Planned decompression dives
TDI Decompression Procedures is a decompression diving course for divers who want to go deeper and stay longer than no-decompression limits allow. You learn to plan and safely make a staged decompression dive to 45 metres, using nitrox mixes or oxygen for decompression.
It is one of the core technical diving courses: after it you can continue with TDI Extended Range, TDI Advanced Wreck and trimix training.
What you learn
- Theory: how required decompression stops differ from a safety stop, how bubbles form, why oxygen-rich mixes help decompression, task loading and stress.
- Tables and computers: decompression models (Bühlmann, DCIEM, US Navy), dive planning with computers and software.
- Planning: gas requirements, oxygen and nitrogen limits, an exact dive and decompression profile, contingency plans for omitted decompression, decompression sickness or equipment failure.
- Equipment: one or two cylinders, a stage cylinder for decompression gas, regulators, wing, reel, lift bag or surface marker buoy.
How the practice runs
You make four open-water dives, two of them deeper than 30 m. Before each dive you check equipment and match gas as a team. In the water you work with a stage cylinder: you remove and clip it back on while holding your position, confirm gas switches with your buddy, deploy a lift bag and ascend with decompression stops.
The instructor also simulates emergencies: a gas leak from a regulator or manifold, a free-flowing decompression regulator, a stuck BCD inflator, lost decompression gas, and a dive that runs too long or too deep so the decompression plan has to change in the water. The course ends with a written exam.
Frequently asked questions
What depth does the certificate allow?
The TDI Decompression Procedures Diver certificate allows planned staged decompression dives to 45 m, using nitrox mixes or oxygen for decompression within your certification.
Do I need Advanced Nitrox?
To use rich nitrox mixes or oxygen for decompression you need TDI Advanced Nitrox or an equivalent. TDI allows taking both courses together, with six dives in total.
How long does the course take?
3–4 days: theory, the exam and four open-water dives. We agree the schedule with you.
What equipment do you provide?
All the course equipment: decompression cylinders and gases, dive computers and tables, BCDs, surface marker buoys and lift bags.