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Frequently Asked Questions

FAQ  Top 10 questions    Lost passwords

Dive planning
Quick start
Important points in VPM & V-Planner
Planning considerations in VPM
Travel gas
Deco gas switch depths / points
Multi level
Multiple plans
Air breaks
Saved plans & logs
Conservatism levels
Guest / Diver mode
CCR & SCR planning
SCR fiO2 adjustments
SCR plans
CCR Levels, diluent, setpoint
CCR bail out, SCR & OC deco
Output files
VPM & VPM-B information
VPM test data
Advanced settings
Palm, Win CE, Handheld devices
Linux, Unix, Mac

Quick Start
  • Enter depth, time and gas details as legs into the left column, using the Add Level button at the bottom.

  • Place a check mark next to the legs to be included into plan.

  • Enter deco gases into the deco gas column, using the Add Deco button at the bottom.

  • Place a check mark next to the deco gases to be included into plan.

  • Set a time interval - either by selecting 24 / 48 hrs, or entering actual time.

  • Press the Calc button at top.
Important points
  • Follow the run times. The displayed stop times include the time required for transit between stops

  • Do not add any extra stops in the deep sections of the dive. This will add significantly to the decompression obligations. You may extend the shallow stops without side affects.

  • Carry out the ascents at the rates used in the plan. Ascending at a rate faster or slower than specified may require additional decompression.
Planning considerations in VPM

VPM now comes in two models. The original produced plans that were on the aggressive side and were quick to complete the shallow stops. VPM-B is a further refinement and generates the same deep stops and now gives more time in the shallow stops.

The VPM in V-Planner is a highly tuned deco tool and you must follow the plans closely. Any large deviations from planned ascent in depth & time during decompression, must be avoided. Significant changes will require additional deco time to compensate.

You may add extra time, if required to the last deco stops without side effects.

Plans with deco mixes will generate slightly faster run times for the mid level stops - even before any gas change has occurred. VPM calculates decos in an iterative process, and adjusts for additional off gassing capability later in the deco from the high O2 mixes to come.

If you are forced to adopt a new plan in water from lost / broken deco gas - wait out the additional time between the two plans, at the current level, and then commence timings per the new plan. (see also question 1 in top ten)

A faster deco from deep dives is usually possible when the first deco gas switch is at, or just above, the same level as the first deco stop. High helium deco mixes after trimix dives, usually do not accelerate deco.



Depth    Select either Feet or Meters.

RMV's    Units for calculating gas consumption's.

Stop Times    Set the rounding up factor for all deco stops.

Water    Fresh or salt water (2.6% change).

Conditions - Deco Steps
Size  Step spacing.
Last Stop  Set if last stop needs to be deeper than Size setting.
Deep Stops  Increase step spacing to double for deeper portion of dive.
Conditions - Deco mix depths
Max ppO2 for deco mix ....%  This value controls when switches are made to deco mixes depending on the O2 content and maximum ppO2 set.
Max depth on 100% O2  Sets maximum depth for use of pure O2 deco.
Conditions - RMV
Bottom  Consumption rate for descent, bottom and climb to first deco stop portions of the dive.
Deco  Consumption rate for all deco stops portion of the dive.
fiO2 adjustments  For SCR and CCR in SCR mode. Allows setting of values to use in the inspired mix from O2 metabolized.

Extend Stops    Force the program to extend a deco stop when switching onto a new deco gas (over stopping). The All deco mix changes will apply the extended time for any deco mix change, otherwise the extended time will occur only if a stop was required at that depth. Two seperate settings for above/below 100ft/30m.

O2 Window affect    Program checks for the condition that when on high ppO2 deco mix, enough off gassing has occured on a previous stop to allow by passing the current level without a stop.

CCR Setpoints    Set this to match the set point controller / ppO2 readout on your rig. Bar = 1000mb. Atm = 1013.25mb

Conservatism    Nominal is the base value, and is for the super fit and divers with a proven track record of fast deco. Plus 2 or 3 is the normal setting for most divers. Set to plus 3 or 4 with strenuous, cold, a series of multi day dives, extra safety, or a prior history of DCS or symptoms.
This setting increases the Critical Radii of N2/He inside the VPM algorithms, from these base values, by this increase: 1 = 5%, 2 = 12%, 3 = 22%, 4 = 35%. The Critical Volume setting is on by default.

VPM Model    Switch between the original VPM and VPM-B. Original will make the deeper plans rather aggressive. VPM-B corrects the shallow portions of deco for Boyles Law considerations, giving more time in the shallow sections.

Descent Ascent rates    Values must cover all dive depths, no overlaps in each range.

