Escaping Down Drafts

[Ayisha]

During our group trip to Cozumel years ago, two friends of mine were caught in a downcurrent near a wall, dragging them both from 80 - 130 feet quickly. The instructor/leader was on the edge of it and kicked his way out, and most of the group saw the two divers fall quickly by the wall. It happened in seconds near the beginning of the dive and the current let go of them just as quickly. After that, I did a lot of research into downcurrents.

You're usually told to stay close to the wall where the current is slower, but I guess we have to be cautious as to how close we stay and to be aware of what the currents are doing in front of/around us.

Two years later, I got caught in a downcurrent innertubing through 7 miles of caves in Belize. We were the first group allowed to go through in a week due to flooding and very high and fast moving water. Some caves were impassable due to no breathing space. We were going through a cave that was particularly challenging and several people opted out and crossed by land outside the cave system. We were daisy chained together linking arms and legs and a trainee at the front was leading us through getting closer to the wall. The leader in the back yelled "Kick away from the wall! Get away!!". We all separated and tried, to no avail. Before I could kick away from the wall, the person beside me pushed off my tube and it flipped, and I plunged 15 - 20 feet underwater, WITH a lifejacket on. I held my breath and kept kicking up, but I wasn't going anywhere. I saw the current and silt going down the wall. I remembered what the guide said, and kicked as hard as I could off the wall and kept kicking away from the wall. All of a sudden I flew up and I was on the surface, gasping for air, flying with the current toward the exit, my headlamp lost. The leader was standing in shallow water holding my empty inner tube, panic stricken because I was held under for a while.

Downcurrents are apparently created when the usual horizontal current converges with a current going down a wall, and this causes a massive fast moving downcurrent.

As some others have said, these downcurrents are usually narrow and you can kick across them to get out of the downcurrent. Kicking up/fighting is less effective and tiring.

If you inflate your BC, be prepared to dump air really quickly to slow down your ascent once you're out of the downcurrent.

To avoid a downcurrent, you should:
-watch what the currents are doing in front of/around you
-watch the particles/sediment in the water for any unusual activity
-stay slightly away from the wall

I would be leery about dropping weights at depth, because you will have a whole other problem once you're out of the downcurrent - controlling your ascent and doing any safety stops. If you've been pulled to any significant depth, you may have obligatory deco stops as well if you still have enough gas. Rather than drop weights, do everything else you can.

 

[CuzzA]

Well no two situations will be the same, but IMO and this is purely conjecture, if you cannot arrest your descent you better drop weight and start blasting gas into your wing. You have no way of predicting when it will stop, how far you would have to swim out of the current and finally you may have been neutral when the down current began, but you will be increasingly negative going down and it will only begin to get worse as your inflator may not keep up and maybe your reg won't either.

Again rather be rescued on the surface than recovered on the bottom.

Here's a story we could make some correlations to. Granted these two knuckle heads did it to themselves, but it shows what could happen in an uncontrolled descent. Weight and diving outside their training was the issue here.

Too Fast To Live, Too Young To Die

And another recent story of a near OOA incident in a crazy current in the "Near Misses" forum.

How I almost drowned -- twice

 

[Kevrumbo]

You don't make things worse by dropping your weights and "blasting" air in your BCD --you will be assured of rapid if not uncontrolled ascent to the surface if you do manage to break free of the downcurrent. Again, such is the dilemma of this worst case scenario: do you risk an AGE with an uncontrolled rocket ascent, or ride-out the downdraft to depth until it ebbs?

I'm now thinking the general solution is that old aphorism for Stress: if you can't fight it or flee from it --then just flow with it. Do a combination of everything suggested above in moderation (inflate BC/Wing, maintain trim & control as best you can; relax and whatever you do, don't physically exhaust yourself uselessly into the greater danger of Hypercapnia and further expend your breathing gas supply), and when the right time is there -i.e. you find the edge or the downdraft begins to slack- then start kicking vigorously to escape it.

Indeed, it can be tough dilemma to be in with several make-or-break draconian decisions to consider & execute at precisely the right time. . .

 

[vincent54]

In our case, the down current dissipated at depth. The problem is the panic, especially a newer diver, that occurred. My thought is to go with the flow, then ascend at a safe rate.

I have been to the same site since, and the current is predictable. I stay shore side to the mound..

 

[Diving Dubai]

Well no two situations will be the same, but IMO and this is purely conjecture,

With respect. Your comments IMO are based on assumption and mere conjecture, rather than real world experience. You're opinions shut be listed as such.

I'm not touting myself as an expert in down currents by any means, however the fact is that since Jan this year over approx 18 dives in my local area I've had 2 down currents. Over the past 2 years (having checked my logs) I've experienced roughly 12 down currents per year. This isn't bad luck its to be expected in the area we choose to dive that has for the most part a lot of fast currents in certain locations.

@John C. Ratliff Asked if treating a down currents as in a similar way to a rip current would work. Technically yes is the answer. However as @NWGratefulDiver pointed out you don't know if the current you are in is localised or not. if you fin out are you sure that you're not going to keep going down?

The majority of the ones' that have caught me have been very localised the horizontal flow has pushed you through before you have had any time to react. Generally you don't pushed down more than 5 - 10m

I have had a very nasty experience where one took us down 22m We stablised at 51m by stablised I mean I was able to get a hold of the wall and stop my descent (the sand was maybe 20-30m below us) . Long story short - we climbed our way diagonally upward until we go out of the flow and then a very tentative ascent to 30m where we launched our DSMBs and got off the pinnicle for a blue water ascent.

