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Suit dumps gas during shutdowns

1951 Views 21 Replies 13 Participants Last post by  Garf
I was diving with a mate recently and we were practicing shutdowns, stage removal etc. As soon as he started closing down the left post all the gas dumped out of his shoulder dump and he hit the bottom face first in a cloud of lovely NDAC silt. Very amusing obviously...but he'd rather it didn't happen again. Personally I'm comfortable with it...
What's causing this to happen ? He uses just the suit for bouyancy (which I think is the problem). It's an Otter Brittanic and he dives twin Faber 12's.
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If you run the suit with minimum gas in it, this probably will not happen :D

IMO wings are for buoyancy, suits are to keep you dry
Two things - don't run the suit for buoyancy, and teach him to go a little head down when he shuts down. Most people naturally become more upright when they are learning shutdowns, because they are reaching backwards, and they are finning a bit.

If you do those two, you might lose a bit, but it won't be much.

Digs.
So is it normal to lose a bit of gas ?
So is it normal to lose a bit of gas ?
If you're doing a shutdown for real it is probably because you are losing lots of gas. :D
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get him to close the shoulder dump
I don't lose any (or not a noticeable amount, anyway) gas out of my suit when I do a shut down. It soulds as though he has too much gas in it in the first place, which may be a symptom of overweighting, especially if he is using his suit for buoyancy.

Does he lose it even when he is shutting down the right post and the manifold, or just the left post?
Just when closing the left post..
I use my suit for buoyancy because I then only have to remember to empty one buoyancy device rather than two. If I'm carrying stages then I use the wing too because you just can't get enough into a suit.
You can lose a little gas when doing shutdowns - and I have - especially when more vertical than maybe the purists would like but with a little practice it shouldn't be an issue. It's far worse if you have a cuff dump. If you're losing a lot of gas then put some more in.
this is a side effect of using the suit for buoyancy. Imagine if he's on a deco stop and that happens. Now he's rapidly heading down whilst trying to sort his problem out. Shutting the valve is a waste of time - you wouldn't dive with it closed so you're not training for reality. There really are only two solutions

1. do as digger says - go heads down during a shutdown so there isn't the gas in the shoulders to escape - but you have to be not fussed about gas migrating towards your feet - which worries some people
2. Stop putting so much air in the suit, either by ensuring he is weighted correctly or by using the wing instead.

Personally, I use the wing and run the suit really tight so that it doesn't matter what angle I am at.
I use the drysuit to keep me dry and the wing for buoyancy as remembering I have two gas cells to manage isn't taxing. The air escaping will most certainly be due to the raised left arm whilst shutting down the left post as said above.
Also, I was diving with a.nother diver who did exactly the same even though they dive as I do, BCD doing what it's named for and drysuit for doing that also, however he had added extra gas to the drysuit due to the water temp being about 4degs. This excess gas didn't last long when he also got to the left post and he started chewing silt. I didn't laugh...for long.
I use my suit for buoyancy because I then only have to remember to empty one buoyancy device rather than two. If I'm carrying stages then I use the wing too because you just can't get enough into a suit.
you say you use the suit so you only have to remember one source of buoyancy, but then when everything is more complicated with multiple stages you add another source of buoyancy into the equation. Nothing like making life difficult :)

Personally i just use the wing so that I only have to remember one source of buoyancy - however many stages I am carrying.
you say you use the suit so you only have to remember one source of buoyancy, but then when everything is more complicated with multiple stages you add another source of buoyancy into the equation. Nothing like making life difficult :)

Personally i just use the wing so that I only have to remember one source of buoyancy - however many stages I am carrying.
Apart from what you have in your suit of course. Nobody runs them that tight.
Apart from what you have in your suit of course. Nobody runs them that tight.
I have no gas in my suit that I have to think about. I take the squeeze off until it doesn't hurt, then forget about it until I am on the surface. Any extra comes out during the ascent of its own accord without me doing anything. In terms of buoyancy control, it's not a factor
The process I use is 1m up, dump the suit, 1m up, dump the wing (which has the majority of the buoyancy in it) and continue; the suit is always much harder to dump from as there is far less gas in it. When I have done shutdowns (loads of practice but once for real above a 30m deck, I was at 18m, had a camera in the hand and the inflator button pinged off), I haven't had any gas escape. This was since I started to run my suit tight and the wing for primary buoyancy, when I had it the other way around and also had a cuff dump, there was loads of gas coming out...

Regards

Regards
I was diving with a mate recently and we were practicing shutdowns, stage removal etc. As soon as he started closing down the left post all the gas dumped out of his shoulder dump and he hit the bottom face first in a cloud of lovely NDAC silt. Very amusing obviously...but he'd rather it didn't happen again. Personally I'm comfortable with it...
What's causing this to happen ? He uses just the suit for bouyancy (which I think is the problem). It's an Otter Brittanic and he dives twin Faber 12's.
just a thought..has he/you spent anytime with a tec instructor recently, your not doing that internet reading thing are you. LOL
I have no gas in my suit that I have to think about. I take the squeeze off until it doesn't hurt, then forget about it until I am on the surface. Any extra comes out during the ascent of its own accord without me doing anything. In terms of buoyancy control, it's not a factor
Clearly I will die a horrible death because I use my suit as buoyancy.
However, should I have to shut down I'll be free to move my arms. Nor will I suffer from bruised testicles due to an overly tight suit :)

GLOC, your strategy seems to be a nice compromise. I might try the 1m up suit... 1m up wing for stages.
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Clearly I will die a horrible death because I use my suit as buoyancy.
However, should I have to shut down I'll be free to move my arms. Nor will I suffer from bruised testicles due to an overly tight suit :)
See, now isn't that a shame. I never said you'd die because of how you are doing things, I just explained a different way. I don't get bruised and I can shut down whenever I need to.
I have not noticed any gas escaping when i practice shutdowns but I dive with my shoulder dump almost completely closed throughout the whole dive. What I do find annoying is turning to look at my buddy swimming along on my left hand side and loosing my gas. Have to remember to either a) not look at them or b) close the valve before turning to my left.

FYI I need to dive with air in my dry suit as I have dry gloves and the squeeze is quite painful and restrictive and prefer only one method of buoyancy as got caught out in the past using two source but only dumping one and forgetting the other and had a rapid ascent for my sins.
See, now isn't that a shame. I never said you'd die because of how you are doing things, I just explained a different way. I don't get bruised and I can shut down whenever I need to.
I was trying to be amusing. There is no shame in that. :)
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