Planning software feature

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taimen

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Currently using Subsurface to plan dives, but I am looking for a feature it seems to lack.

I'd like to set maximum deco time to 15 min with one deco gas (according to my certification level) and have the software calculate bottom time and possibly optimal gases for the dive?

Does any planning software have this feature?
 
Can be interesting to go into Subsurface github and make a request there. Devs are really wonderfull and you might have a chance to have it.

But I wonder if you cant have a spreadsheet formula for it.
 
As the person mainly responsible for the planning part of Subsurface I have to disappoint you: It is unlikely that this feature will be implemented (at least any time soon).

Of course, there is the "recreational mode" that extends the duration of the last manually entered segment to the maximum time the diver can stay at that depth without incurring any mandatory stops (a better version of NDL) but there is no way to say "I want to do a maximum of n minutes of stops/ascent time". It wouldn't be hard to implement but the problem with such requests is that they would increase the complexity of the already very baroque user interface of the planner. You would need at least one field where you can say that 15 is your magical number of minutes. But imagine we would scratch your itch. Then the next user would ask for a feature like "what is the maximal time I can stay at given depth with the deepest stop being 15m?" or anything the like. There would be another box for the 15m. And so on. Part of the problem is that there could be many variations of it and each would ask for additional UI elements. So, unfortunately, no, we are not going to add another value box for the request of a single user. (Things might be different if we were convinced that this particular feature would be useful to a significant fraction of our user base).

That said, even if not automatic, you can easily find that time manually: Plan you dive as usual, then select the last waypoint in the profile graph with the mouse, then use the cursor right key to increase bottom time until you are happy with your ascent time (checking total runtime and end of bottom time in the planner notes on the right bottom). The "plan variations" feature might also be handy here. Plus of course that fact that the Subsurface planner instantly updates the plan when you change parameters of your dive.

The "optimal gases" part is even more difficult: First there is the question "optimal in what respect? minimising ascent time? minimising gas cost? minimising narcotisation? taking into account cylinder sizes? maybe with contingency planning?" Another problem with likely more "correct answers" than technical divers using the Subsurface planner.

A related but possibly not obvious feature: In the gas/cylinder table, you can enter a "*" in the MOD or the "MND" field. That automatically computes the "best mix" where the O2 fraction is computed such that the max depth is the MOD of the gas while the He fraction is computed to have a prescribed END at the bottom part of the dive. But currently, this only works for bottom mixes.

Another problem with optimising the gas for the shortest ascent time is that what would require calculation several plans (one for each trial gas) which likely would compromise the "realtime reaction to parameter changes" that we are quite proud of.
 
Thank you for your reply @atdotde ! I totally agree with your reasoning concerning UI complexity.
In your answer you also nailed the features I was looking for with my question. Optimizing gases for minimising ascent time and dive planning with fixed maximum ascent time are exercises in tek lite training, maybe not so relevant for wider user bases. They are also quite easy to figure out playing around with parameter changes as you suggest.

And thank you very much for developing such a powerful free dive planner!
 
@atdotde I have been using the subsurface planner more now and would like to make a feature suggestion for the planner.
What I think is currently lacking from the planner is "time to surface" display. In other words, the maximum duration of the planned ascent during the planned dive. Many or most dive computers use TTS display and many people plan their dive profiles based on max TTS they want to encounter.
This TTS calculation could be added to the written dive plan without overly complicating the UI. Or is it already somewhere there?
 
This is already there: you need to turn it on with one of the icons (the one with the blue diver the green clock and the red line) left of the profile display. But be aware that its computation significantly slows down plotting (which is why it is turned off by default).
 
Currently using Subsurface to plan dives, but I am looking for a feature it seems to lack.

I'd like to set maximum deco time to 15 min with one deco gas (according to my certification level) and have the software calculate bottom time and possibly optimal gases for the dive?

Does any planning software have this feature?

Multi-Deco (for Windows, etc) and PastoDeco (for Android and not sure if anything else) have a feature that may do what you want, rather than exactly what you asked for. They have a way to have it calculate your max bottom time for the gases you're carrying. I don't think you can set a limit on deco time, though.
 
I had really missed the NDL/TTS button. Thank you @atdotde for your help!
For some reason I don't like the UI of PastoDeco. Otherwise it has nice features like lost gas plans.
That max TTS approach was part of coursework that I completed so it is not that important anymore.
 
This is already there: you need to turn it on with one of the icons (the one with the blue diver the green clock and the red line) left of the profile display. But be aware that its computation significantly slows down plotting (which is why it is turned off by default).

It seems that this TTS display does not take available gases into account. It seems to display TTS with the currently active gas, not the remaining duration of the planned ascent (like divecomputers usually do). This is a great feature too, because it gives me the back gas runtime.
So I still have this item on my wish list. Total ascent time with all available gases. That could be added to the written dive plan easily?
 
https://www.shearwater.com/products/peregrine/

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