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Add text to user manual: Recreational dive planning One figure has been added

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Signed-off-by: willem ferguson <willemferguson@zoology.up.ac.za>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
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willem ferguson 2015-04-28 10:25:42 +02:00 committed by Dirk Hohndel
parent 526b4500ba
commit 2286bc89de
2 changed files with 84 additions and 21 deletions
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Documentation/user-manual.txt
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@ -2767,6 +2767,7 @@ This panel allows two type of selections:
** _Show unused cylinders in Equipment Tab_: This checkbox allows display of information about unused cylinders when viewing the *Equipment Tab*. Conversely, if this box is not checked, and any cylinders entered using the *Equipment Tab* are not used (e.g. there was no gas switch to such a cylinder), then these cylinders are omitted from that list.
[[GradientFactors_Ref]]
** _Show average depth_: Activating this checkbox causes _Subsurface_ to draw a grey line across
the dive profile, indicating the mean depth of the dive up to a particular point in time during
that dive. Normally this is a u-shaped line indicating the deepest average depth just before the
@ -2927,7 +2928,70 @@ image::images/PlannerWindow1_f20.jpg["FIGURE: Dive planner startup window",align
- The dialogue indicating _Dive Planner Points_ is usually not used at this stage of the dive
planning.
*The planning is performed in three stages*
==== Recreational dives
The _Subsurface_ dive planner allows a sophisticated way of planning recreational dives, i.e. dives
that remain within no-decompression limits.
The dive planner automatically takes
into account the nitrogen load incurred in previous dives. But conventional dive tables are also used in a
way that can take into account previous dives. Why use a dive planner for recreational dives? Using
recreational dive tables, the maximum depth of a dive is taken into acount. However, few dives are
undertaken at a constant depth corresponding to the maximum depth (i.e. a "square" dive profile). This means that dive tables
overestimate the nitrogen load incurred during previous dives. The _Subsurface_
dive planner calculates nitrogen load according to the real dive profiles of all uploaded previous dives,
in a similar way as dive computers calculate nitrogen load during a dive. This mean that the diver gets 'credit'
in terms of nitrogen loading for not remaining at maximum depth during previous dives, enabling planning a
longer subsequent dive. For the planner to work it is therefore crucial to upload all previous dives
onto _Subsurface_ before performing dive planning.
To plan a dive, the appropriate settings need to be
defined.
- Ensure that the date and time is set to that of the intended dive. This allows calculation of
the nitrogen load incurred during previous dives.
- Immediately under the heading _Planning_ are two checkboxes _Recreational_ and _Safety Stop_. For
planning recreational dives, check these two checkboxes.
- Then define the cylinder size,
the gas mixture (air or % oxygen) and the starting cylinder pressure in the top left-hand
section of the planner under _Available gases_.
- The planner calculates whether the specified cylinder contains enough air/gas to complete
the planned dive. In order for this to be realistic, under _Gas options_, specify an appropriate
surface air consumption (SAC) rate for _Bottom SAC_. Suitable values are between 15 l/min and 30 l/min,
with novice divers or difficult dives requiring SAC rates closer to 30l/min.
- Define the amount of gas in the cylinder at the end of the bottom section of the dive just before ascent. A
value of 50 bar is often used.
- Define the depth of the dive by dragging the waypoints (white dots) on the dive profile or
(even better) defining the appropriate depth using the table under _Dive planner points_. If
this is a multilevel dive, set the appropriate dive depths to represent the dive plan by adding
waypoints to the dive profile or by adding appropriate dive planner points to the _Dive Planner Points_
table.
- The ascent speed can be changed. The default ascent speeds are those considered safe for recreational
divers.
The dive profile in the planner indicates the maximum dive time within no-deco limits using the
Bühlmann ZH-L16 algorithm and the gas and depth settings specified as described above. The _Subsurface_ planner
allows rapid assessment of dive duration as a function of dive depth, given the nitrogen load incurred during previous dives. The
dive plan includes estimates of the amount of air/gas used, depending on the cylinder settings specified
under _Available gases_. If the initial cylinder pressure is set to 0, the dive duration shown is the
true no-deco limit (NDL) without taking into account gas used during the dive. If the surface above the dive profile is RED
it means that recreational dive limits are exceeded and either the dive duration or the dive depth needs to be reduced.
