CCR diving

CCR (Closed Circuit Rebreather) mode in AeroPlus Deco supports setpoint-based dive planning, loop gas validation, and bailout sufficiency checks. Oxygen consumption and scrubber endurance are deliberately not calculated — see Oxygen & scrubber.

When CCR mode is active:

• The deco algorithm uses a constant loop O₂ partial pressure (the setpoint) instead of a fixed gas mix
• Cylinder roles change to diluent, oxygen, and bailout
• A second card appears for setpoint and bailout configuration
• Many gas-related warnings and calculations adjust accordingly

In this section

• Setup — activating CCR mode and configuring cylinders
• Setpoints — surface SP, switch depth, bottom SP, deco SP, per-segment override
• Bailout planning — independent vs group bailout, sufficiency check
• Oxygen & scrubber — why neither is calculated, and what bounds the maximum loop TTS instead

Key differences from OC

Aspect	OC	CCR
Breathing gas at depth	Bottom-gas cylinder mix	Loop mix (varies with setpoint and depth)
Deco gas switches	Yes — at MOD of each deco gas	No — setpoint changes only
Gradient factor strategy	Andy Davis method recommended	Personal/agency preference
Auto-set GF Low	Available	Disabled (greyed out)
Bailout consideration	N/A	Critical — independent or group
Scrubber tracking	N/A	Not calculated — manage it yourself
O₂ tracking	N/A	Not calculated — monitor your supply in the water
Maximum TTS bound by	Back gas and deco gas	Bailout gas only (independent mode)

Switching modes

In Settings → CCR mode, toggle the switch. The app:

1. Saves your current OC cylinder configuration
2. Restores your previous CCR cylinders (or creates default diluent + O₂ + bailout if first time)
3. Re-renders the cylinders list with CCR roles
4. Shows the CCR setup card on the main plan page
5. Recalculates if a plan already existed

Toggling back to OC reverses this. Both configurations are preserved per plan, so you can compare OC and CCR profiles for the same dive site.