Double vs. Single Bladder Wings (and bungees too).

[kidspot]

Tobin had some very sound advice - what are your lift requirements? Personally I'm new to doubles diving and will be sticking with double AL 80's (had to say farewell to my double 72's ) I'm not planning on needing more than 1 40cf stage in the next few years, if at all (I go slow learning things maybe) so a 40# single bladder wing fits me perfectly. If I was going to start deco diving I'd don my drysuit, so that takes care of redundancy for my needs.

Just my .02 cents as a real newbie to the world of doubles. Have fun!

Aloha, Tim

 

[Dave in PA]

I have a double wing for my double steel 100s. But only because I bought them before I bought a dry suit. I still dive the double wing, but have looked at replacing them with a single wing, as I doubt I'll be wearing the doubles with a wetsuit again.

 

[Jay Roy]

OK wat bout this, double bladder and dry suit, using a 6/94 mix, your argon. bottle free flows. cant inflate your dry suit, have 5 hours deco, your wing goes, theres 100 feet below you, how are you gunna get up. the other WING WOULD HELP NOW. haha, its all bout pratical, nothing is anithing diff, wit a dual wing, OMS doesnt create more drag, its nice

If you foresee this many problems on one dive, maybe you should lose the OMS gear and switch to something good?

PS. Can you upload a pic of yourself so I can be sure to Rule 1 you if we end up on the same charter..we are from the same province afterall..
On 2nd thought, never mind, you'll be the guy with the bungied long hose, argon bottle mounted between the tanks, and just on the brink of puberty..I can pick you out of a crowd.lmao

 

[Dan Gibson]

One shouldn't need 94# with either a bungeed or non bungeed wing. If one actually needs 94# of lift, that person is grossly overweighted. 3+ stages does not make one that negative unless one carries massive steel tanks as stages which isn't a good idea. Somewhere there is likely a thread on the concept of a balanced rig where several scenarios have been run and show the math.

*groan* what happened to my thread?



In the meantime (while we're waiting) any input on my original question?

 

[cool_hardware52]

In the meantime (while we're waiting) any input on my original question?

Barry,
Any BC needs to be able to float your rig at the surface without you in it, and compensate for the potential loss of buoyancy of your exposure suit.

To calulate the minimum required wing you need to know the rig weight, the weight of the gas, and the initial buoyancy of your exposure suit.

Example

Rig weight

Dual HP 100's(full, air) 2 x -9.5 = -19
SS Plate and haness - 6
Bands and Manifold ~ -3
Regulators ~ -2
Can Light ~ -3
Misc (reels, etc.) ~ -2

Aproximate rig weight -35 lbs.


Exposure suit initial buoyancy

Assume is requires 30 lbs to overcome the intial buoyancy of your DS i.e. if we put diver in the water wearing just his undergarment and Dry Suit with minimum gas, it would require 30 lbs of ballast to get the diver neutral. You should test your own, this figure is only an example.

Lets assume we start with the diver weighted so that he is neutral at the surface with no gas in his wing, and full cylinders. This is just a starting point. At this point the diver could loose ~30 of buoyancy in the case of a total DS flood, and therefore need 30 lbs of lift to return to the surface.

Now we need to add the weight of the backgas, here that would be 200 cuft x .08 = 16 lbs gas.

Extra inflation gas of for comfort during deco. If you are going to spend extended times in shallow cold water you will likely want to add some gas to your dry suit.
I assume 5 lbs.

If the diver is weighted to be neutral at the surface with no gas in his wing, and full backgas cylinders he then needs to add 16lbs (backgas) and 5 lbs (extra inflation gas for the DS)

30 lbs (Drysuit buoyancy) + 16 lbs (weight of back gas) + 5 lbs (Dry suit inflation) = 51 lbs.

Conclusion, he divers needs about 50 lbs of lift. This will easily float the rig, and will allow the diver to return to the surface if he suffers a 100% drysuit flood early in the dive with full cylinders.

What are the effects of adding stages? Very little, al stages are only slightly negative when full, and can go positive when empty.

A couple notes:

100% Drysuit flood is very unlikely, but's a easy place to start the calc's. This builds in a bit of a cushion in the figures.

Tank size and weight impacts the required lift primarily due to the weight of the extra gas, not the weight of the tanks. Run the numbers again using dual 130's, a bigger wing is needed because of the extra 60 cuft, or ~ 5 lbs of gas.

