What is proper procedure for downcurrent

[FredT]

not a bit. The OP valve works on the differential pressure between the gas in the bag and the ambient water pressure. Since the bag is flexible there cannot be a differential pressure until the bag is full.

FT

 

[Michael Schlink]

O.K. guys, what did we decide?? Inflate the BC or not, ditch the weights or not. Ihave been blown around but it's been entertaining to say the least. I watched a father slide up the reef hook line of his daughters and knock her mask off at Peleliu "express". Another inst. and I were hanging onto the reef trying to keep from getting blown down and I was having a hard time holding on while my wife was washed 1/2 mile down the reef at the same time near Alor. Nus Penida is known for down currents, the DM's watch the fish, as soon as they start 'hunkering down" you know it's time to hang on. The question was : "what should you do if caught in a down current?" Answer: 1. stop your descent as soon as possible by any means available INCLUDING grabbing coral (this could be a life threatening situation for some). 2. Check your air supply, depth and deco status. 3. Evaluate the situation, look around, are there other divers around ,what are they doing Is this a rouge current or was it expected. Do you know what it's doing?? Some currents are predictable. Is the current picking up, slowing down, the same. Can you see an area that you can swim to to get in a "lee". BEFORE you kick of the reef or try to outswim it make sure you have a plan. Where is your buddy? Let them know what your planning. Once you make your move and you've cleared the current and you are in control again, I'd send a SMB or bag up to let the boat know where you are. Dive Safe-M

 

[Seadeuce]

Hello all, I have just spent an hour looking over the posts concerning what to do in a downcurrent, and it's 3am her in Ireland.
I cannot retire for the night without adding what I consider are some fundamentals that have somehow been overlooked in this thread.
May I first say I agree with some of the points raised, i.e. when caught .... swim away from the wall/grab onto the wall/inflate your BC.

The points I feel have been missed are thus:

When diving one should be WEIGHTED PROPERLY, that is, neutral at 3m (10ft) with an empty BC.
To be otherwise is to be negatively buoyant, which seriously diminishes the lift available by BC inflation at depth.

When diving one should be "DIVED UP" and prepared for the planned dives to be taken on vacation. This does not mean "be dived up for 100ft, then go to Truk Lagoon on vacation, as we can limit our dives when there." This happens all too often, which is why we sometimes find the day's dive site has to be chosen for the less-well-prepared diving tourist, to the chagrin of the remaining divers who had the good sense to prepare adequately.
Good preparation will mean some tolerance of narcosis at depth, and familiarisation with equipment/former training/skills. This will undoubtedly help if the worst should happen.

Finally, an awareness of the effects of STRESS on BREATHING.
Let's face it, if one is caught in a downcurrent it is highly unlikely that he(she) will be concerned with doing the math relevant to coefficients of drag etc.
YES - the first aim will be to halt the descent.
To attempt this will place the diver under stress, fit or not. He will have to swim across the current either to get to the wall, or away from it. Herein lies the danger of OVERBREATHING AT DEPTH.
Stress - overbreathing - depth - higher partial pressures - carbon dioxide buildup - brain closes down - unconsciousness - drowning/death.

I do hope that I do not come across as condescending. It is not my intention to "preach the word" only to highlight what I know from personal experience.

Cabo Marshall, Isabella, Galapagos, March 7th '99, 68m (223ft) for 50mins.

I will not bore you with details, suffice to say that it was not my planned depth. Main points:

Back to the wall, watching hammerheads below. Turned to see my buddy ascending, so I thought! It was I who was going down!!
Particles of sand/whatever shooting down past me between me and the wall.
I decide to head for the wall, and "climb."

I note my depth as 223ft, swim across and upcurrent to reach the wall at 184ft. No feeling of narcosis.

Then it happened - a "tiredness" equivalent to two days without sleep, came over me.

I remember saying to myself: "Inflate/feel the hug/fin up/wait to see bubbles before dumping air.

This I did. Inflated my BC until I could feel it's tightness. Started finning. Saw bubbles/checked my depth - 121ft.
Began dumping air, back at neutral buoyancy by 112ft.

I then continued my dive ascending 10ft every three minutes. Made stops at 95ft (half pressue), and again at 20ft and 10ft. Surfacing after 50mins.

BTW I waited to see bubbles before dumping air because I knew that when surrounded by bubbles you are "passing them out" and you are ready to slow the ascent.
Remember, one can make a faster than normal ascent rate below 100ft, then slow to 33ft/min. and compensate by extra stops, and YES, compensate for the "slowed ascent" too.

