Sinlge vs double bladder

[Josh Levinson]

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

[Scubaroo]

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???

[Flummox]

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.

[Josh Levinson]

[i]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).

[Josh Levinson]

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

[Scubaroo]

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.

[AquaTec]

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

[Ontario Diver]

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.

[MikeFerrara]

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.

[Josh Levinson]

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

[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.

[padiscubapro]

madmole once bubbled...
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

Madmole,
In practice I can't fully agree with you here... First off different dry suits have different buoyancy characteristics.. I find in a shell suit using the dry suit for buoyancy is dangerous and unconfortable, using a neoprene drysuit is much easier..

When diving twin 95s and stages I'm pretty negative the amount of gas required in the suit to make me neutral causes a large buble to move throught the suit, this is very unconfortable and if I go head up I risk the chance of the air escaping through the neck seal..
I dive a DUI cf300 which is a shell suit, even with heavy undergarments its not very bouyant(In mask fins and snorkel I can get below the surface without any weight, I only use 8lbs total with my inspiration), I find its much easier and much more confortable to just add enough gas to eliminate squeeze and control bouyancy with my wing.. I used to dive just using the drysuit but am much happier now.. I also had an experience like mike.. I was ascending up a line and my suit bubbled (I got wet and very negative), That was the lat time I dove it that way.. Besides with minimal air in the suit I can go totally inverted with only minor amounts of gas going into my feet.. I am frequently head down since I lobster hunt alot and air in the feet is not confortable..

If you are using something like a unisuit use the suit for buoyancy is pretty easy until you get deep enough where the suit compression severely comes into play.

Dui suits are pretty common up here in the Northeast so most people use the wings as buoyancy. I do teach the suit as a backup bouyancy device and remind the diver that the attitude in the water column is very important.. The ascent has to be made close to horizontal, Slightly head up.. to level not enough air escapes automatcally to head up you lose gas fast..

[madmole]

I do currently dive a membrane (Aerdura) but in the past 3 of my 7 drysuits have been neoprene. Will never have another neoprene (unless its crushed), they are too cold and have too many buoyancy issues. My CF200 dui leaked like a sieve and went back short of my Northern Diver it was one of the worse suits I owned (neoprene seals suck)

Personally I have no problems with just my drysuit for bouyancy. I wear no extra weight with my twins and stages and 6-8 lbs with my inspirstion depending on the stages I wear. Most of my stages are 3L steels ot 7l Alloys. I've been teaching dry suit only for buoyancy since about 1980 when drysuits first come out to amatuers and they've not had any problems either.

If your neck seal is farting then that suggests that a) it doesn't fit or the suit is restrictive and b) you hav'nt discovered the trick of inverting a latex neckseal, which is much more comfortable as well as keeping the air in. Too much air in the feet suggests the suit is too big.

A suit that is too large will definately give you problems with air migration, and one that is too small will not hold enough air and pull on the neck seal when you move.

I'm not saying drysuit is the ONLY way. I'm more opposed to using more than one method at the same time as that can (and I've seen it) lead to task loading on the ascent when there are several buoyancy sources to handle. Add a rebreathers counter lungs into the equation and pop!!!!. Get rid of one of the sources (doesn't really matter which) to make life easier for yourself

Better still stick outo dumps on the drysuit and counter lungs and add a ADV for the inspiration and youre nearly fully automated. Now who's gonna fit a dry suit ADV first????:)

[nickjb]

Have you got any links or more info on ADVs I was looking for something like this for another application (I don't think I'll put one on my drysuit just yet)

[padiscubapro]

actually to me any noticable air in the feet is too much! For the last several years I've been using rock boots, so I really dont get air down there anymore..

I never liked the feeling of air moving within the suit so I always dive it with the minimum gas required (just enough to relieve squeeze).. I never had a leaking problem with my cf300, I use latex seals myself.. even diving it with minimum volume is still find it occasionally "burps" from the neck if I'm not paying attention to my positioning.. I do the fold on my neck seal as well.. and the suit fits well.. I think its easier for beginers to control it by suit only especially if its a single tank, but I feel once you start becoming very negative its better to use the wings for what they were designed.. When I used to use thinsulate I was much more buoyant and not really any warmer.. I now only use polartec garments since they are warm and not very buoyant. Unless I am very deep the amount of gas in my suit doesn't concern me, on deeper dives I make sure the gas is venting properly and check it on my deco stops..

I have practiced free ascents many times and other than my first try at it with my RB I haven't had any problems controlling the 3rd air space once I got down the rate I needed to dump the loop while ascending.

[jonnythan]

There's definitely something to be said for avoiding the "shopping bag" effect of having a large air bubble in the drysuit. If nothing else, it's uncomfortable and just weird.

