Twins with only drysuit for buoyancy

[drdaddy]

Thank you JeffG.

JeffG was good enough to correct me on some eroneous opinion that I had given (see below).

It's been a some time since I used a drysuit, so I'm erasing any advice.

And I'll try to be more careful in speaking on what I (think) I know, rather than on what I (think) I remember.

I dive wetsuit now.
drdaddy

 

[JeffG]

Good point.

And actually, "there's no point in using your drysuit to control buoyancy" in any diving. Beginning drysuit classes teach buoyancy control using your BCD or BP/W.

The PADI drysuit course teaches the diver to use the drysuit to control buoyancy and the BCD to keep the diver afloat at the surface.

When using an AL80 (or any smallish tank) and having the diver weighted right, the excess gas bubble is not so large. (and thereby easier to manage.)

 

[Buoyant1]

Actually...thats not the reason for the dual bladder.

A drysuit pretty much has consistent buoyancy characteristics throughout the entire water column. Wetsuits are buoyant near the surface but have almost no buoyancy at depth. Add the weight of your gas into the equation a damaged wing would be catastrophic.

or another way of thinking about it.

with a drysuit, a diver will be negative by the weight of his gas alone. A wetsuit diver will be negative by the weight of the gas and the loss of buoyancy of his/her wetsuit.

Interesting...I was just tossing it out how it was once presented to me.

 

[jtivat]

The PADI drysuit course teaches the diver to use the drysuit to control buoyancy and the BCD to keep the diver afloat at the surface.

When using an AL80 (or any smallish tank) and having the diver weighted right, the excess gas bubble is not so large. (and thereby easier to manage.)

Not when I teach it.

 

[TSandM]

Just to throw out another thought . . . When I took Helitrox from AG, he strongly encouraged us to put as much gas in the suit as we could, and use the wing as little as possible. This actually works VERY well for scootering or running line, where it is easy to vent the suit while still using your hands for something else, as opposed to venting the wing, which requires the use of a hand.

How well you can do this does depend, to a great extent, on which doubles you are using and how far they are pumped. I would not have been able to come NEAR solid neutrality with cave filled 95s and just my drysuit -- I would have looked like the Michelin man. But in Al80's in MX, or in my 85s are home, I can easily just use the suit. I have the wing for backup buoyancy if I need it, and I'm much warmer.

 

[DaleC]

When I took my PADI drysuit course we were taught to use the drysuit for bouyancy so we could understand its bouyancy properties (only). During a normal dive the BC(D) is used for bouyancy and the drysuit is just inflated to take the squeeze off and increase the thermal effect.
It's funny, because I just had this discussion with an instructor a couple of days ago as well.

Lynne, How do you vent the DS without using your hands?

 

[Sas]

How do you vent the DS without using your hands?

I usually leave my vent fully open. It vents automatically. Even when I might shut it for some reason, when I want to ascend or change depths, I open it and it vents automatically from that point on. Sometimes I need to raise my shoulder a bit (I have a shoulder dump valve) to get the air out but it doesn't require my hands.

 

[D_B]

I think that aside from having a bigger than easily managed amount of air in your suit ... two full steel tanks and maybe 20/30lbs of lead/plate that you have to swim up to the surface after a total suit failure would not be good (Ok, you have your lift bag/SMB, but still)

 

[caver]

Just to throw out another thought . . . When I took Helitrox from AG, he strongly encouraged us to put as much gas in the suit as we could, and use the wing as little as possible. This actually works VERY well for scootering or running line, where it is easy to vent the suit while still using your hands for something else, as opposed to venting the wing, which requires the use of a hand.

How well you can do this does depend, to a great extent, on which doubles you are using and how far they are pumped. I would not have been able to come NEAR solid neutrality with cave filled 95s and just my drysuit -- I would have looked like the Michelin man. But in Al80's in MX, or in my 85s are home, I can easily just use the suit. I have the wing for backup buoyancy if I need it, and I'm much warmer.

I have to agree with AG under some conditions. When a dive profile is going to have a constant bottom depth, yes, but in the case of a cave dive if the profile of the cave goes up and down, no. Under these conditons you waste so much gas venting the drysuit and blowing it back up, then venting again.
As to the OP's question,,,is he asking if it is OK to dive with NO BC/WING? Only a drysuit? If that is what he is asking - NO !

 

[Reg Braithwaite]

When I took my PADI drysuit course we were taught to use the drysuit for bouyancy so we could understand its bouyancy properties (only). During a normal dive the BC(D) is used for bouyancy and the drysuit is just inflated to take the squeeze off and increase the thermal effect.

Somehow I managed to buy a dry suit without Putting Another Dollar In. I read the PADI instructions and also did a little research on the subject. In the end, I decided that I needed to know how to use the dry suit for buoyancy in case of a wing failure, so I spent the Summer using my wing and my suit for buoyancy control on alternate diving trips. I dive steel singles, and have had no problem using the suit, although I admit that since I am self-taught, I may be Doing It Wrong.

That being said, my thought is to use the wing for buoyancy and just keep the squeeze off now that I have some (possibly misplaced) confidence with the suit. And obviously, that's all I get when diving wet down South.