Undergarment blocking drysuit exhaust valve

[tstormdiver]

Last week while training on my rebreather, I was making an ascent from 95 ft to the surface. I was able to hold the deep stop, but once I got to about 40ft, I noticed that my drysuit had quit venting & I was becoming very positively buoyant. I am assuming my undergarment had blocked the exhaust valve. I struggled to keep myself down, but it was too late. Long story short I wound up making a dangerous uncontrolled ascent all the way to the surface. My instructor was able to catch me & slow me down enough to keep my PPO2's from dropping too low during the ascent, but it was a close call. I was using a generic fleece undergarment. I've had it altered to fit me, but it is a tad baggy (even a little more so since I've lost about 45 lbs over the last couple years). I like this undergarment because it is stretchy & flexible & moves with me. This is the second time this has happened (happened about 3-4yrs ago). Any suggestions for an undergarment that will fit a female 5'6", 188 lbs (& still losing), that moves & stretches easily, but doesn't tend to bunch up or get into the exhaust valve? I don't need a repeat of last week. My hips are the largest part at about 47". I am not against getting one that will be too long. I can easily have it altered to fit my shorter frame.

 

[Dive-aholic]

Rather than get a new undergarment why not fix the issue? Take a scrap piece of neoprene and cut it about twice the size of the exhaust valve. Glue some velcro to at least 3 sides. Glue some velcro around the exhaust valve matching the velcro on the neoprene and then velcro the neoprene in place. This will cover the valve and keep it away from the undergarment but still allow it to vent as it should.

 

[TSandM]

The only really dependable reports I've ever read of undergarments blocking an exhaust valve were Weezles, with the nylon fabric outer layer. Fleece is too porous to do it. My guess is that switching to the rebreather has messed with your trim, and you can't vent the suit the way you think you should, because you aren't in the position you think you are in.

 

[PfcAJ]

^+1

I don't think fleece can make an airtight seal on an exhaust valve.

 

[Dsix36]

I am not trying to bash anyone's skills or training with this post. All drysuit divers need to be aware of the possibility of an exhaust valve failure and be prepared for it. In a worst case scenario, you need to go vertical and pull your neck seal away from your neck to vent a bit of gas. Even in ice water, this is a better option than an uncontrolled ascent.

 

[TSandM]

Dsix36, I have heard that said a lot of times, and honestly, I think the advice is almost absurd for most dry suit diving environments.

Having had uncontrolled ascents, and having tried to help students with them, I can tell you that you don't have much time to arrest the problem. The likelihood that I could pull my hood out of my dry suit and get my dry-gloved fingers under my neck seal in time to exhaust air and stop a runaway ascent is just about zero.

 

[Bopper]

Dsix36, I have heard that said a lot of times, and honestly, I think the advice is almost absurd for most dry suit diving environments.

The likelihood that I could pull my hood out of my dry suit and get my dry-gloved fingers under my neck seal in time to exhaust air and stop a runaway ascent is just about zero.

Personally I only use 3mm gloves and a hood w/o a skirt for this very reason - so I can vent through my neck seal in an emergency. That may not be practical in colder waters though.

 

[Dsix36]

If you do not have your s**t dialed in and end up waiting too long to deal with the situation, then, yes I would agree with you. However, on the other hand, you are controlling your buouyancy as needed and suddenly there is a problem with you exhaust valve, it will not be out of control before you can react and vent. Initally, you can still control with wing or loop volumn. If my suit is too full just going vertical will usually burp a bit from the neck seal.

I have had to pull my neck seal once and even with a hood, it was not a big deal. Granted, I was wearing 3mm wet gloves and not dry gloves at the time.

 

[BabyDuck]

tammy, how about duct taping your undies where they are under the valve, to make them too slick to get sucked in? like - tape a square on your upper outer arm of undies or on your forearm if you have a cuff dump.

 

[tstormdiver]

I currently have well over 500 drysuit dives to date. When the issue arose I was ascending from 95 ft to the surface using no references, other than the computer. When I noticed that there was a problem dumping the air (yes, it was probably much too late by then) I put myself into just about every conceivable position to try to dump the air, when I hit the surface, I looked like the Stay Puff Marshmallow Man. I was then able to get the suit to dump air. I am certainly new to the rebreather (about 12 hrs pool time & about 4- 1/2 hrs open water time), but until that time had been able to manage it, not to say that I may have also been a little over- tasked at that time. I did a 90 min. dive on the drysuit & rebreather yesterday & everything went fine. Even an ascent from 95 ft to about 20. I did notice that I really had to concentrate on the venting of gas from wing, suit & counterlungs