Petrel controller to much info or not enough?

[Markus MDDT]

Been diving my JJ for about 250h now and starting to understand and prioritize the information available on my petrel 3. I have felt that I can not configure the screen to be able to get "status at a glance" as I want it. I work in med-tech industry which I would say gives me a fair understanding on how to do a robust and factual risk-analysis. Doing this and then trying to figure out what I actually want to have on my screen has been on my mind a while. There is of course a space issue for the screen and I think We can learn a lot from car and aviation UI to understand the dynamics of to much information and not enough information. Listening to Kevin Gurrs talk att Rebretherforum gives me more reasons to question the way the petrel displays PO2 for the three cells. I would argue (please argue against) that the way the petrel 3 displays the three separate values with two decimals in real-time falls in the category of "to much info". I also think that during a normal "all is fine" scenario I dont need this and I think its also task-loading my brain through my eyes which needs to be focusing on other stuff as well. I really think that you should always now your PO2 but I dont think this is the best way of doing so.
My suggestion would be to have a similar approach to it as Mr Gurr talked about for their military RB.
My suggestion is:
All good: One avg PO2 value in the middle (just like when you use a backup shearwater)
Any deviation from cells: Show all cells like today including all colors and warnings.

Again I think this way would free up space on both the computer and the LLM(your brain) and mitigate task-loading. There is as you know always possible to check the voltage on the cells (and other stuff) by cycling through the menus.
Is this a reasonable idea and is the way we look at this values a bit of a "snuttefilt" (comfort blanket in Swedish) for us just because we are so used to seeing it this way and feel safe and happy (that could be a valid reason)? OR is this the road to certain death? I hope its a bit more nuanced

What do you think?

 

[LFMarm]

I like the thinking. What are scenarios where you want to see all 3 readings even if they are all in agreement with each other? I cannot think of any but that would be a reason against this simplified visualization.

 

[Markus MDDT]

I like the thinking. What are scenarios where you want to see all 3 readings even if they are all in agreement with each other? I cannot think of any but that would be a reason against this simplified visualization.

I guess you could miss detection of very early warnings of a slower cell which would indicate eventual failure or a moisture issue...BUT is that a real issue if the petrel does warn you when it goes outside proper limits (outvotes) ?

 

[Imla]

One issue is that being the machine it is, deciding which cell to outvote is a bit tricky. This especially comes in to play if it happens to be the situation of two faulty cells and one real one. You need to know the three values to make an informed decision of which cells to trust, or indeed if you should trust any of them.

A typical example of a potential lethal situation of voting logic failure is where 2 cells are current limited at above 1 but below 1,2. This will not be caught by pre dive checks.
I dare to paste the page explaining this from the GUE materials.

 

[Markus MDDT]

One issue is that being the machine it is, deciding which cell to outvote is a bit tricky. This especially comes in to play if it happens to be the situation of two faulty cells and one real one. You need to know the three values to make an informed decision of which cells to trust, or indeed if you should trust any of them.

A typical example of a potential lethal situation of voting logic failure is where 2 cells are current limited at above 1 but below 1,2. This will not be caught by pre dive checks.
I dare to paste the page explaining this from the GUE materials.

I understand this issue but I don´t see how my suggestion would worsen or add to the problem since if one cell is voted out, even if it is the good cell, the computer would show all cells and problem remains. Do I get it right or am I missing something in you argument?

 

[evandroairton]

Maybe if SS sensors were the norm, your idea would be quite ok.
Current limitation is an understated and insidious risk, speccially, as said, it doesn´t appear at pre dive checks, so it would be neccessary to think a procedure to quickly access deviations

 

[Markus MDDT]

Maybe if SS sensors were the norm, your idea would be quite ok.
Current limitation is an understated and insidious risk, speccially, as said, it doesn´t appear at pre dive checks, so it would be neccessary to think a procedure to quickly access deviations

How would the function I suggested be worse during this scenario?

 

[mr_v]

I agree. Seems Shearwater products are falling into the feature-creep territory that are providing diminishing returns. Moreover, the information presented on the screen is mostly ad-hoc and does not correspond to the usual task flows. Some may argue that it is an intentional design logic - the diver must think.

The case posted by the OP is interesting one. Having some background in human factors, here's how I'd approach this.

- Show the average PPO2 when all cells are in sync. The definition of "in sync" is critical here. Ideally, you want to define a monitoring timeframe and acceptable deviation ranges in that timeframe, e.g., "in last 5 minutes the cells were no more than 0.01 apart with sampling done every 10 seconds."

- If the cells become out of sync, switch the display from showing one value to showing value for each cell and prompt the diver to perform a flush/cell reference check using the best reference gas available. For example, if flushing with one gas should give PPO2 of 0.8 and flushing with the other gas should give PPO2 1.1, the other gas is shown as the desired flush gas.

- After performing the flush, the diver can monitor PPO2 of each cell and vote out the cell that is not performing well.

- Go back to the main mode that displays the average information.

 

[evandroairton]

How would the function I suggested be worse during this scenario?

Because the controller is assuming that two are fine, the most logical, and excluding the bad. So, it's up to the diver make a flush to see how fast are the cells responding, and, if they agree on a lower pO2. MAYBE, one feature that would help, is showing only average, is putting a "Flush required" alert, but, again, as trained CCR diver, we must know our pO2 all the times, and not be over confident on Cell readings, from what i see "in field", most divers don´t do a mv cell check before starting a dive series, and, even new cells may com from a bad batch.
I may sound old school, and don´t want to be the owner of the truth", but it's just my way of thinking

Regards

 

[Whitrzac]

Set the alarm levels at something reasonable and a simple glance tells you if all is fine or not.

I've used that quite a bit when working in low vis situations. Press computer against mask, no red means its fine.