2 Finnish divers dead, 3 injured in Plurdalen / Norway

[gianaameri]

In Finland ALL rebreather dives are done in +4 to +2 Celsius. Rebreathers are used for deep dives in cold water routinely. How deep... that I cannot tell as I am not a rebreather diver.

This dive had a deep part. It was not five hours at max depth. A lot of the planned time must have been deco time at shallow depth.

Testing on scrubber duration is done at the moment using two methodologies pertaining to depth: a. constant depth of 40 meters at 4C (therefore average depth of 40 meters) , or b. Quinetic methodology (which is less stringent and the max. depth is 40 meters, the average depth is a lot less). There is a third methodology which is the USN and is done even shallower (and with less CO2 flow)... so I can only see it applicable to shallow diving which is not the case here.

My point is if the best performing scrubber (we are talking duration and WOB, and not overall dimensions and size) out there (incidentally a near copy of the Cis excluding hydrophobic membrane) does not cut it for 5 hours at 40 meters constant depth 4C, then any rebreather unit at 129 meters 4C for a planned total dive time of 5 hours is very hazardous absent specific scrubber duration tests showing that it is not.

It may very well work provided you do not exert yourself, but if you exert yourself on the deep section at 4C even for a short time, then that could be enough to cause a temporary increase of CO2 in the system which incapacitates you, and from then on, once you are incapacitated, even if you bail-out (as was the case here for one of the divers), and even with buddy assistance (as was the case here for both the dead divers), it is too late. You are poisoned and that is it.

 

[Masadist]

In Finland ALL rebreather dives are done in +4 to +2 Celsius. Rebreathers are used for deep dives in cold water routinely. How deep... that I cannot tell as I am not a rebreather diver.

This dive had a deep part. It was not five hours at max depth. A lot of the planned time must have been deco time at shallow depth.

This!

I really don't get ppl that says this is a suicide mission or can not be done.. maybe you're just the type of ppl that dives only in fish tanks with shorties and snorkels??

5 hours total time with max depth at 130 is totally doable. And it has, multiple times as well even in this specific cave with the same conditions (water is always cold up here) and gazillion times in other caves and locations.

I, personally, dive with OC but almost all the other divers in our diving club uses CC ecuipment and we are diving year around min air temp being -30'c and water somewhere between 0'C (surface) and 4'C(bottom). Mostly we are diving in old mines or at sea (water temp at sea, at summer, is close to 4'C when you go deeper).

These conditions requires some more from the equipment than diving in warm waters (hence shorties and snorkels reference), but it also means that our gearing and knowledge is at the required levels.

 

[gianaameri]

This!

I really don't get ppl that says this is a suicide mission or can not be done.. maybe you're just the type of ppl that dives only in fish tanks with shorties and snorkels??

5 hours total time with max depth at 130 is totally doable. And it has, multiple times as well even in this specific cave with the same conditions (water is always cold up here) and gazillion times in other caves and locations.

I, personally, dive with OC but almost all the other divers in our diving club uses CC ecuipment and we are diving year around min air temp being -30'c and water somewhere between 0'C (surface) and 4'C(bottom). Mostly we are diving in old mines or at sea (water temp at sea, at summer, is close to 4'C when you go deeper).

These conditions requires some more from the equipment than diving in warm waters (hence shorties and snorkels reference), but it also means that our gearing and knowledge is at the required levels.

OC is not a suicide mission. Never said that it was or would be.

On rebreather at sea on a square profile with Heliox and a good unit if you dip to 129 meters for 10 minutes at 4C and you do absolutely nothing to exert yourself and then ascend on a deco line, it is risky, but done like this mitigates the risk.

In a cave where you have to negotiate restrictions 129 meters depth, 4C, 5 hours, no direct ascent... maybe a rebreather with not one of the better scrubbers and a not so good WOB - the planning is highly questionable (to put it mildly).

I'd like to see simulated scrubber and WOB performace data for the unit under the expected conditions as part of the dive planning process.

I suspect (hypothesis, not fact) the unit used was not up to the job.

Any news on the unit and mods adopted by the Team?

P.S. On further thinking, on a good rebreather unit, descending on scooter to 100 meters, switching to OC for the deep portion and restriction, and then going back to rebreather on ascent on scooter at 100 meters this dive would have been doable albeit with much much risk.

