Supplemental Manual for the Cave Mode Function (V1.0)
=====================================================

The intended use of hwos Cave Mode is to monitor if the gases that are carried
by the diver are sufficient to end the dive, especially taking into account the
amount of gases that will be needed to finish decompression stops.

The Cave Mode function extends the normal deco and gas needs calculating made for
open water vertical ascent, by tracking back the whole depth profile of the dive
and including final and/or intermediate deco stops that may become necessary.
The cave mode function may be used in OC diving as well as in CCR/pSCR mode. When
using it in CCR/pSCR mode, it will calculate the way back in bailout mode.

  || NOTICE:
  || With cave mode switched on, the normal 3 meter step size of deco stop spacing
  || changes to a 1 meter spacing, reducing the indicated required stop time in front
  || of passages that are less than 3 meters shallower than the current stop depth.

In order to produce accurate results, the user has to understand the following
concepts and settings, and has to configure these settings with appropriate values:

- While on the way in, the depth profile will be sampled once every minute. For
  the return way calculation, it is assumed that the diver will travel at the same
  speed as on the way in and will travel along the same depth profile as on the way
  in.

  || IMPORTANT:
  || The cave mode provides capacity for 4 hours of depth profile recording.
  || 10 minutes before storage capacity is exhausted (i.e. after 4 hours), an
  || attention message will be given. When the storage capacity becomes fully
  || used up, the cave mode function switches itself off and a respective warning
  || is shown.

  If the cave mode function has switched itself off due to running out of storage
  capacity, it can be recovered on exiting the cave: When manually switching it on
  again, it comes back on again in turned state (see below), showing gas needs and
  TTS as of the position where it had switched off.

- Gas needs for the travel portions of the return way are calculated using the SAC
  work rate. While spending time on required deco stops, the SAC deco rate is used.
  Both SAC values, SAC work and SAC deco, need to be set by the diver to consumption
  rates that match personal rates, taking into account elevated rates due to stress
  etc., especially when using the cave mode function for bailout capacity checking.

  || WARNING:
  || If the actual SAC rate is higher than the configured on, or if traveling back
  || slower than on the way in, the real needs will be under-estimated and the
  || diver may run into an out-of-air situation if taking the dive to the limits!

- Every tank needs to be configured with its size and with the amount of pressure
  that is in it. The cave function will use these numbers to calculate how much gas
  will be available from each tank to be used for the way back.

  || IMPORTANT:
  || For tanks that is breathed from while on the way in, the tank pressures have
  || to be set to the turn pressures that have been determined for the respective
  || tanks during dive planning!

- While on the way in, the cave function constantly recalculates how much gas from
  each tank will be needed to exit the cave. Upon reaching 70% utilization on any
  tank, an attention message (color-coded in yellow) will be given. Upon reaching
  100% utilization, a warning message (color-coded in red) will be issued.
  
- In case Dive Setup -> SAC Setup -> Swap on empty is set to yes, at the time a tank
  is calculated to be fully used up, the calculations will try to switch to another
  tank that still contains some gas according to the calculations. If such a tank
  exists, the remaining way out will be calculated based on this tank and hence on the
  gas in that tank, which may be sub-optimal in terms of decompression. If such a tank
  does not exist, or if the swap-function is set no 'no', the remaining gas needs will
  continue to get added on the depleted tank, resulting in displayed required tank
  pressure higher than configured pressure available.

- When turning the dive, i.e. upon starting on the way back out of the cave again,
  the cave function needs to set into 'turned' state. This will stop the cave function
  to assume that the actual way out is still part of the way in and subsequently will
  stop taking further depth recordings and figuring them in for gas needs calculation.

  || WARNING:
  || The diver shall turn the dive ultimately latest when any one of the gases
  || calculates to be fully needed! In this situation, the diver will be without
  || any reserves! It is advised to set the tank pressures a bit lower than their
  || actual fill pressure is, and to set the SAC rates a bit higher, to put the
  || calculation results onto the safe side.

