Questions for the drysuit divers

[Divingblueberry]

Bonjour

I have very limited experience : close to 60 dives, 2 trips to Cozumel and few dives in the cold waters of the St-Laurence. I got a good deal on a drysuit and bought it since it is the best way to dive as much as possible around here. Got a crash course with a very good instructor (2 hours in a pool). After 4 dives in the quarry, here I am sitting in a zodiac heading for a 70' dive. The dive went well in general. I was boddied with a very nice and experienced woman who said to me while we were packing up : " I saw you going around with quite a squeeze for a long time... I was the same, I didn't want to add air when I started. " I didn't have the chance to ask more questions because she had to leave but I can't stop thinking about it...

She was totally right though, I endured a queeze because I didn't want to add more air (and have to deal with it later on). How do you get to manage efficiently air in your suit ?

Any tips for a very green drysuit diver is welcome.

Merci !

 

[arcticat99]

practice i dont have many dives but have 12 dives in a drysuit and each time i go out it gets better .simply put when you feel a squeeze just give it a burp of air.you dont need much .i find its not much difference then adding air to bcd for neutral buoyancy.you will use a little more air and your dives will be shorter but as you learn and get use out of it you will find the right amount to add .i found for myself the biggest challenge was not getting light feet from the air shooting to your boots then having to move the air up to your chest ,so try not to dive head down to make this happen

 

[almostDIR]

with single tanks where the weight shift during the dive is small it is easy to use only the suit for buoyancy control which is how I was taught to do it on padi course. Your bc is basically empty underwater and you will use the suit instead for buoyancy so that the squeeze is never a problem. If using large doubles this may not work at all and some divers may use the bc instead for buoyancy control also with single tanks which is totally OK as long as you don't squeeze yourself to motionless with the suit... it may get very uncomfortable at depth and finally became almost solid if not adding little bit of air to the suit every now and then. You may do this for example every 5m or 8m or so if using the bc for buoyancy control.

I personally tend to use both for buoyancy control, whichever is quicker to use at that moment. OR quicker to get air out at that moment. You will want as little air as possible in the suit but it still being comfortable so your weighting needs to be about correct to start with so that the suit air volume is just right and it is easy thus to keep the air out of legs and not to get uncomfortable ball breaking squeeze on the other hand.
If having the air bubble continuously wandering around and getting to the legs all the time you may want to shift at least 1 liter of it to the bc or alternatively drop 1kg of weight if you're overweighted. For me it was 1.5kg to drop and then it got very very easy to dive dry and legs were rarely a problem anymore. So some balance air needed in the suit but too much makes it kinda trapeze balancing experience so better to keep it closer to the more optimal level

 

[Graeme Fraser]

Don't feel nervous about adding air to your drysuit. Short regular squirts during your descent will be enough to take the squeeze off without creating a huge unmanageable bubble. You've already had a pool orientation so hopefully understand how to recognise and mitigate a partially and fully inverted position. In reality, if you are aware of your trim position this is unlikely to happen. As articat99 says, just avoid head down descents.

What you will quickly find is that a small bubble of air in your suit gives you much greater control over your trim. Work on this and you'll be able to hover completely still in trim in no time.

Assuming you have an adjustable shoulder dump, try and dial this so that a slight positive raising of the shoulder is enough to vent. At this stage, don't fully close, that way you shouldn't have to manually vent during ascent whilst simultaneously venting your BCD. Also don't fully open, otherwise you may inadvertently vent when you don't want to, which just means you need to top up regularly.

Anyway, relax and enjoy. It's takes a little while to become completely synched with your suit, but when you do you should be very happy with the results.

 

[KenGordon]

Bonjour

I have very limited experience : close to 60 dives, 2 trips to Cozumel and few dives in the cold waters of the St-Laurence. I got a good deal on a drysuit and bought it since it is the best way to dive as much as possible around here. Got a crash course with a very good instructor (2 hours in a pool). After 4 dives in the quarry, here I am sitting in a zodiac heading for a 70' dive. The dive went well in general. I was boddied with a very nice and experienced woman who said to me while we were packing up : " I saw you going around with quite a squeeze for a long time... I was the same, I didn't want to add air when I started. " I didn't have the chance to ask more questions because she had to leave but I can't stop thinking about it...

She was totally right though, I endured a queeze because I didn't want to add more air (and have to deal with it later on). How do you get to manage efficiently air in your suit ?

Any tips for a very green drysuit diver is welcome.

Merci !

When diving you really need to be in control of your equipment and have confidence that you can work it. For a drysuit that means knows how to dump the gas and being able to dump the gas. Then you can confidently put enough in it for comfort and warmth (and maybe buoyancy) and be sure you can get rid of it as you ascend.

Since dumping from a drysuit is not so positive as dumping from a BCD I find it worth while to get people to spend a minute or two deliberately dumping and adding at the same time to really appreciate how it feels to dump the gas. Undersuit, position in the water and the dump valve type all make a difference. It is not uncommon for student to question whether the valve works at all.

