Uncontrolled ascent

[crispix]

Is this just a rite of passage for dry suit owners? I feel so embarrassed. I have a new drysuit, and this was my 4th dive on it.

106fsw max depth, lovely dive. Coming back in, at about 30fsw and 700psi, I started to become buoyant. I'm was ascending slowly, knew what was happening, but was unable to handle the situation:

1. I made sure my BC was empty
2. I raised my left shoulder and made sure the valve was turned open.
3. I was still ascending, but kicked down hard and managed to get down to the bottom at 30ft again.
4. Ended up with air in my suit that was not venting and started up again.
5. Buddy grabbed me, but I was just bringing both of us up at that point.
6. Tried to vent from my wrist seal, but my glove was in the way.
7. Realized I was going up and there was nothing I could do about it. I pushed my buddy away (no sense in both of us going up.)
8. I flared my body, blew bubbles.
9. Hit the surface. I went vertical, just the top of my head out of the water, kept very still, and breathed my nitrox.
10. After a few minutes I inflated my BC and swam back to the boat. Checked for signs of DCS: nothing
11. As a precaution, I skipped my planned second dive of the day.

So I'm fine, just a bruised ego. Clearly:

1. I was under-weighted. I had taken 2 lbs off after my previous, successful drysuit dives. Also, I had not been in the drysuit with < 800psi in my tanks. (I know, I know.)

2. I was unable to vent from my wrist during the emergency because my glove was in the way. I need to figure out a solution for this. I've been tucking in my hood, so venting from the neck is not an option.

So many things I should have done differently, pre-dive.

In a wetsuit, I can handle a blue water ascent no problem. Frankly, I'm not ready to attempt this in a drysuit yet. What's a good way to practice? I suppose the next time I do a kelp or boat dive, I should try a blue water ascent next to the line, ready to grab it if needed.

Comments?

 

[Bubbletrubble]

I'm kind of wondering why you did a dive to 100+ fsw on your 4th dive with a drysuit...risked loading yourself up with nitrogen knowing that it might be a challenge to control the ascent...without doing a proper weight check beforehand. Wow! That's several mistakes even before the dive started.
Those issues notwithstanding, if anything, your buddy should have weighted himself a little heavy so that he could do a better job of pulling you down when you got a little floaty during the ascent. To do this, of course, he'd have to be within reaching distance (which he apparently was).

In a runaway ascent, with my setup (drygloves on Viking bayonet rings), it would be very difficult to vent through my wrist seals. In my mind, it's hard to think of a faster, more efficient method of venting than cracking the neck seal. I chose my hood accordingly. It sounds like you might have a DUI drysuit + DUI drysuit hood with warm neck. You might want to consider getting a different hood. Several manufacturers make drysuit hoods that only extend to mid-neck level. The design of my Bare hood is like that, and I don't find my neck getting cold even in the winter months here in SD. FYI, DUI also makes a standard drysuit hood without material around the collar.

Other tips that might help:

• If doing a boat dive, ascend on the anchor line. If you get out-of-control floaty, then simply grab the anchor line while you attempt to vent. (You already mentioned this one in your original post.)
• Make sure that your undergarment isn't clogging up your upper arm exhaust during your pre-dive check.
• During ascent, vent early and often to stay ahead of gas expansion in the drysuit.
• During the ascent, don't be afraid to break trim (go vertical) several times to ensure that you're getting all of the gas out of your feet. As you become vertical, you should start feeling a squeeze in your lower legs that travels up to your torso. This is a great technique to use if your drysuit is a little too baggy in the legs and tends to trap gas down there. That certainly is the case with my drysuit, so I ended up using gaiters which helped a lot.
• I'm a proponent of being able to use either your drysuit only for buoyancy or both your drysuit + BCD. See which method works best for you and go with it. There'll be times when you'll want to run more gas in your suit to stay warmer...or perhaps do a hands-free ascent so that you can keep snapping photos of interesting critters during the ascent. For single tank diving to moderate depths, I don't find it too difficult to manage a larger-than-normal drysuit bubble. YMMV.

You live in the San Diego area, right? La Jolla Shores is an ideal place to get comfortable with your new drysuit. Heading west of Vallecitos, the sand is gently sloping until you hit the canyon wall at about 50 fsw. Follow the bottom contour during your ascent out of the canyon. This will ensure that you're constantly venting on the way up. I recommend doing at least 10 - 15 drysuit dives shallower than 60 fsw before attempting anything deeper.

In the words of the great Sam Snead: "Practice puts brains in your muscles." It takes a while to learn how to use a drysuit properly. Be patient. It will come with time. It makes winter diving here in SD sooooooo much more enjoyable.

 

[ligersandtions]

You may not (or may) be underweighted. Diving a drysuit means you need to stay ahead of it....you can't let the drysuit dive you (essentially). When you are ascending, you need to stay on top of it because the bubble can and will get big very fast if you let it. I find that it is difficult to vent my drysuit at depth sometimes, so I vent my wing....but when I get shallower and the bubble in the drysuit gets bigger, it's very easy to dump.

FWIW, two pounds should not have meant the difference between a smooth, uneventful ascent and an uncontrolled ascent....it sounds more like the bubble got too big for you to be able to manage. You will learn this with time....you'll start to feel when you need to vent and it definitely becomes easier (don't worry, at four dives in a drysuit, it doesn't sound like you're doing badly! At least the uncontrolled ascent came from 30 feet as opposed to 100 feet!). You do, however, need to do a proper weight check. If you need to, purge down to less than 500psi and figure out what you need to be neutral (at your last stop or at the surface....I do it at my last stop with a comfortable amount of air in the suit, that way if I'm below 500psi for some reason, I can dump some more air to remain neutral on my ascent -- I'll deal with a little squeeze then!).

