PADI Drysuit Course confusion REC vs TEC

[Peter Guy]

OP - yes PADI does say that - rec use dry suit, tec use bcd. I does appear to be a task loading issue. Me, I teach a dry suit course or orientation fairly often - sometimes several of my OW students are dry. I just tell them what PADI recommends but that they should be thinking divers and to do what works for them.

Me, I hardly use my bcd at all underwater. I've used different variations (BC primary, 50-50, Dry Suit primary) and have ended up Dry Suit primary with the BC used when I have some additional weight. It really is, what works for you!

 

[stevensamler]

I think that if you are properly weighted for the undergarments and gear you're using and diving a shell ds adding gas to suit for squeeze and then small amounts for bouyancy plus using lung volume should be all you need.

 

[sgl308]

So you want to know why it's taught different at the rec level than at the tec level... Here is your answer. With rec diving, the gear is lighter and the buoyancy you get from a drysuit is usually sufficient lift to maintain neutral buoyancy. There is the task loading issue that most instructors don't want to address because they have a hard enough time teaching all the other basic skills.

With tec diving, the diver wears more gear which is heavier, therefore requiring more lift. You still need to inflate the drysuit to prevent squeeze, but if you inflate it enough to maintain buoyancy, you'll look like the Michelin Man and not be able to move. That's why you need to use the bcd or wing as well.

I do the tec version even if I'm diving with recreational gear. It's easy for me.

 

[DevonDiver]

There is a different policy for drysuit use between rec and tec levels. The essential reason for this is because PADI believe that it is simpler and less risky for a novice drysuit user/novice diver to only have responsibility for controlling one buoyancy issue during a dive, especially on ascent. However, at tec level, the student can be considered an experienced diver/experienced drysuit user; thus competent to control two buoyancy issues.

The quotes that illustrate.....

2. Positive buoyancy on the surface.
a. When resting or swimming at the surface, use your BCD for positive buoyancy.
b. Adding enough air (or argon) to your suit to make you that buoyant is uncomfortable because it accumulates and balloons around the shoulder area, putting pressure on your neck and pushing you down into the suit. It can also interfere with moving your arms and put undue stress on suit seams and the zipper.

4. Adjusting your buoyancy underwater.
a. Underwater, you add air or argon only to the suit. Do not use your BCD.
1. This avoids a suit squeeze (severe pinching due to compression as you descend).
2. You’re not having to control two systems — adding or releasing gas as you change depth.
3. It keeps the proper amount of air/argon in your undergarment for insulation.
b. As you descend, lower your left shoulder so gas does not vent from the exhaust valve and add gas to offset compression. This maintains buoyancy and avoids a suit squeeze. At the bottom if you’re properly weighted, you should need to make no more than a minor adjustment to your automatic exhaust valve so that your suit holds the right amount of gas to stay
neutral. You can close the valve slightly so your suit holds more gas.
c. When adding gas to your suit, do so slowly — short bursts help keep the valve from freezing up in extremely cold water. As you descend, just add short bursts every so often. If you find you need to add a lot of gas during descent to maintain neutral buoyancy, you probably need less weight. [Review with students how to add gas underwater to their particular
dry suits.

3. Dry suits offer the longest durations and coldest water protection.
a. They may provide ample backup buoyancy.
b. You should master dry suit diving as a recreational diver before using a dry suit for technical dives.
• 20 dry suit dives is a conservative minimum before tec diving dry.
• In recreational diving, you only use your dry suit for buoyancy control while underwater.
• In tec diving, you typically add gas to the suit to avoid a suit squeeze and use your BCD. This means controlling the gas in both your suit and BCD – a more complex skill to master.

Personally, I've never agreed with the 'drysuit for buoyancy' approach. It assumes incompetence on behalf of the student (and instructor??) and compensates for this with bad diving procedures.

 

[Xaryo]

For me it depends on the water temperature. In winter, ice, coldwater diving (below 40F) I will use the drysuit as the primary buoyancy device. (more air= more heat), I carry additionnal weight accordingly.

In summer, I'll go with the wing as the primary buoyancy device. And the suit just above the squeeze.

 

[XS-NRG]

Excellent. Thanks Steve and Andy! Great explanations. I think I will be competent enough to manage buoyancy in 2 devices. Obviously it will take practice of course! I think it will be good to understand how it feels to have an inverted buoyancy issue and recover but I think I'll minimize the air in the suit as much as possible and stick to my i3 for maintaining neutrality.