Doing the entire dive squeezed and coming out with an entertaining set of bruises where the seems run isn’t going to be satisfactory. You will be cold and restricted in your movement. Go back to the quarry and do the same sorts of drills as you would for general buoyancy, particularly ascending by breathing control with gentle dumping. Do try both suit only and mixed BCD for buoyancy control, you may find one other easier than you expect.

 

[Johanan]

If you feel that your feet are starting to rise uncontrollably, there is a useful trick for that. Try to spread your arms wide open and then bring them forcefully together forward and a little up - as if joining hands in prayer. That will bring your shoulders up and will help to regain the trim. The air probably will vent from the dump valve and you will need to add some in order to restore a neutral buoyancy. Just remember that this move will thrust the water forward, so try not to stir up too much silt.

 

[Searcaigh]

Another tip, if you are going to deploy a DSMB while wearing a drysuit, make sure that you open your dump valve first before starting on the DSMB.

 

[Gareth J]

Diving a drysuit, there are two schools of thought.
1. Minimal air in the suit (for comfort), buoyancy from the jacket (wing/BCD)
2. Buoyancy from the suit.

As has been said, with a single cylinder, it should be comfortable to run the buoyancy on the suit. Giving you one air volume to manage.
There are two types of dump valve, a wrist dump, CVD (constant volume dump). CVD's are the more modern approach.

With a CVD, you can screw it down, effectively closing the valve. Press on it to force it (fully) open. The correct way to use a CVD is have it set so that it automatically dumps when you become positively buoyant - let me qualify that.
This is easiest done with an assisting buddy (or instructor).
- Position yourself horizontally so that you can do a fin pivot (in shallow water).
- Dump all air from the BCD(wing)
- Fully open the CVD (anti clockwise)
- Add air to the suit - it should start venting out of the CVD (your buddy will confirm this).
- close the valve two clicks -try again.
-You will probably find air is again venting.
- keep closing the valve a couple of clicks at a time and then adding air.
- Eventually you will become buoyant - i.e. you are doing a fin pivot. Breathing in and out adjusts your 'angle' in the water. You are more or less neutral.
- Then roll, dropping your right shoulder and raising your left shoulder. You should immediately start venting gas from the CVD, and go negative. Drop your left shoulder, add gas and you should be back where you were doing a controlled fin pivot.

That is more or less where the CVD needs to be set, potentially another couple of clicks closed so you can hover. Raising your left shoulder should immediately make you dump gas (making you negative).
I would suggest you "count" the clicks on the valve and use this as your starting point on every dive (at least initially).
If your CVD is correctly set. You get neutral easily, and you don't really 'dump', the CVD takes care of this automatically. All you do is roll your left shoulder up, shifting air to the dump valve.

In many ways drysuit diving is easier than wetsuit. All you do is dump all air form the BCD at the start, add air on the descent to the suit. As you ascend the CVD dumps automatically. Simple!

Like anything, its confidence and practice.

If you are shrink wrapped into the suit. In addition to bruising and compression issues (especially if you are male). The thermal insulation you are wearing under the suit is also crushed, reducing its thermal property. You need air in the suit to 'loft' the thermal clothing to keep you warm.
On that note. When you get out, initially close the CVD and wack some air into the suit. That will keep you warm. Put a windproof over the suit, or take it off. Whilst the suit is drying in the wind it is acting like a heat exchanger, your body temperature will be dropping.

 

[Storker]

Another tip, if you are going to deploy a DSMB while wearing a drysuit, make sure that you open your dump valve first before starting on the DSMB.

I assume that the reasoning for that tip is to avoid a runaway ascent if you inadvertently get a little too shallow while faffing with the sausage.

If you prefer to dive with the dump valve closed and manually vent from the suit, I agree. If you dive with the valve (partially) open the way @Gareth J describes, I don't see it as particularly necessary.

 

[Storker]

Diving a drysuit, there are two schools of thought.
1. Minimal air in the suit (for comfort), buoyancy from the jacket (wing/BCD)
2. Buoyancy from the suit.

As has been said, with a single cylinder, it should be comfortable to run the buoyancy on the suit. Giving you one air volume to manage.

Even with a single tank rig, you'll have some 3L or so more gas in your suit than necessary for comfort. While I originally was taught to only use the suit for buoyancy underwater, I don't like that.

For me, suit gas and BCD gas are handled differently. Short-term buoyancy swings caused by ascending or descending are compensated by adding to or venting the suit. That keeps my suit volume more or less constant regardless of depth. The slow, gradual increase in buoyancy due to breathing down my tank is compensated by venting my wing.

The only time I add a significant amount of gas to my wing is immediately after I leave the surface. While sinking, I work the suit inflator and the wing inflator more or less simultaneously until I hover at moderate depth with my suit just as tight as I want it to be. If I'm weighted correctly, I'll have some 3-ish liters of gas in my wing, just enough to compensate for the weight of my gas. Then look to my buddy, "OK?" "OK!", exhale and control my descent rate using my suit inflator only. At depth I might add a puff or two to my wing to compensate for the compression of the gas inside it, but usually I've already breathed down my tank a little, more or less making up for that.

To the OP: as you can see, there's definitely more than one way to skin this particular cat, so just experiment and find out what you prefer. But as others have said, running the suit unnecessarily tight is a tad uncomfortable and more often than not a little chilly.