Diver in a down current - best action to take?

[danvolker]

Interesting question about gas mixes though. I had a question related. If I am on say EAN 32 or something and I am close to my max depth. Say I get in a down current, and I am swimming away, but still descending a bit as I do because of the current. If I have a pony bottle with plain air, can I switch to it until I recover from the down current? Or is it still a problem because I had been breathing 32?

A pony will last only a few minutes at 150 or 200....way less if you are exerting. Ean 32 is not going to make you black out in 2 minutes....I would say, deal with the current, swimming horizontally and fully inflating your bc. Try to keep heart rate low, and stay calm. When you bust out of the down current, your fully inflated BC will yank you up fast, but you should have plenty of time to dump air out of it, and regain a sensible ascent speed. I don't think switching regs during an episode like this is a good idea...it adds task loading, you may lose horizontal propulsion as you mess around with the pony, and you may cause an OOA event with the pony.
Since you have the pony, you can use it if you need it for a shallow stop.....

 

[danvolker]

Indirectly, I got some flak for my last post....someone with a major reading comprehension issue, thought I was saying it is allright to dive with a PO2 of over 2 , or that air dives to 200 feet are okay..... How anyone could have thought I was saying this is beyond me....but since apparently someone did think that....let me "CLARIFY"...

I do not think it is smart to do air dives over 120 feet deep. I am not telling anyone it is OK to do an air dive to 150 or 200.

What I was saying, was that if a diver with OW training, or perhaps AOW, was to be PULLED DOWN by a down current, to 150 or 200 feet, there are certain things this diver should not do.... One, would be NOT to pull the regulator out of their mouth during this crisis situation, in order to switch to a pony bottle.....I said this, because a poster had asked ..."if they were being pulled down fast, and their main tank was 32% Nitrox, SHOULD THEY switch to an air pony?".

I see competing dangers going on, but there is a bigger danger of a diver -- without gas switch training--- pulling the primary out of their mouth in a crisis situation like the downcurrent......when they need to be concentrating on swimming horizontal to the current and staying calm. Next, if they did this switch which I am advising against, because they fear O2 toxity of the Notrox 32 in their main tank ( but want the air in the pony)...then the real threat exists that the pony will be sucked to empty during this crisis, particularly if it is the pony size typical for new recreational divers that think they need a pony or spare air to have redundant back up. These small ponies would quickly be emptied at this depth, and suddenly this diver in a crisis situation, at great depth, is OOA. Now they have to do another reg switch, under the exertion load of their horizontal swimming, and potentially high breathing rate ( work plus fear) . I think that is a severe threat for a fatal result....I think this direction is far more likely to result in a death, than the direction of staying on the main tank with Nitrox, until back to shallow water well after this crisis is past, and the diver is calm again. At that point, if they wanted to switch, they could either go to a buddy for more air, or they could use their pony....

At no time did I say that it is OK to dive high PO2's ...What I said was that OOA will kill a recreational diver faster than the High PO2 possible in this scenario...

I really should not have to have made this clarification post......this was really obvious.

 

[RickyF]

Dan,
Loved the video's. That is some pretty serious downcurrent you had!! Glad you kept your wits about you!

 

[danvolker]

Dan,
Loved the video's. That is some pretty serious downcurrent you had!! Glad you kept your wits about you!

Thanks....If I had not been so intent on getting the perfect sub shot dropping into the blue of infinity, etc., I would have noticed the down current sooner, and certainly would have begun dealing with it sooner....If I remember correctly, I kicked down from like 90 going after the shot of the sub dropping into the blue...and the blues were getting much richer at 100 and 120....normally, you just flare, and you pretty much stop falling....my freedive wet suit was like lycra in buoyancy properties, meaning from 80 feet to 160 feet, there would be virtually no change in buoyancy from the suit....since I planned to stop descending around 120 feet, I just stop kicking down....and then concentrate on the sub and the blues and the composition.....but all of a sudden I realized I was still falling fast, even though I had been dead neutral at 90 feet. Some kicking while still in the viewfinder, and then a glance at my depth guage, and I realized I was falling faster...here probably at 160 feet ..then, a full inflation of the wing, and kicking, but I was still sure that the down current could easily be beaten.....While this became true, the lag in time of a few seconds, was enough for me to fall 50 feet between my realizing I needed to inflate the wing....and the adding of full power kicking to the wing....The time required to fall 50 to 80 feet was just seconds, and the video from above does not really have the depth perception to show the falling motion well...I get smaller in the video, but at that distance, just a tiny bit smaller is a very long distance further down.!!!