Elevation data
Elevation  Dive elevation.
Hours at dive elevation  Time at dive location prior to dive.
Ascended from  Elevation at start of journey to reach dive site.
Travel Time  Time of journey to reach dive site.
Avg. elevation last 2 weeks  Average elevation during last two weeks of surface time. Estimate lower for safety.
Printer    Full will print the dive plan as per the display. Short will print only the depth, stop time and run times, in a vertical display. See output files


Travel gas

Switches in mixes during the dive are controlled by inserting legs into the plan, with a time of zero(-). e.g.

Switch in descent from travel to bottom mix.

25, - , 32       travel gas 32% to 25m.
95, 30, 12/60    30 mins at 95m, on 12/60 mix

Multi level descent with switch

22, 5, 32        5 mins at 22m, 32%
22, - , 18/30    swap to bottom mix when leaving 22m
65, 20, 18/30    20 mins at 65m on mix

Switch in ascent, on a multi level plan.

40, 30, 21       30 mins at 40m, air
21, - , 50       swap to 50% in ascent at 21m
10, 20, 50       20 mins at 10m

The program reads down the list of legs, and creates plans based on the order each leg is encountered. To rearrange the order of legs - drag the selected leg up / down the list (hold down left mouse button), or right click and select Sort List.


Deco gas switch depths

All switch depths onto deco gases / mixes, are controlled by the ppO2 settings in configuration. The program will select a gas from the checked items in the deco gas list, based on the max ppO2 settings, for each of the required stops.


Multi level

The program reads down the list, and creates plans based on the order each leg is encountered. Multi level plans (or cave profiles) are entered by specifying each level (and gas change) in sequence. e.g.

Multi level descent with switch

22, 5, 32        5 mins at 22m, 32%
22, - , 18/30    swap to bottom mix when leaving 22m
65, 20, 18/30    20 mins at 65m on mix

Multi level ascent.

40, 30, 21       30 mins at 40m, air
10, 20, 21       20 mins at 10m, air

Multi level ascent, with gas switches.

55, 25, 18/25    25 mins at 55m, 18/25 mix
21, - , 50       swap to 50% at 21m
10, 20, 50       20 mins at 10m, 50%

Multi level saw tooth dive.

60, 25, 18/30    25 mins at 60m, 18/30 mix
10, 20, 21       20 mins at 10m, swap to air
30, 15, 21       back down to 30m on air
15, 25, 21       up to 15m for 25 mins on air

In all cases above, any gas in the deco column is not utilized until the last dive plan leg has been processed. If a switch to another gas is required in mid water, then insert a leg with a time of zero. See travel gas.

On multi level ascent plans with sufficient change between levels, V-Planner will insert decompression stops mid water prior to reaching the next level. This also triggers the program into Critical Volume off mode.

The program reads down the list of legs, and creates plans based on the order each leg is encountered. To rearrange the order of legs - drag the selected leg up / down the list (hold down left mouse button), or right click and select Sort List.


Multiple plans

Multiple dive tabs Enter multiple dive sequences using the tabs along the top. Each tab for the next dive becomes visible, only after sufficient data has been entered for the current dive.


Air Breaks

Air or other Gas breaks can be put in the plan. These changes in inspired mix, are not just inserted, but actually calculated as part of the decompression for the dive.

Conditions    Select the conditions that will trigger the breaks to commence.

Timing    The Reset will cause the timing intervals to be interrupted each time a new level is started. Leave this unchecked to keep break timings at the intervals specified.

Break gas    Select the gas used on breaks. Last Deco mix will break to the gas used as the previous deco mix (if present) or the bottom mix when relevant. Use Special Mix when a unique gas is used for breaks only.


Saved plans & logs

Saving a plan updates your tissue loading data. This is where V-Planner keeps track of tissue gas loadings for repetitive dives. Note that the repeat factor in VPM can be as long as two weeks.

You may plan and replan a dive as often as you like, but once the Save button is pressed, the data is committed. There is no Undo function. Please ensure that the saved information is an accurate record of the dive.

The Dive log lists all the saved dives to date. The items are

SI: = surface interval in minutes
Profile: (depth,time,mix),(...)
Deco: mix,mix,...

Each diver has a seperate tissue data record and log.


Conservatism levels

Feedback from divers has suggested these settings should be applied. Nominal is for navy divers and the super fit. Plus 2 or 3 is the normal setting for most divers. Set a plus 3 or 4 with strenuous, cold, a series of multi day dives, extra safety, or a prior history of DCS or symptoms.

Inside the program, the conservatism setting increases the Critical Radii of N2/He in the VPM algorithms. From these base values, by this increase: 1 = 5%, 2 = 12%, 3 = 22%, 4 = 35%. The Critical Volume setting is on by default.