[madmole]

Details of ADV's can be found on my website Diver Mole "Your Inspiration Buddy" (http://www.btinternet.com/~madmole/divemole.htm) or on Bob Howells Site (http://www.rebreather.org.uk/)

So the consensus is use the drysuit if your not too negative and only use the wing if your over heavy. Personally I'd suggest you try allow stages if your combi is that heavy

[budgy]

I see lots of dry suit divers are carrying too much ballast, which may account for their large bubble in the back feeling, or an inability for their suit seals to hold enough buoyancy. My experience with ND was a compressed neoprene, bust a gut to get into never dry suit. Some people are happy with theirs I wouldn't buy another one.

[Tibbs]

madmole once dribbled...
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

Are you sure? I certainly wouldn't say most. From (unrepresentative) polls I have seen, it's nearer to 50-50, possibly with a lean in the direction of BCD. Amongst my contemporaries, none dive soley on Drysuit.

But then again I can't say definitively as I have never seen an independent poll. Do you have one?

Don't tar all of us UK divers with your brush.

Chris

P.S. Be very careful about folding in a latex neckseal. It rests beautifully on your carotid artery - and blowing up the suit will result in pressure on said artery. I've seen a guy pass out on the surface after a dive because of this. Oh, he was using the drysuit as buoyancy as well...

[madmole]

All BSAC divers are trained to use dry suit only which are the majority in the UK and as its the biggest dive club in the world must mean a lot of other folks as well

As for folding the neck seal pressing on the carotid artuary, yes, but then so can a normall way up seal if its too tight. With an auto dump its hard to get much above ambient pressure in the suit anyway and you need at least a pressure of 80 mm Hg to stop the flow in an artuary and thats a lot. It would get unconfortable pretty fast with that level of pressure

As an ex paramedic I'm very aware of how hard you have to compress artuaries to stop blood flow

All I saying is that if you are not a ton negative in the water you should be easily able to do you weight control on just one source and not have to involve 2. and as you have to squirt into the drysuit to stop ending up vacuum packed, you might as well need to give it a bit more.

I need approx 8 kg of positive bouyancy at depth (early in dive) to offset my twin set (2x 12.4l aber steels) and stages 2x 7l alloy), now picture that in terms of 4 x 2l coke bottles spread out over your whole body and you'll see why its not an issue (its about a 5mm layer all over you, thinner than your undersuit). If you cant offset your negative buoyancy with just the suit without looking like a michelin man then I suggest your are overweighted or your equipment configuration needs looking at. Remember as the dive progresses you get lighter and need less

[MikeFerrara]

madmole,
That's just the point. With my double steel PST 104's (17 liters) and al stages and canaster light and reels I am very neg and the dry suit alone will not work except as an emergency measure. These tanks alone are almost 13 pounds neg each when full. There is little comparison betwen these and what your using. We also teach new drysuit divers to use their suit for buoyancy control. That limits task overload and they should be almost neutral anyway. In our cave rigs we are not neutral, we are neg.

Balancing those heavy tanks on top of a buoyant suit is a real task I asure you.

What kind of technical training does the BSAC provide?

[madmole]

You might want to try a UK cave diving trick

I dive 2 x 7l 300 bar sidemount steels in a cave, and yes they are very neg. I then often am carrying several stages (also steel, ally tanks would be written off after a 5 hour carry in with several abseils)

We often use polystyrene floats in the cam bands to help offset the negative bouyancy. Thats how I managed 143m with 8 stages

Doesn't mater what you use to offset being that much negative you have a problem. Wings or suit, you are gonna need a lot of redundancy in case something goes pop.

Why do you need such a heavy rig. Mines much lighter and is good for dives to 70-80m with runtimes up to 1.5 hours. Unless your doing longer and deeper

Why not go the rebreather route and save yourself a whole bunch of weight like I did. I dread hefting my twins now, so much bulk, cld air, noise and costly fills. I can do a weekends 70m trimix diving on a 3L $15 fill

[MikeFerrara]

Rebreather...Now your talking. maybe someday. I have to buy two my wife wants one also.

[padiscubapro]

Mike,
Once you get a rebreather AND get confortable on it you will never go back... I cringe at the though of even loading a set of doubles again..

I hear all this shi* about how long it takes to set up... fact is when everyone is trying to get their gear set up between dives I'm relaxing in the sun.. A few minutes before Its time to get in, I suit up and do my pre breathe....

I am doing longest bottom time than I have ever done (On average) with the shortest required decos... I've lost track of how many 3hour dives I have done.....

And its cheap... I get a few days of trimix dives on a single diluent fill, no more lugging multiple sets of doubles and spending a fortune on gas.

[GDI]

:doctor:
I use a double bladder and have no problems with it in terms of inflation or streamlining. I use a Zeagle tech with the big bertha bladder system (yes and a back plate). I tuck the extra inflator hose back out of the way but it's easily accessable. I have practised using each bladder separatly and in conjunction with each other. Train your mind and keep things simple and your skills will get you through. I also dive with a drysuit which depending on my area of environmental choice becomes a third inflation system if required. Face it guys you have a choice to live or die. Train well and you live - let the big guy upstairs decide when your time is up.

[GDI]

:doctor:
So what are types of BCD's use all use? Do we need a poll