- When setting the dive as 'turned', the indicated gas needs are likely to still rise.
  This will be due to the fact that the cave function still calculates the gas needs
  for all the way back from turn point to the surface, not knowing how much of this
  way has been traveled already. In consequence, the tissue saturations that are gained
  on the portion of the way back that has already been traveled are calculated twice,
  resulting in an increased estimated deco obligation at the end of the dive. This
  effect can be overcome by using 'waypoints' (see below).

  || IMPORTANT:
  || Without having set at least one waypoint (see below) before setting the dive
  || as turned, it is not possible to revoke the 'turned' state again!

- When the cave mode is switched off, the gas needs calculation reverts to the open
  water vertical ascent mode, i.e. no dedicated time for horizontal movement is
  figured in any more. It is appropriate to switch off cave mode when the remaining
  horizontal movements (further swimming out of the cave) can be done in parallel with
  doing the decompression "stops". This way, calculation results will become independent
  of the remaining way to go, and thus accurate again.

  || NOTICE:
  || When being back near the cave entrance, with only final decompression stops
  || remaining to be done, and with the remaining way being doable while doing the
  || decompression stops, it is appropriate to switch off the cave mode.

- The cave mode function can be switched off and on again at any time of the dive.
  Temporary switching off the cave mode while the dive is not set as turned yet can
  be used to pause the recording, e.g. while undertaking some tasks that take time
  on the way in, but not while on the way out, e.g. fixing the line or doing survey
  tasks.

- To tell the cave mode calculations where the diver is while on the way out, waypoints
  can be set while on the way in. Initially on setting the dive as turned, the gas needs
  are calculated for the full way back. Then the diver can select one of the waypoints
  and the cave mode function will calculate how much gas will be needed to return from
  this waypoint. Upon physically reaching the respective waypoint, indicated gas needs
  will become accurate again for this position in the cave, given that the rules discussed
  above are obeyed.

  || IMPORTANT:
  || Waypoints should be set at regular distances and/or important features in the cave
  || profile, e.g. at places where intermediate deco stops are expected. While on the
  || way back out of the cave, whenever a waypoint is reached, the cave function shall
  || be updated to this waypoint. This way the indicated gas needs will always stay near
  || the expected real needs, but on the safe side, given that the rules discussed above
  || are met.

  || IMPORTANT:
  || The cave mode function provides for 30 waypoints. Every waypoint that is set
  || reduces the available storage capacity by the equivalent of four minutes of depth
  || profile recording time. Thus, when all 30 waypoints are used, the depth profile
  || storage capacity reduces to 2 hours for the inwards part of the dive.

  || IMPORTANT:
  || To establish a relationship between the numbering of the waypoints within the cave
  || mode function and their physical positions in the cave, it is recommended to place
  || cookies that are marked with the respective waypoint numbers.

- Every time a waypoint is set, also a marker will be set in the normal logbook recording.

- If at least one waypoint has been set, the 'turned' state of the dive can be revoked
  again. To revoke the turned state and thus continue the dive in inward direction, the
  diver has to physically go back to a previously created waypoint in the cave and select
  that waypoint in the cave mode function, too, to keep the backtracking data in sync with
  reality.

  || NOTICE:
  || The turned state can not be revoked while being at the original turn point of
  || the dive. Going back to a previous waypoint is required.
  
- When the 'turned' state is revoked, the depth profile recording resumes. The new recordings
  are appended after the waypoint where the dive was resumed.

  || IMPORTANT:
  || The depth profile and all waypoints that were originally recorded after the waypoint
  || from which the dive is resumed again in inward direction are lost. The respective
  || recording space will be freed up and used for the recording of the new leg.