In VPM this adjustment actually changes the dimensions of bubble nuclei for computing decompression requirements. Contrast this with some other deco programs that "fake" conservatism by simply inflating the depth or time of the dive.

You may notice on some dives in VPM, setting the conservatism higher has little apparent effect. This will happen because at some point, decompression is complete no matter how much extra conservatism is added.

Do not fake conservatism in VPM e.g. using Nominal and inflating the depth or time. Doing so will cause the repetitive factor time penalty to be reduced, and subsequent dives plans (all dives for two weeks) will have insufficient deco time applied.


Guest / Diver mode

The program will save data to each unique diver name entered. Each diver should save dives to their own name / record. The saved tissue gas loading data is used in all subsequent dives for repetitive calculations (two weeks).

The Guest mode starts with a clean tissue status, but cannot be saved too, or used in Advanced mode.


SCR fiO2 adjustments

The program can be configured to adjust the fiO2 for SCR and CCR in SCR mode. Enter sample values to suit the rebreather and depths. Separate value can be used for descent, bottom, ascent (all deco is ascent). The value can be fixed (held constant) below the below the deep value, and applied as a literal loss, or a factor reduction to the mix O2. These values form a linear adjustment that is applied to the inspired throughout the program. For SCR this will applied across the entire dive (if selected), and for CCR it is applied (if selected), for any legs using SCR instead of a setpoint.


SCR - plans

SCR dives plans can be generated with dynamically adjusted inspired mixes by using the SCR fiO2 adjustments. Otherwise, they are identical to OC plans.


CCR - Levels, diluent, setpoint

CCR planning is much like OC planning, with the addition of a Setpoint. The program calculates the inspired mix from the diluent and current depth. The program assumes instant loop changes with new levels or settings - no slides, no time delays.

When setpoint exceeds natural pp of 100% O2 for given depth, the program assumes an O2 flush. When setpoint is lower than natural pp of diluent, the program assumes that the loop has been breathed down. Legs and changes are entered like so:

Dive with changes in diluent and setpoint

50, 30, 10/40, 1.30    30 mins at 50m, 1.3 setpoint
20, - , 21, 1.40       change to air diluent, and 1.4 at 20m
6, - , 21, 1.60        O2 flush at 6m, 1.6 decreasing to sfc.

Gas or setpoint changes in mid dive

50, 30, 12/40, 1.30    30 mins at 50m, 1.3
50, 10, 12/40, 1.20    change to 1.2 with another 10 mins
40, 10, 16/30, 1.20    10 mins on new diluent at 40m
20, - , 16/30, 1.40    switch to 1.4 in ascent at 20m, continue to sfc.

Multi level ascent dive

60, 30, 12/40, 1.30    30 mins at 60m, 1.3
20, 10, 12/40, 1.20    ascend to 20m, program will insert mid stops
6, - , 21, 1.60        O2 flush at 6m, 1.6 decreasing to sfc.

Bail out SCR for 5 mins, then ascend

60, 30, 12/40, 1.30    30 mins at 60m, 1.3
60, 5, 12/40, SCR     5 mins on diluent only SCR, followed by SCR ascent

The Start Setpoint value is used from surface to the first level or leg encountered in the Diluent & Setpoint list.


CCR - SCR & OC bail out

Switching to OC for bail out is done by entering the gas in the OC Deco column. Once the program switches to OC mode, it stays this way for the remainder of the dive.

For bail out from the bottom on diluent, enter the diluent mix into the OC Deco column. For dives that supplement deco with OC gas, enter these in the OC Deco column also. Gasses in the OC Deco column are subject to the Max ppO2 checks.

Bailout or regular planning may be performed in SCR mode. Enter dive legs with the SCR option instead of a setpoint. The SCR fiO2 adjustments control the inspired mix for these legs.



Press the print button at any time to print the displayed screen. Font size can be set with the configuration settings.


Output Files

Each time a calculation is performed, that data is saved to file automatically. It overwrites the previously saved one. All data is saved into a folder named 'output' that is loacted in the VPlanner installation folder.

Calc generates

    vpln-out.txt  same as displayed plan
    vpln-sht.txt  depth, time, runtime - aligned
    vp-short.csv  depth, time, runtime - aligned in csv format

Lost Deco generates

    vp-lost.csv  depth, time, runtime - aligned in csv format

Less or More generates

    vp-mrlss.csv  depth, time, runtime - aligned in csv format

Each of the csv files can be imported into Excell, and manipulated or formatted further.

Files can be numbered sequentially. Right click the mouse on the main screen, and select Sequential Files. All files will be name separately from AA through to ZZ.


VPM & VPM-B information

Varying Permeability Model (VPM) References

Informaion on the VPM model and how it works can be found here.