I WAS weighted properly, wearing shortie and skin, 10lbs. No air at ant depth needed for neutral in my BC.
THIS MEANT I HAD THE FULL LIFT OF MY JACKET ON INFLATION.

I WAS dived up, and to the limit of my qualifications (165ft) BEFORE going on vacation. This meant I had greater tolerance to narcosis at depth, and could think clearer.

I WAS aware of the effects of overbreathing, and recognised it was time to depend on previous training to get myself out of the jam.

If some or all of the factors I've mentioned above were not present, I might not be writing this at nearly 4am today.

I sincerely do so in the hope that others will heed my message - PAY ATTENTION TO BASICS/TRAIN/PREPARE.

Someday it may save your life.

Thank you for listening, now I'm going to bed ...



Seadeuce

 

[simbrooks]

As far as the sailboat, well presumably from the stern

The fastest point of sail is a broad reach (wind on rear quarter), you only go as fast as the wind with a run (from behind), but on a broad reach you have the wind mostly behind you (not causing an opposing force as with a beat/tack), but also using the function of the "wing" shape of the sail with air flowing over both sides of the sail. I am sure that makes sense to you pilots out there as well. When in a sailing race, and having a downwind leg, assuming currents/tides are favourable and wind flow as well, it is quicker to do two or more broad reach courses with gybes, rather than going straight buoy to buoy on a run - it just requires more skill, concentration and effort to do it that way (reaches rather than runs).

Ok, hijack over.

As for the lift in the BC, if you didnt add air, then the lift does diminish at depth due to air volume reduction (density increase, mass the same) and displacement of water - buoyancy. If you have the same volume of air on the surface or at depth it should have a near identical lift - you just have to pump the BC up a bit!

As for Seadeuce's experience, one big lesson there, dont lose your references on the wall (back turned)/forget to look at your gauges, it can be a long way down!! IF there is a good chance of a downwelling, there should be clues that you are going down, some of the most obvious would be the wall streaming in front of you, your buddy "ascending", your gauges, darker water and ear/mask squeeze pressure (harder to tell at that kind of depth i guess though).

 

[pufferfish]

Seadeuce that is quite the story but unfortunately all too common from the Galapagos. When we were there in 98 a women had just been 'lost' at depth off a private dive boat, and another the month before with neither body ever recovered. I suspect this is probably all too common and like in most resort dive areas the news is supressed and the frequency of these diver 'lost' incidents far higher than we think. Bad diving news in not good for business.

The likely mechanism here and as we witnessed last fall with the lady 'swimming' on the sandy bottom is the diver is taken to depth rapidly with the downdwelling and if experienced manages to escape with BC inflation or weight dumping if necessary, otherwise he or she is overcome with narcosis as you experienced and never makes it back to the surface. Part of that experience though would depend on being informed of deep currents in the third dimension. Most divers even experienced ones are often not prepared for this unless forewarned and a plan of action considered.

Just curious did your operator like our DM Paula present this current scenerio to you prior to diving the site or the Galapagos in general, or were you caught in a down dwelling with no prior warning? What time of year were you there?

 

[Gary D.]

I don’t know if anyone has paid attention to what I’ve mentioned several times but the focus still seems to point towards weights and BC. To dump or not to dump, inflation or not.

If you can learn to “Ferry” a current getting caught in one is no big deal. You can swim across a river either above or below the surface and go almost directly across and not get swept away. It’s called “Ferrying the current”.

It takes 3 basic things to deal directly with a current:
1. A level head to recognize that a problem is starting and the direction it is coming from.
2. Good physical conditioning and equipment knowledge.
3. Training on how to “Ferry a current”.

With the 3 above a current going up, down, east or west, can almost be turned into a thrill ride that you would almost pay to go ride.

Most people keep saying train, train and train but in a situation like this totally rely on their gear to hopefully get them out of a problem.

??????????

Gary D.

 

[pufferfish]

Gary I have been paying attention but don't think ferrying will work in the type of situation people are talking about here. We used to do canoe ferrying practice in white water above a three foot ledge and until you became proficient at it you ended up over the ledge wet, and swimming with your canoe back to shore. Practice did make perfect though. In the down dwelling situation described above if the diver is unable or has difficulty in ferrying up instead of just ending up over a ledge in as we did in the canoe, that diver will end deep down, narced, and possibly dead.