No need for the bruised ego. Learning to dive in a drysuit can be a very humbling experience for many divers. So here's some stuff you can do to learn how to deal with this. When you're on the surface (before the dive, for example), invert yourself and pump some air into your suit (it should go straight to your feet) -- then turn yourself upright and dump the air quickly. Do this a couple times with a little more air each time....you'll figure out how to get yourself upright and dump the air.

When you're confident with that skill, do the same thing at 30 feet (at the beginning of the dive when you have on-gassed very little). Invert yourself, put a little air in the suit (will go to your feet again), then get yourself upright and dump the air before you ascend. Do this a couple times (under the eye of a watchful buddy) until you feel comfortable. Then have your buddy hold onto you, and pump some air into your suit....dump it before you float up.

The more you simulate these failures (uncontrolled ascent, broken inflator valve that's pouring air into the suit), the more comfortable you'll get. But remember, it doesn't come naturally overnight for most divers....it'll take a few dives (I've heard of people saying it took them upwards of 50 dives to feel natural in the drysuit). Someday, it will be like auto-pilot, just the way your wetsuit is.

Don't give up, have fun, and stay warm and dry!

 

[Teamcasa]

Good to know you suffered no physical effects as a result of your ascent.

Learning to control your ascents in a drysuit does take a little practice. Start slow by beginning your ascent with a purge of air from your drysuit first. Kick up a few feet and hover, get control and stable. Vent BC, and repeat. Alternate up to 25 feet. Once you are at 25 feet, you should only have a small amount of air in your suit and your BC.

This helps controlling the ascents by not having a bunch of air in your suit or BC that you are trying to vent.

Test your buoyancy once your tank is down to 700-800 and you are at 10-15 feet.

 

[crispix]

Other tips that might help:

• Make sure that your undergarment isn't clogging up your upper arm exhaust during your pre-dive check.

Lightbulb moment for me. I don't think the undergarment was at fault here, but why have I never heard of this check before? I was taught to check the valve and make sure it's open and able to dump air, but to specifically check the undergarment to make sure it won't tend to bunch up around the exhaust port seems like a pretty important item now that you've mentioned it. I'll have to check my course book at home, but it seems strange that this one isn't specifically taught. Thanks.

 

[Rainer]

I'd suggest not doing 100+' dives before you get comfortable in the dry suit. They take a lot more than four dives to master. Also, when you change lots of gear (yeah, a dry suit would count), a weight check with near empty cylinder is a good idea.

As for practice, stay in <30' (it's harder shallow anyway). Practice ascending on a line if possible. Go very slowly to start. Get used to recovering from mismanaged ascents. Have a buddy give you in water feedback. Video is nice. Do lots and lots of shallow dives. The Cove and Shores are very easy places to learn.

 

[BabyDuck]

i think that can be a bigger problem for fluffy weezle-type undies, but it won't hurt to check that your undies are smooth under the valve no matter what kind.

and however ugly you think you were on drysuit dive 4, my dive 3 was worse...

 

[Jim Lapenta]

How much air did you have in the suit. Were you using the BC or suit for buoyancy? Remember just enough air in the suit to take off the squeeze and bc for buoyancy control. Much smaller air bubble to manage. The books will say otherwise but they were written with the idea that using two forms of buoyancy control at the same time was too much task loading for a new drysuit diver. In fact it is not for anyone of reasonable intelligence.

 

[TSandM]

Drysuits are unruly beats. Once the suit has begun to run the dive, it takes a very good diver to reestablish control. The bubble in a suit has a lot of degrees of freedom (google "dynamic instability", and read the BAUE article about this) and air can get a very long way away from the vent (unlike a BC, where the air bladder is smaller and the vents are more numerous). So the trick to diving a drysuit is pure anticipation -- you have to think about what is going to happen, and you have to be able to do something about it before it causes trouble.

A lot is dependent on the dump valve -- where it is located, and how well it works. I have dived suits where the valve was sticky, and it took a lot of pressure inside the suit to vent gas. I have also dived suits where the location of the valve was such that one would never be successful in venting it in any kind of usual diving position. So it is important to understand YOUR suit, and what is needed to manage the bubble inside it.

People are frequently taught to manage buoyancy purely with the suit, as a way to simplify decision-making on ascent. The upside of this is that it is generally easy to vent the suit when it has that much gas in it; the downside is that, if you get even a bit behind the curve, you're toast -- you can't keep up with the expansion.

I believe that it is easier to run the suit with only enough gas to maintain mobility, and use the BC as primary buoyancy control, at least at first. The BC is easy to vent in many positions, and empties very rapidly, and if the majority of your buoyancy gas is there, even if the suit begins to get away from you, you can avoid being positive by dumping from the BC. As you become more facile with the suit and vent, you can run a bit more gas in it to stay warmer, or to adjust your trim. But it's important to know that gas in the suit can ALWAYS, no matter how good you are, bite you in the butt if it can get to your feet. So, if you run the suit loose, you have to be even more vigilant about the location of the bubble.

At any rate, many of us have done what you've done, and frankly, in cold water, accessing a seal to vent the suit isn't very practical. By the time you dug under your hood, or got your dry glove off, you'd be on the surface. Far better to avoid the problem.

 

[AfterDark]

When diving a drysuit being a little overweighted is not a bad thing. You should be adding weight not dropping it. Ankle weights are a big plus. At the surface with the suit properly infalted and the BC empty you should noticabely negitive. That always worked for me. You shouldn't have some much air in the suit that if you went upside you'd be stuck. Have you tried that out yet? Don't do it 100' but try going upside. If you haven't its a surprise you don't want at a 100'!
Like other have said stay ahead of the suit. I'd vent the suit to where I'd just start feeling the compression before I started to surface, it's easier to keep ahead of it that way.