Sinlge vs double bladder

[AquaTec]

I use a dble bladder, and find that there is no more drag than a single. actualy i feel bunggied bladders offer much less drag.

I have both inflator valves connected durring the descent. then durring my dive on the bottom i disconnect it.

with a double bladder using a drysuit is a remote third option putting the lift bag idea even further back.

even if you do believe there is a slight added drag by using a double bladder, the advantage is greatly out weighed.

as for added failure points, it is no more than the added failure points of an backup reg. and if the inflator hose is left disconected then most of the concern is eliminated

 

[Master Chief]

I dive the St Lawrence as well its a wonderfull divers playground. I use an Abysmal double bladder because and only because I dive wet. I wouldn't want to be caught at depth in steel 98's with deco bottles and with out a secondary means of inflation. I think that using your dry suit to get you off the bottom and up should be looked at as a very, very last resort if it works at all. No! dry suit is going to give you the lift required plus its a dangerous manuver if you can't control your inflation and air purge on the way up when deco stops are required. I always look at it this way skill preparation and equipment care will always guarantee you a safe return home and in my 27 years of diving I have never seen a bladder fail at depth unless it was seriously neglected by its owner or wasn't designed for deep technical diving and was unable to provide the lift after the diver reached depth simply because of its low volume and the diver not knowing what he/she is doing. We all have our own opinions on the matter and this can be debated for months and it probably will be.

Thank you

Master Chief

 

[madmole]

Thats a supprise, cos most of us dry bag folks use our drysuits as our primary bouyancy compensation on all dives. Controlling the buoyancy in a dry bag is easier than in a wing (just shrug shoulder to vent) and I dont know what drysuits you've seen but my drysuit easily provides probably about 5 times the boyancy of my 55lb lift wing (think Michelin man).

In the UK must people only use the wing/bc for surface support. Its bloody cold in the water so using the suit as your BC also keeps you warmer

 

[MikeFerrara]

Using a drysuit for a bc may work ok with a light recreational outfit (single tank) because your near neutral and don't need much air in the suit to get neutral. By the time you add enough to control squeeze your neutral and may not need any in the wing. You would not be able to use the dry suit for a bc with my double 104's though. You would have so much air in the suit that the instant your head or a wrist was high enough all the air would burp out and down you go. In the event of a wing failure, using the suit to control buoyancy would be a challange especially while doig decompression stops. It can be done but it isn't comfortable.

 

[MikeFerrara]

By far, the most common failure I have seen in wings or bc's is a stuck inflator. I think tis is a main DIR concern with double bladders. I have seen many stuck inflators and have only seen one total failure of a wing. So...are you fixing a problem or adding one when you add a second bladder? As some have said you could leave it unplugged I guess.

If there is water warm enough for me to do a technical dive in a wet suit and if I ever get to it I will likely use less negative tanks than my 104's.

 

[madmole]

Sorry, It seems to work fine on my double 12's with 2 7l slung stages, and I've used that combo with 8 cylinders strapped to me at 143m (2 of the tanks were stages being postioned for some one else)

Normal UK configuration. We consider it dangerous here to use the BC for buoyancy if you have a drysuit as its task loading. You have to add air in the suit so why add a second thing with air in it into the equation. Then you have 2 things to dump on the way up

We dive dry suits all year round here. ALL have shoulder auto dumps so they vent automatically on surfacing. Much easier than having to physically pull a hose or push a button on a BC

Both techniques work, use what one you are used to

 

[Master Chief]

Madmole

I can see your point, but your dry suit was not meant to be used as an entire diver lift device its purpose is warmth and to keep you dry, thou there are divers who incorrectly use it to over compensate for the weight there carrying. I don't think I've ever seen a technical instructor I know teach dry suit inflation as a means of seconday emergency lift incase of a bladder failer. I would love to see candidates practicing that skill. Even with all the bells and whistles on your dry suit it's still an unacceptable practice by many.

Master Chief

 

[madmole]

Better tell the largest dive club in the world, the BSAC, then as thats what they teach

 

[madmole]

Mike, Basic Diving lesson 8. The volume of a dry suit does not increase with depth if you use it for lift. The volume is constant.

So you are not bloated, or puffed up while diving.

Easy to dive. Stick some air in suit at surface, screw auto valve down 1 turn. Jump in. At shot, unscrew valve 1 turn, lift shouler a little and down you go.

As bottom appears press direct feed on belly, until neutral. do dive.

On surfacing, start to swim up and let drysuit gently lift you at you ascent speed. As you approach the speed you want, just lift left shoulder a little to vent. No hands used, which means you have them free for stage swaps, shotline, DSMB etc

Dry suit is great for staying horizontal at stops if you want to as you get whole body support not just lift from your harness, and you stay warmer

Try it my way, one dive, I suspect you will be pleasently suprised.

 

[MikeFerrara]

That's how I was tought to use a dry suit and it works fine if your not to negative. It takes alot of air to get neutral with my lp 104's. I almost got killed (not really killed but learning did take place) on my first dive with a set of lp doubles. I didn't know any better and tried to use the dry suit alone. One lift of the head and I was plumitting. To float those suckers I had a huge air bubble in that suit that made it unmanageable. The wing is much more stable than trying to balance those heavy doubles as they role around on the dry suit which is now a big air bag.

Now...try it in a cave where getting in a position to dump air from the suit can be hard. I keep as little air in the suit as I can and use the wing for bc.