Sinlge vs double bladder

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Josh Levinson

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Montreal, Canada
Hey everyone,

I have the OMS bungeed dual 100 lb lift wings, and don't like them, so I'm looking for a new set of wings.

I'm focusing right now on the Halcyon 55 lb wings. I've had a good look at them, and I'm quite impressed. The absolute only hangup I have over them at this point is that they only have a single bladder.

Now, I understand that streamlining is an important issue, and fully agree that you need to be as streamlined as possible. But I don't think you should streamline at the expense of redundancy (within reason).

I've heard people say that as long as you have a drysuit, you don't need a double bladder. Then I ask, well does a drysuit provide enough lift on its own? The answer is usually "yes," but I'm not convinced of that.

Then they say, well, you should have a balanced rig, so you shouldn't need all the lift of your drysuit in the event of a bladder failure. But how do you get a perfectly balanced rig? You always have to start off more negative than you need to be at the end of the dive, cuz you use up gas during the dive. What happens if you have a bladder failure early in the dive, where you're the most negative?

The other issue is, what if you dive in a neoprene drysuit? Then you'll need more weight at the surface, but at depth you'll be overweighted, and therefore won't have a "balanced rig."

And if you dive in a wetsuit, what's your buoyancy redundancy there? Some people say a lift bag. But I'd like to see someone using a lift bag in an emergency (i.e. task loading) situation to lift themself from 300 ft.

But then people say, you attach your reel to the bag, and send it to the surface and ascend on the line. Okay, but then when I ask them the length of their lift bag line, they say 100 ft. That ain't gonna do you much good if you're at 200 or 300 feet.

So I know I'm going on a bit, but I'm just trying to start a discussion on the matter, and pull out some useful information so that I'm able to convince myself (or not) that a single bladder is acceptably safe.

Thanks a lot for your input (and patience reading this thing).


Josh
 
Have a look at a Halcyon 55lb wing - it's almost bulletproof. Both the wing and the bladder are constructed from cordura. I've just started diving this wing, wet (about 8 dives so far). Until I get a drysuit, my backup buoyancy is to kick up like sh*t :D I tried it at 100', and I can swim up a set of double Faber 85cf steels full, which are about 16lb negative when full (from memory - they're loaner tanks). I also carry a liftbag and spool with 100' of line.

If the wing should be punctured, it's not going to be useless for lift unless you do a Titanic style slash along the length of it. It's not a balloon which is going to pop - think of it as an open liftbag - massive hole in one end, but it still holds air and creates lift. The lack of bungees will mean air won't be forced out, and you can either continue to inflate either with the LP inflator, or orally, to add air to replace any being lost.

A drysuit should have much more potential lift capacity than a wing. Anyway, who's doing 200fsw+ dives in a wetsuit in Canada???
 
I just did the same switch and am happy with the results. I spent Hours fiddling with my bungies to get the tension (and therefore balance right) and now am better balanced than I ever was. Go figure. Borrow one and try it out...

Drysuit, enough lift? Yes if (as you say) you are balanced.

How to get balanced? You shouldn't be so unbalanced with non-ditchable weight (your doubles and plate) that you can't make it back to the surface by swimming. Stages and lights and be dropped. Aluminum plate is an option to lessen weight. Depends mostly on your suit and tank bouyancy characteristics.

Neoprene drysuit? Quick answer is don't. get crushed/fully compressed or best yet a shell.

Wetsuit? Ditto. Don't. ;-) OR wear more ditchable weight.

In an emergency you could use your guide reel instead if you are really deep. Should assume 1/3 -> 1/2 extra line length to account for drift if you are in current. (300 ft of depth needs 400+ feet of line...)

PS to BenG: water isn't always that cold in canada, we have 200ft wrecks where the water is 70-75 (on a warm day...With a full moon)

Opinions stated above are mine and are not neccessarily DIR, Kosher, Halal, Vegan, or healthy. Consume at you own risk.
 
Anyway, who's doing 200fsw+ dives in a wetsuit in Canada??? [/B]



The St. Lawrence is quite warm during the summer (gets to low 70s), even at 200 ft, and I (and a lot of other people) can do 1.5 or 2 hr dive in that temperature, no problem).
 
Thanks for your input guys.

About the drysuit providing enough lift... I don't know. For example, if you read that accident report on Michel Guerin, you'll notice that the author speculates that Guerin didn't make it to the surface, because his drysuit burped out the air when he got close (he was diving a rebreather, which got a leak in the breathing hose, and it is thought he tried to ascend by inflating his drysuit). I've heard other similar stories.

And about the toughness of the Halcyon bladder... I agree, it looks bloody hard to puncture. But what about an inflator failure?

And kicking like crazy to get yourself back to the surface... even if you're properly balanced and can do that, are you supposed to hold an hour of decompression while doing that?

As for using your guide reel to come up, I don't always bring a guide reel with me (i.e. dives where I'm not doing any penetration), but I suppose I could start.

And about dropping your stage and deco bottles to make yourself lighter... sometimes you NEED those bottles.

Just thought I'd be a pain in the butt and be the devil's advocate :) Later.


Josh
 
Josh Levinson once bubbled...
And kicking like crazy to get yourself back to the surface... even if you're properly balanced and can do that, are you supposed to hold an hour of decompression while doing that?
Not doing decompression dives. Dry suit is WAY ahead on the list of priorities. With only 8 dives using the double tanks, I've got a few more things to work on before I get to decompression diving.
 
with all this discution about how to deal with the fact that you don't have a redundent bladder, i ask myself "why not have a double bladder"

why is DIR so agains the use of a double bladder
 
AquaTec once bubbled...
why is DIR so agains the use of a double bladder

I heard (don't quote me!) that DIR doesn't like the double bladder because if air gets into your secondary bladder, you might deflate the primary but forget about dumping from your secondary.

I dive wet so I think I'll stick with the double bladder and remember to vent both.
 
Double 104's are heavy when full. The dry suit can get you to the surface but you must stay prone or the sir will burp out. At the surface you might have to ditch everything. Using a lift bag can work but if you are sinking and the bottom ia a long way down you could find yourself very deep before it's deployed. If you have never tried using a lift bag for abc, give it a shot it's an education especially when ascending.
 
To avoid accidentally inflating your backup bladder, just keep the hose detached. I dive with one hose for my primary bladder, one for my drysuit, and if I have a hole in my main bladder or whatever, I unplug my drysuit hose and plug in onto my backup bladder. Granted, I can't start inflating immediately, cuz I have to switch hoses, but I think I could react quick enough to save my butt.

As I understand, though, DIR's main hang up about double bladders is it's less streamlined, and there's just more stuff to think about... simple is better. The problem is though, in this case it may be TOO simple.


Josh
 
https://www.shearwater.com/products/swift/
http://cavediveflorida.com/Rum_House.htm

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