Buddies kept grabbing/pulling me to ascend faster than computer said was safe

[eguil]

You have got to go with your computer if you have enough air, which you had. There is an argument to ascend faster on early part of ascent but then to go slow on later part. Certainly after a dive to 90ft for that time you need a safety stop, Diving a ""long time"does not make someone a better diver, sometimes makes them worse. There is no excuse for dragging someone up. Rescue divers are trained to help a diver in distress to ascend and usually only Instructors have any experience of assisting someone to the surface. I can understand air use as someone heading off in wrong direction is stressful for the followers and will cause more air to be used. As you had not too much experience at depth your buddy should have been more attentive. Yes, computers go wrong but not in ascent speed, they will stop calculating completely, say battery"" or just show a deep depth, like 99metres. Will be ok again with a new battery. In this situation your computer was fine.
Not too sure what happened at time ascent was attempted, it is recommended that you always dive neutrally buoyant then at least you will ascend without too much effort and air use. 1100 psi was an excellent point to begin an ascent and as I said before go with the computer on the way up and do a stop.
As you have learned there is lots of dubious theory out there. Best to remember your training, read your computer manual and know its workings and get your information from quality dive books. Even Forums throw up all points of view, some correct and some incorrect.

 

[doctormike]

High respiratory rates result in low CO2 not elevated CO2 hence the symptoms of hyperventilation which are induced by low CO2 (unless something different happens under water than happens on the surface). pH of people breathing fast tends to be high due to that low CO2.

This is a common point of confusion. Hyperventilation means moving excessive amounts of gas in and out of the lungs, and as you might expect, this results in reduced CO2 levels. Tachypnea, on the other hand, means a rapid breathing rate. Tachypneic patients (and divers) often are taking rapid, shallow breaths with less bulk gas movement than normal breathing, so this can result in hypercapnia (elevated CO2, low pH).

If you want the math, respiratory minute volume (the amount of gas moved in and out of the lungs per minute) equals respiratory rate times the tidal volume (the amount of gas moved with each breath). So if the tidal volume is low enough (or the dead space is high enough), a rapid respiratory rate may not actually increase overall functional gas movement.

The practical application of this is that panicked divers are often tachypneic but are not actually hyperventilating, so they may experience increased CO2 levels. That is, they may be breathing rapidly and shallow. But of course, as with most cases, the devil is in the details.

 

[jdzb]

There is a few things that come to my mind about this situation. These are things that are pretty well part of every divers early training:

1) Any diver can call the dive at any time, for any reason, without fear of repercussion.
2) Remain calm. Don't panic. Stop. Assess the situation. Then act.
3) When buddy diving, when there is a disagreement between computers, follow the most conservative computer. By extension, I would say that also applies not only to the computer, but also to the most conservative diver.

I believe Alicia did the right thing to call the dive when her psi reached 1100. Perhaps she should have called the dive earlier when she felt the "experienced" diver was not following the dive plan and going south instead of north.

"Freaking-out" is not keeping calm. Keeping calm is something that Alicia may need to work on. However, Alicia did seem to keep a cool head by not overreacting underwater and doing something like bolting to the surface. The "experienced" buddy did nothing to calm Alicia's nervousness. Instead the buddy contributed to the nervousness/potential panic by not following the dive plan and by forcing Alicia to go against her conservativeness.

The so called "experienced" buddy (actually buddies since there were 3 divers) was not willing to follow the most conservative. There was no imminent danger that justifies his actions.

 

[nodakdive]

3 times I've been in a situation where a diver needed to go up, or possibly get hurt. Or worse. 2 of those times, the diver had to be "dragged", meaning I had to physically grab their tank/bcd and take them up as they were unwilling/unable to do so themselves.

1. 12 minutes into dive, diver is at 110 feet and realizes he only has 400 lbs of air. He freaks. Didn't have to drag him up, but he wouldn't take my octo until he was OOA. On the boat, I explained why he should have taken my octo when I first offered it to him. He still doesn't agree with me about that. Total dive time = 18 minutes. (I stayed close to him during that dive because I saw trouble coming. He was constantly slow and late getting his equipment together, and found out he had 2900 lbs instead of 3000 lbs, which freaked him out. He air consumption was bad to begin with, but I knew this was going to throw him over the line.)