To a diver in a downcurrent at Cozumel, they may well feel a similar surprise and amazement at how quickly they can go from 100 to 200 feet...it may not even feel as though this is happening, except for the need to equalize your ears.
...If you are on a wall, and shooting video, you may need to be attentive to depth far more than usual when shooting.....It would be easy to tell if you were thinking about it and facing a wall, but if you were shooting manta rays or something out off the wall, it would be easy to miss the depth changes beginning to accelerate.

The moral of the story is to be attentive, and to have a plan in case you find this occurring. Additionally, it is one more reason to NEVER stay at depth in a place like this till you are down to 1000 psi.....since this would give you no margin at all if you were to be caught and pulled down. Much larger reserves should be kept in an area like this, for anyone. An argument could be made that we should not even be doing a 100 foot deep dive, in a place where down currents are common....This would be my advice. And you wont see me on top of a sinking sub again, ever

 

[Splitlip]

Dan. What was the subs purpose for the trip?

 

[Mike]

*double post*

 

[danvolker]

Dan. What was the subs purpose for the trip?

First leg of "Race to the Bottom of the Sea" !
http://www.sfdj.com/GoWheretheFishGoIssue/RacetotheBottomoftheSea.aspx

 

[Matt_O'Brien]

Hello all!
I have been in one down current only. I was guiding a large group - possibly 8 customers. It was a reef dive, from memory it was the inner reef and luckily not the continental shelf. It was a new dive site to the live aboard, we dived it on our second to last dive of the day, the one before the night dive. The dive turned into a drift dive as we followed the reef wall around a corner. As we did so we went from approximately 10m to 45m in around 10 seconds. You couldn't fight this - I kept calm and went with the current and tried to keep the group together. There was no point attempting to compensate as I knew i'd end up with divers on the surface when it finished - not being able to release air adequately upon ascent. Luckily it bottomed out at 45m, by this point I knew we were a fair distance from the boat so I brought the group up slowly to finish the dive early. At this point two divers were missing. Once on the surface we were about 3/4 mile away from the live aboard. Signalled for a pick up from the tender whilst I went down to look for the others. No sign of them, once I heard the first tender approaching I signalled it down to inform I had divers missing and I was commencing a search.
Turns out they had re-joined another group and were in the first pick-up and already on board. It was one of those things i'm afraid. Trying to keep the group together without panicking was difficult, I believe going with it and not fighting was 100% the correct procedure. Especially with varied groups of divers. It all turned out OK, needless to say we didn't dive there again and we abandoned our night dive that evening.
I think circumstances of the case dictate your actions, each case is individual and needs to be calmly thought through. If I was on my own - yes I may have held on to the wall or inflated my BCD and finned up. I did not have the confidence in my customers recovering from this once the down current had finished - from experience I know half of them would have ended up in a rapid ascent from depth. If I was on the continental shelf.. well that's a different story - I don't fancy visiting 3,000m.. Take it as it comes. This one you could not fight - it was a bit of a buzz at the same time. I would not have changed my actions and out of thousands of dives this is my only experience.
I worked with a Japanese instructor - he has lost a customer in Palau through down currents. There an instructor needs 3 years of local experience before guiding. It is a famous place for down currents and unfortunately deaths.
Anyway that's my limited experience and I hope it helps with peoples decisions.

 

[MXGratefulDiver]

The two most important things are: not to panic and never dive without a buddy.

... how does diving with a buddy help anything? In this case, that just means that two of you are going to be caught in it ... which will only make getting out of it more complicated as you now not only have to pay attention to what you're doing, but also to what your buddy is doing.

There are many advantages to diving with a buddy ... getting out of a downcurrent isn't one of them ...

... Bob (Grateful Diver)

 

[drdaddy]

The two most important things are: not to panic and never dive without a buddy. Usually the down current will spit you out as mentioned earlier but you may have to do other things too- like swim away from the wall, lessen your weight, inflate your BC (slowly- do not rocket up), assess how effectively you can fin up.

I respectfully disagree about "never dive without a buddy". I have a great buddy for the most part, but currents freak him out. I can't imagine what a down current would do to him - more than once I've grabbed him while whipping around a jetty finger in a drift dive. I would be worrying about saving him while working to save myself - talk about "task loading" !!!