Dive planner MG, TP and FC

[Ivan Wagner]

Dear Robert,

first of all thank you for welcoming me to the list in fact this is one
of my first posts.

Thank you for explaining to me the features that already exist within
the software it helps me understand in detail what we have now.

For me there are minor differences between rec or tech mode. The only
difference is ascent rates and the fact that for tech dives at a certain
point to need to make gas switches (talking about open circuit obviously).

Minimum gas is for me the minimum gas pressure in your cylinders that
you need in the event of an emergency such as an OOG diver making a safe
ascent respecting ascent rates, deep-stops until the gas switch (for
tech dives) or surface is reached (rec dives). Therefore we also need to
take into consideration ascent rates, two divers breathing from the same
unit (twins or whatever).

Turn pressure depends on the type of diving we are doing
- All usable: direct ascent to the surface is not a problem at all (i.e.
drift dives). With this you can reach minimum gas off from the entry point
- Half usable: it's highly recommended to get back to the ascent line
(wreck diving on a 100m long wreck). With this you should reach min gas
back on the ascent line
- Rule of thirds: overhead environment (wreck penetration).

For the last point I'll explain it in a separate post it's better.

ivan


On 10/14/2015 02:46 PM, Robert Helling wrote:
> Hi Ivan,
> 
>> On 14.10.2015, at 14:21, Ivan Wagner <ivan.wagner at tecinvent.ch> wrote:
>>
>> I was taking a look at the dive planner feature within subsurface and I
>> see some useful features that could be added:
>>
>> - Minimum gas (based on a scenario of an out-of-gas event and and ascent
>> respecting ascent rates, deep stops etc)
>> - Turn pressure based on gas rule such as all usable, half usable or
>> rule of thirds
>> - Fractional consumption at depth with 5 minutes interval.
>>
>> This is something I use on a daily basis not only for technical dives
>> but also recreational dives.
>>
>> Could this be interesting for you? I could implement something.
> 
> 
> welcome to the list. Of course, contributors and new contributions are always welcome!
> 
> I have to admit I do not fully understand what the features would be exactly that you describe.
> 
> Let me state what we have: The dive planner computes gas usage for the computed profiles. It warns you in two cases (with different warnings): a) if the gas use of the dive is more than what you have in your cylinders and b) same but with the gas use during ascent counted twice. In my understanding b) would be a violation of minimum gas.
> 
> Then we have the recreational mode. That determines the maximum time at depth that does not violate gas reserves in the sense b) above (possibly plus some constant reserve) and does not get you into deco (no gas changes).
> 
> Are you suggesting to do a combination of the two, i.e. stay at depth as long as gas reserves (in the sense of b) allow you but allow for deco and gas changes?
> 
> What do you mean by you last point? We compute all cylinder pressures at any time during the dive (as a plot). Do you want to display that as a percentage rather than pressure?
> 
> Best
> Robert
> 
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> Robert C. Helling     Elite Master Course Theoretical and Mathematical Physics
>                       Scientific Coordinator
>                       Ludwig Maximilians Universitaet Muenchen, Dept. Physik
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