2. Diver is at 120 feet and narced, ignoring my request that he go up. He's frozen, putting no air in his bcd when I tell him too. He's not kicking. He has his inflator/deflator in one hand and his console in the other, just staring at me, looking like each was a gun pulled out of a holster. He's sinking fast. When I grabbed him by the tank valve, I was at 135 feet. This was the same diver as mentioned in #1 and this happened the day before incident #1. He didn't believe me until I showed him on his own computer that his max depth was 137 feet. I don't know what would have happened had I not grabbed him.

3. Diver is in a quarry that has a max depth of nearly 400 feet. We start the dive, with him ahead of me so I can keep an eye on him as the day before he ignored my request that he stay close enough to me that I can see him. He failed that, over and over. So, we go through the first thermocline, and I realize it's colder than I expected. That was at about 30 feet. At 45 feet, I stop him and tell him I'm cold and to go up a little. He turns and keeps kicking, never adding any air to his bcd, or even looking at his computer. At almost 60 feet, I stop him again, tell him I'm cold and to go up. He turns, making a bee line for the center of the quarry, without even acknowledging me. Finally, at 70 feet, I stop him again and sign the same. He just stares at me. I tell him to put air in his bcd. He stares. I signal OK. He stares. I signal go up again, he stares, so I grab him by the bcd strap, and "drag" him up. We get to the surface, and he says, "What's the big deal?" I explain what happened, and he is non plussed. He didn't think there was a problem, and to this day, he still doesn't understand what "the big deal" was. He has that luxury, as he's alive, which he wouldn't be if I hadn't dragged him up. Had I just gone up without him, he'd be dead. He was sinking like a rock and swimming toward the center of the quarry, completely narced and unaware of his situation. Our max depth was 77 feet. We had been over a shelf with a floor at 80, but when he changed course, there was no bottom at 80 feet. He had zero air in his bcd as he had never added any during the descent. When I remember this dive, it still gives me chills. I was compromised. We were both narced. Thank God I had him in front of me, on the other hand, stupid mistake on my part giving the guy some impression that he was leading the dive.

Both these guys were new divers with less than 20 dives each. In all cases, I had over 150 dives. They knew better though. Although in case #3 the diver has no recollection of anything but me ending the dive early, he would argue that I "dragged" him up.

So, it happens. With regard to the OP, I wasn't there, but being that the "experienced" diver had a slate, he could have explained what was going on. Also, I don't understand there not being clear communication from the experienced divers when everyone was back on the boat. I suspect the "pulling" at the safety stop was someone checking the tank pressure, but again, I wasn't there.

To the Original Poster, it's good (and brave) to question this stuff as you have done here. It means you're on a good track because you're trying to figure it out. People can learn from the conversation, etc. In the moment, on the boat, things aren't always made clear and people might not answer completely and it might not feel ok to question, so I *can* understand the lack of clear communication. If you offered that you were monitoring your computer, were constantly ascending in the green and was aware of your gas situation, you should have heard something like, "Gee, sorry about that, I was worried because you were using your air really fast and when you had trouble beginning your ascent I got a little more nervous and since we didn't break 100 feet the safety stop wasn't mandatory.", if that was the case.

-Blair

 

[omegadivingusa]

It is always a pity to hear about bad experiences. As a number of people have commented "we were not there" however I have never had to grab or pull any diver even if it were a tight situation. Grabbing someone and trying to redirect never works and just freaks people out. Some really clever people design the Galileo and the reality is there are to many Rambo divers who always know better. Stick to the rules of computer use. The one thing I am sure you would have learnt is to be very careful of who you dive with. To say "no" is your choice or ask to be paired with someone else. This forum has seen so many people who ,after the fact, thought they should not have dived or did something else they were prompted to do before a dive and did not. One of those being, chasing after a buddy all dive long it might have paid to just surface properly and sit that dive out. Advice.... don't allow diver bullies to make choices for you and if you can't get away from it don't dive and have a face to face with the dive boat operator or dive shop.

