The ABC of drysuit diving

[pointy]

To the OP.

There are strongly held options on using the suit or BC/wing for buoyancy. It really, doesn’t matter and is down to personal preference.

* With the suit the gas is in one compartment, but you can never forget where the bubble is.
* Using the BC/wing initially appears easier as it’s like diving wet. The challenge is controlling 4 air spaces during a rescue; your BC/wing and the casualty’s.

I dive on my suit and find I’m warmer than those who use their BC/wing.

For what it’s worth. Give both a go and see what works for you.

But don’t do the course until your comfortable driving your suit.

That sounds like the right answer. People on this forum, who dive with more than a single tank, have testified that buoyancy control with the suit alone is problematic. Since I only dive with a single 100 steel tank I couldn't argue with that.

However, I will say that it is possible to have great trim and buoyancy control using the suit alone. I swim effortlessly in a comfortable horizontal position using a trilaminate suit with no air in the BC - I have been diving a long time, but I have never enjoyed such a sense of weightlessness as I do now diving this way.

If you can make it work for you, there are definite advantages to keeping air out of the BC: Buoyancy control is simpler when you only have to deal with a single compartment; and you will have greater warmth per unit ballast if you keep air in the suit and out of the BC.

Are there any people out there, using doubles, who find that single compartment buoyancy control works well for them? If you use a drysuit made of compressible material, is it more difficult to maintain good trim while keeping air out of the BC? Have I overlooked any advantages or disadvantages to keeping air out of the BC while submerged?

 

[tbone1004]

there are also thermal concerns when you use just the suit for buoyancy, particularly with large/multiple tanks.
In an ideal situation you are cool/colder on descent/bottom portion of the dive to slow your inert gas uptake. Conversely you want to be warm on ascent/decompression to expedite offgasing.
If you use your suit for buoyancy, then you are warmer on descent/bottom portion which expedites inert gas uptake and since lead=warmth, you will be cooler on ascent/deco and can put you at increased risk for DCS.
Yes this is real, yes it has been studied.

 

[rabe]

I'm overwhelmed for all these answers, thank you so much.
In random order, here some thoughts:

- The PADI tec manual suggests to log at least 20 dives. I'll try to log more dives as possible between now and my tec practices, but for sure not 20 because I'll start very soon.
- I live in Queensland, that's why I was wondering about the max temperature. Now is ""winter"", and the water is ""cold"". For example Saturday was 18 degrees (at 27 meters) and I was a little bit cold with my 5 mm, but honestly, it doesn't get any colder than that. However, I'm also diving in Southern part of Australia, where is colder. I'm also planning to visit Tasmania and New Zealand, and the DS will be super useful. Despite this, I like the wet feeling of diving (after all, I'm in the water!), therefore, I won't stop to dive with the wetsuit, especially with my 3 mm in summer or on the GBR...
- I went to dive on Saturday, and my buddy used his DS so I had a chance to see how it works: I've got the concept, and the "bubble control", and he told me the same. Now it's just a matter of doing it.
- Speaking of bubble control: I'm pretty sure I will need to move those bubbles on my legs because they are really heavy (that's what ultra running does). I can predict a lot of safety stop upside down.
- I'm lucky enough to have an easy shallow spot not so far from home where I can practice in peace: I'll try to get there asap and try and try and try.
- Undergarment: they told me to use the 4 elements J2 as base. Any other suggestion or brand is welcome...

 

[KenGordon]

I'm overwhelmed for all these answers, thank you so much.
In random order, here some thoughts:

- : I've got the concept, and the "bubble control", and he told me the same. Now it's just a matter of doing it.
- Speaking of bubble control: I'm pretty sure I will need to move those bubbles on my legs because they are really heavy (that's what ultra running does). I can predict a lot of safety stop upside down.
- I'm lucky enough to have an easy shallow spot not so far from home where I can practice in peace: I'll try to get there asap and try and try and try.
- Undergarment: they told me to use the 4 elements J2 as base. Any other suggestion or brand is welcome...

The ‘bubble’ ought not to be too literally a bubble. You need a small amount of gas well distributed to give loft to the undersuit. If you are head up you might notice the gas being squeezed out of your legs but not a huge movement of gas. If you have too little gas you will start to feel constricted and maybe ‘shrink wrapped’, if you end up with bruising which matches the suit seems then you definitely need more gas.

If your legs are heavy then there are other things you can do. If you try to put gas there then inversion may become a problem. Move your centre of mass forwards by moving lead, your cylinder or adding trim weights. Bending you knees and getting lighter fins might help too. Moving where you keep your arms might make a difference too.

 

[rabe]

The ‘bubble’ ought not to be too literally a bubble. You need a small amount of gas well distributed to give loft to the undersuit. If you are head up you might notice the gas being squeezed out of your legs but not a huge movement of gas. If you have too little gas you will start to feel constricted and maybe ‘shrink wrapped’, if you end up with bruising which matches the suit seems then you definitely need more gas.

Same advice I got Saturday by my buddy, thanks!
When we were on the bottom, he also let me touch the DS so i could feel the wrinkles and how tight the suit was...

If your legs are heavy then there are other things you can do. If you try to put gas there then inversion may become a problem. Move your centre of mass forwards by moving lead, your cylinder or adding trim weights. Bending you knees and getting lighter fins might help too. Moving where you keep your arms might make a difference too.

I'm already doing all of the above

 

[FinnMom]

Heavy legs might be really nice. I wear heavy fins but my standard bouyancy-control-escaping is always a feet-skyward tilt. Knees bent is a critical help with bouyancy, DS gas migration and accurate finning as well.

Try not only being upside down and getting upright, but also having your fins pop off and still getting upright (could also happen if on a boat ladder with no fins and you fall in). It's nice to know you can do it, and knowing you can do it will make it much easier to remain calm if you ever get in this situation. I at least found no fins to be a heck of a challenge (thick undersuit, doubles & middle age spread).

 

[clownfishsydney]

The only time I need to add air to BCD when using my neoprene drysuit is if I am below about 30 or 35 metres. Above that, there is no need. On the weekend I did four dives at Jervis Bay, two of which were to 40 or more metres. Had to put air in BCD to get neutral otherwise I would have had too much air in drysuit.

Nearly everyone I know who uses a dry suit also normally uses the drysuit for buoyancy control. Works great so long as you do not get upsidedown!