To deco or not to deco

[tomfcrist]

So as I read that guys thread, I had to ask myself....who is the bad buddy and who is the idiot?

Seems to me if buddy a makes a free ascent and ends up 500m from the boat, and buddy b says "screw that guy", racks up some deco, finds the anchor line and is backn onboard the boat long before buddy a....buddy a is an idiot, and buddy b is a bad buddy...but a smart one.

 

[Bob DBF]

Seems to me if buddy a makes a free ascent and ends up 500m from the boat, and buddy b says "screw that guy", racks up some deco, finds the anchor line and is backn onboard the boat long before buddy a....buddy a is an idiot, and buddy b is a bad buddy...but a smart one

Unless buddy b winds up with more deco than gas and surfaces at the anchor line bent. There are a tremendous amount of ifs involved and I guess it depends on the divers risk tolerance, assuming the diver has any idea of risks involved.


Bob

 

[tomfcrist]

Absolutely true Bob. But if you go back and read that guys original "bad buddy's" post, he comes off as ...IMHO...a whiny person who makes bad decisions underwater and gets pissed at his "instabuddy" who basically says, I'm not following this spaz to my death.

 

[sea_ledford]

We had this happen on one of our trips. Team 1 (one diver on an 80, one on double 80's) was doing surveys on a rig at about 120', vis was pretty poor, probably 10-20' depending on depth, currents above the toppled rig at about 80' were strong, but not bad on the rig itself. Team 1 completed their survey and realized they didn't know where the upline was. They ran into Team 2 (both divers on single 80s) and asked where the line was, and got a raised shoulder "dunno" answer (turns out it was actually "I don't know what those hand signals mean" not "I don't know where the line is"). At this point the diver on the single from Team 1 gives the doubles diver a low on air sign (800 psi). Doubles diver donates (diver still had about 2500 psi, so loads of gas), checks their computers and sees 1 minute of NDL on one computer and 0 minutes on the other, but not yet in deco.

They made the decision to do a blue water ascent rather than go into a few minutes of deco because they had been trained (not by me) that deco was bad, don't go into deco. Team 2 saw the gas sharing going on and figured it was a bigger emergency that what it actually was and decided to go with them. So now 4 divers (out of 6 in the water) are doing a blue water ascent, 60 miles from shore in a current they will never be able to kick against. We have several layers of protection to prevent this, and they abandoned all but they very last one, which is hoping the surface divemaster actually sees their SMB, which they didn't launch until they were done doing their safety stop. Fortunately the DM did see them, and they were picked up about a mile behind the boat, none the worse for wear, but humbled and feeling stupid. Diver certification levels were instructor, divemaster, trimix diver and a relative newbie. It was not the newbie that ran low on gas. De-briefings were extensive.

I've added some basic knowledge of emergency decompression procedures to the scientific diver class since then. Needless to say, I am in the small amounts of deco over the long surface swim camp. Besides what is a greater risk- going into a few minutes of deco and blowing it off (worse case scenario) but getting right onto a boat with help around, or running the edge of no deco then working your ass off for 30 minutes trying to get back to the boat? Unfortunately divers aren't taught this until they are in deco classes due to the Deco-is-bad-don't-go-into-deco mindset that is taught in diving these days.

-Chris

 

[northernone]

We had this happen on one of our trips. Team 1 (one diver on an 80, one on double 80's) was doing surveys on a rig at about 120', vis was pretty poor, probably 10-20' depending on depth, currents above the toppled rig at about 80' were strong, but not bad on the rig itself. Team 1 completed their survey and realized they didn't know where the upline was. They ran into Team 2 (both divers on single 80s) and asked where the line was, and got a raised shoulder "dunno" answer (turns out it was actually "I don't know what those hand signals mean" not "I don't know where the line is"). At this point the diver on the single from Team 1 gives the doubles diver a low on air sign (800 psi). Doubles diver donates (diver still had about 2500 psi, so loads of gas), checks their computers and sees 1 minute of NDL on one computer and 0 minutes on the other, but not yet in deco.

