Deco Planner settings

What this covers

The Settings card in a deco plan holds every value the engine runs on. This page walks it top to bottom, in the order the app shows it, and says for each row what it does, what it can be set to, and whether it changes your schedule, only your gas figures, or only what you read.

Three sections sit at the top because you reach for them while planning: Gradient Factors, Deco Stops, Environment. Everything else is inside one collapsed Advanced group. Every section starts collapsed; Expand all at the top of the sheet opens them all at once when you are hunting for one control.

Each row carries an i that opens a short explanation of that setting in the app, so nothing here is information you can only get from this page.

Your defaults and per-plan overrides

There are two tiers.

Your defaults seed every new plan. Open them from Edit Defaults at the top of the settings sheet, from the same button on the plan list, or from Manage → Settings → Deco Planner. The screen carries the same sections in the same order, each with an ⓘ that explains what the section is for.

Per-plan overrides belong to one plan. Change any setting inside a plan and that setting is marked as overridden: a small accent dot appears beside its label, the value itself is tinted, and a reset button sits at the right of the row. Its section header and the Advanced group header carry the same dot, so a collapsed group never hides a deviation. The groups inside Advanced are drawn as subsections: a smaller title behind a thin left rule, so you can see at a glance which ones belong to it. The collapsed Settings card counts them, “3 overrides”.

Everything you have not touched keeps tracking your defaults, so changing a default flows into every existing plan that has not overridden it. Reset All at the top of the sheet puts every override back, which is what you want after importing a buddy’s plan built on different settings. If a saved plan’s defaults changed since it was last computed, a banner offers Recalculate.

The CCR rig is the one exception to the tracking rule. It is copied out of your CCR defaults once, when you first enable CCR on a plan, and is never pushed back into plans that already have a rig.

Every setting on this page is per-plan, and all but two travel in a share link, so your buddy opens the plan with your gradient factors, rates, caps and thresholds rather than theirs. The two exceptions are both CCR-only: Stay on the Loop and the Apply on CCR loop air-break toggle are not carried in the link, so a shared CCR plan opens with the recipient’s own values for those two. Check them after importing a rebreather plan.

Gradient Factors

The conservatism dial. See Gradient factors for the full explanation of what they do to a profile.

Row	Range	Default	What it moves
GF Low	10 % to 100 %	50	Schedule. Sets how deep your first stop is, as a percentage of the Bühlmann limit
GF High	10 % to 100 %	80	Schedule. Sets how long you hold the shallow stops and how close to the limit you surface
Preset chips	30/70, 50/80, 80/80	The chip matching your pair, if one does	Schedule. Sets both values at once

Lower numbers are more conservative. The pair may be inverted (GF High below GF Low) and the engine computes it faithfully, with an inline note saying what you have done, because limits then tighten toward the surface instead of relaxing.

If your GF High is too low for the plan to ever surface, the engine raises it to the lowest value that can complete the deco and says so loudly: a red critical banner above the graph, a red border on the schedule, an entry in Plan Issues, and a notice on the export sheet. Every export records the gradient factors the schedule was actually computed with. See When a GF High cannot surface the plan.

Deco Stops

Where the stops land and how long you hold them.

Row	Options	Default	What it moves
Last Stop	3 m / 4.5 m / 6 m, or 10 ft / 15 ft / 20 ft	6 m (20 ft)	Schedule. Your final hold
Deco Step Size	3 m / 6 m / 9 m, or 10 ft / 20 ft / 30 ft	3 m (10 ft)	Schedule. The spacing stops snap to
Stop time rounding	1 s / 30 s / 1 min	1 min	Schedule, see below

Six metres is the open-water choice, because holding 3 m in any swell is guesswork. Three metres suits controlled environments and a line to hold. The imperial chips are true imperial depths stored as their metric equivalents, so 20 ft is 6.096 m rather than a rounded 6.

Stop time rounding

This one is worth reading properly, because the name undersells it. It is not a display format: the rounding is applied inside the engine, so it sets the grid a stop can be released on and therefore changes the schedule.

• 1 s releases a stop the moment the obligation clears and shows the precise time as MM'SS". It is the exact answer, and the fiddliest to follow on a timer.
• 30 s holds to the next half minute, shown on the 30 second grid, 25'00" or 25'30".
• 1 min (the default) holds each stop to a whole minute, so the table is followable off a slate and matches MultiDeco’s whole-minute output. It is the easiest to dive and slightly conservative, because every rounded stop is a little longer than the obligation.

The rounding is one-directional: a rounded stop lasts at least as long as the exact obligation, never less. Switching modes never produces an earlier or shallower ascent. The only floor is on the last stop, which is always held for at least a minute so the final hold never disappears. Stops above it have no floor, so in the two precise modes a 20 second hold reads 0'20" rather than folding into the next minute.

The display is consistent down the whole table. In 1 min mode every time reads as whole minutes; in the other two every time keeps its seconds, including a clean 25'00", so the column never flips between 25' and 25'06" row to row.

