What SAC-rate are you planning for from bailout to first stop?
- Thread starter Mr Walker
- Start date
Mark Chase
ATB=AlwaysTalkingBollocks
The joke is a lot of deco tables are bassed on a 9m/min ascent and hardly anyone I know gets close to that.
I have tried and it feels scary fast to me.
I reely went for it on this dive (look at all the ascent warning diamonds) but after when I did the maths i only managed 6.6m/min
ATB
Mark
I reely went for it on this dive (look at all the ascent warning diamonds) but after when I did the maths i only managed 6.6m/min
Interesting, this is one I did last weekend, swam down to 73M fast, bailed after the turn back up to 71M, grabbed a shot for reference then went up it like a bat out of hell, if you ignore the hover at 50M to deploy a bag when the shot ran out
you also end up with a 6.6m/min speed up to first stop depth. I was swimming up neutral but I was heaving to get up fast after a small challenge from my companions to do so. One presumes you have to be strongly positively buoyant to meet or beat the 10m/min rate. The water was a lovely brisk 6 degrees at depth.
GaryL
New Member
The joke is a lot of deco tables are bassed on a 9m/min ascent and hardly anyone I know gets close to that.
I have tried and it feels scary fast to me.
I reely went for it on this dive (look at all the ascent warning diamonds) but after when I did the maths i only managed 6.6m/min
ATB
Mark
Interesting Mark. I get nowhere near 9m/mim, I also think our own kit configuration contributes to the ease of a speedy ascent. For example, using a bov and fmcl's, the faff of an oc bailout ascent with bleeding the valve and then the bov later getting in the way of the oc reg, took a bit of getting used to. Now I have switched to bmcl's and the bov and find the whole process of dumping gas during the ascent a damn sight easier, control's easier and no need to switch the bov valve between oc/loop to vent gas whether or not on it. Hand back, pull lung dump cord, problem sorted.
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Clare
Retired - going diving
We do 9 meters per minute on ascent (as Janos and Richie will testify having caught both of them out with it on a couple of different occasions). It just takes practice. You have to accept that you feel like you lose control and know you can get it back on schedule.
I tend to keep accelerating until an alarm on a gauge goes off
as long as you hit that first stop I tend to take the view that there is almost no such thing as too fast deep - just too slow. David Dolette's work on this is interesting.
I tend to keep accelerating until an alarm on a gauge goes off
as long as you hit that first stop I tend to take the view that there is almost no such thing as too fast deep - just too slow. David Dolette's work on this is interesting.
Chris Brown
Official CAMRA ale tester
What unit was this? Did it have an OPV on the FMCL's? I just squeeze the lungs - job done. I find my BMCL inspo harder as I have to reach round and pull a valve cord.
I guess its what we get used to.
Mark Chase
ATB=AlwaysTalkingBollocks
JJs the same you have to manualy dump
KISS was easy, just go vertical and it would come out the OPV which was mounted behind you head. ALs CLs wewre small so it wouldnt screw with your boyancy much when you were deep
I seem to remeber the large lungs on the inspo neded a bit of manual assistance but i didnt find it that daunting. Id prety much switch between dumping all the wing and then do boyancy control on the counterlungs then back to the wing again.
ATB
Mark
JONT
New Member
I double my actual SAC rate, bailing out assumes a serious problem. I assume that that means worse case scenario.
But if you are forced to exit in near 0 viz without your scooter even thats no where near enough.
Its unlikely for anyone to survive a dive with 3 major issues.
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Mark Chase
ATB=AlwaysTalkingBollocks
I'd have thaught the opposit in so far as most bailouts will be inoperable units due to handset failure or floods. So anoying but hardly anything to get stressed about.
Surely the only bailout on a CCR that will result in sustained super elevated SAC is C02?
OK alowance made for the initial OH SH?T moment, but after that surley its just a routeen ascent / exit on OC?
No CCR, blind exit, no scooter is a little drastic but thats should only be an issue if you planning right to the limit of your bailout.
After all OC cave divers do OC exits all the time??
If we are using third for me third for my buddy and third for stress on OC cave, isnt it caclulating at 150% SAC on two divers exiting?
If so seeing as we dont need gas for a buddy, surley if we ran the equivelent of thirds we would run 150% of SAC?
As it is I do a bit more than that
ATB
Mark
garethingham
New Member
A group in Thailand did some dry controlled testing with a group of willing participants around SAC rates with a C02 hit. They found that the recovery from a CO2 hit went in stages and so developed some standards around SAC rates.
45LPM for the 1st 5 mins (3x)
25LPM for the the next 5mins (1.67x)
Back to normal post this....it assumed a 15lpm sac rate as the base so would need to multiply out with a higher SAC rate.
Of interest was how long people could hold on before bailing, if memory serves me correctly the average was 7mins without a scrubber in place. Out of 7 participants 2 could not bail themselves out and 1 of those 2 was non responsive when symptoms presented. The group bailed out that participant.