They made the decision to do a blue water ascent rather than go into a few minutes of deco because they had been trained (not by me) that deco was bad, don't go into deco. Team 2 saw the gas sharing going on and figured it was a bigger emergency that what it actually was and decided to go with them. So now 4 divers (out of 6 in the water) are doing a blue water ascent, 60 miles from shore in a current they will never be able to kick against. We have several layers of protection to prevent this, and they abandoned all but they very last one, which is hoping the surface divemaster actually sees their SMB, which they didn't launch until they were done doing their safety stop. Fortunately the DM did see them, and they were picked up about a mile behind the boat, none the worse for wear, but humbled and feeling stupid. Diver certification levels were instructor, divemaster, trimix diver and a relative newbie. It was not the newbie that ran low on gas. De-briefings were extensive.

I've added some basic knowledge of emergency decompression procedures to the scientific diver class since then. Needless to say, I am in the small amounts of deco over the long surface swim camp. Besides what is a greater risk- going into a few minutes of deco and blowing it off (worse case scenario) but getting right onto a boat with help around, or running the edge of no deco then working your ass off for 30 minutes trying to get back to the boat? Unfortunately divers aren't taught this until they are in deco classes due to the Deco-is-bad-don't-go-into-deco mindset that is taught in diving these days.

-Chris

I was going to post. But you've said it well.

Thank you,
Cameron

 

[Tom_Ivan]

So as I read that guys thread, I had to ask myself....who is the bad buddy and who is the idiot?

Seems to me if buddy a makes a free ascent and ends up 500m from the boat, and buddy b says "screw that guy", racks up some deco, finds the anchor line and is backn onboard the boat long before buddy a....buddy a is an idiot, and buddy b is a bad buddy...but a smart one.

Needless to say, I am in the small amounts of deco over the long surface swim camp. Besides what is a greater risk- going into a few minutes of deco and blowing it off (worse case scenario) but getting right onto a boat with help around, or running the edge of no deco then working your ass off for 30 minutes trying to get back to the boat? Unfortunately divers aren't taught this until they are in deco classes due to the Deco-is-bad-don't-go-into-deco mindset that is taught in diving these days.

-Chris

That was my thinking as well. Especially considering most good dive charters (at least the ones I've used) hang a bottle 5m down the anchor line for use if need be.

I'd have thought that since they were close to their deco limit anyway, there would be a higher chance of getting bent from ascending then swimming like mad for 30min than staying down a bit longer then carry out a relaxing ascent to the boat.

 

[sigxbill]

Obviously finding oneself in a surface swim vs an unplanned for deco situation is the result of poor dive panning and execution - that needs to be fixed for future dives. Dan P's is the next best solution: swim back underwater but at a shallower safety stop depth - assuming that navigation at the shallower depth is possible.

Ultimately I vote in favor of doing whatever it takes to get back underwater - I am pretty much opposed to surface swims. I'm not sure if this was the point Chris was trying to make or not, but when he wrote, "or running the edge of no deco then working your ass off for 30 minutes trying to get back to the boat..." I was reminded of another possible issue with surface swims: physically exerting oneself swimming after surfacing close to ndl could bring on the very dcs symptoms the divers were trying to avoid in the first place ...

 

[Gareth J]

That being said, recreational diving is NDL diving, and if this was to include NDL violation, plans needed to be in place, including proper gas quantities for the dive. If there was no full knowledge of being able to complete the dive within the parameters present, it is "shoot a marker".

WRONG

My first recreational diving qualification was;
PADI open water - no stop diving qualification
My second;
BSAC Sports diver - recreational diving qualification allowing compulsory decompression.

The assumption that ALL recreational dive qualifications preclude compulsory decompression is incorrect.



Even where the diver is not technically qualified to do compulsory decompression, a fixation with avoiding a compulsory stop is potentionally dangerous.
5 minutes of deco because of a mistake is far safer than a "fast" ascent to avoid a deco stop.

