On 02/01/2018 15:34, Robert Helling wrote:
Willem,
reading your second mail, I understand there are only two different
ceilings left: The one in the divelist which equals the one in the
planner when you remove the ascent points and the second one you get
in reedit until you remove the ascent waypoints.
This is a „feature“ of the VPM-B model: It treats the „decompression
phase“ different from the bottom part of the dive, in particular it
takes note of the ceiling at the beginning of the decompression. In
the planner (as well as replan), we take all the explicitly listed
waypoints as the definition of „bottom phase“ (so in replan before
deleting the waypoints, the whole dive is „bottom phase“). In the
divelist we make a clever guess (thanks to Rick’s code) as to where
the bottom phase ends. This tends to be very close to the true bottom
phase of planned dives (when the entered waypoints end at the deepest
part of the dive and then the planner takes over and manages the
ascent) but is not exactly the same.
I have recently blogged about this problem here
https://thetheoreticaldiver.org/wordpress/index.php/2017/12/22/vpm-b-for-real-dives-or-not/
Best
Robert
Hi Robert,
It's such a pleasure interacting with someone who really understands
this thing, because I do not. I will document this issue in the user
manual. It's really the way that the representation in Subsurface
interacts with the VPM algorithm when a dive plan is reloaded for editing.
Would there be a possibility of a user defining the end of the bottom
section of the dive and for automatically clearing the ascent dive
points when a plan is reloaded from the dive list for editing? I
understand how arbitrary the "start of ascent" can be, e.g. when doing
multi-level diving.
V-planner handles this problem in a bit of a different way. One can
define predetermined segments (e.g. a multilevel dive or a cave dive)
that cannot be avoided in the ascent. However, between these segments,
V-Planner still calculates a deco schedule. For instance if a multilevel
dive has two depths, e.g. 40m for 20 min; then 20m for 20 min, V-Planner
still gives deco stops between 40m and 20m, even though there is a
pre-determined 20min "stop" at 20m. It would be wonderful if Subsurface
has a way of dealing with this situation. You have no idea how powerful
the Subsurface dive planner is for rapid graphical assessment of gas
volumes used, planning for possible failure of a deco cylinder and many
other things. The graphical representation makes an enormous difference.
Thank you so much for your time.
Kind regards,
willem
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