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3.10 stable release
author heinrichsweikamp
date Tue, 28 Apr 2020 17:34:31 +0200
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1
2 Supplemental Manual for the Cave Mode Function (V1.0)
3 =====================================================
4
5 The intended use of hwos Cave Mode is to monitor if the gases that are carried
6 by the diver are sufficient to end the dive, especially taking into account the
7 amount of gases that will be needed to finish decompression stops.
8
9 The Cave Mode function extends the normal deco and gas needs calculating made for
10 open water vertical ascent, by tracking back the whole depth profile of the dive
11 and including final and/or intermediate deco stops that may become necessary.
12 The cave mode function may be used in OC diving as well as in CCR/pSCR mode. When
13 using it in CCR/pSCR mode, it will calculate the way back in bailout mode.
14
15 || NOTICE:
16 || With cave mode switched on, the normal 3 meter step size of deco stop spacing
17 || changes to a 1 meter spacing, reducing the indicated required stop time in front
18 || of passages that are less than 3 meters shallower than the current stop depth.
19
20 In order to produce accurate results, the user has to understand the following
21 concepts and settings, and has to configure these settings with appropriate values:
22
23 - While on the way in, the depth profile will be sampled once every minute. For
24 the return way calculation, it is assumed that the diver will travel at the same
25 speed as on the way in and will travel along the same depth profile as on the way
26 in.
27
28 || IMPORTANT:
29 || The cave mode provides capacity for 4 hours of depth profile recording.
30 || 10 minutes before storage capacity is exhausted (i.e. after 4 hours), an
31 || attention message will be given. When the storage capacity becomes fully
32 || used up, the cave mode function switches itself off and a respective warning
33 || is shown.
34
35 If the cave mode function has switched itself off due to running out of storage
36 capacity, it can be recovered on exiting the cave: When manually switching it on
37 again, it comes back on again in turned state (see below), showing gas needs and
38 TTS as of the position where it had switched off.
39
40 - Gas needs for the travel portions of the return way are calculated using the SAC
41 work rate. While spending time on required deco stops, the SAC deco rate is used.
42 Both SAC values, SAC work and SAC deco, need to be set by the diver to consumption
43 rates that match personal rates, taking into account elevated rates due to stress
44 etc., especially when using the cave mode function for bailout capacity checking.
45
46 || WARNING:
47 || If the actual SAC rate is higher than the configured on, or if traveling back
48 || slower than on the way in, the real needs will be under-estimated and the
49 || diver may run into an out-of-air situation if taking the dive to the limits!
50
51 - Every tank needs to be configured with its size and with the amount of pressure
52 that is in it. The cave function will use these numbers to calculate how much gas
53 will be available from each tank to be used for the way back.
54
55 || IMPORTANT:
56 || For tanks that is breathed from while on the way in, the tank pressures have
57 || to be set to the turn pressures that have been determined for the respective
58 || tanks during dive planning!
59
60 - While on the way in, the cave function constantly recalculates how much gas from
61 each tank will be needed to exit the cave. Upon reaching 70% utilization on any
62 tank, an attention message (color-coded in yellow) will be given. Upon reaching
63 100% utilization, a warning message (color-coded in red) will be issued.
64
65 - In case Dive Setup -> SAC Setup -> Swap on empty is set to yes, at the time a tank
66 is calculated to be fully used up, the calculations will try to switch to another
67 tank that still contains some gas according to the calculations. If such a tank
68 exists, the remaining way out will be calculated based on this tank and hence on the
69 gas in that tank, which may be sub-optimal in terms of decompression. If such a tank
70 does not exist, or if the swap-function is set no 'no', the remaining gas needs will
71 continue to get added on the depleted tank, resulting in displayed required tank
72 pressure higher than configured pressure available.
73
74 - When turning the dive, i.e. upon starting on the way back out of the cave again,
75 the cave function needs to set into 'turned' state. This will stop the cave function
76 to assume that the actual way out is still part of the way in and subsequently will
77 stop taking further depth recordings and figuring them in for gas needs calculation.
78
79 || WARNING:
80 || The diver shall turn the dive ultimately latest when any one of the gases
81 || calculates to be fully needed! In this situation, the diver will be without
82 || any reserves! It is advised to set the tank pressures a bit lower than their
83 || actual fill pressure is, and to set the SAC rates a bit higher, to put the
84 || calculation results onto the safe side.
