Bailout Gas Plan on DiveProMe

[GF99/99]

DiveProMe was originally developed for OC technical dive planning only. In this respect, DiveProMe is better than Multideco. CCR planning was added later and yes you are right it is extremely simple.
DiveProMe is quite a popular planner. It currently occupies about 40% of the Play Store market in this category and is one of the top three popular schedulers on Android. It is user-friendly, easy to understand, and has beautiful informative charts. It is accurate in calculations. Its OC plans are the same as Shearwater and Multideco(in simple bucket mode).
DiveProMe is available as an app for Android, Windows, MacOS or as a PWA app for IOS. Download the latest versions from here:

Release DiveProMe v14.4 · VlasovAlexey/DiveProMe

Added the ability to set different surfacing speed before the first decompression stop and surfacing speed at the decompression stop. Corrected the accuracy of dive planning with the last stop at 6...

github.com

Multideco has problems with the calculation of multilevel profiles using decompression mixtures in the middle of the dive and not only at the end of the dive. Actually one of the reasons for the development of DiveProMe is dissatisfaction with the accuracy of Multideco for complex cave profiles. The second reason is the desire to update the old uncomfortable GUI. To make an understandable modern planner.

Interesting. I will download divepro after this post and play around with it. I am always interested in a new/other dive planning software.

However I must say Multideco has treated me very well and out of all the programs it is what I like the most. Also can you elaborate/screen show some examples of the issues you are talking about. I plan multi level multi deco gas plan all the time with multideco and never had any issues.

I have planned and dove 110m cave dives and 200m open ocean dives with multideco no issues what so ever. So I would say it is a pretty powerful and capable program.

 

[Alexey Vlasov]

Example of a multilevel dive where Multideco does not correctly use the available decompression mixes.

Instead of using the available EAN50 uses less efficient air on the 21 -13 meter segment...

There are no such problems in DiveProMe. Also, DiveProMe has protection for selecting available gas according to PPO and PPN limits. There are also gas overrun warnings for typical cylinder configurations. Also, DiveProMe takes into account the dive height and correctly shifts the beginning and end of the working depth of the mixtures. It also takes into account the ambient temperature. On long dives the difference in water of 4 degrees and 20 degrees decompression will be a few minutes. Beautiful informative charts for teaching, student teaching tools, compartment charts in tissues. All of this is not available for instructors in Multideco.

All this does not mean that Multideco is bad for planning. To reiterate. It works great for simple non-multilevel plans under standard conditions. It's a great tool for its tasks. It's just time to evolve...

 

[Wibble]

Example of a multilevel dive where Multideco does not correctly use the available decompression mixes.
View attachment 858385
Instead of using the available EAN50 uses less efficient air on the 21 -13 meter segment...

There are no such problems in DiveProMe. Also, DiveProMe has protection for selecting available gas according to PPO and PPN limits. There are also gas overrun warnings for typical cylinder configurations. Also, DiveProMe takes into account the dive height and correctly shifts the beginning and end of the working depth of the mixtures. It also takes into account the ambient temperature. On long dives the difference in water of 4 degrees and 20 degrees decompression will be a few minutes. Beautiful informative charts for teaching, student teaching tools, compartment charts in tissues. All of this is not available for instructors in Multideco.

All this does not mean that Multideco is bad for planning. To reiterate. It works great for simple non-multilevel plans under standard conditions. It's a great tool for its tasks. It's just time to evolve...

Just to confirm your dive profile settings that Multideco has applied...

• Dive to 50m / 28mins / air
• Then 27m / 1 min / air
• Then 13m / 30 mins / air

Multideco took that as exactly what you asked for as the 13m stop was on air.

When you're on the bottom phase for open circuit, typically you use a max PPO2 as 1.4 and use backgas. Obviously, in this manufactured plan, the 13m phase could be on the deco gas to shorten the dive. Obviously if you were then to drop below 1.6PPO2 (i.e. 22m) this would be dangerous.

