Minimum surface interval question ...
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TSandM's description is great - and frequently used in knowledge development presentations during the IDC! ;-)
The purpose of this question is exactly as she says - whilst we dive conservatively and take all precautions that we can, including making safety stops and taking surface intervals, sometimes, they simply aren't necessary; given certain conditions, we can dive and surface and then head straight back down again. The purpose of this question is to demonstrate that immediate descent after ascent is possible - and there are a plethora of reasons why this might be so - not least of which might be heading back down to pick up a dropped item, or possibly just the fact that the Open Water training course requires you to make several ascents and descents in succession.
It's not always possible to justify this type of dive profile, but the short answer is that in some cases, when your "bucket is not too full", there is no indication that you are placing yourself at any increased risk of decompression sickness.
Cheers
C.
The purpose of this question is exactly as she says - whilst we dive conservatively and take all precautions that we can, including making safety stops and taking surface intervals, sometimes, they simply aren't necessary; given certain conditions, we can dive and surface and then head straight back down again. The purpose of this question is to demonstrate that immediate descent after ascent is possible - and there are a plethora of reasons why this might be so - not least of which might be heading back down to pick up a dropped item, or possibly just the fact that the Open Water training course requires you to make several ascents and descents in succession.
It's not always possible to justify this type of dive profile, but the short answer is that in some cases, when your "bucket is not too full", there is no indication that you are placing yourself at any increased risk of decompression sickness.
Cheers
C.
chrpai
Contributor
One bucket? 
mac.calder
Registered
Couldn't pass up the opportunity...
So, is the bucket "half empty", or "half full"? 
oldschoolto
Contributor
At what pressure ?.....
Jim
Jim
one picture is better than thousand words ...
Dive 1 analyzed with divePAL:
Surface interval of 0 minutes
Dive 2 analyzed with divePAL:
Continuing with the "bucket" analogy .... one of the various decompression algorithm uses 16 different buckets (compartments - the vertical bars in the 2 images above) to simulate how different parts of the body intake / release nitrogen.
Click here to see the compartments for dive 1 in action (just move the mouse on the graph of the dive profile)
Alberto (aka eDiver)
Dive 1 analyzed with divePAL:
Surface interval of 0 minutes
Dive 2 analyzed with divePAL:
Continuing with the "bucket" analogy .... one of the various decompression algorithm uses 16 different buckets (compartments - the vertical bars in the 2 images above) to simulate how different parts of the body intake / release nitrogen.
Click here to see the compartments for dive 1 in action (just move the mouse on the graph of the dive profile)
Alberto (aka eDiver)
I knew somebody was going to want a whole chain of buckets . . .
It was a good simple analogy, and unfortunately I am going to jump on the complication bandwagon.
Keep in mind that the buckets grow in size the deeper you go, and shrink as you come up. It is important while ascending that your shrinking bucket doesn't overflow, and if necessary stop along the way and dump a bit of nitrogen out as you are ascending
Glenn08
Contributor
Now that you feel comfortable with tables, look at some advanced decompression theory. Blood is a fast tissue, and you will probably have micro-bubbles from the first dive, and they are most likely stuck in the capillaries in your lungs. Arterial pressure is greater than venous pressure, so these bubbles form on the vein side. On the second dive, these micro-bubbles compress and get into your general circulation. If you ascend too fast, these bubbles may expand to a problem size before they get to your lungs.
Does someone with advanced decompression theory want to comment on or correct my post ?
Does someone with advanced decompression theory want to comment on or correct my post ?
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