In this case
An ascent up a shot line with 5 minutes of compulsory decompression is far safer than the risk of losing a diver on the surface because the diver made a direct ascent in a fast current to avoid the technicality of breaking NDL.
(That is assuming they have sufficient gas.)
Therefore, extending the dive time to allow return to the shot would be a far more sensible option.
In addition, in the event of either diver requiring medical assistance, the diver ascending the shot line has surface cover/support and immediate medical support. The diver ascending without contact with the surface (no DSMD), no shot line, fast current and drifting free, has the real risk of no medical support and no surface assistance if required.

Gareth

 

[rhwestfall]

@Gareth J : while I tend to agree, and my OW was so long ago that they did teach decompression principals (YMCA), this diver made no indication of having adequate gas planning and reserves or a comprehension of what could work (or he wouldn't be asking the question). So, without such planning, this recreational dive is and was to be a non-stop. Fiddling around in hope of finding the line with no established plan is still not advisable.

Yes, I too have watched folks race by me on an ascent because they were "staying out of deco", and really surprised to see it done. There have been numerous threads here discussing such behavior.

 

[markmud]

We had this happen on one of our trips. Team 1 (one diver on an 80, one on double 80's) was doing surveys on a rig at about 120', vis was pretty poor, probably 10-20' depending on depth, currents above the toppled rig at about 80' were strong, but not bad on the rig itself. Team 1 completed their survey and realized they didn't know where the upline was. They ran into Team 2 (both divers on single 80s) and asked where the line was, and got a raised shoulder "dunno" answer (turns out it was actually "I don't know what those hand signals mean" not "I don't know where the line is"). At this point the diver on the single from Team 1 gives the doubles diver a low on air sign (800 psi). Doubles diver donates (diver still had about 2500 psi, so loads of gas), checks their computers and sees 1 minute of NDL on one computer and 0 minutes on the other, but not yet in deco.

They made the decision to do a blue water ascent rather than go into a few minutes of deco because they had been trained (not by me) that deco was bad, don't go into deco. Team 2 saw the gas sharing going on and figured it was a bigger emergency that what it actually was and decided to go with them. So now 4 divers (out of 6 in the water) are doing a blue water ascent, 60 miles from shore in a current they will never be able to kick against. We have several layers of protection to prevent this, and they abandoned all but they very last one, which is hoping the surface divemaster actually sees their SMB, which they didn't launch until they were done doing their safety stop. Fortunately the DM did see them, and they were picked up about a mile behind the boat, none the worse for wear, but humbled and feeling stupid. Diver certification levels were instructor, divemaster, trimix diver and a relative newbie. It was not the newbie that ran low on gas. De-briefings were extensive.

I've added some basic knowledge of emergency decompression procedures to the scientific diver class since then. Needless to say, I am in the small amounts of deco over the long surface swim camp. Besides what is a greater risk- going into a few minutes of deco and blowing it off (worse case scenario) but getting right onto a boat with help around, or running the edge of no deco then working your ass off for 30 minutes trying to get back to the boat? Unfortunately divers aren't taught this until they are in deco classes due to the Deco-is-bad-don't-go-into-deco mindset that is taught in diving these days.

-Chris

Hi Chris,

You wrote: "Unfortunately divers aren't taught this until they are in deco classes due to the Deco-is-bad-don't-go-into-deco mindset that is taught in diving these days."

I was uneasy with diving and not knowing what staged decompression was. I sought information regarding staged decompression. It was difficult because dive ops would not sell me a manual because they were worried that I would start doing the procedure without training. That was not my intent at all.

I did get a TDI manual and studied it and my computer to learn the symbols and theory that the computer was displaying on the screen. I gained a theoretical knowledge of the issue and how to interpret my computer.

It paid off.

We were diving with a friend in tow. It was follow-the-leader dive. At the end of the dive, the DM takes Diana down into a hole that was about 60' deep. Here computer alarm goes off. I swam down and checked her computer. She was in deco. We followed the instructions on her screen and performed staged decompression. I was on EANX so I did not exceed NDL.

We got on the boat and she immediately said: "what the hell was that all about." My response was: "you went into staged decompression because you exceeded NDL." Her response: "What is staged decompression?"

Chris, your point is well taken.

markm