Drysuit vs BCD / Wing as Your Buoyancy Control

[Jax]

Okay, I don't get it . . . yes, I'm easily confused; there, saved you from saying it!

I'm reading the PADI drysuit diver manual. It has an interesting set of instructions:

Underwater, you control your buoyancy using only your drysuit, except in an emergency.

BUT

If you're diving with a neoprene drysuit, you will probably use your BCD to control your buoyancy.

AND

In tec diving, you dive (using your bcd) not matter what kind of suit.

I don't get it. Why use your drysuit as buoyancy control at all, given that you may not dive dry all the time, that if you progress into tec or cave you will use your BC or Wing, etc.

Why not use the drysuit inflate for squeeze from the get-go, and stick to using your BC for . . . buoyancy control!

So, am I missing something here? Would someone help me understand the pros and cons, as I don't see the issue with having two gas spaces to manage being an issue?

(if this doesn't belong in exposure suits, feel free to move it, Mr/Ms Mod!)

 

[noreastDIVER84]

PADI's instructions suck. They are basically setting you up for an uncontrolled ascent, either feet up, or any other variation. I was told to use the BC for buoyancy and just enough air in drysuit to eliminate squeeze. I am still working on it though, I am adding very minimal air to my drysuit and do feel some squeeze, but not an uncomfortable amount.

 

[tkdgodess]

drysuit for comfort, bc for buoyancy. It seems to me that the writers of that particular padi manual haven't spent much time diving in actual cold water in an actual drysuit. I have student do all the skills in the pool using the DS, and have them demo the skills in OW using the DS, but I let them know DS for comfort, BCD for buoyancy, and that may vary too, (ie a really cold day I'm using my DS more) it's an ongoing balance between the two. PADI's manual represents minimizing task loading between the ds & bcd imho that's why they say to just use the ds overall...but a good solid hour in the pool doing only ds skills, then 2 good dives in OW most people pick up the basics, but it took me about 20 dives to not be super paranoid about an uncontrolled ascent.

 

[TSandM]

I think what it boils down to is that you have to have enough gas to be neutral. Where you put that gas can vary by the type of dive (it's much easier to use the drysuit for buoyancy with a small, single tank, than with a large one, or doubles), the type of suit, the water temperature, and your experience level.

I believe it is far easier for a novice to run the suit tight and manage most buoyancy with the BC -- at least it really was for me. But you have two problems with that approach: One is that you don't optimize the warmth from the suit and undergarments, and the other is that, if you need to get gas out of the suit, it's quite difficult to do it when there is very little in it.

In a cave, where "unusual attitudes" may be forced upon you by the topography, the minimum amount of gas in the suit is usually the best approach. In a simple open water dive, on the other hand, it may be perfectly feasible to carry the majority or all of your compensation gas in the suit, and stay warmer and more mobile.

I think a well-practiced diver can make situational decisions about where to put the gas, and if you don't have the situational awareness to remember where it is, you have other problems than your buoyancy.

 

[parzdiver]

I learned from my initial instructor to use the suit and he does it with flawless operation. I was doing okay and then a couple other instructors for who I have great respect told me to try using the wing for buoyancy. What a difference, I was able to much easier control myself using the wing and just using the drysuit for comfort. The wing gives you much better responsiveness inflating and deflating than the drysuit.

But of course, YMMV.

 

[peterbj7]

There will always be some air in the suit, but you want to ensure you have enough in the BC that you can dump it quickly and recover from a developing buoyant ascent. You cannot get air out of a suit quickly, especially the last bit. Near the surface I always get rid of all the air from my suit and transfer wholly to BC control. PADI's instructions in this, as in so many other things, are nonsense.

 

[ptyx]

Squeezed drysuits are cold and uncomfortable.

Empty BCs and ballooning drysuits make for unstable trims as the free gas bubble travels from the feet to the arms. The bigger the tank and the more overweight you are the worse it gets.

You'll need to figure out what compromise works for you depending how cold you want to get, how critical the stability of your trim is, and how much you want to fine tune your weighting.

The whole idea around leaving the BC empty makes sense for the first couple dives where you're figuring they dynamics of a new suit. Getting the BC out of the picture makes learning easier. But soon enough, you'll find out that better trim stability/comfort is worth the tiny bit of extra task loading and will bring the BC back.

 

[NC Wreck Diver]

I also use the BC for bouyancy control and the drysuit for comfort and warmth. As mentioned in other posts, it's easier to maintain and/or dump your BC faster. But I find that if my drysuit has virtually no air in it, and it's squeezing bad, I can sometimes feel minor leaks from the empty suit, as I grab an anchor line. IMHO, I always need a little puff of air in it to stay dry.

 

[Jax]

Well, y'all are saying what I thought I'd learned from ScubaBoard - suit for comfort and BC/Wing for . . . well, BC!

I guess I have learn to do it 'their way', or I won't get the cute little cert card!

 

[a22shady]

My instructor during our Drysuit course told us to do it that way because PADI wants it that way, But then told is that it is not the correct way and the Drysuit should be used for squeeze and BCD for bouyancy. So ofcourse I asked why that way then he told me becuase as someone doing the course is new to drysuit diving and they do not want to task load the new diver with trying to maintain 2 differnt sources.

I think to teach someone the wrong way and theyn have them to it a different way later only makes it harder to change or do it right. But atleast for me the instructor clearly new the proper way to do it and explained it to us. In a way it makes sense as it can be little diificult at the start but either way. Since we have dove the way we were told both by instructor/LDS and others. Also wrote something to PADI about it in hopes they might make a change to that in the future