MV-Plan implements the Buhlmann ZHL-16C algorithm (and ZHL-16B as an option) with gradient factors (GF). You pick the algorithm in the Settings.
Gradient factors set how conservative the decompression is. GF Low is the fraction of supersaturation tolerated at the deepest ceiling of the dive (the lower it is, the deeper the stops begin) and GF High the fraction tolerated when leaving the water (the lower it is, the more conservative the final decompression). Between the two, MV-Plan interpolates linearly with pressure, as Subsurface does. Set them in the Settings or through the preset bar of the Plan page.
Because MV-Plan moved from the approximate scale "10 m of water = 1 bar, surface at 1 bar" to real physical pressure (1.01325 bar at the surface, 0.101043 bar per metre of sea water). The old scale underestimated pressure by about 1.1 % on the bottom. Over the 296 reference profiles of the project, 294 see their schedule of stops change, 181 see their runtime go up and none comes out shorter, by +1.13 min on average and up to +8.70 min. The detail is on the New pressure model page.
Because the ascent is now computed the way Subsurface computes it: each leg is tested before being taken, the ceiling is computed exactly and GF Low applies at the deepest ceiling of the dive. The old ascent added a minute at each level evaluated and a minute of "decompression" at 3 m on every dive, even with no obligation. Over the 324 reference profiles, the runtime moves from -12.4 to +1.1 min; over the fifty profiles compared with Subsurface, the mean gap went from 0.85 to 0.33 min. The detail is on the Ascent calculation page.
Because that minute was not owed: it was a calculation flaw, not a safety stop. MV-Plan now holds a real safety stop, named as such in the table, whose duration you set in the Settings (3 min by default). It is held only on a dive with no decompression obligation and does not count towards the no-fly delay.
No. The summary in the saved plans list shows the runtime frozen when you saved, and it is never recomputed. To get today's figure, load the plan, check the Environment line and run Calculate Decompression again. A saved plan now carries the water type and the altitude it was computed for; those saved before that change are read back at sea level in salt water.
Yes, and more than before. Since the move to real pressure, salinity changes the pressure felt at a given depth: at 40 m there is a 3.18 % gap between fresh water and the Red Sea. On a 40 m / 30 min air dive at GF 50/80, the TTS goes from 50 min in fresh water to 54 min at sea and 56 min in the Red Sea. MV-Plan offers four reference points (fresh, brackish, sea, Red Sea) and a custom density from 9500 to 12500 g/l: see Water type and salinity.
No. All your settings, mixes and plans are stored locally on your device. MV-Plan works offline once loaded and sends nothing to a server.
Export a plan from the Saved plans page (the Export action), then import the resulting file on the other device with the Import button.
Turn CCR Mode on in the Settings. You will then be able to manage diluents, choose fixed or dynamic setpoints, and get a bailout simulation. See the Rebreather mode (CCR) page.
The MOD (maximum operating depth) is the depth beyond which the ppO2 of the mix goes past the limit you set. The END (equivalent narcotic depth) estimates the narcotic effect of the mix compared with air. Both are computed automatically on the Gases page.
MV-Plan estimates gas consumption from your RMV / SAC and from the profile. If the volume needed goes past the capacity of the cylinder (volume x pressure), an alert says how many litres and bars are missing. Adjust your consumption, the configuration of the cylinder or the profile. A cylinder marked TIGHT is enough but keeps less than 10 % in reserve; a NOT BREATHED cylinder is carried without the plan ever opening it.
Yes. The mix chosen in the segment dialog is the one the calculation breathes on that segment. If that gas has been disabled or deleted since, the calculation is refused and the message names the segment and the gas, rather than swapping it for another one.
They measure oxygen exposure: CNS (as a percentage) covers central nervous system toxicity, OTU covers pulmonary toxicity. They are shown in the results of the Plan page.
CNS is counted at the ppO2 actually breathed on each line, with the NOAA single exposure limits: 0.6 % per minute at 1.3 bar, 2.5 % at 1.62 bar. On a rebreather, finishing the dive on pure oxygen therefore drives the counter up much faster than a stop held at the setpoint (see CCR mode).
In the Settings, turn the Include dive profile option of the PDF export off. The sheet will then fit on a single A4 page.
Turn school mode on in the Settings and select up to three GF presets. The Profile page then overlays the curves and shows a comparison table (runtime, TTS, CNS, OTU).
Yes, each family of alerts (narcosis, density, ICD) can be turned off in the Settings. That possibility is meant for experienced divers who are at ease with these notions.
No. MV-Plan is a planning aid. It replaces neither your training, nor your dive computer, nor your judgment. Always check your plan against other tools and carry backup tables.