 

[Saltyhawg]

This is a common point of confusion. Hyperventilation means moving excessive amounts of gas in and out of the lungs, and as you might expect, this results in reduced CO2 levels. Tachypnea, on the other hand, means a rapid breathing rate. Tachypneic patients (and divers) often are taking rapid, shallow breaths with less bulk gas movement than normal breathing, so this can result in hypercapnia (elevated CO2, low pH).

If you want the math, respiratory minute volume (the amount of gas moved in and out of the lungs per minute) equals respiratory rate times the tidal volume (the amount of gas moved with each breath). So if the tidal volume is low enough (or the dead space is high enough), a rapid respiratory rate may not actually increase overall functional gas movement.

The practical application of this is that panicked divers are often tachypneic but are not actually hyperventilating, so they may experience increased CO2 levels. That is, they may be breathing rapidly and shallow. But of course, as with most cases, the devil is in the details.

I can see the theororetical possibility here, but there is a big difference in not lowering CO2 and actually raising it to the point to impede cognition. In my experience I've never seen it. The vast majority of anxiously tachypnic people I've encountered had significantly lowered CO2 and respiratory alkalosis. A small few had low normal CO2s and normal pH. However all my experience has been in people who are not diving but anxious for other reasons. What's different physiologically about tachypnea in divers?

Interesting discussion.

 

[doctormike]

I can see the theororetical possibility here, but there is a big difference in not lowering CO2 and actually raising it to the point to impede cognition. In my experience I've never seen it. The vast majority of anxiously tachypnic people I've encountered had significantly lowered CO2 and respiratory alkalosis. A small few had low normal CO2s and normal pH. However all my experience has been in people who are not diving but anxious for other reasons. What's different physiologically about tachypnea in divers?

Interesting discussion.

Yeah, maybe... I'm not a hyperbaric doc, and for any given patient, the devil is in the details.

I do know that it is possible to be tachypneic and hypoventilating. As far as why divers are different, this would a particular problem when a larger than normal dead space is involved (snorkels, regulators, rebreather loops, etc...), since you are now subtracting the dead space from the tidal volume, which makes the minute ventilation even lower for a given breathing rate. Theoretically, if the dead space is big enough, it doesn't matter how fast you breathe, you won't be blowing off CO2.

I was just saying that you shouldn't assume that just because someone is anxious and breathing quickly, then they are immune from hypercarbia, especially if they are working hard and generating more CO2 than usual. Rapid, shallow breathing is fine for oxygenation but inefficient for ventilation and CO2 elimination. That's why even patients who are paralyzed or under deep anesthetic sedation can maintain good oxygen saturation with very limited respiratory minute volumes (O2 diffuses pretty well).

Of course, if you breathe fast enough, you will always overcome the reduced tidal volume of shallow breathing (assuming that your tidal volume is more than your dead space). So that simple equation should let you know if you are ventilating more or less than you should when breathing in shallow, rapid breaths.

I guess my main point was that hypercarbia is an underrated cause of concentration difficulty during diving - just like nitrogen narcosis is overrated.

I certainly could be wrong about the non-theoretical implications of this. But you are right, it is an interesting discussion!

 

[dallaskincaid]

I'd be pissed if someone grabbed me underwater and tried to bully me into going faster than I felt comfortable with even if I WAS going too slow for them. It is your life, and as others have said its your trip to the deco chamber if something goes wrong. You're pretty new to diving and through experience you'll begin to figure out the little things like "My computer isn't always right." and "insta-buddys can be real a-holes." On this dive though, it doesn't sound like you did anything wrong. Don't dive with that person again.

 

[Kharon]

I had an experience yesterday. I was taking my fins off at the ladder and some AH grabbed the fin I was taking off and started pulling (dragging me under). I still had my reg in so no danger. I tried to pull my fin away and thrashed but the AH wouldn't let go. Finally I grabbed him by the BC, pulled him up and yelled "GET THE EFF OFF ME". He finally got the idea. Back on board several people were trying to "help" me get my gear off - on a severely crowded boat. They were effing up my gear and making problems that would not have happened if they just left me alone and gave me some room. Most of these guys were not what I would call skilled divers.

I hate diving a crowded boat, in cold murky water, with muppets.

 

[redacted]

Some folks lack diving skills.

Others lack social skills.

Did you look like you needed help?