Further reading

What this is

Dive Kit’s numbers come from published science, not from house rules. This page collects the sources behind the whole app, the deco engine and the companion calculators alike, grouped by topic, with a short note on each: what it is, and what makes it worth reading.

Three kinds of entry sit side by side here, and the difference matters. The papers and manuals are what the calculations are built from. The planners and open-source projects (MultiDeco, Subsurface, Abysner, and friends) are independent cross-checks: tools whose results and code we compare against after the fact, not sources the app was derived from. And the forum threads at the end are where ideas came from: real divers telling us what they need, which shapes what the app does, never how its numbers are computed. This page is the one place to follow any of the app’s numbers back to their origin.

If you only read a few, start with Baker’s “Understanding M-values” for the decompression side and Anthony and Mitchell for the gas-density side. Both are short and plain.

Decompression theory and the Bühlmann model

• Bühlmann, Decompression: Decompression Sickness (Springer, 1984). The book that defines the ZH-L family of tissue compartments, their half-times, and their coefficients. Dive Kit’s engine runs the ZH-L16C set straight from this work. Worth reading because almost every modern dive computer traces back to it.
• Why is Bühlmann not like Bühlmann? (The Theoretical Diver). Explains why two planners that both claim “Bühlmann ZH-L16C” can still hand you different stops. The half-times and coefficients are only the starting point: choices about gradient factors, the last-stop depth, how the ascent is sampled, and rounding all shift the schedule. Good background for why Dive Kit’s numbers will not always match another tool to the minute even when the underlying model is the same.
• Workman, Calculation of decompression schedules for nitrogen-oxygen and helium-oxygen dives (US Navy EDU Research Report 6-65, 1965). Introduced the linear “M-value”: the straight line that sets how much overpressure a tissue tolerates at each depth. Interesting because gradient factors are just a way of sliding between Workman’s original line and a more conservative one.

Gradient factors and deep stops

• Baker, Understanding M-values (PDF). The clearest plain-language explanation of M-values and the “decompression zone” between your ceiling and the surface. This is where the gradient-factor method most divers use today was popularised.
• Baker, Clearing Up the Confusion About Deep Stops (PDF). Walks through how a low GF-Low pulls your first stop deeper and what that does to the whole schedule. It is the reference for how Dive Kit interpolates GF with depth.
• The Theoretical Diver (R. Helling). A blog that re-derives the decompression and oxygen-toxicity maths from first principles, with runnable code. A useful independent, reproducible check on the equations behind the engine.

Oxygen toxicity (CNS and OTU)

• Baker, Oxygen Toxicity Calculations (PDF). The CNS-percentage and OTU method, including the coefficient table Dive Kit uses to run your oxygen clocks. It turns “how much oxygen is too much” into a number you can add up across a dive and a surface interval.
• NOAA Diving Manual and Shearwater’s CNS oxygen clock. The single-exposure CNS and OTU limits Dive Kit warns against, explained plainly. The same limits most tec training and dive computers use.
• Clark and Lambertsen, Pulmonary oxygen tolerance in man and derivation of pulmonary oxygen tolerance curves (Institute for Environmental Medicine Report 1-70, University of Pennsylvania, 1970). The experimental basis for the pulmonary (whole-body) oxygen tolerance curves that OTU is built on. The data underneath the daily oxygen limit.
• Hamilton et al., REPEX: Development of Repetitive Excursions, Surfacing Techniques, and Oxygen Procedures for Habitat Diving (NURP Technical Report 88-1A, 1988). Where the practical OTU daily-dose limits come from. Interesting because it is oxygen accounting designed for many dives over many days, not a single exposure.

Gas density, CO2 retention, and work of breathing

• Anthony and Mitchell, Respiratory physiology of rebreather diving (in Rebreathers and Scientific Diving, NPS/NOAA/DAN/AAUS workshop proceedings, 2016, pp. 66-79). Sets the gas-density limits Dive Kit warns at: about 5.2 g/L as the ideal ceiling, about 6.2 g/L as the maximum. The source of the density thresholds in the planner, and the clearest account of why dense gas drives up CO2.
• Warkander, Norfleet, Nagasawa, and Lundgren, CO2 retention with minimal symptoms but severe dysfunction during wet simulated dives to 6.8 ATA (Undersea Biomedical Research, 1990). A chamber study in which divers at 6.8 ATA were severely incapacitated by CO2 with almost no warning signs first. It shows CO2 trouble can arrive suddenly, which is the real danger behind a density warning.
• Lambertsen, Gelfand, et al., Respiration and gas exchange during a 14-day continuous exposure to 5.2% O2 in N2 at pressure equivalent to 100 FSW (Aerospace Medicine 44:844-849, 1973). Early human data on breathing dense gas continuously for days at a time, from Lambertsen’s Predictive Studies series. The linked PubMed record is the umbrella report for the same 14-day exposure. Interesting as some of the first controlled work on long, dense-gas respiration.
• Doolette and Mitchell, Hyperbaric Conditions (Comprehensive Physiology 1:163-201, 2011). A broad review that puts gas density, work of breathing, dead space, narcosis, and decompression in one place. The single best overview tying together most of the hazards Dive Kit checks.

Isobaric counter-diffusion (ICD)

• Burton, Isobaric Counter Diffusion (2004). The widely cited “rule of fifths”: keep any rise in nitrogen fraction under one fifth of the drop in helium fraction when you switch gas. It is the threshold behind Dive Kit’s ICD advisory.
• Doolette and Mitchell, Biophysical basis for inner ear decompression sickness (Journal of Applied Physiology 94:2145-2150, 2003). Models why a helium-to-nitrogen switch can bubble the inner ear even when the surrounding pressure never changes. The mechanism-based view that makes the rule of fifths an advisory rather than a hard rule.
• Isobaric counter-diffusion criteria (The Theoretical Diver). A worked, quantitative look at where ICD thresholds come from. Useful if you want the maths behind the advisory rather than the rule of thumb.

CCR diluent switching (dilout)

• MultiDeco user guide (HHS Software). Shows diluent changes planned inside a CCR schedule (“change to air diluent, and 1.4 at 20m”). The established-planner precedent for the diluent switches Dive Kit models.
• Shearwater Perdix Operations Manual, “Select Gas” / “CC Gases”. Documents five closed-circuit diluent slots, switchable mid-dive. Hardware-side confirmation that real rigs plan for more than one diluent.
• Havard, Understanding and safe use of PPO2 set-points for CCR (2002). A practitioner’s account of switching off a hypoxic 8/62 diluent to air or EAN32 at 40 m when it saves 15 to 20 minutes of deco, plus the loop-flush mechanics behind Dive Kit’s two-flush consumption charge. Honest about how debated the deco benefit is.
• Silent Diving, Which CCR Diluent Fits Your Dive Profile?. Covers diluent surface-breathability and frames diluent switching as “a more advanced configuration and not necessary for most dive profiles”, which is exactly how Dive Kit presents it: empty by default, opt in when your dive calls for it.

Other hazards

• Bennett and Elliott, The Physiology and Medicine of Diving. The standard textbook of diving medicine. Dive Kit’s high-pressure nervous syndrome (HPNS) onset depths, a caution near 80 m and a critical flag near 120 m, trace to it. The reference work to reach for on any diving-physiology question.

Cylinder capacity and real gas

• NIST Chemistry WebBook, Thermophysical Properties of Fluid Systems. The reference data behind Dive Kit’s compressibility (Z) tables for nitrogen, oxygen, and helium, served from the published reference equations of state (Span and colleagues for N₂, Schmidt and Wagner for O₂, Ortiz-Vega and colleagues for He). The Cylinder Database page shows the exact tabulated values and how to reproduce them.
• Dive Gear Express, Calculating SCUBA Cylinder Capacities. The clearest published statement of the US capacity convention: free gas at one standard atmosphere (14.696 psi) and 70 °F, with ideal capacity divided by Z to get the true capacity manufacturers publish. Dive Kit’s imperial capacity figures follow this convention exactly, which is why an AL80 reads 77 ft³ in the app and 77.4 on Luxfer’s sheet.
• Dive Gear Express, Z Factors for SCUBA. A diver-friendly companion table of compressibility factors at typical fill pressures. Its Z(air, 3000 psi, 70 °F) = 1.032 agrees with Dive Kit’s Amagat mix of the NIST components to within about 0.2%.
• Wikipedia, Diving cylinder. Documents the two regional sizing conventions side by side: the US free-gas naming and the European water-volume stamping (ISO 13769).

Buoyancy and body physics

• Deurenberg, Weststrate, and Seidell, Body mass index as a measure of body fatness: age- and sex-specific prediction formulas (British Journal of Nutrition 65:105-114, 1991). The formula Dive Kit’s buoyancy estimator uses to turn BMI, age, and sex into a body-fat estimate. It lets the tool estimate your body’s buoyancy from numbers you already know.
• Siri, Body composition from fluid spaces and density (1956). The body-density to body-fat relation that sits under the estimate above. A foundational piece of body-composition science.
• DuBois and DuBois, A formula to estimate the approximate surface area if height and weight be known (Archives of Internal Medicine, 1916). The body-surface-area formula Dive Kit uses to scale how much lift a wetsuit provides. Old, simple, and still standard.

Open-source planners and cross-checks

• Subsurface. The open-source dive log and decompression engine. Dive Kit reads its deco.cpp as an independent implementation to cross-check against, for example to confirm that water vapour belongs in gas loading but never in the ceiling.
• MultiDeco. A widely used commercial planner. Dive Kit publishes a cross-reference of identical plans run in both, so the numbers can be compared side by side. The public, on-the-table accuracy check for the engine.
• Abysner (NeoTech-Software). A free, open-source (AGPL-3.0) dive planner whose Bühlmann engine is plain Kotlin anyone can audit. Dive Kit reads it the way it reads Subsurface: an independently written implementation of the same model to compare engine choices against. Its own README encourages cross-checking planners against each other, which is exactly the spirit of this section.
• buoyancy.cc. A community scuba buoyancy calculator. Dive Kit’s suit-lift and body-composition maths were cross-checked against it and agree within about 0.1 kg.
• rsingler, Optimal Buoyancy Computer (ScubaBoard, 2019). A community Excel weighting calculator with a 50-page manual behind it: diver biometrics, suit thickness, neoprene compression at depth, salt versus fresh water. Studying it helped us improve parts of Dive Kit’s buoyancy estimator; we adapted some of its ideas into our own independent implementation rather than reusing its formulas. The two tools also knowingly disagree where the physics warrants it: the spreadsheet treats wetsuit foam as massless, which overstates suit lift by roughly a quarter, while Dive Kit subtracts the foam’s own mass and lands within about 0.1 kg of buoyancy.cc.

Community discussions that shaped the app

Plenty of what Dive Kit does came from divers saying what they actually need, in public, where anyone can read the exchange. These threads contributed feature direction and field experience, not formulas; the science above is where the numbers come from.

• r/diving CCR planner feedback (Reddit, 2026). A CCR diver’s detailed field feedback on Dive Kit’s planner. This conversation directly shaped the diluent-switch (dilout) model, the two-flush switch consumption charge, comma decimal input on European keypads, and the EU 232 bar CCR bottles in the cylinder database.
• ScubaBoard, “Current state of deco planing apps” (2026). Instructors and tec divers comparing the planning apps they actually use and what they want from them, cross-platform support and a consistent mobile UI chief among the asks. A useful read on where the field stands, and part of why Dive Kit treats mobile-first design as the whole point rather than an afterthought.
• ScubaBoard, “Dive Kit: cross-platform dive planner with OC/CCR support” (2026). The developer’s own feedback thread. Suggestions raised there, from trial visibility to feature requests, feed directly into releases; if you want to influence the app, this is a good place to do it.

Related

• Assumptions and limits lists every modelling choice the engine makes and the core sources in brief.
• Hazards beyond decompression is where the gas-density, ICD, and HPNS thresholds above are applied.
• How the deco engine works and Gradient factors put the decompression sources into practice.
• Buoyancy calculator is where the body-composition and suit-lift sources above are applied.