density start to limit concentration, work of breathing and decision-making in a real way, and that is exactly where the margin for error is smallest. Helium solves both problems at once, at the cost of more complex planning and noticeably more expensive gas.
The course teaches planning and carrying out dives to 65 metres with normoxic trimix as the bottom gas and nitrox and oxygen as decompression gases. The programme covers the physiological properties of helium, choosing mixes, advanced decompression planning with software and team procedures during deep dives.
We put a lot of weight on conscious risk management. At these depths, procedural discipline is not a matter of style: it is the only safety mechanism available.
4-5 training days, depending on conditions, location and the pace of the team.
Theory sections, practical sessions and 5 training dives.
5 training dives of increasing depth, from a check dive of the skills from the Tec 50 level to a target dive in the 45-65 metre range.
Maximum depth: 65 metres.
Bottom gas: normoxic trimix, with oxygen content of at least 18%, which lets you breathe it from the surface.
Decompression gases: nitrox and oxygen (up to 100%).
A maximum of 2 people per instructor: at this level we work only in very small teams.
The PADI Tec Trimix 65 Diver certificate allows you to plan and carry out dives independently:
- to a depth of 65 metres,
- with normoxic trimix as the bottom gas,
- with decompression gases up to 100% oxygen,
- with full, multi-stage decompression, in a team of divers with the right qualifications.
Tec Trimix 65 covers the first five dives of the full Tec Trimix Diver programme. A diver who continues training with the same instructor within 6 months then completes only the three deepest dives instead of the whole course.
- Age: 18 years completed;
- Technical certification: PADI Tec 50 Diver or an equivalent certification from another organisation;
- Rescue certification: PADI Rescue Diver or equivalent. For a qualification from another federation, confirmation of first aid and CPR training from the last 2 years is required;
- Experience: at least 100 dives recorded in a logbook;
- Health: a current medical statement (signed by a doctor within the last 12 months);
- Insurance: current dive insurance that covers decompression diving and treatment in a hyperbaric chamber.
Beyond the formal requirements, we expect real, recent decompression experience from the Tec 50 level. A trimix course is not the place to fix skills from the previous level.
Main configuration
- twinset (at least 2 × 12 l, larger preferred) with an isolation manifold, or an equivalent sidemount set,
- backplate and single-piece harness,
- wing with buoyancy suited to the full kit with decompression cylinders,
- two independent regulators: a primary on a long hose (about 2 m) and a backup on a bungee around the neck,
- a pressure gauge on each first stage,
- backup buoyancy control: a second lift bag, or a dry suit suited to the weight of the kit.
Decompression cylinders
- two decompression cylinders (7-12 l) with full fittings,
- regulators prepared for use with oxygen: oxygen cleaning, suitable lubricants and seals,
- a pressure gauge on each cylinder and a harness with double-ended bolt snaps,
- clear marking of the mix and maximum operating depth (MOD) of each cylinder.
Instruments and safety equipment
- a dive computer that handles trimix and multiple gases, and a second independent instrument with the same capabilities,
- a decompression buoy with a reel or spool of at least 30 m, and a spare buoy,
- two cutting tools placed independently,
- a spare mask,
- a slate for underwater notes with the dive plan and contingency profiles,
- a primary and a backup light.
Additionally recommended
- a dry suit with an undersuit suited to very long exposures,
- a suit inflation system with argon: helium significantly worsens thermal insulation,
- decompression software that handles helium mixes,
- your own oxygen and helium analyser,
- a set of tools and consumables.
Training fee
The price is set individually, depending on the training location, dive logistics and the number of training dives.
Registration and certification fee
According to the current price list of the certifying organisation.
Training materials
The PADI Tec Trimix Diver package (manual and planning materials): charged separately.
Additional costs
Breathing gases, dive logistics, equipment rental, travel, accommodation and meals. At this level the biggest variable item is helium, so it is worth budgeting for it separately.
Theory
The theory part builds on the knowledge from the Tec 40, Tec 45 and Tec 50 courses and introduces trimix topics:
- helium as a breathing gas: physical properties, effect on narcosis, gas density and work of breathing;
- choosing trimix blends: equivalent narcotic depth, gas density, oxygen content and MOD;
- planning decompression with helium mixes, including isobaric counterdiffusion during gas switches;
- advanced planning with decompression software and building your own tables;
- the effect of helium on thermal comfort and the equipment consequences that follow;
- risk management and emergency procedures in deep diving, where an emergency ascent is not an option.
Practice
Five training dives of growing complexity, from checking your skills to the target dive:
- a check dive confirming the skills and procedures from the Tec 50 level;
- working with multiple cylinders and gas switch sequences at increasing depth;
- team planning: dividing tasks, and checking each other’s configuration and cylinder markings before every dive;
- precisely holding long, multi-stage decompression stops;
- emergency procedures in deep conditions, including loss of a decompression gas and a buddy’s problem;
- target dives in the 45-65 metre range, carried out to a plan you prepare yourself.
The aim is confidence in action and repeatable procedures. At these depths, a skill done correctly once is not enough: it has to be a reflex.
FAQ
Projects
Dives with a specific task to carry out: at this level a project is the natural goal of the training:
- wreck projects on deep sites, beyond the reach of the Tec Deep Diver path;
- photographic and photogrammetric documentation of deep sites;
- exploration and survey of new sites, working with a line and taking measurements;
- research and conservation work with institutions that deal with underwater heritage;
- taking part in technical expeditions as a deep diver or in a support role.
We pick team members by training level and how recent their experience is, not by the order of applications. For trimix dives we require a check dive before every project.
Trips
Several days in a row in the same team build experience faster than the same number of dives spread over the whole season:
- trips abroad to deep sites: the basic format for trimix dives;
- the Baltic: deep wrecks that become accessible only from this training level;
- small teams, a dive plan of growing complexity and gas supply agreed before departure;
- confirmed availability of helium and oxygen on site: with trimix, this decides whether the whole trip is feasible;
- a contingency plan that covers the nearest hyperbaric chamber, and instructor support on site.
Before a trip it is worth planning an equipment check, a check dive in the target configuration and insurance that covers decompression diving. We keep the trip calendar separately.
Further training
The natural continuation after Tec Trimix 65. The order depends on which direction you want to develop your diving range:
- PADI Tec Trimix Diver: the full trimix training, dives to 100 metres with hypoxic trimix;
- PADI Tec Gas Blender: preparing helium mixes yourself, a real saving if you dive trimix regularly;
- PADI Tec Sidemount: if you took the course in a backmount configuration and want to master both;
- specialty training: wreck, exploration and closed-circuit courses.
If you continue to the full Tec Trimix Diver course with the same instructor within 6 months, you complete only the three deepest dives of the programme.