Regards,


Tobin

 

[Dan Gibson]

Tobin,

Is this a cut and paste? God knows you've posted this or other examples many times. Maybe a sticky is in order. It would save a lot of typing

Barry,
Any BC needs to be able to float your rig at the surface without you in it, and compensate for the potential loss of buoyancy of your exposure suit.

To calulate the minimum required wing you need to know the rig weight, the weight of the gas, and the initial buoyancy of your exposure suit.

Example

Rig weight

Dual HP 100's(full, air) 2 x -9.5 = -19
SS Plate and haness - 6
Bands and Manifold ~ -3
Regulators ~ -2
Can Light ~ -3
Misc (reels, etc.) ~ -2

Aproximate rig weight -35 lbs.


Exposure suit initial buoyancy

Assume is requires 30 lbs to overcome the intial buoyancy of your DS i.e. if we put diver in the water wearing just his undergarment and Dry Suit with minimum gas, it would require 30 lbs of ballast to get the diver neutral. You should test your own, this figure is only an example.

Lets assume we start with the diver weighted so that he is neutral at the surface with no gas in his wing, and full cylinders. This is just a starting point. At this point the diver could loose ~30 of buoyancy in the case of a total DS flood, and therefore need 30 lbs of lift to return to the surface.

Now we need to add the weight of the backgas, here that would be 200 cuft x .08 = 16 lbs gas.

Extra inflation gas of for comfort during deco. If you are going to spend extended times in shallow cold water you will likely want to add some gas to your dry suit.
I assume 5 lbs.

If the diver is weighted to be neutral at the surface with no gas in his wing, and full backgas cylinders he then needs to add 16lbs (backgas) and 5 lbs (extra inflation gas for the DS)

30 lbs (Drysuit buoyancy) + 16 lbs (weight of back gas) + 5 lbs (Dry suit inflation) = 51 lbs.

Conclusion, he divers needs about 50 lbs of lift. This will easily float the rig, and will allow the diver to return to the surface if he suffers a 100% drysuit flood early in the dive with full cylinders.

What are the effects of adding stages? Very little, al stages are only slightly negative when full, and can go positive when empty.

A couple notes:

100% Drysuit flood is very unlikely, but's a easy place to start the calc's. This builds in a bit of a cushion in the figures.

Tank size and weight impacts the required lift primarily due to the weight of the extra gas, not the weight of the tanks. Run the numbers again using dual 130's, a bigger wing is needed because of the extra 60 cuft, or ~ 5 lbs of gas.

Regards,


Tobin

 

[LavaSurfer]

These are my thoughts so far on the double bladder wings:

- They probably don't provide the redundancy you need. Looking inside a double bladder wing it's pretty clear that any incident which punctured one bladder would almost certainly puncture both.

- Properly weighted, I am only negative by the weight of my gas at the start of a dive - around 4kg with double-12s. I can certainly achieve this much bouyancy with my drysuit. I may need to ditch stages but I can certainly survive a defective wing using my drysuit (and I'm carrying two DSMBs at least if I really want the extra bouyancy - maybe to send the stages up?).

Barry, seems like these two items do hit the nail on the head.
If your negitive only by the weight of the gas and life is on the line you ditch a tank. If you are at the end of your dive the weight is no longer an issue as you may have breathed some gas off. I guess ditching a stage is a bad idea if you have an hour of hang left The bottom gas you used at this point would reduce your weoght some though.

Might I suggest a lift bag as a backup? It works and could be deployed in an emergency to get you up. maybe a 500# bag would do the trick since you didn't get the 94# wing

I am trying to think of the obvious ways out of a wing malfunction. There is also the fact that once your on the line, you could pull yourself up at the rate you need.

The questions you ask are good as I am adventuring into the Tec/Deco arena myself and want to get into doubles with stages.

 

[rookers]

I use a secondhand OMS wing, 60#, single bladder, debungeed. I dove a double wing when I first tech trained in warm water, no drysuit, and it may have application there. I actually drilled switching things around. At this point, everything is drysuit and I that is my redundancy. I also carry a substantial enough lift bag for that to be my a tertiary source of buoyancy, though I have never drilled it, and would probably be hard pressed to manage it correctly under stress.

 

[Jason Ooi]

I used Halcyon 40lb explorer lift aluminium 11lt back-gas and four aluminium 7lt deco, stage and travel gas with no problem, I don't need 94lb wing

Why do you need 94 lbs of lift with three bottles?

 

[cool_hardware52]

Tobin,

Is this a cut and paste? God knows you've posted this or other examples many times. Maybe a sticky is in order. It would save a lot of typing

Ok by me, it would save time.

Tobin