Drysuit Squeeze/DCS

[Subcooled]

Deleted

It warms my heart to notice that someone else, besides me, does this.
Whatever the reason, I have some deleted posts too because Scubaboard does not offer a delete option.

 

[Wibble]

I had not used a BCD or wing for buoyancy control before, just the suit, and an emergency situation is not the moment when new skills are picked up.

Oooh, very interesting point about the training.

That is a very good reason to say that the whole "only use the drysuit for buoyancy" is utter nonsense and not something that should be taught. However, if you arrive at that conclusion through your own experience, that’s another matter entirely.


Everyone who dives with a drysuit has forgotten to connect the hose at sometime in the past.

---

Writing this shameful incident as a penance to atone for my stupidity…

This summer I’d had a dose of covid. Got over it after a week — was just a cold/light flu. I had a dive booked two weeks later and was feeling OK so decided to go. Was a long trip out in pretty bouncy water on a crowded boat.

I forgot to connect my drysuit hose — was distracted when kitting up (was asked to move halfway through) and obviously didn’t check properly. That’s bad, very bad and have changed my pre-dive checks to do a final check.

Jumped in, solo as ever, and descended the shot line. Got to about 5m/20' and the suit started squeezing. Went to inject and no hose. Grr. Reached back to the suit inflation cylinder but couldn’t free the hose.

Now the stupid and "human factor" thing; for some crazy reason I didn’t stop and listened to my inner voice that said "sod it, go down and sort it out on the wreck". As I said, stupid.

So carried on descending to the top of the wreck at 35m/120'. My arms were forward and I could easily reach the controls for the wing and gas injection. The suit was tight but I was in control.

Arriving on the wreck and hovering a metre above it I then realised that I could no longer reach backwards, so tight was the squeeze! "You utter idiot" I said to myself.

I then looked around for another diver to pull the inflate hose out. Found one and frog kicked over to him. Flashed the torch at him which he ignored. Again flashing it in his face and he looked at me and turned back to what he was doing. Did it a third time and shouted at him, pointing at my drysuit and he then grabbed, not the drysuit inflation hose, but the spare inflation hose on my bailout and connected that.

I pressed my inflator and the squeeze vanished. Yes, a considerable relief as it was tight!

I then shouted at myself for forgetting that both bailouts had inflator hoses on them. Double or triple idiot.

Completed the dive OK. On the boat had a fantastic bruise on my LH shoulder, looked like a blue cheese! and a massive bruised ego.

Throughout that incident I felt it was an inconvenience, not a danger. My buoyancy and control wasn’t affected. OK a little.


Lessons learned…

• Task fixation, both the descent and the hose, seemed to override logical thought
• failure to properly check before jumping (inflate wing & drysuit, PPO2)
• failure to complete my pre-dive checklist correctly — if distracted, re-start the checklist
• if something is wrong, stop and deal with it! Nothing gets getter if left
• listening to my inner (idiot) voice
• completely forgot about the bailout tails — am most angry about this as this is crucial for self sufficiency
• maybe brain-fog is real: allow time to get over an illness before diving
• training, such that core skills are second nature, works

 

[happy-diver]

Great recount Wibbles

Introduce yourself to the staring directly ahead as you are gearing up principle (same as when standing at
the urinal principle) in a trance, and anyone that leans forward or cocks their head into your zone you tell
them to get off. Softly sternly is all that's usually required to send them to the other end of the boat then
continue through your gearing up zen and hi ho it's off you go

Now I always hook up the drysuit hose, I have chosen not to subscribe to Gareths stupidity principle so
only make minimal inconsequential oversights, my thing is when I'm standing with my back to the tub of
my ute with whatever I have strapped to my back resting on the edge, that's when I forget to disconnect
my drysuit hose and when I slip out of everything else and dump my gear into the ute, it flips me up and
drags me into the back backwards wriggling around on top of it!

 

[Wibble]

Ouch. So easily done.

 

[Subcooled]

Oooh, very interesting point about the training.

That is a very good reason to say that the whole "only use the drysuit for buoyancy" is utter nonsense and not something that should be taught. However, if you arrive at that conclusion through your own experience, that’s another matter entirely.


Everyone who dives with a drysuit has forgotten to connect the hose at sometime in the past.

Yes. All buoyancy compensators need to be used, at least sometimes.

