JDeco Manual

Dive Planning - Open Circuit (OC)

• You enter information about depths and times at the different levels. You don't have to fill in all the levels.
• The time you enter for a dive level includes the time for the depth change to get to that level!
• You select your decompression mixes, if you have specified some in the mixes menu. The deco mixes are selected by writing the depth at which you want to make the corresponding gas switch. If you define switching depths that are not multiple of the deco step size the gas switch will be performed at the next (shallower) regular deco stop depth.
• You can change the durations of each gas switching stop independently. The changed times are taken into account in the decompression calculations.

Dive Planning - Closed Circuit Rebreather (CCR)

• You enter information about depths and times at the different levels, desired PPO2 and diluent. In case that the chosen setpoint is not achievable due to depth/diluent combination the achievable PPO2 will be used instead. This corrected PPO2 will also be displayed to the user in the decompression schedule.
• The time you enter for a dive level includes the time for the depth change to get to that level!
• You define your decompression settings by choosing depths at which to change the PPO2 setpoint and/or diluent. You can change diluent and/or setpoint before leaving the bottom (by specifying the desired settings for the depth of the last bottom level). Furthermore you can change diluent and/or setpoint at decompression stops. Between ascent from bottom and reaching the first decompression stop changes are not possible.
  If you do not specify any decompression settings the last bottom diluent and the last bottom PPO2 will be used for decompression.
• Define the bailout mixes. The maximum depths and switching depths for each bailout mix can be entered by the user. The program assumes that bailout starts at the bottom, which makes it necessary that a bailout mix is present that does not violate the MAX DECO PPO2 setting at the last bottom depth (an error is displayed otherwise).
• The bailout plan can be calculated from within the screen which displays the ordinary deco schedule by choosing "Options->Bailout Plan".

Decompression Schedule

You can select (in the "program settings" menu) to display either run times, stop times, or both. The runtimes should always be interpreted as the times at which to leave a certain dive level or decompression stop. The interpretation of the stop times is accordingly and best explained by an example:

Bottom: 50m/20min, deco stops: 24m/1min, 21m/1min, 18m/2min, ... You ascent to the first deco stop with your chosen rate (e.g. 10m/min). You arrive at the first deco stop at 22.6min and leave it at 23min. You arrive at the second stop at 23.3min and leave it at 24min, arrive at the third stop at 24.3min and leave it at 26min, etc.

Calculations

• After having calculated a decompression profile you can increase or decrease the time and the depth of the last dive level by just selecting the corresponding option in the menu. The increments are set in settings.
• Using the same menu as in the previous option you can calculate a bailout table for different decogas-loss options (OC) or for the chosen bailout gases (CCR).

Gas Mixes (Menu: Mixes)

In the gas mixes menu you add gas mixes that you afterwards can use in the definition if dives.

• The oxygen content of a gas mix needs to be at least 5 percent to be accepted as valid gas mix.
• In the metric version you can specify a tank size in liter. Then the required amount of gas for a dive is shown in "bar". Setting the volume to 1 liter lets the program display the gas amount in "liter" instead.
• You can specify if a certain mix is a deco/bailout, a travel, or a bottom/diluent mix.
• Changing a mix leads to deletion of the current dive series. This is necessary for security reasons. Adding a new mix, however, does not delete the dive series.

Gas Mixing and Topping Tools (Menu: Mix Tools)

The gas mixing and topping tools are completely self explaining.

More General Settings (Menu: Program Settings)

Start Screen:

determines in which screen JDeco is starting. (Main Menu, Dive Series, Mix Tools).

Number Levels:

determines the number of levels that can be entered for multilevel dives.

System:

choose between open circuit (OC) or closed circuit rebreather (CCR).

Algorithm:

choose between Bühlmann ZH-L16B/GF or VPM-B.

Deco Table:

choose to display stop times, run times, or both in the deco table.

Alternative Plan:

after having calculated a deco table you can increase or decrease depth and time of the last dive level, allowing to easily calculate backup plans. Here you choose the increments to use for time and depth.

Please note that switching from CCR to OC or vice versa will delete the current dive series.

Dive Specific Settings (Menu: Dive Settings)

Altitude:

Altitude of dive. It is assumed that the diver is already acclimatized.

Depth Change Rates / Dive:

When using the Bühlmann algorithm this setting determines the rate of depth change between different dive levels. For the VPM-B algorithm this setting determines the descent rates (initial descent and descents between dive levels).

Depth Change Rates / Deco:

For both algorithms this setting determines the rate of ascent to the last deco stop. For the VPM-B algorithm this setting also determines the ascent rate between dive levels.

Deco Step Size:

Determines the step size between deco stops (usually 3meter or 10feet).

Last Stop / Depth:

Depth of last deco stop.

Last Stop / Rate:

Rate from last deco stop to surface. This value is used in the calculations.

Gas Usage / Dive:

Respiratory minute volume during dive.

Gas Usage / Deco:

Respiratory minute volume during deco (including ascent from bottom to first deco stop).

Max Dive PPO2:

Maximum desired O2 partial pressure (OC). If max PPO2 is larger a warning is displayed.

Max Deco PPO2:

Maximum desired O2 partial pressure during decompression. If max PPO2 is larger a warning is displayed.

Initial Descent:

Rate of initial descent to first dive level (Used only for Bühlmann algorithm).

Gradient Factors / Low:

Low gradient factor setting in percent (Used only for Bühlmann algorithm).

Gradient Factors / High:

High gradient factor setting in percent - max 120! (Used only for Bühlmann algorithm).

Crit Vol Algorithm:

Set the critical volume algorithm to on or off (usually "on")(Used only for VPM-B algorithm).

Conservativity:

Set the conservativity level of the VPM-B algorithm (Used only for VPM-B algorithm). The different levels are pretty much the same as in V-Planner (Nominal, +1, +2, +3, +4, +5).

Please note that changing the dive altitude will delete the current dive series.

Questions?

If something is unclear, please contact me at info@jdeco.de and I will help you.