I'm very happy that MultiDeco sticks with the exact request and doesn't throw in curve balls to run on the deco gas for an active portion of the dive.


Back in the land of reality, you'd plan the dive to get the approximate runtime and also to play with some settings (e.g. set the 13m phase to use 50%) and see if this has sufficient gas.
BTW also remember that an active phase requires higher SAC than at deco -- has DiveProMe taken that into account when calculating gas usage?

Once you've planned the dive, you then dive the plan using a computer to work out the TTS and deco plan by telling it when you've changed gasses. I trust Mr Shearwater with my life: all dive planning software is left on the boat.




Looking at MultiDeco's plan, I've set it to use the following gasses for the active phase of the dive...

• 50m / 28mins / air
• 27m / 1 min / air
• 13m / 30 mins / 50%
• Then deco on 50%

MultiDeco does NOT go into the deco mode until the bottom phaseS have completed.
This means it runs on air up to the 13m gas switch to 50% (where I've forced the switch to 50%).

BTW if you're in the active phase, you run at 1.4PPO2 as it could be dangerous to use 1.6PPO2 when exerting oneself. This means that the MOD for 50% is 18m (1.4/0.5=2.8), NOT 21m which is 1.6PPO2. You can see that in your screenshot.

Therefore DiveProMe has a DEFECT where it puts the diver into using 1.6PPO2 during the active phase of the dive.


Decompression model: ZHL16-B + GF

DIVE PLAN
Surface interval = 5 day 0 hr 0 min.
Elevation = 0m
Conservatism = GF 50/75

Dec to 50m (2) Air 18m/min descent.
Level 50m 27:13 (30) Air 1.25 ppO2, 50m ead
Asc to 27m (32) Air -9m/min ascent.
Level 27m 1:00 (33) Air 0.77 ppO2, 27m ead
Asc to 21m (34) Air -9m/min ascent.
Stop at 21m 0:47 (35) Air 0.65 ppO2, 21m ead
Stop at 18m 3:00 (38) Air 0.59 ppO2, 18m ead
Stop at 15m 4:00 (42) Air 0.52 ppO2, 15m ead
Level 13m 30:00 (72) Nitrox 50 1.14 ppO2, 5m ead
Asc to 6m (73) Nitrox 50 -9m/min ascent.
Stop at 6m 23:33 (97) Nitrox 50 0.80 ppO2, 0m ead
Surface (98) Nitrox 50 -6m/min ascent.

NOTE: This Multi Level dive requires intermediate deco stops between levels.

OTU's this dive: 99
CNS Total: 35.7%
Gas density: 7.2g/l

3124.2 ltr Air
1632.4 ltr Nitrox 50
4756.6 ltr TOTAL

 

[Mobulai]

This discussion is flying over my head as a diver but maybe not entirely as a coder

It's a workaround to use a 1% offset.

I was peaking at dive_build.js in the src code; could we not benefit by adding a switch case regarding the workaround?
Have it up to the user to go this way or the other?
(Forgive me I am no JS user, I’m more of a C/++ user; also I know this is not the place for opening a github ticket but I’m trying to understand the requirements 1st)

Also if someone has the time to explain me the diving context of this.. why is such a workaround needed? I’m rereading the entire thread anyway in case I missed it

Thanks btw for putting in the effort to build this, I really do like the webbased gui and friendliness of it

 

[inquis]

Have it up to the user to go this way or the other?

I think it's safe to assume if there is no appropriate deco gas at the BO point, then the most appropriate of the bottom mixes should be used (and required BO volume displayed). Regardless, it should be able to use a deco gas that is the same mix as a bottom gas (and again, give the required volume).

 

[Alexey Vlasov]

Apparently you didn't plan on cave multilevel diving. Diving with siphons. That's neither good nor bad. It's just a lack of experience
There is no such thing as active or inactive phase of a dive. There are decompression commitments. They should be passed as efficiently as the mixture allows.
I don't want to get into an argument with you about training methods and planning approach. It is pointless because we use this approach in expeditions around the world in caves. We will get bogged down in an endless discussion of why 1.4 on the bottom (where is the bottom, by the way?) and 1.6 on the deco. I'm not interested. Have a good dive my friend.