 

[Redshift]

If you look at the video on the first post, you see clips from a very similar dive. Total time was 5h40, but the time below 40m, for ex, was around 1h.
From what we see of the equipment used, one diver seemed to have a modified Inspo and one in the support team, a Meg?
These were different divers and we don't really know what they were using, but some were quite experienced, I don't think they'd go all crazy without reasons to support their plan. Besides, we don't know exactly what the plan was. We've heard of multiple rebreathers, but not sure how/when/if they were used. We know they had scooters. And why assuming that the whole dive was conducted on a same unit? If there were drop tanks in specific places, a diver would need OC gas to take him to the next tank and the deco could be done on OC, not rebreather, or on extra rebreathers...
I think that when you say their plan was too risky you are jumping into conclusions because the fact is that we don't know their plan, we only know depth and expected dive time.
Furthermore, the deaths come as "rebreather failure", but the first diver was somehow stuck in a restriction, damage could have been caused during the attempts to get him free, and the second diver could have had CO2 buildup due to panicking when confronted with that situation. (Even that could have happened to the first diver, at the moment we don't know).

 

[Tigerman]

More so, MAXIMUM depth.. Average? Dont think thats been mentioned anywhere..

 

[gianaameri]

More so, MAXIMUM depth.. Average? Dont think thats been mentioned anywhere..

That is easy.

We need the full cave map/cartography if someone can post it.

Max. depth they said is 129 meters, right?

 

[Tigerman]

That is easy.

We need the full cave map/cartography if someone can post it.

Max. depth they said is 129 meters, right?
...

Yeah, then we'll need the deco schedule, expected time of travel for the various sections and so on. We just don't have the data to keep nailing these guys to the cross as reckless, incompetent fools the way you do based on "130 meters for 5 hours is lunacy"
Whats for sure is that their planned average depth for those planned 5 hours was a lot shallower than 130 meters..

 

[gianaameri]

Yeah, then we'll need the deco schedule, expected time of travel for the various sections and so on. We just don't have the data to keep nailing these guys to the cross as reckless, incompetent fools the way you do based on "130 meters for 5 hours is lunacy"
Whats for sure is that their planned average depth for those planned 5 hours was a lot shallower than 130 meters..

With the cave map/cartography you can plan the dive on Vplanner and get all that you seek.

You can run a number of "what if" and get a range of the expected average depth and dive time.

Clearly there is no substitute for local knowledge and local experience, but what is for sure is that no rebreather that I know of can safely do that dive as described on the internet.

This because at the moment we do not have data suitable for that type of diving for any rebreather (that I know of).

 

[vincent54]

Testing on scrubber duration is done at the moment using two methodologies pertaining to depth: a. constant depth of 40 meters at 4C (therefore average depth of 40 meters) , or b. Quinetic methodology (which is less stringent and the max. depth is 40 meters, the average depth is a lot less). There is a third methodology which is the USN and is done even shallower (and with less CO2 flow)... so I can only see it applicable to shallow diving which is not the case here.

My point is if the best performing scrubber (we are talking duration and WOB, and not overall dimensions and size) out there (incidentally a near copy of the Cis excluding hydrophobic membrane) does not cut it for 5 hours at 40 meters constant depth 4C, then any rebreather unit at 129 meters 4C for a planned total dive time of 5 hours is very hazardous absent specific scrubber duration tests showing that it is not.

It may very well work provided you do not exert yourself, but if you exert yourself on the deep section at 4C even for a short time, then that could be enough to cause a temporary increase of CO2 in the system which incapacitates you, and from then on, once you are incapacitated, even if you bail-out (as was the case here for one of the divers), and even with buddy assistance (as was the case here for both the dead divers), it is too late. You are poisoned and that is it.

I agree with your conclusion. I just didn't think it fair to call an exploration team's plan " lunacy" when we have no specific information on what units they were diving and their exact dive plan. The information may help future teams.

 

[gianaameri]

I agree with your conclusion. I just didn't think it fair to call an exploration team's plan " lunacy" when we have no specific information on what units they were diving and their exact dive plan. The information may help future teams.

The term "lunacy" was in respect of the suggestion by a poster to replace a scrubber underwater as part of planned dive to 129 meters, 4C, 5 hrs. (in a cave, under ice...).

The deep section of this cave traverse runs for "only" 400 meters.

My suggestion to future planners (and there is a body recovery or two to do) is to avoid the prior mistakes by:

1. Using a Meg ISC with 8 lbs. Radial
2. At 100 meters switch to OC, negotiate the restriction, 400 meter run on OC for the deep section
3. End of the deep section, switch back to Meg ISC with 8 lbs. Radial

A little bit of constructive criticism so that we can learn from the mistakes made on this dive ought to be appreciated by the families of the survivors.