What is proper procedure for downcurrent

[mars2u]

Are we in agreement that the 1st course of action to get out of the current is to get closer to the coral?

Adv: You can grab coral, stay put and assess what ur next steps need to be.
Dis: Current can rip ur reg, mask, etc.

Hantzu

Although I don't want this to sound like it's "OK" to grab coral for buoyancy...taking pics...etc., I have to admit that when it comes to downcurrents, you have to think about your own safety first. This is exactly what I did in my previous post....and followed the rule of:
STOP-BREATHE-THINK-REACT
Unfortunately, even if you do stop...the current is still flowing and can cause your regulator to start sucking in water. As long as you keep a level head and use the "sipping" technique using your tongue...you should be OK. My decision was to "abort" after I had my descent under control.

 

[hantzu701]

I don't like grabbing coral either, but I've seen what a stiff horizontal current like that at the Spegial Grove can do to divers. You're basically flagging in the current until you get some shelter from the wreck.

Is there any guarantee that swimming away from the coral will result in diminished current?

On a dive in the Bahamas, we had a surface current of about 1knot. It was very funny to watch people surfacing along the anchor line. There was very little current at 55 ft. However as divers hit 20ft, the surface current would grab them. As they were often preoccupied with watching their computers, many would end up surfacing 60 yards back by the last chase boat.

 

[SDAnderson]

I don't like grabbing coral either, but I've seen what a stiff horizontal current like that at the Spegial Grove can do to divers. You're basically flagging in the current until you get some shelter from the wreck.

The SG is a different situation - you're trying to complete a dive in a moderate current and most of the conversation here has been relevant to escaping a heavy current that is threatening your existence. The SG dive was one of the most entertaining afternoons I've ever spent in the water, a veritable three ring circus. A lot of unsafe diving goes on there. 150ish divers in the water from 8 boats, we saw folks running out of air, coming up the wrong lines, letting go of lines and getting blown away, just about every mistake possible. If you have to pull yourself hand over hand because of the current, you should think hard about putting the thumb to the dive.

Is there any guarantee that swimming away from the coral will result in diminished current?

Absolutely not. On a wall that's a pretty safe guess due to the dynamics of the current. Less so in a channel but at least you'll end up on the surface and can drift until someone picks you up.

On a dive in the Bahamas, we had a surface current of about 1knot. It was very funny to watch people surfacing along the anchor line. There was very little current at 55 ft. However as divers hit 20ft, the surface current would grab them. As they were often preoccupied with watching their computers, many would end up surfacing 60 yards back by the last chase boat.

If you aren't drift diving, ascents and descents should always be done with a line close enough to instantly grab hold of. Surface currents, mid-water currents, bottom currents, all can occur with little notice. With practice, it becomes possible to read the signs (quivering lines, odd angles in the line, visual distortion in the water, fish tumbling head over fins, etc.) of disturbed water but the line is your friend, don't get cocky 'cause a tied-in boat can't chase you until the line is pulled. It doesn't take long at all to put a great distance between yourself and your ride in a stiff current.

 

[Web Monkey]

Unfortunately, even if you do stop...the current is still flowing and can cause your regulator to start sucking in water.

How does that happen?

Terry

 

[mars2u]

How does that happen?

Terry

Simply put, the force of the current can overwhelm the regulators exhaust causing you to "taste" water during breathes.

 

[DocVikingo]

http://www.undercurrent.org/UCnow/articles/Upwellings200102.shtml

Best regards.

DocVikingo

 

[Gary D.]

http://www.undercurrent.org/UCnow/articles/Upwellings200102.shtml

Best regards.

DocVikingo

Thanks Doc.

You just re-enforced what some of us have been saying.
Listen to the DM or Operator. They should know the conditions (Nitrox, yes/No)

Stay Calm and breathe as normal as possible.

Pay attention to what is going on around you and react as it happens not after.

Be physically fit. At least enough to handle the conditions you might encounter.

Be trained in diving current. It can be a lot of fun.

Don't dump and blow thinking that will cure the problem as either one or both could compound the situtation you are in.

Thanks again.

Gary D.

 

[pufferfish]

http://www.undercurrent.org/UCnow/articles/Upwellings200102.shtml

Best regards.

DocVikingo

DocV,
That is the best summary I have seen on this infrequently but important topic discussed anywhere. Just printed it off as a keeper.

