Recognizing squeeze in Drysuit

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Morning all,

Just completed the NAUI drysuit class. Very helpful. As always, my questions come after the class is over, lol.

Am trying to get a handle on the degrees of squeeze and at what point I should add air.

For example after venting the trilam suit on shore and upon entering the water and using my BC to float on the surface the entire suit is "snug" on my body. I recognize that is, in fact, a level of squeeze.

As I submerge it gets naturaly tighter and so I add a bit of air and a) I warm up a little, and it is not so tight, though I leave it a bit snug. I continue this patterm throughout my dive.

One thing I noticed, which is why I am wondering if I should add more air, is that some of the tighter spots were also significant cold-sinks. This was mostly in my arms.

They didn't really affect my overall comfort, but they were noticable, and had we been down more than 30 minutes it might have been problematic, but during these dives it was annyoynce more than anything.

I liken it to holding on to a cold metal tool in the winter with gloves on; you can feel the heat being sucked away from that body part at a rapid rate and while not ruining your overall comfort, it becomes uncomfortable.

As I began to think more about it, I was wondering should I leave things a bit snug or loosen them up more with a bit more air? If loosen up, then how much more should I loosen it?

I realize that most of that thought process will be subjective and opinion, but that's kind of what I'd like to hear.

Thanks for your input!
Drysuit diving is an art. Are you doing single tank dives? If so, try doing a dive using just the drysuit for buoyancy. Assuming you are weighted correctly, you should have more air in your suit than before, but it shouldn’t be a crazy amount. Even if you don’t prefer diving this way, it’s worthwhile to experience what it’s like, and something you’d have to do anyway in the case of a BC failure.

If you feel significantly warmer, then next time add more air to your drysuit. If you still feel the same cold spots, maybe increase your undergarment thickness.

Only using BC with bare minimum drysuit inflation is the other end of the spectrum from using only the drysuit for buoyancy. But it is a spectrum, and you should be capable of diving anywhere within that spectrum. Experiment. And then do whatever you think makes you the best diver and you feel the most comfortable with.
Three things you need: experience, practice, diving time. It's basically the same thing.

Descents: when you're on the surface, vertical in the water, and dump your wing/BCD you go into the skydiver flat position. It's very obvious when the squeeze starts, within 6m/20ft. A quick squirt into the drysuit relieves the squeeze. As you continue down, you'll periodically add a bit more gas into the suit. As you get closer to the bottom you (well I do anyway) add gas to the wing/BCD to slow the descent and stop 1m/3ft above the wreck/bottom. Then you shake it all around to get nice and comfy, possibly balancing the wing/BCD and drysuit -- maybe adding more gas to the drysuit and dumping from the wing/BCD or vice versa.

Practice and it becomes second nature and obvious.

On the bottom there's little tweaking required unless you're ascending/descending a fair way.

Ascents: These are the challenge and need lots of practice. As you ascend your gas bubbles in the suit and wing/BCD will get bigger. You need to be able to effortlessly dump from the suit by twisting to the right such that the shoulder dumps when there's plenty of gas. The wing/BCD is dumped from the hip as you're flat in the water during the ascent.

The skill is dumping sufficient to control the ascent, but not too much that you stop the ascent and start descending again! In the beginning it's a bit messy; practice sorts it out.

When you arrive on the surface you'll go vertical. This will squeeze most of the gas from the drysuit, but you'll have your wing/BCD fully inflated for buoyancy. If you've a while to wait, tighten the shoulder dump and squirt in a bit of gas -- but not too much as you could burst your neck seal.

Aim to be "great" on every dive, therefore every ascent is a practice opportunity.

All part of the fun of diving :cool:
You know the concept, practice practice practice.

the point of the suit is to stay warm, squeeze the loft out of the undergarments won’t do that, you need enough air to stay warm but not to much or you’ll get cold from the bubble smashing the lower Insulation as it tries to float away.

avoid so much squeeze that you feel movement restriction, weighting is crucial, practice practice practice.

try the suit for buoyancy and try the b/c for buoyancy and pick a method that works for you the best.
Very simple when your car key hanging from a leash, get's squeezed into your skin... that's when there is too much squeeze ;-)


All joking aside... people have different ranges of squeeze, some like to dive their drysuits as balloons, others quite tight. I prefer on the tighter side of things, just comfortable enough to allow full range of motion, but no travelling air bubbles.

The above mark was really when I forgot to connect my drysuit inflation hose, and only managed to get it connected on a wreck dive around 30m (100ft) during descend. Not a happy place!
Add a shot of air. Did that fix the squeeze feel? yes, you had a lot of squeeze. No, you didn't.
If I add a puff of air and things loosen up a lot, add another and see if it happens again.
I dive with the exhaust a few clicks from fully open and use that for consistency. If I think the current amount squeeze is a little more than normal, I roll slightly right and add air until I hear it exit. Using the exhaust on ascent will become second nature, but it can help you find that same level of comfort anywhere in the dive.
I wonder if you have your hands lower than the rest of your body, causing a little more squeeze on your arms (one of your trouble spots). If so, it might help to raise them.
Very simple when your car key hanging from a leash, get's squeezed into your skin... that's when there is too much squeeze ;-)

View attachment 717235

Were you very cold or just excited there?
As I began to think more about it, I was wondering should I leave things a bit snug or loosen them up more with a bit more air? If loosen up, then how much more should I loosen it?
Add more air until you have enough insulation to keep yourself warm and comfortable. You need to carry enough lead to make this possible and that's why I carry two pounds of extra weight when the water is extremely cold or the dive is a long one (especially with deco stops). How much is enough? Well, it depends, but do not inflate yourself to a balloon... because...

If you add too much air, it might migrate inside the suit, and keeping "the air bubble" where you want it (usually not in the boots) becomes a struggle. The more air you have in the suit the faster the expansion of the suit volume is on ascent. It is thus more difficult to control ascent speed - especially at shallow depth. It is advisable thus to get rid of that extra air once you continue your ascent from 30 feet up.

When insulation goes up, boyancy control comes down, and vice versa.
It's safe to start from the middle and then choose which way you want to move the slider - and during which phase of the dive.

Some divers use argon as their suit gas, but I have been happy with plain air for my one hour dives in 39F. A decent activity level during the dive, last nights good sleep and a sturdy meal also help you to enjoy those colder dives. Here you have another important choice to make: activity will keep you warm but also increase your breathing gas consumption. If you float motionless you'll suffer a longer and colder dive 🥶

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