Buoyancy Control: Dry suit or BC?

[Dive-aholic]

Another ditto on Bob and Rick. In a single tank with proper weighting, alleviating the squeeze will keep you neutral. If more air is needed for any reason, then go with the BC. It's a lot easier to control and dump air in the BC than the DS. To purge a DS you need to be vertical, head up, or more specifically, left arm up. I don't know many people who dive that way.

 

[BarryNL]

For me, definitely use the BCD for bouyancy control. The main reason for this is that a lot of air in the suit becomes difficult to control - particularly if you use a frog kick - you're constantly on the edge of a feet first ascent. And in that case, there is no way to vent air from the drysuit, while a BCD should have a dump valve on the bottom and also has the advantage of keeping the air nearer your centre of gravity.

You don't use a BCD to keep you warm: why use a drysuit for bouyancy control?

 

[SubMariner]

Whether you use the suit for buoyancy control and only inflate the BC on the surface to conserve energy, or use the BC u/w and only put enough air in the suit to offset squeze, it's all good.

It all depends on your training & how comfortable/experienced you are with the method you prefer to use. There is no RIGHT or WRONG way.

 

[Dean810]

When I took my drysuit course, the official PADI line is to use your suit for bouyancy. I have had a tough time finding a single diver that does this in practice. Every non-PADI book devoting time to drysuits that I have read state pretty clearly that the suit is NEVER used for this. The only thing I can figure is that PADI feels a new diver will be confused if having to use the BC for bouyancy and at the same time adding a little air to the suit to account for squeeze. So, if you go the PADI line, it is something you un-learn with time.

 

[do it easy]

You don't use a BCD to keep you warm: why use a drysuit for bouyancy control?

I generally use the wing for bouyancy, but I will add gas to my drysuit to control my trim. My feet and legs are negative, so I'll pump SOME gas and let it shift up there to hold my feet up. I'm not talking a lot, just enough for trim. Outside of the drysuit class, I can only remember being inverted once and it was in a high flow. I do have to remember to release the extra gas when I'm ascending.

 

[SadiesMom]

:::raising hand:::

Still new to DS diving - I only have about 6 dives on my suit and all those have been shallow - none deeper than 25 fsw. And so far, none colder than 50 degrees F. I'm using a DUI TLS350 with 300 weight fleece undies and lightweight polypro underneath and so far, I've been pretty darned cold!

However, those 6 dives *have* been while DMing classes, so I've spent a great deal of time hanging out on the surface with students (read: with a lot of squeeze on my legs and no way to add air to relieve that) and then hanging out relatively motionless on the bottom with students while they do their skills (i.e. very low New England vis means you can't hover over them and swim around - you need to be *right* there next to them).

On the guided dives, I've definitely been warmer, but I feel like I still have some squeeze on my suit - but so far, the air I've added for warmth has been enough to give me enough buoyancy.

So I guess my questions here are: Am I just diving too light? Do I need to add a couple of pounds so I can add more air for loft/warmth and then use my BC for buoyancy? Or is this due to the fact that I'm diving so shallow and the problem should go away when I do some deeper dives? Is the coldness thing primarily because I'm not moving around very much? Do I need thicker undies? Expedition weight polypro? (I don't consider myself to be a cold-natured person - I can comfortabley dive 50 degrees wet in my farmer jane and do two dives) Does any of this make any sense???

Any advice from you more seasoned folks would be great....

 

[Viscya]

With doubles, adding enough gas to the suit would be very awkward. The BCD is located in the proper place to add buoyancy in a stable fashion. The suit is not.

Our PADI class taught that you should use the BCD not the suit.

SadiesMom, I would recommend adding loft to your under garment rather than just adding weight and air. I will often add a layer of clothing then some weight in colder water. This is much more stable, and traps the air where it is needed. Also try to maintain a horizontal trim. On the surface lay on your back rather than keeping your feet below you. This relieves the squeeze on the legs.

