Bouyancy Control with a Dry Suit

[Uncle Pug]

pdoege once bubbled...
How would you handle a runaway suit inflator?

I have to pitch up severly to get the auto dump working (the DR 905 has a "bicep" dump) and pop the inflator off with my right hand. It then have to cover the inflator nipple to stop the suit from flooding.

Big time pucker factor. I normally grab the BC inflator as well. Way easy to elevator to the surface. I would not want that to happen at a bad time.

I keep the dump and inflator very clean. Learned a lesson after a beach dive.

Peter

I have had it happen a couple of times. In fact I just took my inflator apart and cleaned it up and re-lubed the o-rings on the shuttle valve.

How would I handle a runaway inflator? Well, first thing I wouldn't let it *runaway*... I would do just what you did ASAP with the disconnect before much gas had a chance to get into the suit. Since I dive my suit fairly snug it isn't a big problem. Second, plugging the inflator nipple with your finger isn't a bad idea either if you remember in time... if not you will be reminded.

I have had the inflator stick while using an argon suit bottle and it is very easy to manage then... just turn the bottle off.

Here is an anecdote describing a stuck inflator, a missing argon bottle and airsharing with a drysuit inflator hose.

 

[pdoege]

Are you sure that is a DIR technique?



Good story.

Peter

 

[String]

BC dump valves WILL dump quicker than a drysuit and even the oral inflator (which everyone these days uses to dump) will in NORMAL USE.

However, in the event of a runaway ascent starting there is a guaranteed way to get a dry suit to dump faster than a BC:

Stick 2 fingers in the wrist or neck seal and open it. You'll lose a LOT of air very quickly, get very wet but will be able to stop.

Theres also a lot of talk still about feeling the bubble of air move in the suit - i still think a lot of people are overweighted when describing that. You really shouldnt end up with a bubble of air on singles in a dry suit.

 

[SubMariner]

BC dump valves WILL dump quicker than a drysuit and even the oral inflator (which everyone these days uses to dump) will in NORMAL USE.

No offense, but Is this from personal experience or some other source?

It has been my experience that a dump valve on a suit can be manually activated simply by pressing on it to release air in the suit as quickly as it goes in. (Also, a properly adjusted valve will automatically vent when in the proper body position to auto-exhaust.)

AAMOF, one of the techniques performed in the PADI drysuit course is to hold down the inflator in the suit while at the same time purging it:

5. demonstrate the ability to maintain neutral buoyancy, near the bottom, when both the inflator and deflator mechanisms on the dry suit are depressed.

 

[String]

ITs from personal experience and everyone elses i know. As well as being slower to dump they are also (for good reason) slower to inflate.

Ive got no idea on the auto dump you're on about though as i use a cuff dump and so does everyone else i dive with so pressing to release isnt an option. Most people around here had the auto dump removed and replaced with cuff.

As for the PADI thing, the dump and the inflate on the drysuit work at roughly the same rate - example trying to perform a CBL on an unconcious casualty in a cuff dump dry suit, you inflate their suit but if you dont hold their left arm down, the air comes out at the same rate and nobody goes anywhere.

However this rate is slower than a BC for inflate and deflate.

When i first got my drysuit i had initial problems because to get neutral in my BC a very short squirt was needed. I tried the same with dry suit and hit the bottom, its near twice the time needed to get the air in to get neutral.

 

[SubMariner]

Ive got no idea on the auto dump you're on about though as i use a cuff dump and so does everyone else i dive with so pressing to release isnt an option. Most people around here had the auto dump removed and replaced with cuff.

Ah..... I see... it's a local geographical thing. From reading various UK based boards I've seen a lot of reference to cuff dumps. They're not as popular over here Across The Pond. AAMOF, I don't recall seeing anyone diving with them in North America. Can you give me a brief overview as to why they are so widely used in your area? Pros & cons?

As for my own personal experience, it has been with a couple of different inflate/deflate valves:

1) Both valves on the chest. The inflator on the right, the exhaust on the left. And BOTH were totally manually: you want air out? You have to get in the correct body orientation & push that button! 5mm neoprene suit with back entry.

2) Inflator just a little right of centre with a swivel. Dump valve on the left upper arm (deltoid area). Dump valve can be set to auto dump or manual. Trilam suit with front entry.

Gawd I love this board!

 

[Col.Maniac]

String once bubbled...
[B
Theres also a lot of talk still about feeling the bubble of air move in the suit - i still think a lot of people are overweighted when describing that. You really shouldnt end up with a bubble of air on singles in a dry suit. [/B]

Hi string,

I had done a buoyancy check with the drysuit i need 8KG with 15L steel tank and i sink very slowly at the surface,
at the bottom 20 meter 30 meter mark ul need extra air in the suit as the water pressure is greater so i do get a small air bubble in the suit. Unless there is a different way of doing this,

As far as i understand it air rises in water so the air is going to the highest point in the suit i.e your back, if you got the right amount of air in it to relese the squeeze and to be N/B in water
you are going to get an air bubble in there. Perhaps i missed something again
Tony

 

[WoofDiver]

My.02 worth;

These all all good answers to this question but, there is a situation in which you WOULD use your drysuit insted of your BC- that is if you damaged your BC bladder. I am involved in tech diving, in which redundancy is the rule, not the exception. If I accedently damage my BC to the point that it can no longer hold air, I will use my drysuit in place of my BC to allow me to make a safe ascent to the surface. This is why you should never use double tanks with a wetsuit.:doctor: :doctor: