Build the diver.
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the plan.

Edition 2.1 · 21 October 2026 · Planner V2 RC3 · QA6

This manual describes the repaired equipment-aware open-circuit planner, including independent primary-cylinder reserves, physical end pressures, pressure-history visualization and portrait/landscape A5 slates.

Evidence and version scope

The QA6 replacement files and their local Chrome checks are the implementation reference. The original RC2 manual supplied the chapter structure, historical screenshots and worked cases. Those cases retain their explicitly entered inputs; their reserve values are not QA6 defaults. No authenticated account workflow, real dive or physical printer is certified by this edition.

The downloadable PDF and this online guide contain the same revised chapter text. The earlier RC2 edition is retained separately for historical comparison.

The page follows the planning sequence from inputs to evidence.

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The shortcut links jump to Profile, Equipment & gas, Model & settings, Calculate & results and Local jobs. The last label still says “Local jobs” even though signed-in storage is account-backed.

Build the diver first. Review the result as a whole.

After any edit

Recalculate. Profile, equipment and settings changes can clear the displayed result. Saving also calculates first. A screenshot or copied plan is a snapshot of one calculation, not a live view of later edits.

Two time modes describe different quantities. Choose one before entering rows.

Worked time conversion

At the default descent rate of 18 m/min, descending to 40 m takes 3 rounded minutes. A 25-minute hold therefore ends at runtime 28. Enter 28 in Leave-level runtime to describe that departure; entering 25 leaves 22 minutes at depth.

Whole-minute travel matters

Travel duration is rounded upward to a whole minute for each leg. Even a 6.0 m to 5.8 m movement can add one minute. This changes gas use, tissue loading and comparisons with a computer using continuous travel.

Use rows to describe the intended profile; inspect the resulting transitions.

A multilevel teaching exercise

Enter 30 m / 10 min, then 18 m / 10 min on the same gas in Time at level mode. Compare the generated schedule with a single 30 m hold. This is an exercise setup, not a validated dive schedule or a guaranteed no-stop result.

Hypoxic mixtures require explicit transitions

A hypoxic bottom blend cannot simply be selected for a descent beginning at the surface. The engine checks the shallow and deep ends of travel against its 0.16 bar lower oxygen threshold and the configured working pO2 limit. Configure an appropriate carried travel gas and explicit travel level before the bottom gas; verify the return route too.

Intermediate ascent checks

This V2 source checks user-entered ascents against the GF ceiling and checks the final trajectory. Do not use manually drawn shallow levels as a substitute for validated decompression planning. The automatic ascent is generated after the last profile row.

The configuration changes the available workflow and planning restrictions.

Technical-capable is a software classification

It reflects gas-source architecture, not diver competence, valve/regulator configuration, team readiness or verified emergency capacity for every failure. Extra deco gas alone does not turn a single bottom source into redundant bottom gas.

Progressive controls

Advanced loadout reveals helium, material, volume, roles, lower slots, manifest and engine table. Advanced controls can open automatically when the configuration or gases need them. “Technical options active” means these controls remain required.

A highlighted cylinder is only the cylinder being edited.

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The cylinder editor describes a physical resource, not just a blend name.

Readouts update with the environment

The editor shows gas, applicable MOD, pO2 and density at the deepest entered level, and capacity. A deco cylinder showing a high pO2 at maximum depth is not an instruction to breathe it there: its use must remain within its switch and oxygen limits.

In a twinset, enter the water volume of one cylinder. A 12 L + 12 L selection produces 24 L total; do not enter 24 L per cylinder.

The printed cylinder table reports each twinset cylinder separately using equal pressure drop. A 2 × 12 L system at 200 bar contains 4,800 surface litres in the ideal-gas model.

Entering Sidemount creates a left primary at 200 / 66 bar. Adding the right primary through Pair or Carry this cylinder initializes that primary's reserve from its own starting pressure. Both primary cylinders, including a single-primary setup, use the editable one-third default.

Fresh standard stage/deco slots default to 50 bar. The additional-manifest cylinder initializer and some historical/demo slots retain 40 bar; inspect the displayed reserve rather than assuming all carried resources share one default.

A pooled gas surplus does not hide an individual-cylinder reserve deficit under the stated allocation. Promoting an active carried stage to a sidemount primary applies the primary default.

V2 preserves cylinder data when it changes a carried position.