Environment

Row	Range	Default	What it moves
Water density	Fresh, EN13319, Salt, Red Sea	Salt	Schedule. Sets how depth maps to pressure
Water temperature	−2 °C to 40 °C (28 °F to 104 °F), step 1	15 °C (59 °F)	Gas density readings only
Altitude	0 m to 10000 m (0 ft to 32800 ft)	0	Schedule

Water density is roughly 1.000 kg/L fresh, 1.020 for the EN13319 dive-computer reference, 1.025 salt, and 1.040 for the Red Sea. Denser water means more ambient pressure at a given depth, so it loads your tissues slightly faster and moves the ceiling with it. This row is shared with Settings → Diving, so changing it in either place changes both.

Water temperature is the reference every gas-density figure is computed at. Gas thins as it warms, so a warmer setting reports a lower density. It is density only: the Bühlmann model has no temperature term, so your stops do not move, and the 5.2 and 6.2 g/L limits are published figures that stay where they are, which means a warmer setting warns a little deeper. Use the temperature you expect at your deepest level. It is not the Gas Blender’s fill or ambient temperature, which describe what happens inside a cylinder. This row is also shared with Settings → Diving.

Altitude lowers your surface pressure, which makes the last part of the ascent a bigger relative pressure drop and adds decompression. Above about 300 m the effect is visible. Altitude is the one setting with no default of its own: it belongs to the plan, so there is no row for it on the defaults screen and no override mark on it.

Advanced

Seven sub-sections of things you set once and revisit rarely.

Ascent and descent rates

Row	Range	Default	What it moves
Deep ascent rate	1 to 100 m/min (3 to 330 ft/min)	9 m/min (30 ft/min)	Schedule
Shallow ascent rate	1 to 100 m/min (3 to 330 ft/min)	3 m/min (10 ft/min)	Schedule
Rate change depth	3 to 200 m (10 to 650 ft)	6 m (20 ft)	Schedule
Descent rate	1 to 100 m/min (3 to 330 ft/min)	20 m/min (66 ft/min)	Schedule

The deep rate applies from depth up to the change depth, the shallow rate from there to the surface. Match them to the rates your computer uses, and never set the shallow rate faster than the deep one.

The descent rate row prints what the rate means under its value, “Reaches 30 m in 2 min”, so a slow descent is visibly slow before you dive it. It governs every descending leg of the dive, not just the first. See Descent.

Oxygen partial pressure caps

The PPO₂ section sets the open-circuit gas caps. On a rebreather the loop runs on setpoints instead, and these caps apply to its bailout gases.

Row	Range	Default	What it moves
Max PPO₂ (O₂ < 28%)	1.0 bar up to the mid cap	1.4 bar	Schedule and warnings
Max PPO₂ (28% ≤ O₂ < 45%)	Between the lean and rich caps	1.5 bar	Schedule and warnings
Max PPO₂ (O₂ ≥ 45%)	Up to 1.6 bar	1.6 bar	Schedule and warnings
Minimum PPO₂	0.16 to 0.21 bar	0.18 bar	Warnings only

Each cap sets the maximum operating depth of the gases in its band and fires their hyperoxia warning, so the depth you switch at and the depth you are warned at are always the same number. A gas at exactly 28 % counts as mid; one at exactly 45 % counts as rich. The three are kept in order, so raising one pushes its neighbour rather than crossing it.

Minimum PPO₂ is the low-end caution. Below it the planner warns you about a thin gas; the red critical floor sits at 0.16 bar and cannot be moved. Set this to 0.16 and only the critical tier can fire.

All four are in bar in both unit systems, as PPO₂ always is.

Gas Consumption

Row	Range	Default	What it moves
Working SRMV	1 to 200 L/min (0.05 to 7.1 ft³/min)	20 L/min (0.71 ft³/min)	Gas figures only
Deco SRMV	Same	15 L/min (0.53 ft³/min)	Gas figures only
CCR metabolic O₂ rate	0.4 to 2.0 L/min	0.85 L/min	Gas figures only

These never move a stop. Measure your own rate with the SAC/SRMV calculator rather than guessing: a novice often sits at 20 to 30 L/min and a calm experienced diver at 12 to 18, and the difference sizes your cylinders.

On open circuit the two rates follow the cylinder, not the clock: a gas assigned to a dive level is charged at the working rate for every segment it breathes, stops included, and a cylinder carried only for deco is charged at the deco rate. On a rebreather bailout they split by phase instead. The metabolic oxygen rate is depth-independent and only appears on a plan that has a rig.

The same two rates are the first two rows of the Plan Modifiers sheet on the Base Plan tab. Editing either place is the same edit.

Gas Switch

Row	Options	Default	What it moves
Gas Switch Point	At MOD / At Deco Stop	At MOD	Schedule
Switch Time	0 to 300 s, step 30	0 s	Schedule
When a cylinder runs out	Show shortfall / Switch gas	Show shortfall	Schedule and gas figures

Switching at MOD maximises off-gassing on the richer gas and shortens the time to surface; switching at a stop is older practice and easier to brief. Switch Time holds you at the switch depth on the old gas while you change regulators, so the plan grows by roughly what you enter, and it applies to open-circuit switches only. Rebreather setpoint changes on the loop are instant.