My solution to buoyancy control:

1. buoyancy is adjusted by adding or removing lead - be neutral at three feet
2. suit inflator is needed to counteract suit squeeze while descending
3. suit exhaust valve is needed to counteract suit ballooning while ascending
4. starting descent/ascent is controlled by breathing; fully exhale/inhale; suit volume change will make sure the vertical movement continues even when breathing is resumed; at greater depths we might use finning - or if we are lazy, adjust the suit or BCD volume a little bit.
5. Advanced topic: the BCD only compensates for used breathing gas weight. It will hold a small amount of gas in the beginning of the dive and later it will get dumped. On shallow dives the BCD is barely needed, but on long deep dives where a lot of gas is consumed, the BCD must contain enough gas to compensate for loss of weight later on. Volume of gas in the BCD must equal the weight of gas in all the tanks carried. Once you are neutrally buoyant will less/small tanks, and then add more/heavier tanks, you will notice how much gas needs to go to the BCD (or else you will sink). Note: in wetsuit diving the BCD also compensates for neoprene compression.
6. The BCD is an emergency float too, and needs to be used at least a little bit, on each dive. Perhaps let the suit get a little bit more compressed and use the BCD instead - just for practise. I tend to do this after 15 or 30 feet...

Drysuit diving is like riding a bicycle. It cannot be fully explained. It needs to be learned. Practice is the key.

 

[fsardone]

Yes. All buoyancy compensators need to be used, at least sometimes.

My solution to buoyancy control:

1. buoyancy is adjusted by adding or removing lead - be neutral at three feet
2. suit inflator is needed to counteract suit squeeze while descending
3. suit exhaust valve is needed to counteract suit ballooning while ascending
4. starting descent/ascent is controlled by breathing; fully exhale/inhale; suit volume change will make sure the vertical movement continues even when breathing is resumed; at greater depths we might use finning - or if we are lazy, adjust the suit or BCD volume a little bit.
5. Advanced topic: the BCD only compensates for used breathing gas weight. It will hold a small amount of gas in the beginning of the dive and later it will get dumped. On shallow dives the BCD is barely needed, but on long deep dives where a lot of gas is consumed, the BCD must contain enough gas to compensate for loss of weight later on. Volume of gas in the BCD must equal the weight of gas in all the tanks carried. Once you are neutrally buoyant will less/small tanks, and then add more/heavier tanks, you will notice how much gas needs to go to the BCD (or else you will sink). Note: in wetsuit diving the BCD also compensates for neoprene compression.
6. The BCD is an emergency float too, and needs to be used at least a little bit, on each dive. Perhaps let the suit get a little bit more compressed and use the BCD instead - just for practise. I tend to do this after 15 or 30 feet...

Drysuit diving is like riding a bicycle. It cannot be fully explained. It needs to be learned. Practice is the key.

Yes but …
Neutral at 3 ft with empty tanks …
4 and 5 only applies to open circuit: breathings changes nothing in closed circuit.

I usually prefer to keep minimum gas in the suit …. and in the loop.
I use BCD for buoyancy this because I can dump bcd and loop in any attitude while suit can only be dumped if the left arm (in my case) is higher …. this makes a difference in obstructed environments …. wrecks and caves.

Bonus points … you can dive not considering weight loss with rebreather since you use very little gas, but in case of bailout to OC the bottles will be buoyant and to avoid being pulled up by them you need to jettison the stages. This can be done by clipping them to the DSMB line Alu tank will float to the surface ….

 

[Subcooled]

Yes but …
Neutral at 3 ft with empty tanks …

With an empty BCD. See my post: advanced topic: The BCD should contain enough air to compensate for the weight of the breathing gas carried. Small lung volume and suit volume adjustments help quite a lot when there is only a little bit of gas to carry. I do not think we disagree, unless I missed something.

4 and 5 only applies to open circuit: breathings changes nothing in closed circuit.

True. I am not a CCR diver. I did mean OC diving. Sorry for my inexact terms!

I use BCD for buoyancy this because I can dump bcd and loop in any attitude while suit can only be dumped if the left arm (in my case) is higher …. this makes a difference in obstructed environments …. wrecks and caves.

It depends on the positions of your dump valves and on the topography of the narrow(?) tunnel you are diving in, I guess. But I 100% believe what you say. I have not experienced the same but we probably dive different kinds of environments.