A diver air lifted off the coast of Galveston, Texas by US Coast Guard on July 16, 2017

[Dan]

If you have that much experience, you know that a two hours interval is not enough to clean your nitrogen load from your tissues. My only comment is and was that this is a procedure that increases the chances of getting a DCS hit. Nothing more, nothing less.

For all these years of diving, I never looked into my residual nitrogen load prior to doing my next dive of the day. I was just making sure that I have at least 1 hour surface interval (SI) between dives or longer SI for deeper diving like we do in Flower Garden, until withnessing this incident. Thanks for pointing that out.

 

[Dan]

I played around with DM5 & finally figured out how to find the Average Depth under "Mixtures" tab below the dive profile chart. Here are my Dive Time (DT), Average Depth (AD) & Surface Interval (SI):

7/15/2017
Dive 1: DT = 00:54:20, AD = 68 ft, SI = NA
Dive 2: DT = 00:46:40, AD = 71 ft, SI = 02:17
Dive 3: DT = 00:56:00, AD = 57 ft, SI = 02:33
Dive 4: DT = 00:58:40, AD = 60 ft, SI = 02:32
Dive 5: Skipped

7/16/2017
Dive 1: DT = 00:44:40, AD = 72 ft, SI = 12:55

 

[catone]

It looks like they were all NDL dives, padded nicely with long SIs. Plus I'm sure not many other divers had similar profiles, as they would've run OOA (assuming all were diving al80s).

 

[Steve_C]

The numbers for any algorithm are all approximations with padded safety margins. The more you push them the thinner the safety margins are. The other diver may have not ascended as carefully as you did from the dives. The other diver may have had a prior history of DCS. The other diver may have been physically exhausted and dehydrated. The other diver was taking on nitrogen during the night dive while you were off gassing. The other diver may have had a more aggressive computer so that his being within NDL does not mean that he would have been within NDL on your computer. I wear two different computers, one conservative (Suunto) and one more liberal on subsequent dives. On dive 2 I have seen them differ by 15 or more minutes of NDL. Also one is much quicker to give me more credit for going up a bit while the other is a bit slower to give credit.

 

[Dan]

I found this SAC calculator DiveNerd - SAC Rate / RMV Calculator, Imperial Units , plugging in my data & got these numbers on my all 5 dives: 0.39, 0.40, 0.37, 0.41, 0.44 CFM

 

[Freewillow]

very low SAC Rate indeed.

Do not worry too much about residual nitrogen load if you wear a dive computor. It does it for you .
Residual nitrogen however should have been covered during OW training, it is on the back side of the PADI tables

 

[Dan]

The numbers for any algorithm are all approximations with padded safety margins. The more you push them the thinner the safety margins are. The other diver may have not ascended as carefully as you did from the dives. The other diver may have had a prior history of DCS. The other diver may have been physically exhausted and dehydrated. The other diver was taking on nitrogen during the night dive while you were off gassing. The other diver may have had a more aggressive computer so that his being within NDL does not mean that he would have been within NDL on your computer. I wear two different computers, one conservative (Suunto) and one more liberal on subsequent dives. On dive 2 I have seen them differ by 15 or more minutes of NDL. Also one is much quicker to give me more credit for going up a bit while the other is a bit slower to give credit.

Glad to hear that SUUNTO algorithm is conservative.