Planning

The Plan page is the heart of MV-Plan: this is where you build the dive, run the decompression calculation and read the results.

Dive segments

A dive is described as a series of segments. Each segment gives a depth and a time.

To add a segment, click Add Segment:

• Depth (m): from 1 to 200.
• Time (min): from 1 to 999.
• Gas (open circuit): the mix breathed on that segment, among your enabled gases. That mix really is the one the calculation breathes on the segment. If you disable or delete that gas later, the calculation is refused with a message naming the segment and the gas: MV-Plan never silently swaps a gas you chose for another one.
• In rebreather mode: the diluent and the setpoint (see CCR mode).

A segment whose time is shorter than its own descent (with the Descent time included setting on) is refused, and the message gives the descent time.

Every segment in the list can be edited or deleted (with confirmation). You can chain several segments to describe a multi-level profile.

Picking gradient factors quickly

A bar of GF presets sits above the calculation. Click a preset to apply its GF Low / GF High pair straight away and run the calculation again. The Custom button lets you type values of your own; it becomes active when the current GF match no preset.

Presets are managed in the Settings.

Dive information

• Dive Site: name of the site (prefilled from the settings).
• Divers: names of the people diving (prefilled from the settings).
• Notes: free text for instructions, reminders or information meant for the dive supervisor. These notes appear on the printed PDF.

Environment

A collapsible section repeats the environment parameters (gas temperature, water type, altitude) that you can adjust for this particular dive without changing your default settings. Collapsed, the title recalls the three values in force, for instance (35°C, Salt water, 0m).

Water type offers four reference points with their density (fresh, brackish, sea, Red Sea) and a custom density from 9500 to 12500 g/l. That choice is not cosmetic: it changes the pressure actually felt, and therefore the length of the stops. See Water type and salinity.

Running the calculation

Click Calculate Decompression. MV-Plan computes the whole profile and shows the results under the button.

Results

Configuration summary

A grid recalls the parameters used for the calculation: gradient factors, descent and ascent rates, algorithm, last stop depth and mode (OC or CCR).

Table of stops

The table details the profile: descent, bottom, ascent and decompression stops, each line carrying the depth, the time, the runtime, the gas, the ppO2, the END and the gas density. A few lines deserve a word:

• Gas switch: every change of mix has its own line, naming the gas left behind and the gas taken, including when it happens on the bottom before starting up. The duration of the switch (adjustable) counts in the runtime and in the TTS.
• Safety: the safety stop, held only when the dive owes no decompression at all (see Settings). A dive with no obligation therefore no longer shows a one-minute "decompression stop" at 3 m.
• Flush: in rebreather mode, a planned loop flush (see CCR mode). The line names the mix taken and the one it replaces, with the ppO2 actually breathed: during a flush the setpoint does not hold, so the Setpoint column stays empty.
• Empty setpoint: in rebreather mode, on any line where the loop does not hold the setpoint - a loop on pure oxygen, or water shallower than the setpoint. The ppO2 shown is then the one ambient pressure gives (see CCR mode).

How the ascent is computed is described on the Ascent calculation page: each leg is tested before being taken, a stop is left when arriving at the next level is safe, and the results line up with those of Subsurface.

In rebreather mode, two tables are shown: the CCR plan and the bailout simulation (see CCR mode).

Figures

• TTS (Time To Surface): total time to reach the surface.
• Total Runtime: total length of the dive.
• Deco Time: stops added up.
• CNS: central nervous system exposure (oxygen toxicity), as a percentage.
• OTU: oxygen tolerance units (pulmonary toxicity).
• Max Depth and Bottom Time.

Gas consumption

The consumption table estimates, for each cylinder, the volume of gas needed (from your RMV / SAC) and compares it with its capacity. Each line carries a verdict:

• OK: the cylinder is enough, with at least 10 % held in reserve;
• TIGHT: the cylinder is enough, but with less than 10 % in reserve - one more minute of stop and it is short;
• INSUFFICIENT: litres are missing, and the figure is given (with the bars when a single cylinder carries the mix);
• NOT BREATHED: the cylinder is carried but the plan never opens it.

Two cylinders of the same mix add up. A cylinder of another mix is never added in: it is named as a backup, with what it has left, when it could take over at the depth concerned. A cylinder that falls short and that you described (volume and pressure entered) is also raised in the alerts of the plan, with the same figures.

On bailout, when a cylinder runs dry during the ascent, the plan moves on to the next one at the depth where it empties, and says so: the gas switch line appearing there is not a decompression switch you planned, and an alert names the emptied cylinder and the depth.

Fullscreen

A button shows the results fullscreen, handy for reading on the dashboard or before printing.

Exporting and sharing

Once the plan is computed, several actions are available:

• Save Plan: stores the plan in your saved plans.
• PDF: produces a printable dive sheet. Whether the profile chart is included depends on the matching option in the Settings.
• Share: passes the plan on through the native sharing of your device (on a phone) or of your browser (on a computer).

The PDF always repeats that it is a planning aid and that backup tables should be carried.