As for looking at the fish for reference I had to laugh as it reminded me of a dive in a down dweller where I looked at my buddy with his reg having been yanked out of his mouth and him pulling it back hand over hand. As he was doing that and I was dealing with my own issues with a fin I looked down and saw a six foot white tipped sharked flipped upside down trying to regain his composure. The fish were upside down and struggling too

 

[pufferfish]

Another risk in a heavy large down current is narcosis and then further bad decisions. Last fall we were on a dive which had ten AOW and higher divers. Due to the difficulty of the currents which could be very unpredictable the operator sent along two instructors and a DM. They had their best boat captain too as groups often would get split up on this dive.

The surface was very decieving as we jumped in close to the pinnacle wall with no current. The plan was to stick close to the wall and max depth 100 ft but the hard bottom was about 135 ft. Well no sooner than we got below 30 ft and I was going horizontal in a 3 knot current. As that was the direction we were supposed to go I just enjoyed the ride while descending further in the current. At about 60 ft we came to the edge of the large pinnacle and depending where you were in the water column you either got sucked out to sea very quickly, or if deeper the current here was down dwelling at about 3 knots. You could actually see an interface between the two currents.

We were now about five minutes into the dive and I saw about half the divers up shallower just go shooting off into the wild blue yonder with a DM in pursuit. Another group managed to see what was happening and grabbed hold of the rock and slowly made their way back to 20 feet where there was no current. I had been pulled down to about 100 feet and managed to duck under a ledge and watch the wife of one of the divers who was stuck in the horizontal current above just blow by me right to the bottom. Next thing I saw her face down in the sand at 135 feet literally swimming in the sand. At first I thought she was just horsing around but after a minute of this and some other strange behaviour I realized this was not the case. I had been buddied with the instructor who also saw this and she went down to get her to come up. First she tapped her on the shoulder and just receive a blank stare. Then the instructor grabbed her tank valve and the wife became combative and tried to punch the instructor above her and continued to claw in the sand. At this point I was ready to head down to assist as the current was still pushing quite hard but she managed to get the diver to the ledge where I could grab the valve as well. We swam her up (she continued to flail at us) and it was amazing as soon as we hit about seventy feet the diver stopped fighting us and gave us a look like what the heck just happened. We released her and she ascended and completed a safety stop under her own steam.

This diver had been swept down by the current to a depth where she was was heavily narced and separated from her husband and buddy. If it had not been for the quick thinking instructor and our presence I think she might have been still swimming in the sand. Once the three of us surfaced we had a long wait by the pinnacle as the one group with her husband was about 500 m out in the ocean. The third split group has ascended and been picked up first.

The boat was pretty quiet on the way home but what amazed me was this women didn't acknowledge she was severly narced and never did apparently. Nor did she say thanks to the instructor who likely saved her life.

It was a good thing there was a hard bottom too.

 

[Scubaguy62]

Once in a current the size of the object makes no difference in its' speed. The current will move all items at the same speed regardless of size.

Taking into consideration my somewhat minimal dive experience, counteracted by my quite extensive flying experience, and considering that the difference between air and water is about 33% in density, I can tell you that in theory alone, this is only true when the mass of the object is undisturbed. So if we're talking only about the size of the diver, then the statement is true.

This is a question of area. Newton's second law of motion states that Force=Mass X Acceleration (F=MA). The product of greater mass, times the acceleration (the current), will result in greater force, which will affect the diver when you add the coeficient of drag to that equation.

Inflating a wing in a current is no different than trying to land in high winds. When I flight instructed, I taught my students to use 1/2 the amount of flaps used in normal landings when landing in gusty conditions, or in high winds, if any at all. Applying this to diving, in a current of about 1 - 2 knots, or better yet, as Walter puts it, "when the bubbles are going down," there is no question that inflating a wing will require stronger finning, as in the aircraft, using full flaps in high winds will require about 30% more power to land at the same speed (Newton's third law of motion, "for every action there is an equal and opposite reaction"). Hence, if you inflate your wing in a down current, and you're unable to keep up the propulsion necessary to counteract for the increased drag, there is no way you're going to avoid a greater speed going down than if you don't inflate the wing and try to swim out of it, or do something else to avoid it.


Semper Safe,

Rick