drysuit diving, how much squeeze?

[Yoyoguy]

I know there are numerous threads out there about using your suit for most of your buoyancy or using your wing for buoyancy. I don't want to start a debate on that. As a new drysuit diver I am simply trying to figure out the best weighting to start off. I have noticed several things in the 5 dives I have made with a drysuit. When I was underweighted, I felt a LOT of squeeze...obvious reason being I needed almost all of the air out of the suit in order to prevent floaty feeling. I also felt very cold...guess being there was little air in the suit to help create a sort of warmth barrier. My buddy ended up giving me 2lbs in order to help. Now the last couple dives I started adding weight and I have noticed both of these problems going away (obviously now I can add more air into the suit to prevent squeeze and keep me a bit warmer). But how do you know how much weight is starting to be "too" much weight? thanks.

 

[Dhboner]

Anytime you make a substantial change to your "kit" you should try to put your self in a controlled situation for the first dive or two to sort things out. This is particularly true when diving dry for the first time. There are a couple of considerations that will influence how much air you end up adding to the suit...duration and depth of dive, quality and efficacy of the underwear and (as you get more advanced) whether or not you use argon or air for inflation. If you have access to an easy shore dive location start out weighted neutral with a few "squirts" of air in the suit...remember you only want to assist the underwear in "lofting" so very little air is required to stay warm. Practice venting the suit during the dive so you can ascend and hold a stop without corking to the surface. If you simply can't do that then add some more lead (if you have surface support who can hands you extra weights this will be a lot easier). The goal is to be able to use enough gas to keep the loft in the undergarment and then vent that air as you ascend at the end of the dive. As you gain more experience you will get good at moving the "bubble" around to assist in venting and prevent a feet first ascent.

 

[Diver0001]

Good question.

When drysuit diving you will *always* have a split between air in your suit and air in your BCD unless you are underweighted. This might sound controversial but I've been diving in a drysuit for 30 years and I'm pretty confident about this opinion.

That's the trick about drysuit diving.... you will normally have a little more ballast than the absolute minimum. When you're diving in a wetsuit it's really irritating to have too much ballast. Your feet hang down, you have trouble staying neutral and the more air you need in your bcd, the worse it gets..... In a wetsuit you need to really focus on having it dialed in perfectly.

However, in a drysuit, as you noticed, a kg or 2 of extra weight will just allow you to put that bit of extra air in the suit to keep you warm and to keep you balanced. You can allow the air to go to the feet and once you get the fine control, you will be able to lay horizontal in a drysuit in a way that makes being *absolutely motionless* (when you want to be) a norm and very comfortable.

The question is when it's too much..... trimming works like you learned in OW. Suit empty, BCD empty, tank empty, normal lung volume and holding at eye level.... Once you have that then add 2-4lbs and you're good to go. Looked at another way, when you are at the safety stop at the end of the dive, your suit should be in a *bit* of a squeeze and your BCD should be empty.

R..

 

[RJP]

As TSandM says "Lead = warmth"

 

[tbone1004]

what Ray said, and the answer is "it depends"

How cold is the water?
How long are you diving?
Are you somewhat chilled before getting into the water?
How much deco do you have?
Are you kicking a lot or are you on a DPV/doing a drift dive/hanging out without having to move to much?

So many factors go into this and this is why I hate it when instructors tell students to only use their drysuit for buoyancy. You put enough air in there until you are comfortable. That will change depending on all of those factors above. I dive a very tight suit squeeze on the way into a high-flow cave. Less drag and I'm working so I don't want to overheat. On the way out when I'm letting the current carry me, after I've cooled off, I'll put some more air in there to be more comfortable. Same when I'm on deco. If I'm babysitting students while they're doing their checkout dives and I'm just hovering there for an hour and the water is 50F and it's snowing outside, then I'll put the steel backplate on and not feel bad about being the Michelin Man. I don't dial weight in perfectly with my drysuit because I don't always have the same circumstances throughout the entire dive and unfortunately there is no magic number with drysuits because YOU control how much buoyancy they have.

If you want to be warmer, then add more lead, if you are comfortable and still have a bunch of air in your wing when the bottle is close to empty, then take a couple pounds off. It's a very different situation than when you're in a wetsuit that will lose buoyancy going down and you could be dangerously heavy

 

[Storker]

As TSandM says "Lead = warmth"

Which is why I like to add a couple of kilos in the winter


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[Michael Guerrero]

When I was diving in the lake and it was cold, I would find a heavy rock to hold onto at my deco stops so I could add air to the suit and stay warm at the end of the dive. You don't want to be grossly over weighted, but your suit squeeze should not interfere with mobility (i.e., being able to kick effectively and perform valve drills).

 

[Subcooled]

1) If you struggle to stay on the surface then you carry too much weight for the BCD/Wing.

2) Too much lead also means too much air in the bcd/suit and too much buoyancy change per foot. If your dive profile looks like sawteeth then you might carry too much lead.

3) Take the minimum amount of lead you need to finish a dive (test with near empty cylinder in a safe shallow pool) and add 2-4 pounds for comfort.

4) There is no exact answer.

 

[FinnMom]

I just think that I sould empty my suit and wing, WITHOUT making any huge effort or acrobatics to get everything well & truely empty, and at least with a defite emptying of my lungs and maybe a teeny-tiny bit of effort I should notice that I begin to very slowly decend from the surface. That's proper weighting for me (carrying 2400 liters of gas).

As you get more experienced your proper amount of weight for the same setup will slowly begin to fall. Keep taking off weight as it seems possible, and add weight back if it seems truely necessary (the general trend being downwards, i.e. less lead). Once in a while when you have run your air supply low but don't have to exist immediately, take the opportunity to test whether you can keep yourself at 3 meters with very light tanks. It's a comfort to know you can maintain a stop even with light tanks and it confirms that you have not taken off too much weight.

 

[gcbryan]

As others have mentioned, with a near empty tank in shallow water at the ended of a dive you should still be able to have enough air in your suit to be warm and you shouldn't have to struggle to stay down.

More weight than that is too much. You will probably have a bit of extra weight until you gain more experience with the drysuit as you may not be proficient in getting all the air out yet without getting vertical and maybe causing yourself to raise to the surface when you aren't ready.

Drysuit diving is a process for sure as far as the learning curve.