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The planner Plus

The maths, done honestly.

Two decompression models, Bühlmann ZHL-16C and VPM-B, with gradient factors and full trimix, validated against Subsurface on every build. If a plan can’t be dived, it says so and names the limit that broke it.

Get the planner Why “honestly”?

Quick-slate, no-stop planning is free forever. The full deco planner is part of Plus, bought once.

A 35-metre dive with a little decompression: gas, MOD, water, method, cylinder and SAC, with a dive-conduct table of stop-by-stop schedules

The model

The same maths the serious tools run.

Sixteen tissue compartments, nitrogen and helium throughout, gradient factors under your control. Plan a single no-stop dive or a staged technical descent with multiple gases, and read the result like a slate, not a puzzle.

Algorithms
Bühlmann ZHL-16C with gradient factors, and VPM-B, the bubble model, with conservatism levels. Full nitrogen + helium; trimix is first-class, not an afterthought.
Gradient factors
Yours to set. A conservative 30/70 out of the box, tightened or opened as your training dictates.
Gases
Air, nitrox, normoxic and hypoxic trimix; multiple bottom and deco gases with switches at depth.
Profiles
Multi-level dives, held at each depth in turn, and repetitive dives that carry residual nitrogen. Plan at altitude too, adjusted for the thinner air.
Outputs
Runtime, first stop, stop-by-stop schedule, total deco, CNS % and OTU oxygen exposure, gas use per cylinder, plus longer, deeper and worst-case contingencies on the same slate.
Validation
Every build compares its schedules against Subsurface reference output; the build fails if they diverge.
Determinism
The engine is pure and deterministic: the same plan always produces the same schedule, to the minute.

The honesty

It tells you when a plan won’t work.

A planner that produces a tidy number for an impossible dive is dangerous. ScubaOS refuses to. An unbreathable mix, a missing deco gas, an ascent the model can’t honour: each is surfaced as a labelled error with the limit that broke it.

Warnings are an icon, a label and the offending value, in the same place every time. Never colour alone.

Built to be read by every diver, including the colour-blind
  • ppO₂ and MOD checked for every gas at every depth
  • Impossible schedules raised as errors, never quietly bent
  • At the no-stop limit it offers decompression, not denial
The planner at the no-stop limit: a labelled warning with an icon, explaining the choice: stay within the limit or plan decompression

Recreational

Depth, time, gas. Done.

The planner asks in order and only shows what you’ve set, so it never overwhelms. A recreational diver gets a clean no-stop slate: how deep, how long, which gas, answered on the spot with the minutes in hand. Everything else stays tucked away until you want it.

  • Leads with the one question that matters, answered live
  • No-stop limit, MOD and turn pressure, always on
  • Warnings carry an icon, a label and the number, never colour alone
The guided planner on a recreational dive: 18 metres for 20 minutes, a no-stop dive with 9 minutes in hand, and gas and setup tucked into collapsed sections

Technical

Multi-level, mixed gas, staged deco.

Turn on the capabilities you hold and the same planner grows to match. Multi-level profiles held at each depth, trimix, deco-gas switches, gradient factors or VPM-B, CNS and OTU. The depth is there when you need it and hidden when you don’t. It is never a different app.

  • Multi-level profiles and repetitive dives
  • Deco-gas switches, twinsets and stages
  • Bühlmann GF or VPM-B, trimix, altitude, CNS and OTU
The planner on a technical mixed-gas dive: a 45 metre decompression dive on trimix 21/35, the gas plan switching to EAN50 at 21 metres and to oxygen at 3 metres, and the stop-by-stop deco slate below

Trips Plus

A whole trip, planned like a story.

Plan a trip step by step, or on one page. Your dates and the days it spans, then the dives you want, then the best times. It orders each day’s dives around the tides, carries residual nitrogen from one dive to the next, and resets it overnight across a multi-day trip.

  • A guided flow that only asks what it needs, with a one-page mode a tap away
  • Order by tides: the drifty dives land on slack, the rest fit your day
  • Multi-day trips, first dive and back-by times, and surface intervals worked out for you
The guided trip builder on the best-times step: a day with a first-dive and back-by window, an order-by-tides button, and the first dive at HMS Scylla

Conditions Plus

Plan the water, not just the gas.

Depth and runtime are half the plan; the other half is what the sea is doing. Set a site and the trip planner reads the tide heights, currents and slack windows for that spot, on the day you’re diving it. Give it the dives you want and it works out the running order, dropping the drifty ones onto slack water and fitting them into your day.

  • Tide heights, currents and slack windows, worldwide
  • A diveable or marginal read for your dive time, from the current, wind and waves
  • Multi-day trips ordered around the tides, with residual nitrogen carried between dives and reset overnight
The trip planner reading tides and currents for a dive site: looks diveable near slack, with low and high tide times, slack windows and the current, wind and waves at the dive time

The same slack water, sharper on Pro

Plus reads worldwide modelled tides and slack windows. Pro adds high-resolution stream data for the UK and north-west Europe, so slack is pinned to the minute and a window Plus calls marginal becomes one you can dive with confidence.

Plus The tide reading on Plus: modelled Open-Meteo data, marginal at 10:30 with a strong 2.3 knot stream, and slack windows rounded to about 09:12
Worldwide modelled tides. At 10:30 it reads marginal, and points you at slack around 09:12.
Pro The same site on Pro: high-resolution Copernicus stream data, slack pinned to 09:09, and a diveable read at a gentle 0.3 knot stream
High-resolution Copernicus streams. Slack lands at 09:09, and it reads diveable at a gentle 0.3 knots.

Free, Plus & Pro

What each tier plans.

The quick no-stop slate is free forever. The full decompression planner is a one-time Plus purchase. Pro is the subscription for divers who time tidal streams and who want their plans on every device.

Free
The no-stop slate: depth, time and gas in; the no-stop limit, MOD and turn pressure out. Recreational planning, free forever, no account.
Plus
The full decompression planner (Bühlmann and VPM-B, trimix, multi-level, altitude, CNS and OTU, cylinder and gas planning, contingencies), plus worldwide tides, slack windows and multi-day trips ordered around them. £24.99, once.
Pro
Everything in Plus, and high-resolution tidal streams for the UK and north-west Europe, so you can time slack water to the minute on a drift or a wreck. Your plans and trips sync across every device. A subscription.

Plan your next dive.

Quick-slate planning is free forever. The full decompression planner is Plus: £24.99, once. Pro adds high-resolution tidal streams and syncs your plans across every device.

See the plans Next: the log

No software can guarantee a safe dive. ScubaOS is a planning aid for divers trained for the dives they plan: check every schedule against your own training, your agency’s tables and your computer’s planner, and trust your certified dive computer in the water.