Uncontrolled ascent

[Uncle Pug]

A couple of days ago a friend sent me a post from another list where the diver had his right post (doubles) first stage fail and the IP went to 300psi. That for some reason overpowered his inflator without relieving itself through his second stage reg. He had just gone onto his deco gas reg and had 30 minutes of deco but shot to the surface in <10 seconds. (He ended up doing a chamber ride.)

Supposedly he tried to disconnect his lp inflator hose but was unable. He was also unable to vent his rear dump while turning off his right post to shut down the reg.

I doesn't hurt to make sure that you can disconnect your lp hose... it should pop off easily. Doing so at the same time you vent any excess from your inflator hose would be a good idea. Shutting down the valve isn't the best option for a single tank diver.

 

[jlayman800]

Seems like there might be more than one way to acomplish the objective, ie nutral bouyancy with a dry suit.

The only advantage of using your BC is that it is able to dump at a much faster rate than a dry suit vent valve and in any position. The BC has multiple available dump valves and they have larger capacities.

In about 20 years of diving, I have had two OOC ascents, both of them in dry suits, both without significant negative effects. Just lucky, I guess. On one, the dry suit inlet valve stuck open and I filled up in seconds. I popped to the surface in about 10 seconds from 30 feet down. I looked by the Michelin Man. I was so shaken that I spent the rest of the weekend out of the water.

On the second, my buddy lost a weight belt. She was in a 7mm wet suit. I went up to help her out. She was about 15 feet above me by the time I noticed and swimming hard for the bottom. I don't use my suit for bouyancy, but I did have enough air in it to be comfortable. The water was pretty cold and I had a small leak in my dry suit so I had a little more air in my dry suit than usual. When I got to her at about 65 feet, my suit was already much too positive. We swam downward to get back to her belt. In that position, it's impossible to vent a dry suit, so my feet filled with air. No matter how hard we tried, we never got back to the bottom. After about 60 seconds of swimming downward, UP WE WENT FROM ABOUT 75 FEET DOWN. Once again, it only took seconds to reach the surface. We sat the rest of the day out and neither of us seemed to have any negative effects. This one deserves some lessons learned. Fix known problems so you don't have to compensate for them. Stay close to your buddy and use a buddy line with a new buddy so you can stay in constant contact. Use you BC for bouyancy, not your suit. The BC is much more capable of dumping air, when needed ... my opinion, of course.

Stuff happens. All you can do is your best and learn from the mistakes. If you live through it, you will be a better diver.

 

[DEEPLOU]

Use you BC for bouyancy, not your suit. The BC is much more capable of dumping air, when needed ... my opinion, of course.

I have only been diving for abt 10 years now, of which only abt 7 are dry. But I wholeheartedly agree.

Remember what the names of these pieces of equipment are:
Dry suit.. that means suit that is meant to keep you dry (and warm)

Bouyancy Compensator... that means something that is meant to compensate for your negative bouyancy.

 

[jimisurf]

Hello all,

Just my own personel preference (and peice of mind) but I always use my BCD for boyancy unless I'm on a shallow (and long) dive. Only then I will use my suit to regulate boyancy and only because I will stay warmer and an unintentional acent from less that 50 feet is less likely to result in complications (imho).

Thanks,

JImI

 

[Jaci]

I found it interesting in reading this thread, and as a forensic engineer, I just have to add a couple of comments. I'm considering a dry suit and doing a lot of research and asked my instructor, who has been diving and instructing for over 30 years, about the pro's and con's.

At first I thought using the drysuit for buoyancy would make sense. Leave the BC as a "reserve" or surface floatation and just concentrate on the drysuit to adjust the buoyancy, leaving the BC alone, since it's empty. However, it appears that the drysuit valves and locations are not up to the job of protecting the diver from an uncontrolled ascent. With this in mind, I have to side with the use the BC as the buoyancy device and minimize the use of the drysuit valves, better yet, maybe the drysuit manufacturer's will come up with a solution to this problem. My instructor confirms that he minimizes his use of the drysuit, gets a squeeze, adds some air and leaves it alone except to vent on the way up.



BTW, glad that everyone here that posted and experienced the problem shared their experience and survived.

 

[coastie720]

Let's see ... drysuit = suit to keep you dry
buoyancy compensating device = device to compensate for the buoyancy changes that occur while diving

Easily said my friend. I dive w/ a drysuit all the time and it seems that using a drysuit for control takes twice as much air as a BC to get the same effect.