Diving in a dangerous current.

Recently I have read a number of posts regarding down currents and some stories regarding their potential dangers. I thought it might be a good idea for it to be discussed here.

For instance, what would one do if an unexpected or unexpectedly strong current pulled you over the edge of the reef and down the wall? Or if the current came over the wall and pushed you down further?

What would I do? (keep in mind I'm new and still learning! corrections welcome!)

Well, I guess I'd first try to fight it and get as close to the wall as possible. Maybe look for something to hang onto. Probably inflate the BC, drop the weights if that didn't work. Perhaps I'd try swimming out towards the blue in hopes of breaking free. But really, honestly, I don't know.

Especially, what would you do if you were at say 60ft and suddenly got swept down to say 200ft.

Scary stuff.

Thanks for taking the time to read and reply, your experience and opinions are greatly appreciated.

From my experience, down currents are a bit like waterfalls- if you swim away from the reef it gets better. But yeah- if they get you- it gets very scary very quickly.

I was guiding one Xmas day a few years back when 2 beginner divers swam ahead and were unaware that they were sliding down the reef. They responded to my fairly urgent "UP" signals with smiling "OK"s while equalising happily. I signalled to my other 2 divers to stop and swam down to pick them up- we were at perhaps 25m (70) and going down pretty quickly. I grabbed them and started inflating all BCDs, turned and my other 2 divers had joined us. Bugger. Inflated all jackets and was kicking like mad, holding on to their BCDs by the side pockets. 2 other divers from another group appeared- "you're screwed" was my initial thought until the DM appeared and started doing the same.

I blew maybe 70 bar (1000) in the few minutes that it took to get to an approximate safety stop- rapidly dumping air when we reached 15m or so. We were well away from the reef at that stage (not by intention). The "safety stop" was anywhere from 3m to 12m- my safety sausage was being forced underwater as we rode a hell of a rollercoaster. I got the group to link arms and we were thrown about a bit. Surfaced maybe 1 km from the normal spot- well out to sea. Luckily the boat crew were on to it fellas and saw us before we went out towards the afternoon sun.

I think that was the scariest dive I've led so far. One Xmas day I won't forget.

This is a question that comes up periodically, so there are a bunch of threads with great information floating around. Start with this one, and then follow the links contained within it:
http://www.scubaboard.com/forums/advanced-scuba-discussions/395497-dealing-down-currents.html

Most currents are horizontal. And those are generally strongest at mid-depth, weaker on the bottom.

Best way to avoid strong currents is to stay in the boat. If they're over one knot, you're going to run out of energy and gas fighting them if you get too far downcurrent and are trying to get back. So, start your dive heading into it, *not* drifting with it.

"Worst-Case Scenario"? (I liked that book)--hug the bottom, use rocks or other stuff to propel yourself forward, or if nothing but sand, knife in one fist, scissors in the other, dig in and pull yourself upcurrent to the anchor line (you do have an anchor line, right?)

Really worst case scenario? Surface before you run out of air and take your chances on top.

It can happen - the most important thing is not to panic. Make sure you always dive with a buddy. Get yourself stabilized if you can by grabbing onto something and then inflating the BC and taking off some weight. Mind you- don't take all the weight off at once- take off enough so you can go back up. You don't want to rocket up. I have had it happen a few times and it is an uncomfrotable feeling- you are finning but not going up - this is not the time to be afraid of grabbing the reef and using it to stabilize.

If I hadn't read the thread about the lost diver in coz, I could see myself being in a bad situation. But now that I researched the topic a bit, I think I would stay calm and extract myself from the current.

I'll tell any dive buddy about them before diving a wall too. If they take you by surprise I think you would be more prone to panick

How can we determine the strength of the current before we jump in the water? It seems that "the locals" may have a different idea of what constitutes a significant current than I do. I've never heard anyone on a dive boat discuss current in terms of "knots" - just "is there a current?" - answer with a yes or no.

I can't recall ever discussing how many knots of current there were. But we changed sites twice in December when the Aldora DM hopped in, held onto the line while looking at the bottom, and said "Nope, too much current. We're going somewhere else."

I know you can look at the soft corals and sponges and judge the current by their position and movement. Swaying gently? Go for it. Swaying a LOT? Think carefully. Pointed straight out to the side like a windsock at an airport? Not going to happen...

I wrote this post for a thread called Neat Little Tricks are Good to Know

Quero:

• When there is little or no current, small fish like anthias and damselfish swim in random directions a good ways above their coral head.
• When the current gets to about .5 kn, and up to 1 kn, the anthias all face in one direction (into the current). Divers swimming against this current will have to work a little. Newer divers tend to think currents like this are strong and may use up their air more quickly, but more experienced divers don't have much difficulty with these mild currents.
• When the current picks up to reach "moderate current" rates, between 1 and 2 kn, you begin to notice that larger fish face into the current, but are not yet sheltering. Swimming against this kind of current is tiring and doing so for long periods should be avoided unless you specifically plan the dive like this for a particular purpose. Drift diving in the direction of the current is advised.
• In stronger currents faster than 2 kn, bigger fish face into the current and shelter behind rocks, in crannies, and in the lee of coral heads. Small fish are all hiding in the corals and are no longer seen. Divers who need to swim against a current of this magnitude may have to drag/pull themselves along by holding rocks. It is difficult to move against a strong current of this velocity and the dive should definitely be a drift.
• If even big fish disappear entirely, you are faced with a current that is extremely difficult to handle and which has the potential for mortal peril. In this case, abort your dive.

Click to expand...

This thread and the missing diver thread in Cozumel has had me reading all the down current threads. I have been in strong currents where I had to abort.

But let me add the.... If you are diving a 32% NITROX understanding that 111 feet is your MOD... A down current as described in the resent threads could be you last dive in an instant ! A 36% mix and your reaction time is now next to none.

I may rethink that wall dive on NITROX in the future!

Sarge


Sarge
Sent from my iPad using Tapatalk