 

[Peter Guy]

Personally, I've never agreed with the 'drysuit for buoyancy' approach. It assumes incompetence on behalf of the student (and instructor??) and compensates for this with bad diving procedures.

With tec diving, the diver wears more gear which is heavier, therefore requiring more lift. You still need to inflate the drysuit to prevent squeeze, but if you inflate it enough to maintain buoyancy, you'll look like the Michelin Man and not be able to move. That's why you need to use the bcd or wing as well.

For the record, I disagree with both of these statements -- but that is not why I've quoted them.

Both statements are from people who dive in warm water (although the author of the first is FROM a cold water background) and I wonder if they are just reflective of the differences.

I dive dry in cold water and as I've written, I use my dry suit as my primary bouyancy device. It is warmer and, to me, simpler (a mere lift of my left arm to vent as I ascend).

Is my gear significantly heavier if I'm doing a "technical" dive? Double 100s vs a single 130 but a Kydex plate vs. steel with weight plates. Yes, a bit heavier but from a bouyancy standpoint, not so much (even with a deco bottle). While I may leave a little air in my wing, I'm still using my dry suit as my primary -- again, more air (argon), more insulation, warmer me.

I contend there is no Right answer -- it is whatever works for you in that particular situation.

 

[Hawkwood]

Where my air goes depends to some extent on the season. Our water temps will range from 32/33F to 55/60F through the year. Depending on the temperature I might have a lot of air in my suit vs by BCD (yes, I mean BCD), when it is warmer it might be the other way around.

I have gone through stages in learning to work with the dry suit (I do like to think of it as "working with" the suit). Started with the suit for buoyancy only, swung to suit for warmth only and BCD for buoyancy, and now it is "it depends".

I teach the PADI Dry Suit Diver course. I teach students to use the dry suit for buoyancy to start. However, they are also taught to think about it - if we have not got their weight and trim right and they feel too "floaty" in controlling the suit only, why not compensate with some air in the BCD. Eventually a thinking diver should work it out.

Bill

 

[DevonDiver]

Both statements are from people who dive in warm water (although the author of the first is FROM a cold water background) and I wonder if they are just reflective of the differences.

I dive dry in cold water and as I've written, I use my dry suit as my primary bouyancy device. It is warmer and, to me, simpler (a mere lift of my left arm to vent as I ascend).

I contend there is no Right answer -- it is whatever works for you in that particular situation.

Absolutely - it's a case of personal preference. My issues with drysuit-for-buoyancy stem from the risk of getting inverted and 'blowing your fins off'. There were quite a few occasions when I'd have to be 'head-down' in my drysuit diving/penetrating wrecks... and I didn't like a large volume of air in the suit when that was necessary.

The risk of losing control inside a wreck... or making an unintended rapid feet-first ascent, over-rode any issues of convenience or possible thermal benefits.

As with all things scuba... I developed an ingrained skill-set with one approach and stuck with it, so as to gain the benefit of familiarity.

Good under-garments and, if necessary, argon takes care of the cold. I don't think there's a need to use inflation in that respect. I used to dive in 3 degree Celsius freshwater in the UK winter... sometimes argon was needed (for longer deco), but good layering of undergarments meant I never got cold, even when 'shrink-wrapped'. I used merino wool long-johns and long-sleeve shirt underneath 4th Element Xerotherm Artic two-piece mid-layer, with a Weezle down-filled vest over the top. I was also quite fat But I was never cold.

Another factor was trust in the buoyancy device. I know where I am with a wing... it inflates, holds air securely... and deflates just as I know it will. There's no chance of a 'torn seal', or air migration causing a critical loss of control/stabilization. If I have a problem underwater, I don't want a single problem causing multiple issues. If my drysuit is my buoyancy... then a torn seal causes multiple problems that I have to deal with simultaneously - the shock of cold and the loss of buoyancy. If however, each component is used for its intended purpose, then a failure only causes a single problem.

I used a drysuit.... to keep me dry.
I used a buoyancy control device.... to control my buoyancy.

Nowadays, I dive in shorts and a rash guard..... what was the question?

 

[VooDooGasMan]

So I will add My suit has boots and air fills them easily, the clothing underneath is what keeps you warm, air will get cold.

Now saying that if you kick the whole dive for the most part you will stay warmer air or minimal air in suit. Just slowly moving along it is going to chill, so I prefer less air and I stay warmer. I dive a 7mm titanium twrex which is less colder water cooling inside my suit.

I dive wet now and the water is 44 F, so it also determines how well you can handle the cold.