My normal SAC is 13 -14l/m on that dive I peaked at 32 l/m

My point is that being able to hang on to something is the best course of action. You require a surprisingly small amount of effort to pull yourself up vs finning. Gas conservation means more time to work things through. as well as trying to avoid Hypercapnic CO2 retention etc.

Any diver having a change of buoyancy will immediately add (or dump) air - it's a reflex. I do it. we all would.

But if you recall in normal diving the lag from you adding air to it having a change in your buoyancy you'll realise how futile it is to try to arrest your downward ascent. That said if I didn't have a wall to hang onto of course I'd add air. As long as once you achieved positive ascent you start to dump it. Ditching weights. no way. i need to be able to control an ascent.

Coming out of a current - and this may seem counter intuitive - I don't try to get too shallow. previous experience has shown to me that down currents can be paired with up currents - hence I like some depth to work with until I'm happy we're in control and continue the dive or surface.

Anyway this is just based on my experience, I don't claim to be an expert.

 

[MXGratefulDiver]

Any diver having a change of buoyancy will immediately add (or dump) air - it's a reflex. I do it. we all would.

I wish that were true, but unfortunately it's not as reflexive as you might believe with some divers. I've watched divers lose buoyancy and cork to the surface more than once without ever making an attempt to dump air from their BCD. Afterward, when asked, they said they just never thought to ...

... Bob (Grateful Diver)

 

[CuzzA]

With respect. Your comments IMO are based on assumption and mere conjecture, rather than real world experience. You're opinions shut be listed as such.

Um, yeah didn't we already do that... That's why I said,

this is purely conjecture

and you are parsing my words. You left out the part where I said

if you cannot arrest your descent you better drop weight and start blasting gas into your wing.

I also said,

no two situations will be the same

yet everyone keeps saying just grab on to the wall. Well, what if there isn't a wall or you are too far way? What if the side of the drop off is 1,000 ft. deep and the down draft finally slows down at 300 ft.? Are you just going to ride it out, see where you end up?

I'm not suggesting you ditch weight in every single situation, but like I said, If you can't stop your descent you better do something... ditch weight, fill BCD, try to swim out of it without over breathing your reg. Thinking about that scenario, "In My Opinion" that's what I would do. I don't recall down drafts being discussed during OW/AOW training. If so can someone clarify what the textbook says?

Here are some more stories... One of which the diver did exactly as above and survived to tell the story.
Down Drafts: 5 Life-Saving Tips

Neal had taken a weeklong dive trip on a live-aboard in the Pacific. On many of the dives, a small tender from the live-aboard took divers to a site, dropped them off, then picked then up as they surfaced. On one trip, the divers were dropped off near an island with the admonition to stay close to shore. The offshore currents were not only strong, but vortexes were not uncommon in this area, causing the water to swirl in a downward flow, as in a whirlpool.

Due to delays among the other divers, and the crew not being sure of their position, Neal was the last to enter the water. By the time he descended, he was not only no longer with the group, he was also not with his assigned buddy. He almost immediately realized that he was in a very strong current with no bottom in sight. Putting it all together--no group, no buddy, no bottom, strong current--Neal decided to abort the dive and started swimming for the surface. Within moments, he realized that not only was he not moving toward the surface, he was being pulled downward at an accelerating rate.

Fear was rapidly turning to panic as he passed 100 feet, still kicking. Then the voice of his instructor, Fred, started playing inside his head--"If all hope is lost, get positively buoyant." Neal ditched his weights, pushed his power inflator button and continued to kick for the surface. After a few more agonizing moments, he paused at 135 feet, then started up, at first slowly, then faster and faster until he had to dump air from his BC to slow his ascent as he approached the surface.

The crew later apologized for their mistake of dropping divers at the wrong place. Neal suffered no physical injury from his near-miss, but he became much more careful about putting his safety in the hands of others.

 

[Kevrumbo]

In a Drysuit, the absolute worst thing to do at depth is to ditch your weights, especially if you've got mandatory deco stops before surfacing. The only time I would ever consciously ditch weights in this instance of a downcurrent as a last resort, is if separated from buddy or solo diving -->and Out-of-Gas for whatever unfortunate reason beyond my control. . .

 

[Diving Dubai]

I wish that were true, but unfortunately it's not as reflexive as you might believe with some divers. I've watched divers lose buoyancy and cork to the surface more than once without ever making an attempt to dump air from their BCD. Afterward, when asked, they said they just never thought to ...

... Bob (Grateful Diver)

Good point well made (he say's remembering his own OW dive 1) It's an easy trap to fall into believing what you think is the norm is the norm for everyone else. Thanks for the correction.

 

[PeterNBiddle]

Although I have never encountered a down current I have a personal rule that I won't dive any Nitrox mix on a dive where the hard bottom exceeds the MOD unless I have two independent buoyancy systems. Don't flame me, it is a personal decision, but on wetsuit dives along a wall where a loss of lift can potentially send me below the MOD of my back gas and ruin my day I dive air only. If I am dealing with a loss of buoyancy or a down current I don't need to add an O2 tox to my growing list of concerns.

I wouldn't have worried about this until after my Coz down welling. Now that it's happened, it's definitely at least going to become part of my pre-dive briefing discussion.