- This feature can e.g. be used for exploring different branches of a cave:

  1) set a waypoint at the forking point of the branches,
  2) explore the first branch (further waypoints may be set),
  3) when done, set the dive as turned,
  4) return to the forking point,
  5) recall the respective waypoint that was set at the forking point,
  6) check if gas reserves allow for exploring another branch,
  7) select 'continue' to revoke the turned state and start the recording
     for the next branch to be explored now.

  Steps 2) to 7) may be repeated several times.

- The cave mode function can account for gases that are temporary unavailable because
  their tanks have been staged. On page two of the dive menu item 'Gaslist', tanks
  can be toggled between available, staged (disabled color and "S" marking for staged),
  and lost (disabled color and "x" marking aka crossed-out).

- If a tank is set to lost state, it will not be considered in deco as well as gas
  needs calculation any more. This state is revocable.

- If a tank is set to staged state, it will currently not be considered any more,
  but: Whenever a waypoint is set, a snapshot of the staged / not staged state of
  all tanks is taken. When the cave mode function works it way through the stored
  cave profile recording and hits a waypoint entry, it extracts this snapshots again
  and continues choosing gases for deco and gas needs calculation based on these
  snapshots.

  || IMNPORTANT:
  || When staging a tank:
  ||
  || 1) Set a waypoint.
  ||
  ||    Within this waypoint the tank will be recorded as (still) being available,
  ||    that is it will be available (again) upon passing this waypoint on the way
  ||    out again.
  ||
  || 2) Set the tank as staged.
  ||
  ||    This will set the tank as being not available during the portion of the dive
  ||    that lies to the inside of the above waypoint.

  || NOTICE:
  || While a tank is set as staged, no better gas cue will be generated for it!

  || IMPORTANT:
  || When a tank is picked up again, it needs to be set to available state again
  || in order to positively confirm that it really is available again!

- When diving in OC mode or when in bailout mode, selecting a gas that is still set
  as staged automatically reverts that gas to the available state. The same holds
  true for gases that were declared as lost: on selecting them, they are also set
  to the available state again.

  || IMPORTANT:
  || When diving in CCR or pSCR mode and initiating a bailout, the dive will be
  || automatically set to turned state (given cave mode is switch on and the dive
  || is not already turned)!

  || IMPORTANT:
  || While the cave mode is switched on and the dive is in turned state, the fTTS
  || calculation will be suppressed - gas needs are calculated on the basis of an
  || immediate return to the exit.



Operating the Cave Mode Function:
---------------------------------

The Cave Mode Function is activated by setting the the surface menu item

         Dive Setup -> Dive Setup (again) -> Cave Mode to 'on'

It will then be active right from the start of the following dives. All further
operation is done during the dive via a dedicated cave mode menu. This menu can
be accessed via the left button: after pressing the left button for 'Menu?',
press it again to show up 'Cave?', then press the right button to enter the cave
mode menu. In OC mode, the cave mode menu is also reachable via the main dive menu,
using the menu item 'Cave Mode'.

Depending on the 'dive turned' state, certain menu items are available or not.
This will be indicated by the color coding of the respective menu items.

When the cave mode menu is active, the custom view is temporary replaced by a
graphical representation of the waypoint situation. The last waypoint placed is
shown in the middle of the display. The "-|" symbol depicts the end of the line,
representing the deepest penetration point during the dive. The green arrow shows
for which position in the cave the return gas needs are calculated.

In the message field, either a "cTTS xx'" or "WPyy xx'" is shown. While the dive
is not turned yet, cTTS (Cave Time-to-Surface) is shown, with xx being the total
time in minutes required for swimming all the way back and doing the decompression
stops, if required. When the dive is turned, WP is shown to indicate that the TTS
is computed from off the waypoint yy. If yy reads the symbol -|, the TTS is computed
from off the turn point of the dive.

All cave mode functions are usable in simulator mode, too. Opposite to that, the
deco calculator does not support cave mode, it calculates vertical open water ascents
only.

|| IMPORTANT:
|| It is strongly advised to familiarize with the cave mode functions by using
|| the OSTC simulator mode!