When a cylinder runs out is explained in full under that heading on the gases page. In short: the default keeps the schedule on the empty cylinder and reports the shortfall, which is the gas-sizing answer, and the other option moves the rest of the deco onto the best gas you still carry.

Oxygen Breaks

Short breaks off a high-oxygen deco gas onto your back gas, to slow the CNS clock on long shallow stops.

Row	Range	Default	What it moves
Enable Oxygen Breaks	On / off	Off	Schedule
O2 Time Before Break	5 to 30 min	20 min	Schedule
Break Duration	1 to 10 min	5 min	Schedule
Min PPO₂ to Trigger	0.8 to 1.8 bar	1.4 bar	Schedule
Apply on CCR loop	On / off	Off	Schedule, rebreather only
O₂ break setpoint	0.1 to 9.9 bar	0.7 bar	Schedule, rebreather only

The four timing rows are hidden until breaks are enabled. Twenty minutes on, five minutes off is the classic NOAA and Navy protocol. A break costs you deco: the fast tissues take a little inert gas back on, and the rest of the plan has to clear it.

The last two rows appear only on a plan with a rebreather rig. With Apply on CCR loop off, breaks still apply to open-circuit bailout; with it on, the loop setpoint drops to the break setpoint during high-PPO₂ deco.

Behaviour

Row	Default	What it moves
Include travel in level time	Off	Schedule
Treat O₂ as narcotic	Off	Warnings only
Stay on the Loop	On, rebreather plans only	Schedule

Include travel in level time decides how each level’s time is read. Off is classical scuba planning: the travel to reach a level is added on top of the time you typed. On matches MultiDeco and the way a dive computer counts runtime: the travel comes out of the time you typed. Turning it on also enables the warning that a level’s time is shorter than the travel needed to reach it.

Treat O₂ as narcotic decides whether oxygen counts toward equivalent narcotic depth. Most agencies treat it as non-narcotic at diving pressures, which is why it is off. It changes END figures and the warnings that read them, never the stops. It is the same value as the row in Settings → Diving, so setting it in either place sets it everywhere.

Stay on the Loop keeps a rebreather diver on the loop through deco rather than switching to open-circuit oxygen at the shallow stops. It is a per-plan setting with no row on the defaults screen.

Warning thresholds

Row	Range	Default	What it moves
Gas density warning	3.0 to 8.0 g/L	5.2 g/L	Warnings, and the auto-gas tie-break
Gas density critical	3.0 to 8.0 g/L	6.2 g/L	Warnings, and a hard veto on auto-gas
Max END warning	20 to 100 m (65 to 320 ft)	30 m (100 ft)	Warnings only
CNS warning	50 % to 100 %	80 %	Warnings only
OTU warning	200 to 500	300	Warnings only

The two density figures come from Anthony and Mitchell (2016) and are shared with Settings → Diving. They are kept in order, so raising the warning above the critical pushes the critical up with it. The critical one is the exception to “warnings only”: the auto picker refuses a gas that would breach it, so it can change which gas a level breathes and therefore the schedule.

Thirty metres of equivalent narcotic depth is the GUE, TDI, NAUI Tec, BSAC and CMAS consensus; some agencies use 24 m. The CNS critical tier at 100 % and the hypoxia floor at 0.16 bar are physiological constants and are not configurable.

The app settings the planner reads

Four rows outside the planner change what it shows you. All of them live in Settings → Diving, and the two marked shared are the same value as the planner’s own row.

Row	Effect on a plan
Gas reserve rule	Thirds, Fourths, Fifths, Sixths or Fixed. Sets the “Default” side of every cylinder’s Reserve control and therefore the yellow line on its gas card. Never moves a stop
Water density (shared)	The only row on that screen that moves the schedule
Water temperature (shared)	Gas density readings
Treat O₂ as narcotic (shared)	END figures and their warnings

Your Units settings change how every figure reads, never what it is. One exception holds everywhere: PPO₂ and rebreather setpoints are always shown in bar. See Units and settings.

Behaviour and limits

• A setting that moves the schedule moves it for every scenario tab and every view at once. Only the plan modifiers are scoped to one tab.
• The defaults screen has no override marks, because there is nothing to override there. Its only reset is Reset All to Defaults at the bottom, which rewrites every default including the CCR rig template.
• Changing a default re-resolves saved plans that have not overridden that setting, so a plan you computed last month can change when you change a default. The stale banner tells you when that has happened.

Related

• Deco Planner is the tour of the whole tool.
• Gradient factors explains GF Low and GF High in depth.
• What changes your deco, and why is the cause-and-effect view of this page.
• Gases in the Deco Planner covers the PPO₂ caps from the gas’s side.
• Units and settings covers the app-wide settings.