Below is an image of a dive plan for a recreational dive at 30 metres. Although the no-deco limit (NDL) is 23
minutes, the duration of the dive is limited by the amount of air in the cylinder, reflected by the information in the
text box at the bottom right of the panel.
image::images/rec_diveplan.jpg["FIGURE: A recreational dive plan: setup",align="center"]
==== Non-recreational open circuit dives, including decompression
Non-recreational dive planning involves exceeding the no-deco limits and/or using multiple breathing gases.
Such dives are planned in three stages:
*a) Nitrogen management*: This is performed by specifying the rates for descent and ascent,
as well as the gradient factors (GFLow and GFHigh) under the headings _Rates_ and _Planning_
@ -2952,7 +3016,6 @@ often in the range of 4-9 m/min. The descent rate is also specified. If the opti
is activated, then the descent phase of the planned dive will be at the maximal descent rate specified
in the _Rates_ section of the dive setup.
*b) Oxygen management*: In the *Gas Options* part of the dive specification, the maximum partial
pressure for oxygen needs to be specified for the
bottom part of the dive (_bottom po2_) as well as for the decompression part of the dive (_deco po2_).
@ -3041,6 +3104,25 @@ level is indicated in the _Dive Plan Details_. This duration INCLUDES the transi
time to get to that level. However, if the _Display transition in deco_ option is checked,
the transitions are shown separately from the segment durations at a particular level.
=== Planning pSCR dives
To plan a dive using a passive semi-closed rebreather (pSCR), select _pSCR_ rather than
_Open circuit_ in the dropdown list.
The parameters of the pSCR diver can be set by selecting _File -> Preferences -> Graph_
from the main menu, where the gas consumption calculation takes into account the pSCR dump
ratio (default 10:1) as well as the metabolism rate. The calculation also takes the oxygen drop
accross the mouthpiece of the rebreather into account. If the
pO~2~ drops below what is considered a save value, a warning appears in the _Dive plan
details_. A typical pSCR configuration is with a single cylinder and one or more bail-out
cylinders. Therefore the setup of the _Available gases_ and the _Dive planner points_ tables
are very similar to that of a CCR dive plan, described above. However, no oxygen setpoints
are specified for pSCR dives. Below is a dive plan for a pSCR dive. The dive is comparable
to that of the CCR dive above, but note the longer ascent duration due to the lower oxygen
in the loop due to the oxygen drop across the mouthpiece of the pSCR equipment.
image::images/Planner_pSCR1_f20.jpg["FIGURE: Planning a pSCR dive: setup",align="center"]
=== Planning CCR dives
To plan a dive using a closed circuit rebreather, select the _CCR_ option in the dropdown
@ -3065,25 +3147,6 @@ image::images/Planner_CCR1_f20.jpg["FIGURE: Planning a CCR dive: setup",align="c
Note that, in the _Dive plan details_, the gas consumption for a CCR segment is not calculated,
so gas consumptions of 0 litres are the norm.
=== Planning pSCR dives
To plan a dive using a passive semi-closed rebreather (pSCR), select _pSCR_ rather than
_Open circuit_ in the dropdown list.
The parameters of the pSCR diver can be set by selecting _File -> Preferences -> Graph_
from the main menu, where the gas consumption calculation takes into account the pSCR dump
ratio (default 10:1) as well as the metabolism rate. The calculation also takes the oxygen drop
accross the mouthpiece of the rebreather into account. If the
pO~2~ drops below what is considered a save value, a warning appears in the _Dive plan
details_. A typical pSCR configuration is with a single cylinder and one or more bail-out
cylinders. Therefore the setup of the _Available gases_ and the _Dive planner points_ tables
are very similar to that of a CCR dive plan, described above. However, no oxygen setpoints
are specified for pSCR dives. Below is a dive plan for a pSCR dive. The dive is comparable
to that of the CCR dive above, but note the longer ascent duration due to the lower oxygen
in the loop due to the oxygen drop across the mouthpiece of the pSCR equipment.
image::images/Planner_pSCR1_f20.jpg["FIGURE: Planning a pSCR dive: setup",align="center"]
[[S_Replan]]
=== Modifying an existing dive plan