Dive_TC_Calculator
This is a minor revision. I changed the bold blue "Yes" or "No" for the AD uses this table on the ALT sheet to not bold black. I wanted to be consistent and keep bold blue for user-entered values. I added some comments under the heading Excel and Calc and added a Key column in the ALT sheet. The calculations have not changed. The revision date is 04-JUN-2015 and the file is dive_EFX_rev9.1.xls and can be downloaded by clicking on the link above.
marc.Collin brings up an interesting point. Can we use a constant depth (Haldane) equation to calculate NDL's for descents and ascents which are changing in depth. I haven't seen an actual dive computer algorithm but I'm guessing it uses the same equation to calculate NDL's for descents/ascents. The DC calculates NDL every so many seconds. For each calculation it uses the current depth. Using this methodology a descent looks like a series of constant depth dive segments. I simulated this in the spreadsheet by making each segments 10 ft. deeper to an ending depth of 60 ft for 30 minutes, and compared the NDL's for each profile. There was only a one minute difference between the two profiles. Here are the profiles:
...........SD.. FD .Rate .Time .NDL
Seg 1:... 0... 60.. 60..... 1.0... 58
Seg 2: .60....60.... 0... 30.0... 27
Seg 1:... 0.. .10.. 60.... 0.2... NV
Seg 2:...10.. 20.. 60.... 0.2... NV
Seg 3:. .20.. 30.. 60.... 0.2.. 505
Seg 4:. .30.. 40.. 60.... 0.2.. 165
Seg 5:.. 40.. 50.. 60.... 0.2.... 90
Seg 6:.. 50.. 60.. 60.... 0.2.... 58
Seg 7:.. 60.. 60.... 0.. 30.0.... 28
The one minute difference might be due to rounding errors in the calculations. At any rate I think we can have confidence in using the Haldane equation for ascents and descents in the spreadsheet.
This is a minor revision. I changed the bold blue "Yes" or "No" for the AD uses this table on the ALT sheet to not bold black. I wanted to be consistent and keep bold blue for user-entered values. I added some comments under the heading Excel and Calc and added a Key column in the ALT sheet. The calculations have not changed. The revision date is 04-JUN-2015 and the file is dive_EFX_rev9.1.xls and can be downloaded by clicking on the link above.
marc.Collin brings up an interesting point. Can we use a constant depth (Haldane) equation to calculate NDL's for descents and ascents which are changing in depth. I haven't seen an actual dive computer algorithm but I'm guessing it uses the same equation to calculate NDL's for descents/ascents. The DC calculates NDL every so many seconds. For each calculation it uses the current depth. Using this methodology a descent looks like a series of constant depth dive segments. I simulated this in the spreadsheet by making each segments 10 ft. deeper to an ending depth of 60 ft for 30 minutes, and compared the NDL's for each profile. There was only a one minute difference between the two profiles. Here are the profiles:
...........SD.. FD .Rate .Time .NDL
Seg 1:... 0... 60.. 60..... 1.0... 58
Seg 2: .60....60.... 0... 30.0... 27
Seg 1:... 0.. .10.. 60.... 0.2... NV
Seg 2:...10.. 20.. 60.... 0.2... NV
Seg 3:. .20.. 30.. 60.... 0.2.. 505
Seg 4:. .30.. 40.. 60.... 0.2.. 165
Seg 5:.. 40.. 50.. 60.... 0.2.... 90
Seg 6:.. 50.. 60.. 60.... 0.2.... 58
Seg 7:.. 60.. 60.... 0.. 30.0.... 28
The one minute difference might be due to rounding errors in the calculations. At any rate I think we can have confidence in using the Haldane equation for ascents and descents in the spreadsheet.