Ferrying relies on two things as I see it. One is the ability to angle up stream at an angle appropriate to the current speed so as to offset the current vector that would end up carrying you downstream. The second is one requires a certain minimum amount of power while paddling or finning to maintain this angle. If that power is not there or the current is too fast the canoe or diver will 'crab' from point A to point B, but there will be a component of 'slip' in the direction of the current. This amount of slip is of no consequence in the horizontal plane but change the scenerio to the vertical one with the current heading down and any slip can have bad consequences.

This is where I feel ferrying is not appropriate in the situation as described by the experiences of the divers such as Seadeuce. We are talking specifically in this thread about a diver caught in a high velocity (greater than 3 knots) unexpected down dwelling with no hard bottom in site.

Usually in these situations as the one described by Seadeuce one can end up 100 feet deeper in under a minute and by this time the **** has hit the fan. Unlike ferrying in a horizontal current such as in the typical river current or drift dive in Cozumel where that slip vector is always horizontal and of no immediate physiological consequence to the diver, in these down dwelling situations any travel in the downward direction can have immediate negative physiological consequences, namely nitrogen narcosis. The key is in these situations to immediately try and maintain neutral buoyancy with whatever trick it takes. Swimming to the wall, ducking under a ledge, inflating a BC, and if that doesn't work ditching some weight as a last resort are all acceptable maneuvers. You are better off leveling off at 223 fsw with a full BC and some weights gone than continuing narced into the deep blue yonder. Trying to ferry 'upstream' on the other hand in a down dwelling requires time which often is not at hand and if overpowered by the down dwelling one will always have that slip vector towards a deeper depth. In the situations discussed above the divers did not have the power or time to even think about ferrying upwards but instead found themselves below the 200 fsw mark with heavy narcosis.

I'd say once you are going over Niagara falls you can swim or ferry all you want, but the only parachute that may ultimately work will be BC inflation and if needed dumping of some weights.

 

[Gary D.]

Gary I have been paying attention but don't think ferrying will work in the type of situation people are talking about here. We used to do canoe ferrying practice in white water above a three foot ledge and until you became proficient at it you ended up over the ledge wet, and swimming with your canoe back to shore. Practice did make perfect though. In the downdwelling situation described above if the diver is unable or has difficulty in ferrying up instead of just ending up over a ledge in as we did in the canoe, that diver will end deep down, narced, and possibly dead.

Ferrying relies on two things as I see it. One is the ability to angle up stream at an angle appropriate to the current speed so as to offset the current vector that would end up carrying you downstream. The second is one requires a certain minimum amount of power while paddling or finning to maintain this angle. If that power is not there or the current is too fast the canoe or diver will 'crab' from point A to point B, but there will be a component of 'slip' in the direction of the current. This amount of slip is of no consequence in the horizontal plane but change the scenerio to the vertical one with the current heading down and any slip can have bad consequences.

This is where I feel ferrying is not appropriate in the situation as described by the experiences of the divers such as Seadeuce. We are talking specifically in this thread about a diver caught in a high velocity (greater than 3 knots) unexpected down dwelling with no hard bottom in site.

Usually in these situations as the one described by Seadeuce one can end up 100 feet deeper in under a minute and by this time the **** has hit the fan. Unlike ferrying in a horizontal current such as in the typical river current or drift dive in Cozumel where that slip vector is always horizontal and of no immediate physiological consequence to the diver, in these down dwelling situations any travel in the downward direction can have immediate negative physiological consequences, namely nitrogen narcosis. The key is in these situations to immediately try and maintain neutral buoyancy with whatever trick it takes. Swimming to the wall, ducking under a ledge, inflating a BC, and if that doesn't work ditching some weight as a last resort are all acceptable maneuvers. You are better off leveling off at 223 fsw with a full BC and some weights gone than continuing narced into the deep blue yonder. Trying to ferry 'upstream' on the other hand in a downdwelling requires time which often is not at hand and if overpowered by the down dwelling one will always have that slip vector towards a deeper depth. In the situations discussed above the divers did not have the power or time to even think about ferrying upwards but instead found themselves below the 200 fsw mark with heavy narcosis.

I'd say once you are going over Niagara falls you can swim or ferry all you want, but the only parachute that may ultimately work will be BC inflation and if needed dumping of some weights.

It will work nomatter which way the current is running. BUT you have to be able it ID the direction and change the Ferry angle to match the direction of the current.

Sure there are going to be currents that can't be defeated this way but for the most part don't go from A-Z without trying some of the letters between or a combination of them.