Lean to rich: occupied slots only

For backmount/twinset, ordering is S1 left upper → S2 left lower → S3 right lower → S4 right upper, from lower to higher oxygen fraction. Empty positions stay empty. When sorting occurs, the complete cylinder object moves, including its pressure, reserve, size and role.

Dual-sidemount exception

The independent primary left/right pair stays fixed and can have the same gas. Lean-to-rich sorting applies to the additional carried stage/deco/bailout cylinders, not across that primary pair.

Bailout scope matters

In this build, the technical-mode bailout check uses the four carried slots. An extra manifest cylinder marked Bailout is not included in that mode-unlocking check. The +depth/+time feature is not a lost-gas simulation.

Go beyond the four visual carry slots without hiding resources.

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Engine gas table

Expand this table to inspect the gas resources, volume and pressures generated from the loadout. Same-mix sidemount primaries can appear as one combined resource; carried and extra resources remain individually identified. Although the table cells look editable, this build regenerates gas inputs from the loadout when calculating. Make durable changes in the cylinder editor or manifest, then recheck this table.

The quick helper and the main engine use different environmental assumptions.

Simple sea-level teaching formulas

pO2 = FO2 × (1 + depth / 10). MOD = 10 × (pO2 limit / FO2 - 1). EAD = (depth + 10) × (1 - FO2) / 0.79 - 10. These are helper formulas, not the exact environmental calculation used by the main planner.

Why a switch can appear at 5.8 m

At 1,013 mbar, salt-water density 1.030 kg/L and a 1.60 bar oxygen limit, the main engine permits oxygen at about 5.8 m. It rounds switch depths toward shallower water. EAN50 can show MOD 21.7 m in a rounded readout but switch at 21.6 m in the schedule.

The same GF pair does not guarantee the same runtime in two planners.

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The model is Bühlmann ZHL-16C with gradient factors and separate nitrogen/helium tissue loading. These are mathematical compartments, not measured body tissues. Changing GF is not a simple universally ranked “safer” slider.

Separate phase settings explain why two gas reports can differ.

Surface litres are not bar per minute

RMV here is litres per minute referenced to the surface. It does not change with cylinder size. A consumption rate expressed as bar/min depends on water volume and must not be entered as if it were RMV.

Read the event-level gas assignment

Profile and ascent phases can use different RMV settings, and gas changes have their own timed events. The detailed schedule is the right place to reconcile a gas-use difference with another tool.

Pressure assumptions affect MOD, gas use and decompression.

Using pressure retrieval

Select the METAR button only if you want location-based lookup. The implementation first attempts nearby aviation observations and has weather/location fallbacks. If retrieval fails, the existing pressure remains unchanged. The manual did not trigger location permission or test the external weather services.

Avoid double altitude correction

The sea-level pressure field and altitude are used together. Entering local station pressure and then adding altitude can apply altitude effects twice. Use an appropriate sea-level-adjusted value and confirm the actual conditions independently.

Reproducing a case

Use salt water, density 1.030 kg/L, altitude 0 m and 1013 mbar for all numerical cases in this guide. Do not fetch weather while reproducing them; it would change the inputs.

A transparent estimate with a defined endpoint.

No-stop endpoint

The estimate generally runs from maximum depth to the surface if there is no independent gas handover. It is separate from the normal-plan calculation, simple cylinder reserve and optional safety-stop gas.

Decompression endpoint

The estimate runs toward the first independent ascent/deco gas handover, including planned bottom-gas decompression holds before that handover. It does not prove the downstream independent gas will cover every emergency.

When no estimate is supplied

A decompression plan without an independent gas handover returns an unavailable estimate rather than an invented reserve. A schedule can still be displayed; the missing emergency estimate is a separate unresolved issue.

Saved profiles and previous tissue history are different mechanisms.

What carries forward

The model carries nitrogen/helium tissue state. During the surface interval it models surface off-gassing before the next profile. It does not reset tissues just because the next profile is shallow.

What does not carry forward

CNS and OTU in the results are for the current calculation only. V2 does not accumulate prior repetitive oxygen exposure. The displayed percentages must not be interpreted as a whole-day exposure total.

Session and saved-profile nuance

Session history is not a permanent logbook. A saved input can also contain an initial tissue snapshot, so a retrieved profile deserves explicit history review. Saving a profile is not equivalent to storing the current result as the previous dive.

The top cards answer different questions.

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Segment time is a duration; Run is cumulative elapsed time.

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Read left to right

Action identifies descent, level, ascent, switch, deco or safety stop. Depth is the segment endpoint or hold depth. Segment is time spent in that row. Run is the runtime at its end. Gas is the resource used.

Show detailed event schedule

Expand it when investigating rounding, individual holds, gas consumption or a difference between planners. The compact table groups compatible events for readability; the detailed table exposes the underlying event sequence.

These checks answer different questions; none replaces the others.

The 40 m air case demonstrates the distinction

The result has positive gas margins and bottom pO2 around 1.06 bar, but density around 6.4 g/L triggers a danger warning. Passing one check does not cancel another.

The 50 m trimix case is not a simple depth comparison

Tx18/45 at 50 m displays about 4.8 g/L density and END about 23 m under the model’s narcotic assumption. This does not establish equivalent training requirements, equivalent decompression or equivalent overall risk to a shallow air dive.

Distinguish a rejected input from a calculated result that still needs revision.

Some audit messages block; others inform

Zero start pressure, reserve not below start, or a manual deco switch deeper than MOD can block. A steel-cylinder trim note is informational. Density can be a danger finding even when it does not prevent the engine from returning a schedule.

The contingency label is broader than it sounds

“CONTINGENCY NOT GAS-FEASIBLE” can be triggered by a danger warning as well as a negative capacity margin. In the 40 m air example, the contingency has positive litre margins but fails the density check. Read the accompanying details.

Do not wait until the reserve pressure before starting an ascent.

Case 1: a positive departure margin

At 18 m / 25 min, the 12 L Air cylinder predicts 91 bar at departure. The displayed required-from-turn target is 64 bar, with a +27 bar margin. That is not a universal turn rule; it belongs to this exact profile, ascent and reserve.

Case 2: no-stop but insufficient gas

At 20 m / 30 min, departure pressure is about 57 bar while about 65 bar is needed. The initial banner reports roughly 8 bar short. Independently rounded cells can show a -7 bar margin; one-bar display differences do not remove the shortfall.

Final level is not always deepest

In a multilevel profile, the turn report refers to the last entered level. Minimum gas instead uses the deepest working point. These are different locations in a plan and should not be interchanged.

Keep surface litres, cylinder water litres and pressure separate.

Example: 18 m teaching case

The 12 L cylinder at 200 bar contains 2,400 L in this model. The 50 bar reserve is 600 L. Observed use is 1,480 L, leaving about 320 L above reserve. Estimated end pressure is therefore about 77 bar.

Why the sums may differ by one litre

Each displayed cell can be rounded independently. For example, 1,309 L profile + 172 L ascent appears beside a rounded total of 1,480 L. Use the underlying calculation for reconciliation; do not treat the display as exact laboratory measurement.

Physical cylinder estimates

The result now lists each physical cylinder, including each twinset or sidemount bottle: used surface litres, start pressure, estimated end pressure, reserve and remaining margin. End pressure = start pressure - allocated litres / water volume. Same-mix pooled resources allocate litres in proportion to water volume, producing equal pressure drop. Negative end pressure indicates a gas deficit, not a physically achievable gauge reading.

The pressure-history chart and slate end-pressure table use this same accounting. Real compressibility, temperature, gauge error and cylinder-switching technique are not modelled.

This searches for a whole-minute hold at the last deepest level while retaining entered reserves. It is an optimizer for software constraints, not an instruction to use the maximum duration.

1. Set the complete loadout, profile, model settings and each cylinder's reserve.
2. Choose Find max stay to reserve. In recreational mode the search is additionally capped by the no-decompression limit.
3. Read the maximum-stay message and limiting gas. The deepest hold changes; in leave-runtime mode later leave times shift accordingly.
4. Review the regenerated schedule, individual-cylinder margins, oxygen/density warnings and contingency.

The search ceiling is a 600-minute hold. If even a zero hold cannot cover the modeled route and ascent, no feasible stay is reported. A returned maximum may still have warnings and does not reserve extra contingency or account for unmodelled failures.

The + plan recalculates the modified profile and ascent.

Time-mode behavior

In Time at level, the extra time adds to that level’s hold. In Leave-level runtime, the extra time shifts that and following leave runtimes. Added travel from the deeper level still affects the interpretation; do not assume identical hold increments across both modes.

Repeated deepest levels

The source modifies the first deepest level for contingency, while maximum-stay search targets the last equally deepest level. With repeated equal maximum depths, explicitly inspect which row changed.

