Question Aqualung i770r N2 bar graph/warning

[travellingsalesman]

Hi all,

Not currently my issue, as the computer belongs to a customer but I'd love to understand more of how it works/why it's happening.

A customer has a new aqualung i770r computer and is diving on 32% nitrox at the resort.

He completed a dive:
Max: 18m
Length: 51 minutes
0² Exposure (after 1h10 surface) 6%

1h10 surface interval

Plan mode:
18m ->23 minutes

During the dive that he completed his NDL went as low as 5minutes which is understandable but fairly conservative.

When using the plan mode at 18m for the second dive I find that crazy. Makes diving the second dive lets say it was deeper nearly impossible.

On the computer there's also a setting to do with the tissues and has levels: OFF, 1, 2, 3, 4 (Which is currently set to 4.

I googled and found this is in the manual

The N2 Bar Graph represents your relative No Decompression or Decompression status. As your depth andelapsed dive time increase, the bar graph will grow in length, shift from green to amber, and ultimately to red (in-dicating a Decompression condition). As you ascend the bar graph recedes, indicating that additional No Decom-pression time is available. The i770R monitors multiple theoretical nitrogen compartments simultaneously. The N2Bar Graph displays the one that is in control of your dive at any given tim

I also found it uses the Z+ algo based on Buhlmann ZHC-16. Would anyone have any insights?

Thanks Leon

 

[inquis]

Not sure of the question. If you're wondering why the NDL was seemingly low, one reason is because the conservatism factor was on. The manual indicates this is an On/Off setting (not 4 levels), and it simply pretends the dive is at 915 m altitude instead of 0. There are NDL tables in the back indicate about 13 minutes less NDL with conservatism On at 18m/32% (using the 15m row).

I don't have any Z+ residual tables to gauge that impact on Dive 2, but there might be hidden penalties of Z+ at play here. It is only *based* on ZHL-16C, so there are definitely differences. Perhaps a rapid ascent may be penalized? (total speculation). Only the designers know, as it's proprietary. I agree that 23 mins is VERY low.

The N2 bar is merely a graphical version of the NDL time, so don't overthink that. (The bar is full/red when NDL goes to 0.)

If the user is comfortable with the idea of diving times closer to DSAT (designed and tested for NDL dives), have them turn the conservatism Off.

 

[inquis]

Deleted