85
86 - When setting the dive as 'turned', the indicated gas needs are likely to still rise.
87 This will be due to the fact that the cave function still calculates the gas needs
88 for all the way back from turn point to the surface, not knowing how much of this
89 way has been traveled already. In consequence, the tissue saturations that are gained
90 on the portion of the way back that has already been traveled are calculated twice,
91 resulting in an increased estimated deco obligation at the end of the dive. This
92 effect can be overcome by using 'waypoints' (see below).
93
94 || IMPORTANT:
95 || Without having set at least one waypoint (see below) before setting the dive
96 || as turned, it is not possible to revoke the 'turned' state again!
97
98 - When the cave mode is switched off, the gas needs calculation reverts to the open
99 water vertical ascent mode, i.e. no dedicated time for horizontal movement is
100 figured in any more. It is appropriate to switch off cave mode when the remaining
101 horizontal movements (further swimming out of the cave) can be done in parallel with
102 doing the decompression "stops". This way, calculation results will become independent
103 of the remaining way to go, and thus accurate again.
104
105 || NOTICE:
106 || When being back near the cave entrance, with only final decompression stops
107 || remaining to be done, and with the remaining way being doable while doing the
108 || decompression stops, it is appropriate to switch off the cave mode.
109
110 - The cave mode function can be switched off and on again at any time of the dive.
111 Temporary switching off the cave mode while the dive is not set as turned yet can
112 be used to pause the recording, e.g. while undertaking some tasks that take time
113 on the way in, but not while on the way out, e.g. fixing the line or doing survey
114 tasks.
115
116 - To tell the cave mode calculations where the diver is while on the way out, waypoints
117 can be set while on the way in. Initially on setting the dive as turned, the gas needs
118 are calculated for the full way back. Then the diver can select one of the waypoints
119 and the cave mode function will calculate how much gas will be needed to return from
120 this waypoint. Upon physically reaching the respective waypoint, indicated gas needs
121 will become accurate again for this position in the cave, given that the rules discussed
122 above are obeyed.
123
124 || IMPORTANT:
125 || Waypoints should be set at regular distances and/or important features in the cave
126 || profile, e.g. at places where intermediate deco stops are expected. While on the
127 || way back out of the cave, whenever a waypoint is reached, the cave function shall
128 || be updated to this waypoint. This way the indicated gas needs will always stay near
129 || the expected real needs, but on the safe side, given that the rules discussed above
130 || are met.
131
132 || IMPORTANT:
133 || The cave mode function provides for 30 waypoints. Every waypoint that is set
134 || reduces the available storage capacity by the equivalent of four minutes of depth
135 || profile recording time. Thus, when all 30 waypoints are used, the depth profile
136 || storage capacity reduces to 2 hours for the inwards part of the dive.
137
138 || IMPORTANT:
139 || To establish a relationship between the numbering of the waypoints within the cave
140 || mode function and their physical positions in the cave, it is recommended to place
141 || cookies that are marked with the respective waypoint numbers.
142
143 - Every time a waypoint is set, also a marker will be set in the normal logbook recording.
144
145 - If at least one waypoint has been set, the 'turned' state of the dive can be revoked
146 again. To revoke the turned state and thus continue the dive in inward direction, the
147 diver has to physically go back to a previously created waypoint in the cave and select
148 that waypoint in the cave mode function, too, to keep the backtracking data in sync with
149 reality.
150
151 || NOTICE:
152 || The turned state can not be revoked while being at the original turn point of
153 || the dive. Going back to a previous waypoint is required.
154
155 - When the 'turned' state is revoked, the depth profile recording resumes. The new recordings
156 are appended after the waypoint where the dive was resumed.
157
158 || IMPORTANT:
159 || The depth profile and all waypoints that were originally recorded after the waypoint
160 || from which the dive is resumed again in inward direction are lost. The respective
161 || recording space will be freed up and used for the recording of the new leg.