 

[Alexey Vlasov]

This discussion is flying over my head as a diver but maybe not entirely as a coder

I was peaking at dive_build.js in the src code; could we not benefit by adding a switch case regarding the workaround?
Have it up to the user to go this way or the other?
(Forgive me I am no JS user, I’m more of a C/++ user; also I know this is not the place for opening a github ticket but I’m trying to understand the requirements 1st)

Also if someone has the time to explain me the diving context of this.. why is such a workaround needed? I’m rereading the entire thread anyway in case I missed it

Thanks btw for putting in the effort to build this, I really do like the webbased gui and friendliness of it

Yeah, of course we can do that. But it will be another switch in the GUI. Strictly speaking the difference of 1% is the measurement error of gas analyzers of any model except for industrial or scientific purposes. There the accuracy is of course higher. So this workaround seems to work without additional switches in DiveProMe.

 

[Mobulai]

Yeah, of course we can do that. But it will be another switch in the GUI. Strictly speaking the difference of 1% is the measurement error of gas analyzers of any model except for industrial or scientific purposes. There the accuracy is of course higher. So this workaround seems to work without additional switches in DiveProMe.

I wish I could help with a pull request, but again lack of JS experience

 

[Wibble]

Apparently you didn't plan on cave multilevel diving. Diving with siphons. That's neither good nor bad. It's just a lack of experience

Cave dive planning is extremely specialised, way outside of any normal dive planning. Mostly it's about calculating the diive limits; bailout requirements, deco bailout, oxygen, diluent, even down to the number of spools/reels and line markers you take.

There is no such thing as active or inactive phase of a dive. There are decompression commitments. They should be passed as efficiently as the mixture allows.

We will need to differ on this. Most agencies and divers will treat the two phases differently, not least in terms of the gas consumed (SAC) plus the tendency to use lower PPO2s for the active phase of the dive (where you're swimming around and crap can happen), as opposed to the decompression phase where nothing happens and you have a low SAC.

I don't want to get into an argument with you about training methods and planning approach. It is pointless because we use this approach in expeditions around the world in caves. We will get bogged down in an endless discussion of why 1.4 on the bottom (where is the bottom, by the way?) and 1.6 on the deco. I'm not interested. Have a good dive my friend.

If you're promoting a general purpose tool for dive planning, then you should care. What works in the specialist world of complex cave planning isn't necessarily applicable to general purpose diving.

Would genuinely like to know more of your adventures in diving. Would make a change from all the Floridian divers


Good diving to you

 

[MultiDeco]

MultiDeco can plan all these dive scenarios with ease. You just need to read the instructions.

In the bail out sample, the commencement of the 28% will depend on the selection of using diluent as bail gas, or not. If its intended to use 28% OC as the only bail gas, then de-select the 20/30 from the bail screen. Now its makes plans with 28% from the bottom up. However, with 20/32 diluent selected as bail gas, then diluent is used as bail gas up to the point where 28% comes into use per normal ppO2 limits set into the config. Or instead if we want to exceed these ppO2 limits temporarily, then specify a new deco gas entry for 28% with a manual depth override i.e. say 28% 40m, and select it as bail gas instead.


In the OC sample, as Wibble points out, the program does what you to tell it to do. If you specify an extra shallow level, then the program will do that with the gasses as specified. If instead we want to swap mix in ascent at some mid point between levels, then enter a new leg that specifies this gas change: (21, 0, 50) Translated that says, at 21m, swap to 50%. Note the 0 time here. i.e. Make the gas swap on the move passing this depth, but do not stop here.

MultiDeco can plan almost any type of complex dive. In the 23 years since the introduction of this V-Planner / MultiDeco program format, we have accommodated many different planning needs and ideas... you just got to follow the instructions: MultiDeco planning FAQ