Problems Venting A Drysuit on the Ascent

WKenny · Aug 23, 2007

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.

PerroneFord · Aug 23, 2007

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.

Dirkadiver · Aug 23, 2007

Getting acquainted w/ a drysuit takes some time. It almost seems like task loading at first with trying to keep the air out of your feet, releasing air as you ascend, eliminating "suit squeeze", etc. Unfortunately, having to add/dump air will never end. Fortunately, it will become second nature the more you dive it. I dive a White's Catalyst & absolutely love it. My dump valve isn't the quickest either, but like you, simply raise the left arm to invite the air there & squeeze. Little bit of a hassle, but a small price to pay to stay dry. I'm sure you'll get a lot of opinions on how to use your drysuit here. I never use my drysuit as as a BC. I treat it as a redundancy and would only use it for this purpose if something happend to my wing.
Not using the drysuit for buoyancy will dramatically reduce having to constantly add/dump air.

David P · Aug 23, 2007

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

rookers · Aug 23, 2007

Use your wing for buoyancy, and dive dive dive. It took me a while to become accustomed to managing a DS and I even had some issues with some new undies just a few weeks ago.

dave4868 · Aug 23, 2007

I wonder if the undergarment's outer nylon shell is slowing the movement of air out of the suit as a whole or perhaps slowing down the exhaust by wrapping around the base of the exhaust valve.

Is the drysuit a tight fit in the arm while wearing that undergarment? Tight in the armpit perhaps, slowing down flow from the rest of the suit? Harness straps too tight around the front of the armpits? Try loosening your straps a little.

You could test the first possibilities by placing a wool sock under the base of the valve and see if it vents better.

For another test, try something like a wool scarf along the outside of the undergarment so it goes from the base of the valve to somewhere past the armpit.

Does the suit vent well with a fleece undergarment?

My TLS 350 and CLx450 both vent fine with a thick Weezle Extreme Plus, but it's not a tight fitting suit. I use only the drysuit for buoyancy control.

Dave C

DivingCRNA · Aug 23, 2007

I agree with using the wing for buoyancy and the suit to stay warm. I still do not get why PADI advocates using the drysuit for buoyancy.

Thalassamania · Aug 23, 2007

There is either something wrong with the valve or your underwear is cloging it. A shoulder mounted valve of the sort you describe should be able to easily maintain constant suit volume throughout your asent.

The idea is to maintain constant suit volume (you can measure this pretty well by maintaining just a little squeeze in the suit) by adding on descent to releave the buildup of squeeze and automatically venting on ascent. You BC or Wing should be used only to offset the weight the gas remaining in your cylinder(s).

tedwhiteva · Aug 23, 2007

DivingCRNA:
I agree with using the wing for buoyancy and the suit to stay warm. I still do not get why PADI advocates using the drysuit for buoyancy.

Me either - its not designed to be that and its too easy for that much air to go to the wrong place just when you don't need it.

dave4868 · Aug 24, 2007

DivingCRNA:
I agree with using the wing for buoyancy and the suit to stay warm. I still do not get why PADI advocates using the drysuit for buoyancy.

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

Problems Venting A Drysuit on the Ascent

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