What the + plan does not simulate

It is not automatic lost-gas, regulator failure, lost teammate, missed-stop, delayed rescue or staged-cylinder-access planning. Those scenarios need separate deliberate modeling and independent procedures.

A shared timeline, with two different units on the right axis.

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Move the pointer over the graph, or focus it and use arrow keys, to inspect runtime, depth, gas, GF99 and phase. During the planned ascent, TTS is the remaining scheduled time including switches and stops. A value of 50 on the right axis means 50% for GF99 but 50 minutes for NDL/TTS.

Estimated cylinder pressure graph

A second graph shows remaining bar over runtime for every physical cylinder. Its smaller labels, thin traces, grid and rounded time divisions match the main profile. Dotted lines mark reserves. Identical traces can overlap; each cylinder retains a separate readout card with start, end and reserve values.

Use the main graph, timeline slider or play controls to move the shared cursor. Gas unused during a segment stays flat. Below-reserve values carry a textual warning; negative pressure is labelled GAS DEFICIT. The plotted curve integrates gas use against changing ambient pressure during travel. These are modeled estimates, not live gauge readings.

Inspect the modeled compartments at a particular runtime.

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Sixteen rows run fastest to slowest. Black bars represent dissolved nitrogen + helium pressure, cyan marks inspired inert pressure, and the white tip identifies the GF99 leader. Green/yellow/red are pressure zones, not permission to ascend. Each row uses its own changing scale; compare its values, not just bar length.

Use these settings before comparing any of the measured cases.

Two additional cylinders for technical cases

Case 4, Case 5 and Case 6 use S2 EAN50 in an S80 11.1 L aluminium cylinder, 200 bar / 40 bar reserve, and S3 O2 in a 7 L aluminium cylinder, 200 bar / 40 bar reserve. Both are carried with Decompression role and automatic switch ceilings.

The primary twinset reserve is deliberately overridden

Those three cases use 2 × 12 L steel, 200 bar, 50 bar manually entered reserve. Selecting Twinset alone initially gives 66 bar at 200 bar, which will not reproduce these cases.

These are arithmetic and interface exercises, not measured decompression schedules.

Exercise A: linked mix, unequal pressure

Choose Sidemount → Pair. Keep both S80 cylinders at 11.1 L on Air. Enter 200 bar left and 180 bar right, with 50 bar reserve each. The combined engine row should represent 22.2 L at a volume-weighted 190 bar and 50 bar reserve: 4,218 L total, 1,110 L reserved and 3,108 L above reserve.

Exercise B: change one mixture

With Link left/right primary sidemount mix enabled, change a primary mixture. Observe that the other mixture changes while its starting pressure and reserve remain independent. Then disable linking and compare the separate engine resources. Recheck whether both gases support maximum depth.

Exercise C: a selected but absent cylinder

Select an empty carried slot. Its editor and default blend become visible. Before enabling Carry this cylinder, check that it still says OFF / Not carried. Enable it and inspect the manifest and profile gas list.

Exercise D: empty-slot preservation

Enable two non-primary carried slots with different oxygen fractions. Reverse their relative richness through an edit. V2 can move complete cylinder objects between occupied slots; empty slots should remain empty. Check pressure and reserve travel with the object.

Saved profiles contain the complete dive and cylinder setup.

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Capacity and location

Guests have 5 total slots: 1 fixed demo + 4 personal profiles in this browser. Signed-in users have 15 total: 1 demo + 14 personal account profiles. Browser-local data can be lost when site data is cleared or may be unavailable in restricted/private sessions. Calculations run locally, but account saves transmit the complete setup to the account service; the page’s local-calculation statement should not be read as a promise that cloud saves stay only on-device.

1. Calculate and review the current plan. Edits invalidate the prior result.
2. Copy plan exports settings, schedule, gas information and physical-cylinder estimates. Paste the clipboard into a temporary document to confirm success.
3. Choose Slate layout: A5 portrait (default) or A5 landscape, then Print A5 slate.
4. The separate preview checks the schedule and page fit. Select Print / save vector PDF. Use A5, the chosen orientation, 100% scale and no browser headers/footers.
5. Inspect the exported file. A printer's non-printable margins may differ from the preview; no physical printer is validated by this manual.

What is printed

One page inside 4 mm margins: depth/bottom time/runtime/GF/ascent-rate header; vector profile; stop table; gas specification table; and a physical-cylinder table with Start, End, Reserve and Min turn pressure. End pressure is emphasized separately for each cylinder.

BT is time held at maximum depth; RT is total runtime. The three ascent rates are first-stop / between-stops / surface. Table travel durations are explicit additions to holds or switches, so cumulative runtimes can be checked. Min turn is scheduled ascent use plus the entered reserve, not the separate emergency estimate.

Strict page-fit behaviour

Portrait accommodates longer stop lists better. Oversized tables or graph labels are blocked rather than shrunk below readable sizes, clipped or silently split. Runtime continuity, gas-list consistency and switch MOD/ppO2 are checked against the calculated plan. More than four switch labels are refused by this compact layout. A longer landscape case may fit in portrait.

The slate intentionally contains no logo, disclaimer or full warning/contingency narrative. Keep the website review and separate copied record with it. A successful print is not a validation of the plan. No automatic contingency backside is generated; this planner is open circuit, so no CCR setpoint is invented.

Match inputs first; investigate differences instead of forcing agreement.

For a Perdix or another dive computer

The original guide included a Perdix 2 reference. This edition avoids assuming unchanged firmware menus. Consult the current manufacturer manual for that exact model and firmware, then record the comparable settings above. Sharing a GF pair does not guarantee identical schedules.

When the numbers differ

Find the first differing event: travel, switch, hold or stop. Compare that event’s gas and duration, then examine tissue/history and pressure assumptions. Do not alter real gas fractions or reserve requirements simply to make displays agree.

Read the error literally, then inspect the setting it names.

Reserve does not change as expected

Confirm RC3 · QA6 is loaded after a hard refresh. For a sidemount primary, change its own starting-pressure field and leave the field to commit the edit. Selecting a cylinder alone does not change its reserve. Stage/deco pressure edits intentionally keep their reserve. Saved reserves are retained until a starting-pressure edit. Manual overrides last until the next starting-pressure edit of that cylinder.

Invalid gas totals, negative reserves and invalid cylinder volumes are not silently corrected by the equipment editor; fix the displayed values before calculating.

Different reports can be correct while answering different questions.

Print preview is blocked

Read the error outside the slate. Try portrait if landscape is too crowded. The export does not reduce its minimum text size, omit stops or invent an absent schedule. Resolve input/schedule inconsistencies rather than bypassing the check.

These are UI limits in the inspected build, not recommended operating ranges.

Continue the field dictionary. Values describe the inspected UI.

Make the unit visible whenever you compare a number.

Capacity and pressure

Available = water volume × start pressure. Reserved = water volume × reserve pressure. Estimated pressure consumed = surface litres used / water volume. For a twinset, use total water volume in these equations.

Consumption at a constant level

Gas use ≈ RMV × ambient pressure × time. At a simple illustrative 3 bar ambient, 18 L/min for 10 min uses about 540 surface litres. The planner uses its actual environment and event structure, so this is a sense-check, not a replacement calculation.

A compact dictionary of the labels used throughout the guide.

Gas percentages must describe the analysed cylinder contents. A preset name is a convenience, not evidence of what a real cylinder contains.

Know which labels describe a model, a resource or an exposure estimate.

A 60-minute structure using the verified cases and interface exercises.

Answer key

Case 1: contingency consumes the main plan’s spare capacity. Case 2: no-stop time is a decompression constraint, not a gas guarantee. Case 4: density warning remains; switch rounding is toward shallower depth in the configured salt-water environment. Sidemount: linked composition does not imply linked pressure or equal emergency sufficiency.

Further discussion

Why does First deco jump to 9 m when Case 4 says First stop 15 m? Why can a 5.2 g/L display still produce a warning? Why should a repetitive calculation’s CNS percentage not be read as a day total?

Print or duplicate this page for a software comparison exercise.

A one-page summary to return to after the detailed chapters.

Edition 2.1 / 21 October 2026 / RC3 · QA6. The reference is the QA6 replacement package prepared for the site owner. This document does not independently confirm which package is deployed on the public server.

Recorded local checks include 21 QA4 browser checks, eight QA5 focused checks and eleven QA6 reserve checks. These counts belong to different release suites and should not be added as distinct coverage. The sample PDFs were one-page vector exports. Authentication, account sync, location services, physical printing and real-world physiology remain outside that verification.

The retained RC2 cases and screenshots are historical observations from the 19 October 2026 manual. They are not represented as re-run against QA6. See the archived RC2 guide for the original context.