Strategies for handling deco schedule deviations

[IDS_Bill]

I would stay at 100 to catch up and pad the last stop by 50%..... Just to be safe.

 

[Rick Murchison]

OK... let's look at the other end of the schedule - blown shallow stop(s).
Never mind the reason you got in the predicament, what's your plan for a blown shallow stop?
Basically, mine is to make damn sure I have enough gas & oxygen aboard to either - with no DCS symptoms - grab more gas and descend to the stop below the first blown one and recommence the schedule from there, adding time shallow depending on how much gas I have and how much of a "blow" had occured, or, with DCS symptoms, get on oxygen and execute the evac plan.
IWR (with symptoms) would only be considered if no chamber was available within 12 hours or more...
Rick

 

[boulderjohn]

OK... let's look at the other end of the schedule - blown shallow stop(s).
Never mind the reason you got in the predicament, what's your plan for a blown shallow stop?
Basically, mine is to make damn sure I have enough gas & oxygen aboard to either - with no DCS symptoms - grab more gas and descend to the stop below the first blown one and recommence the schedule from there, adding time shallow depending on how much gas I have and how much of a "blow" had occured, or, with DCS symptoms, get on oxygen and execute the evac plan.
IWR (with symptoms) would only be considered if no chamber was available within 12 hours or more...
Rick

My thinking as well.

 

[Norway]

First a general comment on gas choices. I would definitely save some bucks on helium using probably 20/25 for this dive (18/30 for those afraid of high po2, but this is really nothing on a 15 minutes BT dive)

And this would definitely be a two deco gasses dive for me. EAN50 would shorten your deco with about 15 minutes.

When it comes to missing this deep stop, I would have done nothing. As many people already pointed out, you do the deep stops in order to eliminate free bubbles, not dissolved gas, so either you already got bubble or your are not. If you´ve got it, it does not help waiting 4 minutes at whatever depth you managed to stop. So I would just continued up to the surface 4 minutes ahead of schedule or as you did, waited to come in line with the schedule if you don´t like rewriting your plan under water (and the best place to kill those 4 minutes is actually at gas switch to ean50)

I also agree, I would eliminate 10ft stop on O2 completely and move all this deco time to a 20ft stop on O2. This is where the oxygen works best. You gain nothing by going up 10ft on O2. But you loose some of the oxygen window due to the drop in partial pressure. (remember going up to 10ft on ean50 makes sense, since you drive the gradient up, this is not the case with O2)

When it comes to missed shallow stop, it depends which of the shallow stops . Probably, I would jump into the water with oxygen and deplete it at 20ft

 

[Diver0001]

In summary... situation 1: Blown deep stop, looks like the general concensus is to hold at whatever depth you do manage to stop at until your schedule catches up with you, and to add time to the shallowest one or two stops.

That would be my first intuition too as long as it's only a couple of minutes of deep stops and you hadn't blown through the deepest stop on the minimum deco schedule yet.

Is there some point at which you'd descend to intercept your schedule?

I guess in this scenario I would descend until at *least* the depth of the first missed stop on the minimum deco schedule (in this case 70ft) and at *most* the point where the depth and run-time intersected. If you only go to the minimum schedule stop depth then I would stay at that stop depth and wait for my clock to catch up (try to fix what you can on the deep end) and then go from there. In either case, I'd extend all the stops 6m (20ft) and shallower to try fixing it.

OK... let's look at the other end of the schedule - blown shallow stop(s).
Never mind the reason you got in the predicament, what's your plan for a blown shallow stop?

Same as above, assuming whatever caused me to blow it was fixable in the water; descend to at least the depth of the last stop you missed on the minimum schedule and at most the depth where you intersect your runtime and go from there, extending the stops at 6m and 4.5. Personally, I would be unwilling to get out of the water until I at least tried to do something about it unless there was some really compelling reason not to. It wouldn't occur to me to try fixing messed up stops if they're deep and then give it up if they're shallow. On the contrary. I would be HIGHLY motivated to try fixing it if it were a shallow stop.

R..

 

[rjack321]

OK... let's look at the other end of the schedule - blown shallow stop(s).
Never mind the reason you got in the predicament, what's your plan for a blown shallow stop?
Basically, mine is to make damn sure I have enough gas & oxygen aboard to either - with no DCS symptoms - grab more gas and descend to the stop below the first blown one and recommence the schedule from there, adding time shallow depending on how much gas I have and how much of a "blow" had occured, or, with DCS symptoms, get on oxygen and execute the evac plan.
IWR (with symptoms) would only be considered if no chamber was available within 12 hours or more...
Rick

I'll assume "shallow" = 30-20-10ft kinda depths. And a short time on the surface (<5mins)

I'd just redescend to the depth below where I lost it and redo the schedule for there. Add maybe 5 to 10mins on O2 (gas permitting). I would do this regardless of whether I had minor DCS symptoms on the surface or not. More deco isn't going to make those symptoms worse and will almost assuredly make them easier to treat if further medical treatment proves necessary.