schford
Registered
Fair enough - my helpful advice would be to remain consistant....FLTEKDIVER:Please keep this in mind , and try to help here, rather then question my ability's , or Luke's for that matter.
The sentance below leads one to believe that you have not yet completed any decompression dives or training for decompression..
but then within a few posts....FLTEKDIVER:We talk about doing decompression diving, but yet last week, we didn't even know the basic's to go drift diving off my boat!!
It would appear that you are do undertake decompression dives.FLTEKDIVER:I do allot of wreck penetration, sometimes plan decompression diving.
I am sure you would agree, statements like that lead one to question the veracity of your other statements.
As for
This really really should have been covered in your dolphin course, it is common especially with SCR sivders to run their decompresison form a nitrox computer.FLTEKDIVER:I disagree, with using a Nitrox computer for CCR. How can you use something with a fixed FI02 , when your PPo2 changes, and your manually flying a unit at 130' ? Like i said, i don't know much in that area, that's why i asked these question's.
However let me cover this for you.
What you are doing in this case is working out your decompression obligation extremely conservativly.
You calculate a Nitrox mix based on what your % of o2 will be at the deepest part of your dive, and then calculate your decompression as if you are breathing this for your whole dive - which of course you are not.
Even if you managed to cock c up maintaing your set point for the deep part of the dive - the impact on your decompression obligation will be minimal as long as you are within a few tenths of your target set point.
This is more than covered then when you come off your deepest point and ascend as you start breathing gas with a greatly increased o2 %. Your decompression computer does not know about this and thinks you are still breathing Nitrox when in reality you are gaining a significant advantage in terms of decompression obligation as you rise due to the increase of O2 in the gas you are breathing.
Ergo a much increased safety margin
Lets look at a real example to illustrate this point. Imagine we are diving CCR to 30m and a setpoit of 1.2 - that gives us an equivelant nitrox mix of 30% @ depth
If we worked out decompression obligation for this assuming nitrox then we get 6 minutes of decompression.
However as the setpoint increases when he rises he only actually has a 3 minute decompression obligation.
Now what happens if he cocks up maintaining his set point and only manages ot hold a 1.0 set point for the whold of his dive - well his decompresison obligation is only 5 minutes so you can see that by using a nitrox computer you are building in a substantial safety margin.