Why do agencies teach wrong drysuit use?

[airsix]

The trip I took last week to Puget Sound was with 3 other divers who are not in the water too frequently. They were all new to drysuit diving, with two of them having just finished their first (checkout) drysuit dives prior to our trip. The third diver had dove a drysuit several years earlier, but only a few times. After the second dive the conversation turned to drysuit frustration regarding buoyancy, trim, and ascent control.

I talked with them about what they were doing and what they were experiencing. I also shared what I observed when we were in the water together. I asked if they would mind if I shared my thoughts and they were very eager. So I explained about diving with a moderate squeeze at all times , using the bc for buoyancy, and 'staying ahead of the curve' on ascent with regard to suit venting. (Note to Nailer, Burntchef, LCF: I replaced my exhaust valve and air-tight undersuit which cured my own venting problem you saw in June). We also talked about keeping the exhaust valve loose and using shoulder position to control venting vs. having to manually vent a tight valve.

The response I got was "But that's the opposite of what the instructor said! He said get to depth, crank the exhaust valve closed, air-up the suit, and keep the bc empty except at the surface." I talked about the big air bubble moving around inside the suit and it's effect on trim as well as the difficulty of managing (venting/dumping) a large volume of air from the suit. They agreed to try the technique of keeping a moderate squeeze on the suit throughout the dive and managing buoyancy with the BC.

Verdict: They came up from the next dive raving about how much more in control they felt regarding both buoyancy and trim. They didn't mention it, but I also observed that their air consumption dropped dramatically as well. It really felt good when one of them said "Thanks. That's the best diving tip anyone's ever given me."

They asked "Why were we taught the other way. This way works so much better." I explained that the best we can figure is that the agencies feel there is less task loading if you are only managing the suit and not suit+BC. One of the guys replied that it was a lot less of a task load to not be fighting the migrating suit-bubble all the time. I'd have to agree with him.

I'm wondering how many new drysuit divers are being frustrated into inactivity by the poor techniques being taught. What do we do besides helping our friends after-the-fact the way you folks helped me and I was able to help these guys?

-Ben

ps - I recognize there are good instructors who teach excellent technique. I'm not talking about them. I'm talking about agency policy of teaching the less-effective method.

[Joshua Smith]

I know good divers who use their suit for buoyancy control, and others who use their wings. For me, it was easier to use my wing and keep a moderate squeeze on the suit at first. These days, I use both, but without even thinking about it, I find myself using my suit more, and my wing less. So, in my opinion, you should use whatever combination works for you, but try both ways.

[cardiver]

Me too. When I first went dry I would have bruises that looked like creases in my suit. It really bothered me the first time I saw that! I was so worried about having to adjust air in both the suit and the wing that I let the suit squeeze me so I could only adjust the wing.

[CaptnJack]

With winter coming on and scootering a bunch I am using my suit more and more...

But then again I don't have any issues managing the bubble except on my scooter. Then there can be a bit of contortion to shift it towards my head and dump when I stop. I rarely "crank the valve closed" more than 1-2 clicks. Never touch it while scootering.

Beginner drysuit divers I think should use the BC for bouyancy. The suit is a big bag and good trim is hard enough without a buble sloshing around.

[Dmitchell]

On OC, I use both. On the Rebreather I was taught to use the suit and that's mostly what I do but I still revert back to the BC from time to time because I don't like that much air in the suit.

When I teach, I teach students to use the suit but I explain that I use both and why.

With a new student, they have so many things going on that learning to use just the suit initially simplifies one thing for them. That way on an ascent when they are only concerned with venting the suit and don't have to worry about the BC.

I try to get them to understand the what's and why's of everything and to understand that if they want to use the BC that's fine. Just remember that you have to vent both on the way up.

I teach them to keep the valve open all the time unless they have some compelling reason to close it.

Dave

[Tom Nic]

Beginner drysuit divers I think should use the BC for bouyancy.

This seems to be the easiest way to "get used" to diving with a drysuit, and the anectodal evidence seems that it is therefore the "best" way as far as initial training goes. I agree with the OP, this should be taught that way.

Once you are comfortable in the suit you will find yourself using both, and doing so almost without thinking about it.

[Grateful Diver]

It's a common issue, and one related to how a certain agency prefers to teach dry suit usage. In truth, many drysuit manufacturers also recommend using the suit for buoyancy, although that is changing. DUI changed their "official" position on the subject only a couple of years ago.

There's a good article floating around the Internet on the mechanics of using your BCD vs your drysuit for buoyancy control.

http://www.divetekadventures.com/Techni ... bility.htm

I'll leave it to you to draw your own conclusions. Personally, I was taught to use my drysuit for buoyancy control, and did so for hundreds of dives. I got pretty good at it. But as my diving started reaching a point where I wanted finer control over my position in the water, I found I was fighting a moving bubble too much, and switched over keeping minimal air in the drysuit and using the BCD more ... and after an initial adjustment period, I discovered I could more easily control precise movements in the water.

The argument about not controlling two buoyancy sources is a red herring ... almost all of us, no matter which method we use, leave our drysuit vent valve open while diving. When you do this, the act of raising your BCD inflator hose to vent air from the BCD will automatically place your drysuit dump valve in a position where the air bubble in your drysuit will travel ... and the excess gas in your suit will vent automatically as you're venting your BCD. If I don't want to break trim, and just want to vent a little bit of gas from my suit, the simple act of "flexing" my shoulders will force gas out of the dump valve while I remain horizontal and only slightly move my left shoulder higher than my right. It doesn't take much movement at all to force the gas bubble to travel where you want it to go.

In the end, this argument is much like the one between split fin users and blade fin users. With enough practice, you can get good either way ... your body adapts to whatever method you use, providing you apply yourself to learning how to get the most out of the equipment and technique that you're using. But one method will get your more precise control than the other. For many divers, precision control isn't important ... and for the divers who want that level of control, they'll eventually make the switch anyway.

Keep in mind ... the majority of what you get taught in scuba classes applies primarily to the occasional, recreational diver. As long as it "gets the job done" it's good enough. From this perspective, either method works.

... Bob (Grateful Diver)

[Aquanautchuck]

Like most divers, I too was told to use the dry suit. This never sounded right to me so I just kept using my BC just like I had been doing with a wet suit. I discovered that if I left the valve just a couple of clicks back from full open it would be perfect. As Bob mentioned just the act of rolling a little will dump air. As you start coming up from your dive the valve will dump the air almost automatically.

Just as a side issue on squeeze. I have discovered that neoprene suits have a softer squeeze and also the bubble is not as big as in bag suits.