Problems Venting A Drysuit on the Ascent

[Thalassamania]

DUI also advocates using only the drysuit for buoyancy control. Simpler and safer was their reasoning.

Since I don't want to hijack this thread, I'll just say there are good reasons that support both methods.

Here's a thread that presented the arguments pretty well.

http://www.scubaboard.com/showthread.php?t=185890

Dave C

One needs to think about what "Buoyancy Control" is for this discussion to make any sense. You change buoyancy as you change depth as a result of the change in volume of air that is in your drysuit and in your BC. You also change buoyancy as you use up gas from your tank. You need to be weighted so that when your tank is empty and your BC is empty and your suit is inflated to a hair beyond squeeze you can comfortably hold your 10 foot precautionary stop. You add and subtract air from your suit to keep it's volume constant (just barely feel the squeeze) and you add and subtract air from your BC to ballance the weight of the gas in your tank(s).

Which one is "buoyancy control?" I think that they are both part of a good diver being able to control their position in the water collumn.

 

[David P]

It could be the undergarments, but I honestly think it just body positioning. He said something about raising his arm to get the bubble up by his cuff then bringing the arm down to get the bubble to migrate towards the dump valve. If he does not have his left shoulder high enough, the bubble will travel down the triceps then disperse across the back of his shoulder and back. If he rotates more then the bubble will go to the highest point(actually it has a funny habit of always doing this...) which should be his shoulder. When I do this I get the majority of the air out, but it still have a good size bubble that is hovering just behind the dump valve a little towards my back. I grab the valve and kind of push it away from my chest towards my back and then the rest of the air escapes. Whenever I get another drysuit Im considering asking to have the dump valve placed just an inch or two further back.

 

[Belmont]

sometimes I think my dump valve is slightly misplaced. If I roll to the right, it doesn't necesarily (I wish my iPhone had a built in dictionary) dump all the air, so
Sometimes i use my right hand to squeeze the air out on ascents

dictionary.com

 

[TSandM]

It IS possible that the valve itself is sticky and taking too much pressure to open.

The USIA rep on this board gave me a great tip for that: Soak the valve overnight in distilled water. Then repeat the soak in distilled water with a few drops of Ivory soap in it. This has rehabilitated two valves for me.

I also make a practice of soaking my dry suit exhaust valve every couple of dives, in addition to the good rinse it gets every dive.

 

[WKenny]

How fast are you ascending? And how much air do you have in the suit? What you described sounds perfectly reasonable to me which is why people suggest NOT using the DS as a buoyancy device. They vent slowly and can trap air.

My suggestion would be to first use your BC for buoyancy, and second, ascend more slowly.

Thank you for your response.

 

[WKenny]

Thank you for your response

 

[WKenny]

Thank you for your reply

 

[nereas]

I dive in freshwater with a DUI TLS 350 shell drysuit and a Bare "Hi Loft" undergarment. Up to now I have been using the DS for buoyancy control although I intend to change that practice to use a wing for buoyancy control. I have made about 10 dives in this DS. The exhaust valve is on the left shoulder and I dive with the exhaust valve fully open. On ascents the air vents very slowly. On ascents from about 100 feet I literally need to raise my left arm to fill it with air and then lower the arm to vent air out the exhaust valve. It is almost like a pumping action as I raise and lower my left arm continuously during the ascent. I have inspected the exhaust valve and it appears to be clean with no debris in it. When I use the manual override on the valve to vent air, I seem to get water in the drysuit. Is it unusual to have this difficulty in venting air from a drysuit? Any suggestions? Thank you.

That is exactly how it works. Mine works that way too.

I have played with the idea of moving the valve to the right top forearm area, and plugging the hole at the left shoulder.

Reason being is that my right arm and wrist are always unencumbered. Whereas I wear my gauges and slates on my left arm and wrist. Therefore the right arm is in a better position to collect up the excess air for venting. And with the valve on top of your right wrist/forearm it vents better that way.

I know a fair amount of people who have moved their valve to the top right forearm.

In the olden days, when drysuits were new, and when horsecollar B/Cs were all there was, it was common to use the D/S for buoyancy. Today that is no longer necessary, although a fair amount of techdivers still do it, since they have been around for a long time, and old habits die hard.

I normally descend quickly, as fast as I can clear my ears, and during the descent I slow it down only a little by controlling suit squeeze from my D/S, without using my wing at all.

Then when I get to where I want to stop, I first counteract the suit squeeze, then inflate the wing to stop me. This normally brings me to within 5 ft of the rocky reef. For the rest of the dive, then, at that depth, my buoyancy is fixed, and I neither need to add air to the wing nor the suit.

Before ascent, I dump excess air from the suit, kick up, and dump air from the wing as needed to stay neutral throughout the ascent. This means raising my arm from time to time like you do, and shaking it too. Then I dump a little air from the wing to stop the ascent, and resume kicking up slowly.

That results in a nice controlled, slow ascent.

 

[Ber Rabbit]

I had a similar problem and eventually it resulted in an uncontrolled ascent from 100 feet with my arm completely full of air and the valve refusing to dump until about 5 feet from the surface. That was AFTER I had sent the suit back to the company to have the valve pressure tested and the results came back fine. We never did figure out what the problem with the valve was, I was wearing undies from the drysuit manufacturer so I wouldn't think they would interfere with the valve. Someone told me to spray a bit of food grade silicone into the valve before each dive to keep it working right. That really seemed to help but I never could trust the suit again and ended up buying a new suit but I bought the same model. I haven't had any problems with the new suit.
Good luck!
Ber :lilbunny:

 

[crosing]

Sometimes high loft undies block the valve. I've seen some folks duct tape the undie on the arm where it would make contact with the valve to prevent it from getting sucked into the opening and blocking it.

Also, high loft undies have a tendency to trap more air making them a bit more difficult to get the air up to the arm area.