Not only do I know it works but we train for it and I have it on video to show it does work in a down or which ever direction current.

When we got caught on the Santa Rosa Wall in Coz I was filming fish swimming backwards while holding my own with ease. I would drop down the wall a ways then Ferry back up. I did that several times before I realized everyone was in trouble which is also on tape. Bad manouver on my part as far as the rest of the group's safety.

When I first noticed the rest of the group I was 15-20 feet below them as they fought to get to the wall. I just Ferried over and started helping push and pull some to the wall.

Training and using that training is a big key to success. Don't just rely on gear to get out of a bad situtition.

There is no one right way to do this but some are sounding like if the water starts moving dump and blow and thats not the best way.

Ferrying with dive gear on is simular to a canoe but still quite different in a lot of ways. If anyone lives in an area close to a "DRI Swift Water Rescue" certified tream try to get with them and see if they will teach some of the tricks. It could be very rewarding.

We re-cert every other year. When we got caught in the Coz current I had just finished the re-cert just a couple of days before we left on the trip. So it was major fresh in my mind and the stuff we just came out of in training was worse. In my mind it was no big deal which was unfare to the rest of the group.

Bottom line, current training WILL help!!

Gary D.

 

[Seadeuce]

The likely mechanism here and as we witnessed last fall with the lady 'swimming' on the sandy bottom is the diver is taken to depth rapidly with the downdwelling and if experienced manages to escape with BC inflation or weight dumping if necessary, otherwise he or she is overcome with narcosis as you experienced and never makes it back to the surface. Part of that experience though would depend on being informed of deep currents in the third dimension. Most divers even experienced ones are often not prepared for this unless forewarned and a plan of action considered.

Just curious did your operator like our DM Paula present this current scenerio to you prior to diving the site or the Galapagos in general, or were you caught in a down dwelling with no prior warning? What time of year were you there?

Pufferfish - As stated on my post, I was there in March. No mention of downcurrents in any dive briefing we had. Come to think of it, downcurrents have never been mentioned in a brief anywhere else I've gone, and I have seen quite a few places with deep wall diving.

To answer your question, yes, it caught me totally unexpectedly. Simbrooks' post mentions my not having the reference point of the wall, which is very true. I was enjoying the spectacle of hammerhead heaven, which would be normal practice on any dive there.

One thing I must emphasise, which was the main reason behind my post, is that I was NOT narced. Believe me, I know when I am! Proof of my not being subject to the raptures of the deep lies in the fact that I ASCENDED from 223ft to 184ft before receiving a hit. That was not narcosis, it was a CO2 hit. Going up 40ft would lessen the effects of narcosis, if they were present to a great degree. In this case, at a shallower depth, the sh** hit the fan!

To be brief in my post I did not mention that I swam to the wall to hold and "climb", but when I tried, the wall kept crumbling away! There was nothing solid to hold on to.
With the effort required to fin to the wall, and up to 184ft, I had obviously not been flushing my system of CO2 by breathing shallow and rapid.
My brain suddenly began to close down, and I reverted to what I knew from training.
BTW I am diving nearly 18 years, and consider training as ongoing! NOT something I did in a pool back in '86.
I have been past the 200ft mark a few times, and the depth did not faze me. When I turned and saw things shooting down past me I acted rationally. If I were to find myself in the same situation again, I would inflate immediately, finning towards the wall, but I would not dump weights unless I wasn't getting lift.

Gary - your "ferrying" is something I believe I have done on the horizontal. Usually as part of a navigation exercise where I go down a shotline, go on compass bearing across current for a set time, then turn and track back to a point where I stop finning and drift back to the vicinity of the shotline. With practice this gets easier.

I would not care to do it in a downwelling!

Current diving is enjoyable if you maintain control, and do not lose orientation.

I wish I could experience some of your training sessions, they sound interesting. Distance is a curse sometimes.
If there was an explanation of what you do online, that would be welcome.
In return I can explain how to "scuba-surf" on a current at depth, while holding your position!!
Maybe you already know this technique, it depends a lot on topography.

Nice talking to you guys,

Seadeuce

 

[Gary D.]

The likely mechanism here and as we witnessed last fall with the lady 'swimming' on the sandy bottom is the diver is taken to depth rapidly with the downdwelling and if experienced manages to escape with BC inflation or weight dumping if necessary, otherwise he or she is overcome with narcosis as you experienced and never makes it back to the surface. Part of that experience though would depend on being informed of deep currents in the third dimension. Most divers even experienced ones are often not prepared for this unless forewarned and a plan of action considered.

Just curious did your operator like our DM Paula present this current scenerio to you prior to diving the site or the Galapagos in general, or were you caught in a down dwelling with no prior warning? What time of year were you there?

Pufferfish - As stated on my post, I was there in March. No mention of downcurrents in any dive briefing we had. Come to think of it, downcurrents have never been mentioned in a brief anywhere else I've gone, and I have seen quite a few places with deep wall diving.

To answer your question, yes, it caught me totally unexpectedly. Simbrooks' post mentions my not having the reference point of the wall, which is very true. I was enjoying the spectacle of hammerhead heaven, which would be normal practice on any dive there.

One thing I must emphasise, which was the main reason behind my post, is that I was NOT narced. Believe me, I know when I am! Proof of my not being subject to the raptures of the deep lies in the fact that I ASCENDED from 223ft to 184ft before receiving a hit. That was not narcosis, it was a CO2 hit. Going up 40ft would lessen the effects of narcosis, if they were present to a great degree. In this case, at a shallower depth, the sh** hit the fan!

To be brief in my post I did not mention that I swam to the wall to hold and "climb", but when I tried, the wall kept crumbling away! There was nothing solid to hold on to.
With the effort required to fin to the wall, and up to 184ft, I had obviously not been flushing my system of CO2 by breathing shallow and rapid.
My brain suddenly began to close down, and I reverted to what I knew from training.
BTW I am diving nearly 18 years, and consider training as ongoing! NOT something I did in a pool back in '86.
I have been past the 200ft mark a few times, and the depth did not faze me. When I turned and saw things shooting down past me I acted rationally. If I were to find myself in the same situation again, I would inflate immediately, finning towards the wall, but I would not dump weights unless I wasn't getting lift.

Gary - your "ferrying" is something I believe I have done on the horizontal. Usually as part of a navigation exercise where I go down a shotline, go on compass bearing across current for a set time, then turn and track back to a point where I stop finning and drift back to the vicinity of the shotline. With practice this gets easier.

I would not care to do it in a downwelling!

Current diving is enjoyable if you maintain control, and do not lose orientation.

I wish I could experience some of your training sessions, they sound interesting. Distance is a curse sometimes.
If there was an explanation of what you do online, that would be welcome.
In return I can explain how to "scuba-surf" on a current at depth, while holding your position!!
Maybe you already know this technique, it depends a lot on topography.

Nice talking to you guys,

Seadeuce

"Ferrying" vertical or horizonal are the same. You just read the current differently. Some places do train compass runs in light current which is good to get exposed to. The longer and the more you do it the stronger the current you feel comfortable in.

It works well in a downwelling but you need to know how and what your doing. It gets easier the more you do it. The biggest thing is hold your streamlined form and stay relaxed.

I have never heard of it called "Scuba Surfing" but I wonder if we are talking about the same thing. A combination of body position in relationship to the current using minamal power to hold or advance a position.

We go way overboard in training. We train at 150' yet set rescue for MOST the team at 100' and recovery at 130'. Only 2 of us exceed those limits. We also train in current we will not get into in a scuba rig during an actual rescue. Recovery can wait untill conditions are right.

To many teams try to train in conditions that are equal to what they will be working in. Wrong approach. Train in worse conditions so the factors your working in are no big deal and your not pushing your limits. It's a been there done that mind set.

Besides limits change from dive to dive. If it doesn't feel right it most likely isn't. I backed out of simple 30' dives where I could see the bottom on a bright sunny day. We don't feel 100%, 100% of the time. ZERO PEER PRESSURE! I will make a point to intentionally back out of a simple dive around a new member just to show them that, see I'm not there 24-7.

In the 40+ years my team has been in existence there have only been 2 accidents. Both were somewhat minor and on the surface, not underwater. Not bad for a team allowed 10 divers with an average of 200 callouts a year. But the last 2 years have been the slowest in the teams history.

A few years ago one of the newer members came to me and said, I wish I had your experience, you'll never have an accident. Whoa, get rid of that attitude. I'm the one most likely to have an accident on the team. Your still checking things that I don't worry about. Besides I spend a lot of time watching you gear and actions instead of mine. He is today a very good member I don't have to play mother hen with.

Try to get with your local PSD team and see how they are trained. If it is a strong well trained team ask to go along on trainings. Not to dive but to watch. You can learn a bunch.

That got out of hand ;^)

Gary D.