Drysuit or BC for boyancy control?

[mainedvr]

I just finished a drysuit course (PADI) for the most part I took it for the card to be able to rent a suit if I should need to or want to try some different suits. But I found I learned a few things which was great. The one thing I was wondering is I have noticed at least two schools of thought....Using the drysuit for boyancy control at depth and the bc only on the surface, and then just using the drysuit as thermal protection with just enough in it to stop the squeeze and give the air space for thermal properties and the BC for compensation.

I don't care which one people think is better I was just curious as to why the two different schools of thought. I can see trying to manage two air volumns on accent the suit and bc but the dump valve should take care of that. Again this is not to bash either one just wondering about others thoughts on the pro's and con's of each and maybe why they exist.

Thanks

 

[Diver0001]

The truth of the matter
First of all, there are not two schools of thought.

People on the innerwebs seem to have this idea that PADI says that you should always use the suit. It's so entrenched in people's thinking that even when you point out that PADI does not say this, that they don't believe it. Some instructors even get to that point and instruct students incorrectly.

What PADI says is that depending on the type of suit you have, this may or may not be an option. Some suits do not lend themselves at all to using only the suit for buoyancy control and it would be dumb to recommend it. Other suits are much more forgiving in that regard, in which case the diver could do so if it suits their personal preference.

The actually reality of the matter is that no matter what you do, you will *always* have some air in your suit. If the amount of air you can *comfortably* fit into the suit is enough to get neutrally buoyant then there may be no need to use the BCD for additional lift. If not, you use the BCD.

The history
back in the day, and we're talking late 70's when the BCD was first beginning to gain main stream traction, the alternative buoyancy control we had for the drysuit was a horse collar BCD. They had a terrible tendency to ride up when you used them under water so most people tended to put as little air into them as possible while diving and only use them on the surface when/if necessary.

Somehow this idea of not putting air in the BCD seems to have carried over from that practicality into the general swarm thought of people who talk about this stuff on the internet. It's likely that this was even incorporated into early PADI materials regarding use of the drysuit but that recommendation (if it ever was) hasn't been in the book for years.
R..

 

[TMHeimer]

r, Thanks for the info. I've never dived dry but did wonder about that.

 

[runsongas]

depends also how much gas you are compensating. with large doubles, you pretty much have to use the wing for buoyancy.

 

[fmerkel]

Either way can work. Sometimes it's taught as 'use the suit only' to make the (usually short) drysuit course simple.

IMO, baggy shell suits don't lend themselves too well to that method as the air bubble becomes a problem.
Well fitted shell suits can work either way.
I have a well fitted neoprene suit and rarely use my BC unless it's a pretty deep dive, have plenty in the suit, and need a bit more buoyancy. I also have a forearm dump that exhausts like crazy if I want it to. Some suits can be more problematic making the BC a bit easier to use.

 

[wetb4igetinthewater]

The truth of the matter
People on the innerwebs seem to have this idea that PADI says that you should always use the suit. It's so entrenched in people's thinking that even when you point out that PADI does not say this, that they don't believe it. Some instructors even get to that point and instruct students incorrectly.

What PADI says is that depending on the type of suit you have, this may or may not be an option. Some suits do not lend themselves at all to using only the suit for buoyancy control and it would be dumb to recommend it. Other suits are much more forgiving in that regard, in which case the diver could do so if it suits their personal preference.

The actually reality of the matter is that no matter what you do, you will *always* have some air in your suit. If the amount of air you can *comfortably* fit into the suit is enough to get neutrally buoyant then there may be no need to use the BCD for additional lift. If not, you use the BCD.

The history
back in the day, and we're talking late 70's when the BCD was first beginning to gain main stream traction, the alternative buoyancy control we had for the drysuit was a horse collar BCD. They had a terrible tendency to ride up when you used them under water so most people tended to put as little air into them as possible while diving and only use them on the surface when/if necessary.

Somehow this idea of not putting air in the BCD seems to have carried over from that practicality into the general swarm thought of people who talk about this stuff on the internet. It's likely that this was even incorporated into early PADI materials regarding use of the drysuit but that recommendation (if it ever was) hasn't been in the book for years.
R..

Have you looked at the performance requirements for the dry suit specialty course lately?

 

[tmorg]

I use my suit for buoyancy at depth,and BCD on the surface.

I'm not saying this is the only way it should be done.

But this method has worked well for me.

YMMV

 

[matt_w]

I will tell you the real secret. It doesn't matter.

I usually end up negative and my BCD compensates for that and I add air to the suit on descent because I have to add air to the suit anyway. Part of the reason there is confusion is because people think you have to dump your BCD completely to descend. I also dive with my drysuit dump valve all the way open.

What you do will depend on what kind of diving your doing, what kind of suit you have, etc.

As an unimportant aside, the PADI quiz for PPB definitely has drysuit as the right answer to this question. I am not sure what they say in the drysuit course.

 

[Diver0001]

Have you looked at the performance requirements for the dry suit specialty course lately?

Yes, I give that specialty regularly.

Have you read the book?

R..

 

[Diver0001]

As an unimportant aside, the PADI quiz for PPB definitely has drysuit as the right answer to this question. I am not sure what they say in the drysuit course.

The drysuit course (the book) says what I said above aside from the history lesson.

There is a performance requirement in the drysuit course that requires the student to achieve neutral buoyancy using only the suit. This is completely logical seeing as how they are learning how to control the suit. That is not the same as recommending that they dive like that at all times in every circumstance.

You can compare this to the performance requirement in the Open water course that lets the student hover and control their buoyancy only with breathing. This is not the same as requiring the student to control their buoyancy at all times under all circumstances with ONLY their breathing. It's teaching a step in the skill set, not setting a rule in stone.

R..