Near miss diving doubles for 2nd time

[SmpleGreen]

In response to previous query... I have 160+ dives in locations around the world. Some of this has included deep diving (120ft) in cold temperatures (Mediterranean Sea, Puget Sound in Oct), always with thick wetsuits (I had no problem with full 8 mil in Puget Sound in Oct).

Honestly, I was a little shocked when I checked the wetsuit once I had finished the dive. I had gone on the recommendations of the dive shop, which provided me all my gear. I wasn't happy when I realized I had a 5/7, complete with rip in the knee, for diving those kinds of temperatures. The suit I was diving clearly had some serious use in the past, which further erodes its protection, in addition to being too thin to start with. That being said, mistakes happen and no one put a gun to my head to continue the dive once I realized I was too cold.

 

[SmpleGreen]

The student had to repeat the drill correctly at 30ft before doing it at 90ft, which he did. His out of air ascent was a result of not turning his right bottle back on before shutting off his left. He learned this lesson the hard way at 30ft.... but I don't think it was particularly dangerous to have him repeat the drill at 90ft once he understood how to do it.

 

[Gombessa]

Honestly, I was a little shocked when I checked the wetsuit once I had finished the dive. I had gone on the recommendations of the dive shop, which provided me all my gear. I wasn't happy when I realized I had a 5/7, complete with rip in the knee, for diving those kinds of temperatures.

You didn't know the thickness of the suit you were wearing on the dive? How did you determine the weighting you'd need? And conversely, if you were properly weighted, that should tell you the buoyancy of your exposure protection. As you approach deep and technical diving, it becomes very important to really start to understand how your gear works and what the proper and balanced setup is for that gear; it sounds from what you've stated so far in this thread that you didn't know this, and that's more than a bit alarming!

 

[tonka97]

Thanks Smplegreen for a rich thread!

During your uncontrolled ascent, why didn't you simply dump air from your wing using the inflator/deflator corrugated hose valve?

Did you have a buddy on this dive? If so, why didn't you thumb the dive to him, and ascend when you sensed you were in trouble?

 

[SmpleGreen]

I have no problem determining proper lead for neutral buoyancy with my own jacket BCD/single steel or aluminum tank.

However, as I mentioned previously, this was basically my first time diving steel doubles with bp/w. This is not my own equipment, so I was relying on other people to tell me what I needed to dive it properly. I had no idea one wetsuit versus another would make any difference.

I am sure we can debate the wisdom of that approach, but that is the truth.

It was clear even at 30ft that I was way too negatively buoyant with the configuration I was diving, ankle weights or no. For all I know, it is proper to dive steel tanks being negatively buoyant, and just compensate with the wing. At 30 ft, while this took a little practice, it wasn't too much of an issue. At 90 ft and going hypothermic, it became a much bigger problem.

It is true that I didn't have any redundancy for my wing setup, and that a failure of the wing would have put me on the bottom. Again, the wisdom of this setup I put in the hands of others. Perhaps a big mistake.

Instead of the Advanced Nitrox/Deco course as my first experience in tech, this might have been the better choice for a first try at doubles I guess, which I think some have been alluding to with discussion of proper weighting, Double U Double U Double U DOT tdisdi DOT com/index DOT php?did=114&site=2

Won't let me post URL's.

 

[AreJay]

The OP's experience opens up a lot of questions, but more for me provides a validation of "suggestions" I've received from more experienced divers/mentors and information gleaned from post I've read, every so often people know what they are talking about. Thanks SmpleGreen for opening yourself up on this one and hopefully this thread stays constructive. As a rec diver transitioning to the tech side I have had the opportunity to make these same mistakes but good mentors steered me in a different direction without having to learn the hard way.

Just a couple of the suggestions I've adopted, that I feel this post validated are the follows.

Don't introduce more than two new pieces of kit you've never used on a dive, try to limit it to one. It will take some time to become competent with a drysuit, a wing and doubles. I was instructed to get some time with a single BP/W setup diving wet. Then learn the drysuit with the BP/W single, about 15 dives until I had regained my buoyancy and trim, mostly. Then I introduced steel doubles and 35 hours underwater later with this setup I'm feeling pretty stable and reactions are automatic. We stayed in shallow bottom area until I was no longer messing up.