The other interesting piece was about the onset and recovery from C02 issues, the longer it took for symptoms to come on (retainers as opposed to breakthrough) the longer it took for a full recovery.
45LPM for the 1st 5 mins (3x)
25LPM for the the next 5mins (1.67x)
Back to normal post this....it assumed a 15lpm sac rate as the base so would need to multiply out with a higher SAC rate.
Of interest was how long people could hold on before bailing, if memory serves me correctly the average was 7mins without a scrubber in place. Out of 7 participants 2 could not bail themselves out and 1 of those 2 was non responsive when symptoms presented. The group bailed out that participant.
The other interesting piece was about the onset and recovery from C02 issues, the longer it took for symptoms to come on (retainers as opposed to breakthrough) the longer it took for a full recovery.
Mr Walker
Relax /Frankie
JONT
New Member
Mark,
I'm not so sure, for experienced CCR divers the only reason to get off the loop is a flood or CO2 issues, but most CCR divers will never get to that level because most CCR divers just dont do the kind of dives that require that level of skill and thats great, bailing out is the safest and best option.
I've had a caustic cocktail and a co2 hit and I was amazed at how much gas it took just to get squared away,
Mark Chase
ATB=AlwaysTalkingBollocks
I think your misunderstanding my point
I have had to bailout in the past but the problem was progressive so the act of bailing out was no more stressfull than a OC gas switch for deco.
Like most people once on Deco my SAC would drop off significantly usualy below 12LPM from memeory I averaged arround 10
So my point is 95% of bailouts will be (or should be) relaxed afairs causing no significnat increase in SAC.
The 5% that takes you by surprise are the problem ones.
ATB
Mark
Chris Brown
Official CAMRA ale tester
Are we all at the point where we understand 45lpm is physically possible and sensible for B/O calculations for CO2 hits yet??
Mark Chase
ATB=AlwaysTalkingBollocks
No I still maintain is a stupidly high number that makes absolutly no sense in proper planning for deep dives and is simply not sustainable on long decompression.
IMHO the maximum any OW wreck diver can carry safely is three AL80s or 10s Past that point the task loading becomes more of an issue than the perceived benifit
Three not four for issues of pure physical weight for carrying on the boat, gtetting back on the boat and because having only three keeps access to one leg pocket easy for critical equipmnet like spare mask and emergancy SMB & spool
I also found it the only side I could access my Pee valve when I had an unbalanced rig
If you disagree then gas plan me a bailout stratagy for 45lpm for my recent 25mins at 95m dive
Or a normal dive for me 45mins at 70m
Teem bailout is about as good as Russian roulette in my book so forget that as a primary responce as it has far too many failure modes.
ATB
Mark
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Chris Brown
Official CAMRA ale tester
Don't get me wrong, I agree that 45lpm is a challenge to carry. Thats why bailout calculation threads are so interesting. Once you get past 50m it gets unwieldy to say the least.
My point is that you were previously claiming it was impossible to breathe those volumes, but we have had both medical professionals stating it is, plus real live experience from divers who have experienced it.
So, we should move the debate on a bit from "what rates should we calc" to "we can't physically carry enough gas for a deep bail from a CO2 hit, so what do we do?"
Personally, I don't plan for a CO2 hit. I mitigate it as much as poss by using CO2 monitors / Temp sticks and I fastidiously maintain my o rings and mushroom valves. I also don't push my scrubbers.
Didn't help me when I forgot to install the lid on my MKVI and skipped the pre breathe
But that was a few years back, in a pool and I modified my behavior as a result.
Mark Chase
ATB=AlwaysTalkingBollocks
Don't get me wrong, I agree that 45lpm is a challenge to carry. Thats why bailout calculation threads are so interesting. Once you get past 50m it gets unwieldy to say the least.
My point is that you were previously claiming it was impossible to breathe those volumes, but we have had both medical professionals stating it is, plus real live experience from divers who have experienced it.
So, we should move the debate on a bit from "what rates should we calc" to "we can't physically carry enough gas for a deep bail from a CO2 hit, so what do we do?"
Personally, I don't plan for a CO2 hit. I mitigate it as much as poss by using CO2 monitors / Temp sticks and I fastidiously maintain my o rings and mushroom valves. I also don't push my scrubbers.
Didn't help me when I forgot to install the lid on my MKVI and skipped the pre breathe
Sorry ponit me at the post where any medical expert said a RESTING sac of 45 was safe?
If your running a marathon its fine. IF your stationary on deco your f##ked
ATB
Mark
Chris Brown
Official CAMRA ale tester
Ask Tamas or Simon Mitchell. I never said it was safe, I said it was possible. There are people reporting examples of it in this thread. You said it was IMpossible. I also said medical professional not 'expert'
(meaning I would take their recommendation above a layperson)TDI use 45lpm for training standards. That number wasn't just plucked out of their arse.
So, as I was suggesting, perhaps the debate would be more useful if we discuss CO2 mitigation & bailout strategies, accepting that an elevated SAC level is possible, rather than arguing whether an elevated SAC is possible. I think you are the only person I have ever come across that says it isn't?