V

 

[pants!]

Our PADI class taught that you should use the BCD not the suit.

Your PADI class taught you that the book was wrong? Interesting.

I wonder if this is specified in the instructor standards.

 

[MSilvia]

If you're still cold with loft in a good undergarment, you might consider getting a small cylinder to use as an argon inflation system. Argon is a better insulator than air, and should help keep you from losing heat to the water outside your suit.

 

[scubadobadoo]

:::raising hand:::

Still new to DS diving - I only have about 6 dives on my suit and all those have been shallow - none deeper than 25 fsw. And so far, none colder than 50 degrees F. I'm using a DUI TLS350 with 300 weight fleece undies and lightweight polypro underneath and so far, I've been pretty darned cold!

However, those 6 dives *have* been while DMing classes, so I've spent a great deal of time hanging out on the surface with students (read: with a lot of squeeze on my legs and no way to add air to relieve that) and then hanging out relatively motionless on the bottom with students while they do their skills (i.e. very low New England vis means you can't hover over them and swim around - you need to be *right* there next to them).

On the guided dives, I've definitely been warmer, but I feel like I still have some squeeze on my suit - but so far, the air I've added for warmth has been enough to give me enough buoyancy.

So I guess my questions here are: Am I just diving too light? Do I need to add a couple of pounds so I can add more air for loft/warmth and then use my BC for buoyancy? Or is this due to the fact that I'm diving so shallow and the problem should go away when I do some deeper dives? Is the coldness thing primarily because I'm not moving around very much? Do I need thicker undies? Expedition weight polypro? (I don't consider myself to be a cold-natured person - I can comfortabley dive 50 degrees wet in my farmer jane and do two dives) Does any of this make any sense???

Any advice from you more seasoned folks would be great....

Here are my opinions but you know they are no good! LOL!:10:

Becky and I also use almost exactly what you use. 300 weight fleece and polypro. We are cold once we hit the 50's so we have been adding ANOTHER fleece layer AND expedition weight undies when we drop into the 50 degree mark. That requires ANOTHER 5 pounds of weight or more to off set the extra fleece and to allow us to use a little more air but not much. I prefer to have the squeeze but Beck prefers to have more air and thus more loft and thus a little more warmth and I almost forgot, a little more weight. Make sense?

You will find that as you dive deeper in your dry suit you will need to add more air to both your suit (for the squeeze and loft) and to your BC (for the control). Much of the time you may find that at depts above 60 feet, you only need to add air to your Dry suit to get rid of the squeeze AND to help with your buoyancy. As you dive deeper, you will find that even more air is needed and thus it becomes easier (for me) to use my BC for buoyancy and the suit only needs air to give the fleece loft and to prevent turning me into a flap jack. Fleece squeezed to death will not keep you warm like already compressed thinsulate. Fleece tends to require more air and thus more weight than thinsulate materials. Make sense?

I agree that not moving will make you colder!

As for feeling cold in a dry suit and warm in a wet suit, I agree at times. I frequently feel colder in my dry suit than I did in my wet suit and after two years of this i have FINALLY realized that (for me) 300 weight fleece even with expedition weight undies isn't enough to keep me warm when diving the NE. Blame it on the undies maybe? I will probably try some 400 weight thinsulate next...And the money keeeps rolling out...

IMHO, dry suits are great but they don't always keep one feeling "warmer" IN the water. Keep you from getting chilled to the core longer, yes. Out of the water is where a dry suit really shines. If it's 40 degrees outside and you come out of the water in a wet suit, life sucks!

Long answers, sorry, but I hope they help. Some will also suggest dry gloves, a thicker hood like a 12 mil, or even argon but I think when you spend as much time in really cold water as you do, nothing will ever keep you toasty. I hate when people use that word when talking about how they feel in a dry suit in really cold water. "Toasty." What a lie! Does that mean I will go back to using my wet suit? HECK NO!