Fwd: Re: Dive planner MG, TP and FC

[Ivan Wagner]

Hi Willem

thank you for sharing.

>> The planning takes into account all gas available and subtracts the
>> amounts required for gas sharing as well as a 'residual' amount that
>> needs to remain. If one requires 50 bar for buddy-sharing (calculated by
>> the planner automatically) and another 30 bar residual was requested on
>> the dive planner form, the minimum gas use at the end of the dive is
>> start-pressure minus 80 bar. So the concept of minimum gas required is
>> not really relevant here, at least for recreational dives.

Exactly... An example was missing... It's crucial for tech dives in my
opinion.

>> This is the gas pressure in the cylinder at the start of the ascent
>> phase? This is a meaningful request but would require another selection
>> to be made in the planner (gas turn rule). This is something that I use
>> all the time in dive planning.

No this is that gas pressure at the point you should return to the line.
Let's consider if that you have a MG of 100bar and start with your
cylinders with 200bar. It means that you can only use 50bar if you go
one way on a wreck as an example. Turn pressure would be that at 150bar
you should start going back to the ascent line. These are all pragmatic
approaches (which is really what counts underwater) in order to have an
idea of your plan without complicated calculations.

I think the best thing is to have a separate dialog for all this.

ivan

On 10/14/2015 03:26 PM, Willem Ferguson wrote:
> 
> Ivan, Robert,
> 
> I think I understand the request.
> 
> On 14/10/2015 14:21, Ivan Wagner wrote:
>> Dear list,
>>
>> 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)
> 
> The planning takes into account all gas available and subtracts the
> amounts required for gas sharing as well as a 'residual' amount that
> needs to remain. If one requires 50 bar for buddy-sharing (calculated by
> the planner automatically) and another 30 bar residual was requested on
> the dive planner form, the minimum gas use at the end of the dive is
> start-pressure minus 80 bar. So the concept of minimum gas required is
> not really relevant here, at least for recreational dives.
> 
>> - Turn pressure based on gas rule such as all usable, half usable or
>> rule of thirds
> 
> This is the gas pressure in the cylinder at the start of the ascent
> phase? This is a meaningful request but would require another selection
> to be made in the planner (gas turn rule). This is something that I use
> all the time in dive planning.
> 
>> - Fractional consumption at depth with 5 minutes interval.
> 
> There is a continuous trace of the gas pressure throughout the dive and
> the precise pressure can actually be read from the profile information
> box (the moving black box on the profile panel). Would fractional gas
> information really give one more useful insight?
> 
>> 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.
>>
>> Let me know,
>>
>> ivan
>>
>>
> Kind regards,
> willem
> 
> 
> 
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