When I first started diving the way I was taught to use the computer I had was to not let it go into the red. As well as don't go too far into the yellow. As long as it was in the green on the little graph on the side I would probably be ok.
Then I went to a different shop and instructor for tech training. Here is where I actually began to learn about the REAL risks of diving that were glossed over in the recreational training I received.
Computers accurately track NDL times based on the particular deco model they are using.
They do not accurately track your NDL times.
In order to do that they would have to be able to track
1 your physiology
2 level of fitness
3 hydration
4 age
5 workload you are experiencing
6 whether or not you have a PFO
7 any issues with your respiratory or circulatory system
8 how much sleep you had the night before
9 whether you smoke or not
10 family medical history that may predispose you to DCS
11 what Zodiac sign is dominant on that day (sarcasm yes, but in the case of some so-called undeserved hits, who knows?)
as well as a host of other variables.
Most of the models have been well tested and documented. They are just that, however, models. Some based on tests with high fitness level 20 something Navy divers and still have a measure of Wild A$$ Guess thrown in.
I have a 19 yr old student who I've been diving with for a few years now. No issues and she has dived all over the world thanks to her amazing parents and their jobs. This past Labor Day weekend she was on a seemingly benign dive well within the NDL's at school and got bent. Testing discovered an ASD - Atrial Septal Defect. Similar to a PFO but with a different cause.
"Much more common than an ASD is a congenital cardiac lesion persistent into adulthood called a patent foramen ovale (PFO). In simplistic terms, a PFO is the result of incomplete closure of atrial tissue, whereas an ASD is the result of complete absence of such tissue between the right and left atrial heart chambers."
She's since had successful surgery to correct it and got cleared to dive again beginning in January.
How far to push the NDL's is a highly subjective and personal decision that each diver must make. One based on an HONEST assessment of your acceptable level of risk, maybe your family's acceptable level of risk, your experience, training, physical condition, and of course - your supply of available gas should something go wrong and require mandatory deco.
I'm not willing to push the NDL's to the level I was ten years ago. If I'm thinking I'll come close it's just going to get planned as a more conservative mandatory decompression dive. Depending on conditions I'll push the level of conservatism up to make what would possibly be an NDL dive a mandatory deco dive to allow for the extra time off-gassing with higher O2 content gas.
SCUBA diving is an extreme activity and depending on the person, the "safe" amount of pushing NDL for one could be a serious problem for another.
Then I went to a different shop and instructor for tech training. Here is where I actually began to learn about the REAL risks of diving that were glossed over in the recreational training I received.
Computers accurately track NDL times based on the particular deco model they are using.
They do not accurately track your NDL times.
In order to do that they would have to be able to track
1 your physiology
2 level of fitness
3 hydration
4 age
5 workload you are experiencing
6 whether or not you have a PFO
7 any issues with your respiratory or circulatory system
8 how much sleep you had the night before
9 whether you smoke or not
10 family medical history that may predispose you to DCS
11 what Zodiac sign is dominant on that day (sarcasm yes, but in the case of some so-called undeserved hits, who knows?)
as well as a host of other variables.
Most of the models have been well tested and documented. They are just that, however, models. Some based on tests with high fitness level 20 something Navy divers and still have a measure of Wild A$$ Guess thrown in.
I have a 19 yr old student who I've been diving with for a few years now. No issues and she has dived all over the world thanks to her amazing parents and their jobs. This past Labor Day weekend she was on a seemingly benign dive well within the NDL's at school and got bent. Testing discovered an ASD - Atrial Septal Defect. Similar to a PFO but with a different cause.
"Much more common than an ASD is a congenital cardiac lesion persistent into adulthood called a patent foramen ovale (PFO). In simplistic terms, a PFO is the result of incomplete closure of atrial tissue, whereas an ASD is the result of complete absence of such tissue between the right and left atrial heart chambers."
She's since had successful surgery to correct it and got cleared to dive again beginning in January.
How far to push the NDL's is a highly subjective and personal decision that each diver must make. One based on an HONEST assessment of your acceptable level of risk, maybe your family's acceptable level of risk, your experience, training, physical condition, and of course - your supply of available gas should something go wrong and require mandatory deco.
I'm not willing to push the NDL's to the level I was ten years ago. If I'm thinking I'll come close it's just going to get planned as a more conservative mandatory decompression dive. Depending on conditions I'll push the level of conservatism up to make what would possibly be an NDL dive a mandatory deco dive to allow for the extra time off-gassing with higher O2 content gas.
SCUBA diving is an extreme activity and depending on the person, the "safe" amount of pushing NDL for one could be a serious problem for another.