VPM-B is a revision to the VPM model. Considerable diver feedback, and additional research by Erik Baker, found the the model could be improved further by allowing for Boyles Law considerations.


VPM test data

VPM is experimental. There is no database of proven dives, or scientific results to look over. However many divers around the world are using this and other bubble models in their diving, and feeling better than ever before.

Note that VPM is a highly tuned deco model and it requires disciplined control of depth and time during decompression.

If you're getting started and unsure about VPM, try planning with conservatism of +4 and padding out the last two or three stops to look like any M-Value deco model. Over several dives work your way closer to a +3 or +2 setting, without the padding.


Advanced settings

V-Planner allows you to set the raw parameters in the VPM model and algorithms. For more information on these values, consult the numerous documents at http://www.decompression.org/maiken/VPM/VPM_Program_Site_Map.htm and http://www.decompression.org/baker/home.htm.

WARNING - changes to these values will have a significant affect on the deco schedules produced.


Palm, Win CE, Handheld devices

VPM is available for use in handheld devices. Julio McWilliams has been working on a project to put a V-Planner style application onto the Palm. You may join his Yahoo user Group here.



Linux, Unix, Mac

V-Planner is a Windows only program at present. If sufficient interest exists, then I will create a Linux version. Contact me if interested. There is no probability of a Mac version at this time - maybe later.


Top 10 questions
  1. Lost Deco planning times do not line up? Is it a bug?
    Not a bug. In VPM-B, your ascent is calc'd for the entire profile, before the final plan is generated. i.e. using 80/oxygen (or any deco gas) in a dive, has deco benefits across the whole dive, some of which can be realized ahead of time. Adding deco mix to a dive changes the entire ascent, and each plan is different.
    Older programs and table based models are single step models. i.e. what happens next has no affect on what just been done and visa versa.
    The tricky part is when you get to deco level and discover the deco tank doesn't work. My suggestion, is to wait out the additional time at the current level, and pick up on the subsequent deco times. Remember, this is for emergency planning, and might never happen to you ever in a whole career. Also you have a margin of extra time above bare minimum req'd deco, so are you still OK.

  2. Mix changes in ascent won't work?
    For open circuit dives, any change in mix in ascent is done in the Deco mix column. These change depths are controlled by the max ppO2 settings in the configuration. Dive legs entered with a zero time on the last leg, are ignored or converted into changes in ascent to deco.
    For multi level legs in ascent (time greater than zero), the program will complete the dive plan to the last leg, using only details from the Bottom mix column. From this point it looks to the surface and considers deco. Any deco gas that may have been used deeper, is bypassed if it no longer applies to the current depth.

  3. Deco gas is ignored?
    Much like in (2) above, for open circuit the mix is selected automatically by depth and max ppO2 settings.

  4. CCR Bail out to diluent at bottom?
    To utilize the diluent as an OC gas from the bottom, enter the diluent mix into the OC Deco column. Also SCR legs can be entered directly into plans in the Left column.

  5. Deco using helium based deco mix is slower?
    After a trimix dive, the body is off gassing helium that was absorbed during the bottom phase. The rate of off gassing is driven by the partial pressure differences in inspired mix and absorbed gas. When breathing helium as part of the deco mix, the gradient between inspired and absorbed pressures is reduced, and the process is slowed.

  6. Extended stops are ignored?
    In version 3.10 and before, the Extended stop feature only applied when a stop was actually required at the depth of the deco mix change.
    In version 3.20 onwards, the All Deco mix changes option will allow the Extended time to be applied regardless of a stop requirement.

  7. Printing tables - copying data?
    See the output files topic.

  8. Mutli Level plans are different?
    A multi level plan triggers additional limitations and has a tougher set of rules applied. Multi level planning is designed to be used for changes of 1 ATA or more. Small depth changes (3m) often result in plans longer than no depth change at all.

  9. Second computer and registration?
    Each registration is valid to user name, and can be reused for other computers (laptop / desktop / work / etc.). Your computer does not need to be connected to the web, or have email enabled to enter details.

  10. Program wont install?
    Many programs like this, use a common installation program and routines. If your computer failed to fully install some other program previously, then the installation routines may be left over and can conflict, and errors occur.
    To remedy this, navigate to C:\Windows\temp and delete everything here. Windows may prevent deleting some items if they are in use. Restart the computer, and try installing again.

    Sometimes the file download is corrupted by internet transmission. Some operating systems or web the browser, will cache the downloaded files, and present this one to you again, even when requesting a fresh file from the web. To get around this, navigate to the downloaded file in question, highlight it, hold down the Shift key, and press Delete. This deletes the file for real, and now a new download attempt will retrieve a fresh file.