162
163 - This feature can e.g. be used for exploring different branches of a cave:
164
165 1) set a waypoint at the forking point of the branches,
166 2) explore the first branch (further waypoints may be set),
167 3) when done, set the dive as turned,
168 4) return to the forking point,
169 5) recall the respective waypoint that was set at the forking point,
170 6) check if gas reserves allow for exploring another branch,
171 7) select 'continue' to revoke the turned state and start the recording
172 for the next branch to be explored now.
173
174 Steps 2) to 7) may be repeated several times.
175
176 - The cave mode function can account for gases that are temporary unavailable because
177 their tanks have been staged. On page two of the dive menu item 'Gaslist', tanks
178 can be toggled between available, staged (disabled color and "S" marking for staged),
179 and lost (disabled color and "x" marking aka crossed-out).
180
181 - If a tank is set to lost state, it will not be considered in deco as well as gas
182 needs calculation any more. This state is revocable.
183
184 - If a tank is set to staged state, it will currently not be considered any more,
185 but: Whenever a waypoint is set, a snapshot of the staged / not staged state of
186 all tanks is taken. When the cave mode function works it way through the stored
187 cave profile recording and hits a waypoint entry, it extracts this snapshots again
188 and continues choosing gases for deco and gas needs calculation based on these
189 snapshots.
190
191 || IMNPORTANT:
192 || When staging a tank:
193 ||
194 || 1) Set a waypoint.
195 ||
196 || Within this waypoint the tank will be recorded as (still) being available,
197 || that is it will be available (again) upon passing this waypoint on the way
198 || out again.
199 ||
200 || 2) Set the tank as staged.
201 ||
202 || This will set the tank as being not available during the portion of the dive
203 || that lies to the inside of the above waypoint.
204
205 || NOTICE:
206 || While a tank is set as staged, no better gas cue will be generated for it!
207
208 || IMPORTANT:
209 || When a tank is picked up again, it needs to be set to available state again
210 || in order to positively confirm that it really is available again!
211
212 - When diving in OC mode or when in bailout mode, selecting a gas that is still set
213 as staged automatically reverts that gas to the available state. The same holds
214 true for gases that were declared as lost: on selecting them, they are also set
215 to the available state again.
216
217 || IMPORTANT:
218 || When diving in CCR or pSCR mode and initiating a bailout, the dive will be
219 || automatically set to turned state (given cave mode is switch on and the dive
220 || is not already turned)!
221
222 || IMPORTANT:
223 || While the cave mode is switched on and the dive is in turned state, the fTTS
224 || calculation will be suppressed - gas needs are calculated on the basis of an
225 || immediate return to the exit.
226
227
228
229 Operating the Cave Mode Function:
230 ---------------------------------
231
232 The Cave Mode Function is activated by setting the the surface menu item
233
234 Dive Setup -> Dive Setup (again) -> Cave Mode to 'on'
235
236 It will then be active right from the start of the following dives. All further
237 operation is done during the dive via a dedicated cave mode menu. This menu can
238 be accessed via the left button: after pressing the left button for 'Menu?',
239 press it again to show up 'Cave?', then press the right button to enter the cave
240 mode menu. In OC mode, the cave mode menu is also reachable via the main dive menu,
241 using the menu item 'Cave Mode'.
242
243 Depending on the 'dive turned' state, certain menu items are available or not.
244 This will be indicated by the color coding of the respective menu items.
245
246 When the cave mode menu is active, the custom view is temporary replaced by a
247 graphical representation of the waypoint situation. The last waypoint placed is
248 shown in the middle of the display. The "-|" symbol depicts the end of the line,
249 representing the deepest penetration point during the dive. The green arrow shows
250 for which position in the cave the return gas needs are calculated.
251
252 In the message field, either a "cTTS xx'" or "WPyy xx'" is shown. While the dive
253 is not turned yet, cTTS (Cave Time-to-Surface) is shown, with xx being the total
254 time in minutes required for swimming all the way back and doing the decompression
255 stops, if required. When the dive is turned, WP is shown to indicate that the TTS
256 is computed from off the waypoint yy. If yy reads the symbol -|, the TTS is computed
257 from off the turn point of the dive.
258
259 All cave mode functions are usable in simulator mode, too. Opposite to that, the
260 deco calculator does not support cave mode, it calculates vertical open water ascents
261 only.
262
263 || IMPORTANT:
264 || It is strongly advised to familiarize with the cave mode functions by using
265 || the OSTC simulator mode!