Drysuit use and buoyancy

[boulderjohn]

Those diving drysuit, do you use it like a bcd or just adjust for squeeze and use bcd? Tried both ways myself. PADI try’s to tell you to use drysuit. Thankx in advance.

a drysuit should not be used as a primary source of buoyancy control. i am surprised padi would say otherwise.

As a PADI drysuit instructor, I know that PADI's course teaches that how you control your buoyancy (drysuit and/or BCD) depends upon a number of factors, and they go over those factors. They do NOT just say to use the drysuit for buoyancy.

On the other hand, the book on drysuit diving that I have that was authored by the creators of DUI and Viking drysuits DOES say that a new drysuit diver should just use the drysuit for buoyancy until they get more experience and then use both the drysuit and the BCD for buoyancy.

In theory you should use your BCD for buoyancy control but in practice a correctly adjusted drysuit means you do not have to touch your bcd

If you are a properly weighted diver with a single tank, and you descend and put enough air in the drysuit to be comfortable and avoid a squeeze, you should not need much air in the BCD--if any at all. That amount of air should make you neutrally buoyant. In that case, adjusting that level of air in the drysuit would be all you would need to be properly buoyant throughout the dive. If you are a single tank diver and have the drysuit filled enough to be comfortable and also have a fair amount of air in the BCD, you are likely overweighted.

When I am doing a tech dive and holding deco stops, I may decide during a stop that I am a little negative, and when that happens, I will usually just give my drysuit a touch of air.

 

[Ulfhedinn]

Or not!!

You use your suit for buoyance?

 

[lexvil]

You use your suit for buoyance?

Yes, easier to control and I see no point in packing along extra lead just so I can add air to the wing.

 

[Degenerate]

You use your suit for buoyance?

Suit for buoyancy while diving CCR, wing for buoyancy when diving OC.

 

[stretchthepenn]

On the other hand, the book on drysuit diving that I have that was authored by the creators of DUI and Viking drysuits DOES say that a new drysuit diver should just use the drysuit for buoyancy until they get more experience and then use both the drysuit and the BCD for buoyancy.

If you are a properly weighted diver with a single tank, and you descend and put enough air in the drysuit to be comfortable and avoid a squeeze, you should not need much air in the BCD--if any at all. That amount of air should make you neutrally buoyant. In that case, adjusting that level of air in the drysuit would be all you would need to be properly buoyant throughout the dive. If you are a single tank diver and have the drysuit filled enough to be comfortable and also have a fair amount of air in the BCD, you are likely overweighted.

I concur with the authors' suggestion and with your analysis, @boulderjohn .

When I was a relative n00b and learning drysuit diving on a single AL80 tank, I quickly realized that managing two airspaces was more complicated than managing one, so I just used my drysuit for buoyancy. I like to think I got pretty good at it.

Later on, once I started diving SM with steel tanks and venturing into deeper waters, I realized that relying on the drysuit for buoyancy wasn't gonna work anymore, so I retrained myself. It took some concerted thinking.

By now, using my BCD for buoyancy and my drysuit for comfort requires zero thought. Had I tried that straight off, though, I would've been overwhelmed.

 

[REP]

I dive with a shell type drysuit year round in Canada. I no longer own a 5mm or 7mm wetsuit, since the drysuit works for ice dives throught to summer dives until the water is warm enough for my 2mm wetsuit (…in a river with no thermocline or down south). I have about a dozen WS and DS configurations based on different conditions which all have different weights. That being said, l’ve used both the DS and or the the BCD for buoyancy over the decades. In the end, I really consider the DS and BCD as one system. Predominantly, the BCD is often just easier to adjust for buoyancy, due to better and more vent locations. However, I often move air adding to one and subtracting from another. Every one thinks about adding air/fluffing up the DS to warm up, but in the summer removing air from the DS can also help cool u down. I also will move air around the suit to adjust trim or for a specific purpose. Sometimes moving air to my feet to invert for a bottom photo where I can drop vertically to get a photo while hanging upside down, …or walking upside down under the ice.

In short, I may favour the BCD, but I don’t really think about one or the other, I just adjust air as needed for what is needed. Eg. I may add air to my DS to increase buoyancy, since I want to warm up as well. I also will carry a couple of extra lbs of lead in very cold water to ensure I’ll be able to fluffy up my DS without having buoyancy issues. Can’t say enough about a shell DS. Way more comfortable wearing a bag DS than a 7 mm WS.

 

[boulderjohn]

I thought I would quote a section of a book I mentioned earlier. The title is Dry Suit Diving: A guide to Diving Dry (4th edition). The authors are:

• Steve Barsky--this author has produced drysuit training materials for Aqualung, Diving Concepts, DUI, and Viking.
• Dick Long--Former head of DUI
• Bob Stinto--former chief engineer and V.P. for DUI.

from Proper Descent Technique (Page 94)

As you begin to feel the "squeeze" on your body, push the inflator button on your suit using short bursts to add enough air inside the suit to relieve the pressure. Add just enough air to remove any uncomfortable suit squeeze and control your descent. You should be able to stop your descent at any time by adding just enough air to make yourself neutral at that depth.
​

from Proper Dry Suit trim Underwater for Sport Diving (Page 94)

Once you reach the bottom, adjust your buoyancy using only your dry suit so you are neutral. Do not add air to your buoyancy compensator to adjust your buoyancy. It is very difficult to adjust your buoyancy when you have air in two separate compartments at the same time, i.e., the B.C. and your suit. Controlling both air compartments is an advanced dry suit diving skill and is not recommended for the novice dry suit diver.​

 

[lexvil]

I thought I would quote a section of a book I mentioned earlier. The title is Dry Suit Diving: A guide to Diving Dry (4th edition). The authors are:

• Steve Barsky--this author has produced drysuit training materials for Aqualung, Diving Concepts, DUI, and Viking.
• Dick Long--Former head of DUI
• Bob Stinto--former chief engineer and V.P. for DUI.

from Proper Descent Technique (Page 94)

As you begin to feel the "squeeze" on your body, push the inflator button on your suit using short bursts to add enough air inside the suit to relieve the pressure. Add just enough air to remove any uncomfortable suit squeeze and control your descent. You should be able to stop your descent at any time by adding just enough air to make yourself neutral at that depth.
​

from Proper Dry Suit trim Underwater for Sport Diving (Page 94)

Once you reach the bottom, adjust your buoyancy using only your dry suit so you are neutral. Do not add air to your buoyancy compensator to adjust your buoyancy. It is very difficult to adjust your buoyancy when you have air in two separate compartments at the same time, i.e., the B.C. and your suit. Controlling both air compartments is an advanced dry suit diving skill and is not recommended for the novice dry suit diver.​

Proper weighting being key.

 

[Steelyeyes]

Those diving drysuit, do you use it like a bcd or just adjust for squeeze and use bcd? Tried both ways myself. PADI try’s to tell you to use drysuit. Thankx in advance.

I used just enough air to control squeeze in the suit and buoyancy was handled with the BCD. It gives you two dump valves to get rid of positive buoyancy you no longer need. My wife just used her suit because that's what PADI taught.

 

[boulderjohn]

Proper weighting being key.

Absolutely. If you are overweighted, you will need to add air to the BCD as well.

As a technical diver, I am vastly overweighted (by the recreational definition) on almost all my drysuit dives, so I am used to using my wing as my primary buoyancy controller. It is different for single tank recreational divers.