Another "suggestion" is not diving steel and a thick wetsuit. This is because of the loss of positive buoyancy at depth from the compression of the neoprene resulting in being over weighted and has been discussed in many threads. It sounds like you experienced this.

Trust your gut, and if you wanted to ascend and communicated it to the team that should have been it. As it was said earlier "Thumbing" a dive for any reason is not open for discussion at depth and should not be treated as a request.

I sincerely hope your next dive goes better. Thanks for learning the hard way so others don't have to.

 

[SmpleGreen]

tonka97... I think this is in my original post, but I tried to dump out of the corrugated hose valve deflator. The problem was that I was picking up speed very rapidly, since I had a lot of air in the wing to compensate for the negative buoyancy at 90 ft. I think that my orientation in the water was preventing air from escaping the hose (I know on my jacket BCD that sometimes I have to tilt in a certain orientation to get the air to come out).

I realized that if I couldn't get it to work in a few seconds, that the issue was going to be moot because once I got close to 1 ATM (33ft) below water (I was already in the vicinity of 50 ft on the ascent), the massive amount of air in my wing was going to send me Free Willy style to the surface, which was going to be very, very bad. The rate of acceleration was far beyond anything I had experienced with jacket BCD's....the wing holds a lot more air to compensate for the weight of the steel tanks.

I decided to flip and fin, and then could reach for the back dump while fighting the runaway ascent with my fins. It turned out that just the action of flipping face down burped off enough gas from the back vent to stop my ascent, and I started heading down. Unfortunately, this also coincided with my mask flooding, and the downward finning made me hyperventilate further (I was already having issues due to the cold).

 

[a22shady]

I know it's hard to spend all that money and sometimes we are all eager to get in and go. But I have to say from talking and researching that if you really want to dive doubles you should have a drysuit. and If not some form of secondary boyancy Incase of wing failure.

I believe being comfortable in your gear is a big advantage in moving forward. I took my OW and bought all my equipment. I know most people will take there AOW right after, But I decided to wait till next year and just dive and get comformtable in my gear which i did. As a result I really felt as I had gotten a lot more from the class as I didnt have to sit and practive with boyancy and other little things.

My G/F and I are just getting ready to start diving doubles and purchased a set. We are not focusing on Valve drills or anything of that nature all we are doing is simply diving the doubles same we would a single. If there is an issue we surface same as a single. Once we feel good in our trim/boyancy and comfort we will then progress into an official class to learn the fundementals of it.

I want to thank you for sharing, and Your story really demonstrates on the importance of the little things and How any one person should end a dive if any one thing feels off. As it is very easy for something small to cascade into a dangerous situation.

Also Not sure what type of finns you were using but if you needed to get your feet down I would first look at going into a pair of negative fins Vs Ankle weights. The turtles are great finns

 

[Garth]

Forget about reflecting. Quit the class and find another instructor. Everything you have said thus far scares the crap out of me and i have half your dives.
This feels like this is a joke or something. I would be reconsidering tech diving to be honest. At least for now.
Oh and find a shop that understands the physiology behind deco diving regarding vasoconstriction related to hypothermia, and hydration.

If you really want an honest opinion post your comments on thedecostop.com.
Although everyone here has been spot on with there comments I think you'll find a different tone.

 

[SmpleGreen]

Regarding thumbing the dive to buddy... I was one of three students, with one instructor. The other two students knew each other, and dived together in the past (I think relatively frequently).

The exact hand signals I gave were the "I'm not ok" (waving sideways back and forth of the hand), followed by "I need to ascend" (thumb). I gave this first to the other student who wasn't doing the valve isolation drill. He pointed me to the instructor, at which point I swam over to the instructor, tapped him on the shoulder, and gave him the signal. We then waited for the valve isolation drill to finish.

In hindsight, I should have given the signal that I wanted to return to the line before ascending (sideways finger point followed by thumb). Since we had not moved very far from the line when we started doing drills, I had just assumed we would ascend the line again. However, it was murky down below, and the location of the line was not immediately obvious, even though it was clearly close by.

The instructor mentioned later that he wasn't sure where the upline was either, and that was the reason for ascending up the incline instead. Whether this was the correct decision or not I suppose is open for debate.