Dry suit uncontrolled ascent

[Dan89]

Hi everyone, I'm Dan from Norway.

I'm new to diving. Recently took the padi open water and have only about 8 dives experience.
My questions are regarding dry suit and weighting.

Will try to explain my problem as good as possible.
My problem is with ascending. I have tried my drysuit two times now, and every dive resulted in a rather stressfull uncontrolled ascent from about 6m. We didn't go deep, only about 14m, since we were still testing the gear, and wanted to stay safe incase anything happens while we learn to dive.. so luckily I didn't get any symptoms from ascendig too fast.
So I got some old second hand used gear for cheap from a guy that quit diving. I think it's from the 80's. The gear was inspected and repaired by a local diving shop so no concerns there. Actually had to replace the seals on the suit. It doesn't leak a single drop so thats good.

My problem is with dumping air. When I start to feel positive buyancy I can't dump my air. The suit is really compressed. My thinking is that maybe I'm not diving with enough weights, for the suit to be able to make an air buble that can be dumped. I was doing the technique right, my friend tried to help me also but no air came out of the valve. We were going slooow, but when I ascended more to try help air expand things got ugly, air got to the legs and I was unable to shift around, was basically just hanging on to my friend to not ascend, but I couldn't drag him with me so I let go at about 6m. I could have opened my neck seal but figured I was safe to just float up since I didn't stay deep for long in the first place.

I felt that I wasn't getting all the air out of my suit before diving, so when I dive I have to swim down about 1-2m to become negative. At surface my head is under water, but I won't sink. My suit is a scale with thick undergarment. So basically what happens is that my undergarment is compressing alot, and thats why I sink fast at depth.
The first time I tried with this setup I thought maybe I was overweighted since I sink fast below 5m, but now I'm thinking that I need to add more weights.
The second dive I filled air into suit, but also into bcd below 10m since I was afraid to turn into a rocket.
Next time I will be ascending from an anchorline.. And instead of filling my suit, I will use my bcd. This seems more safe. Could be deadly at more depth if this happens again..
I dive using a 12l 200bar tank. But haven't added weights for the air being used, how much should I add?
Any similar experiences? Thoughts?

 

[BRT]

More weight!

 

[Imla]

Hi! Sorry to hear that you are having difficulties. Your profile doesn't state where you live, but if you are close to the Oslo area, you could join either BAUS (The UNIs student diving club) for their dives, or Torsdagsdykkets dives every thursday. If you post your challenges in the respective FB groups, you could be lucky and get a person that would help you figure out your problem.

There are a few issues I have seen when new with drysuits. While you experience your ascents to be slow... If you cannot vent your suit until shooting to the surface, you are in essence not spending enough time doing it. Some suits that are common in the area have a slightly funky out-valve position (Mainly BARE-suits). This can make dumping gas problematic. While the answer _may_ be more lead, fresh divers in the area tend towards being overweight more often than underweight. Have you done a proper weight check with a nearly empty tank??

 

[Dsix36]

Make sure your feet are slightly lower so that they get squeezed as the air migrates upward to the dump valve. Personally, I like to have about 2 extra pounds of lead just so that I can keep some gas in the suit if it is cold on deco. Just like your wing, dump often and dump early to stay ahead of the uncontrolled ascent.

 

[lowviz]

...//... I can't dump my air. The suit is really compressed. ...

Leave your suit valve wide open for the entire dive and go back to focussing on your BC for buoyancy control. You now have two sources of buoyancy and might be focussing on the one that isn't causing you a problem...

 

[KevinNM]

Is there an issue with the valve? Can you easily purge the suit before getting in the water and on descent?

Do you have the valve fully open?

Are you putting the valve at the highest point of your suit during ascent? On my Bare it came from the factory such that I had to do some stupid things to get it to dump, do what you have to do to get it properly positioned.

Once you get the valve positioned to vent are you leaving it there? Do not be in a hurry, it takes a while to get the air out and if you hurry you'll end up in an uncontrolled ascent (done it more than once).

When I'm doing an ascent I vent the suit as I slowly rise, then as I get close to my target I vent the BCD so I come to a stop at my target. I find I have more margin to screw up venting late the BCD than the suit, the suit has a LOT more air in it coming up from depth.

Oh yeah, please do a weight check. I did my first dive with a new suit in the ocean without adjusting my weighting from fresh water. That was a disaster, couldn't stay down at the end of the dive even after the instructor lent me 5 pounds of weight so I could descend.

 

[Diving Dubai]

1. Weight check.

2 . On ascent t 10m buoyancy changes become more pronounced. So start watching your purge valve (which should be fully open for the ascent) You need to feel in control. Depending on how you feel buoyancy wise you may have dumped all or most from your BCD

3. If your suit is empty of air at 10m you will see air start to come out as you rise up the water column and the air in your suit expands

4. At your 6m stop I would suggest at this stage you are a bit heavy, i.e. you need some air (I use my BCD) If things go wrong you can dump air from your BCD faster than the suit.

5 Relax and keep your feet down (at the moment) for the final ascent s that air doesn't' get trapped

Slowly is the technique whilst learning. I started with a D/S this year after 300+ without and it was a big learning step for me as things were hugely different from what I was used too. It took about 10 -15 dives to really get the hang of it

 

[Storker]

Leave your suit valve wide open for the entire dive

...or closed just a few clicks down from wide open. It's not very uncommon to get a wet upper left arm with a wide open valve, so the mileage varies between divers.

I too, just like @Dsix36 , prefer to keep a little air in my suit to stay warm, and that means a kilo or two more than the bare minumum. Even if I don't do deco. A thoroughly squeezed DS with ditto undergarments (think shrink-wrapped) is pretty cold in cold water.

Otherwise, I'll second the points from @Imla and @KevinNM . And kudos to everybody so far for not jumping to the conclusion that the OP is overweighted just because many newbs are

 

[Bric Martin]

One thing that might help is to limit the amount of air you put in the dry suit. Instead of filling the suit, start by just putting enough air in the suit to take the squeeze off. As you start to ascend stay ahead of the air expansion, get your release valve to the highest point. As has been said, I would start with the valve wide open.

 

[Storker]

One thing that might help is to limit the amount of air you put in the dry suit. Instead of filling the suit, start by just putting enough air in the suit to take the squeeze off.

Although this is the approach I prefer myself, I don't believe that this is the solution to the OP's problem. His (her?) problem seems rather that they apparently doesn't have any air to vent from the suit.

Me, I'd try adding a kilo or two and see if the problem disappears or at least becomes smaller. If it disappears or becomes smaller, the OP's problem probably was underweighting. If it doesn't, the problem lies somewhere else. I don't think a couple of kilos above "optimal" weighting is a big issue in a DS, where you have redundant buoyancy. It makes managing the bubble(s) a bit more awkward particularly if you use the suit for buoyancy, but IMO it's not a very big deal. Like I said, I prefer to add a couple of kilos in the winter when the water is colder than I'd prefer.