Technical Diving Cheat Sheet

The key takeaways for beginners – doubling up on redundancy, clean gas planning and the training path beyond recreational dive limits.

Equipment: doubled-up safety

Item	Priority	Tip
Doubles/sidemount	High	Doubles for direct access via one manifold, sidemount for visual access to each tank.
Backplate & wing	High	Flat profile, individually adjustable – the standard in technical diving.
Long hose	High	A long hose for team gas-sharing in an emergency – core of the DIR configuration.
Team standard	Medium	Identical gear positions across the team – found blindly in an emergency.

Where technical diving begins

No direct way up: Mandatory decompression, overhead environments or depths beyond recreational limits – this is where technical diving starts.
Training before depth: Around 25 logged dives plus Advanced and Nitrox are the typical entry point – automated basics matter more than the number.
Choose the agency by instructor: TDI, IANTD, GUE and PADI TecRec differ in philosophy – instructor quality matters more than the agency's name.

The 3 golden safety rules

Factor 1: Every system exists twice

Concept: A regulator failure or an empty valve must never cost your entire gas supply – redundancy is mandatory in technical diving, not optional. Tip: Two gas sources, two regulators, two lights – standard body positions that every team member can find blind.

Factor 2: Gas planning is fixed before the dive

Concept: The rule of thirds splits your gas into the way in, the way out and reserve – turn pressure holds no matter the visibility or mood. Tip: Calculate minimum gas for a team emergency ascent and call out the turn pressure to the team out loud – no mental math under stress.

Factor 3: Hold a horizontal trim consistently

Concept: During long decompression stops with no bottom contact, any off-angle position drags like an anchor and burns extra gas and warmth. Tip: Set up your backplate, wing and weight distribution so your body stays horizontal on its own – even motionless at a deco stop.

Gas switches & marking

Topic	In short
MOD marking	Both sides and the bottom, large numbers for maximum operating depth – 1.6 bar oxygen partial pressure as the reference.
Gas switch routine	Show the cylinder, check the regulator, get buddy confirmation – only then breathe from it.
S-drill	Simulate gas donation and receiving before every dive – the final check before entry.
Valve drill	Reach blind to every valve and isolate it, until the motion runs on its own.

Extra risks under control

Cold protection during deco: A cold body off-gasses more slowly – argon cuts heat conduction by around 20%, but only after six purge cycles.
Plan DPV range: A scooter multiplies your range – and the swim back without power. Plan gas for both scenarios.
Keep team signals small: A small, fixed set of hand signals is more reliable under stress than a large repertoire.
Hold plan discipline: With mandatory decompression, the dive is already planned at entry – deviating from the profile is not an option.

Pro tip: Technical diving does not forgive improvisation: if redundancy, gas planning or training are not fully checked off, you postpone the dive – not the rule.