Dive planning for caves

Willem Ferguson willemferguson at zoology.up.ac.za
Thu Jun 16 23:41:50 PDT 2016


Robert,

1) When diving caves, a large part of the dive profile has to be "hard 
coded" because of the physical characteristics of the cave system. For 
instance, see the attached image, planned for deco using both EAN50 and 
oxygen. This cave system has three levels at 17m, 26m and 36m. The 
descent to the lowest level , as well as the ascent from the lowest 
level, is determined by the physical necessity to swim horizontally at 
each level, and, in addition, by the time required to fasten and lay 
lines. Thus a minimum-level dive plan to the 36m level may perhaps 
resemble the attached graph. However, on ascent, I would have liked the 
planner to recommend switching to EAN50 somewhere between the 26m and 
17m levels, not at the end of the 17m level. (Normally, one would leave 
the EAN50 cylinder at the exit of the 26m level, pick it up on ascent 
and do the gas switch during the transition from the 26m level to the 
17m level). It looks like the planner only starts calculating gas 
switches after the last "hard-coded" segment at 17m, not before. The 
switching sequence during ascent, from back gas to EAN50 to Oxygen, is a 
mess. Moreover, one cannot force a switch to EAN50 by right-clicking the 
last "hard-coded" point at 17m on the profile because there is no option 
to specify a gas switch when right-clicking that last point. When using 
the planner, is there an easy way around this problem?

2) Of course, a solution is to "hard-code" a switching point at around 
21m and then force a gas switch. But I encounter a lot of problems with 
this. When I force a gas switch to EAN50, it erroneously inserts a 
switch to Oxygen, not EAN50. I can play around a bit, eventually forcing 
the gas switches to be correct, but the indication of cylinder pressure 
(P in the black info box) disappears.

3) In addition, when working with different cave dive plans in the above 
way and I select "Cancel" dive plan, I get a segfault.

If there is any way that I can help you, e.g. specifying sequences to 
generate any of the conditions I mention above, I would gladly oblige.

Kind regards,
willem

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