Wings suitable for both double-7s and double-12s

[cool_hardware52]

I'm a touch confused here about why the wing needs to compensate for the 24 pounds -- maybe I am not getting something. Are you assuming a wetsuit?

With a drysuit (assuming non-compressible), then I dont think the wing needs that much, right ?

Maybe I will try my double 12's and add stages and see the results

So far I have determined:

40 pound wing, double 130's, 2 Al40's -- not a good idea unless you can drink seawater
40 pound wing, double 130's, 1 AL40, 1AL80 + video camera -- same

But in these cases, I dont think it was as much the buoyancy of the wing, more that I just sat low in the water. The 55 pounder seems to have me a bit higher out of the water, which is definitely more comfortable.

Although highly unlikely it is possible for a drysuit to loose all of it's buoyancy regardless of whether or not the undies are compressible or not. It cannot however loose more buoyancy than it starts with, so the initial buoyancy of the suit can be considered a safe "maximum" for calculating the amount of wing lift necessary to deal with a total suit failure.

If you throw your undergarment in the water it will saturate and sink, same for your shell suit, the materials they are made of have a specific gravity of greater than 1.0

If OTOH we put you in the undies and in the suit and at teh surface vent all the gas possible from your suit you will be buoyant. Depending on the size of the dive, and type of undies 16-30 lbs is pretty typical.

Why? Because the suit and undies are trapping gas, even when you have vented all you can at the surface.

What are effects of a suit flood on buoyancy? Very little, as long as the suit can still trap the ~1/3 of a cuft of gas that is creating the ~20 lbs of buoyancy. This is analogous to a wing that has some water in it. As long as there is enough volume left for the required gas water in your wing has no effect on buoyancy.

A total suit failure is another matter. For the sake of this example think of jumping off the boat with your zipper open, or having your neck seal fail catastrophically, i.e. the suit can no longer trap any gas. It will no longer be buoyant, just like a wing could no longer provide buoyancy if you ripped off the corrugated hose.

If you need to start the dive negative by the weight of your back gas AND be able to deal with a total suit failure then you simply add these two values together, the minimum buoyancy of the suit, and the weight of the gas. I recommend adding 2-3 lbs to allow the diver to inflate his drysuit for comfort at the shallow stop.

Tobin

 

[rjack321]

12L = Faber 85s
7L = Faber 50s (I think)

When my 12L/85s were full, I floated too low using a 40lb wing (drysuit, 200gm thinsulate undie, 10lbs of lead) in saltwater. Survivable but not comfortable.

The 55lb wing is a good alround size although its probably too big for the 7L tanks. The 40lb size range wing will probably work for the 7L, it may or may not work for the 12L. Not something you are going to be able to conclusively figure out on the internet. You'll just have to try something in that size range to know.

 

[JeffG]

12L = Faber 85s
7L = Faber 50s (I think)

When my 12L/85s were full, I floated too low using a 40lb wing (drysuit, 200gm thinsulate undie, 10lbs of lead) in saltwater. Survivable but not comfortable.

The 55lb wing is a good alround size although its probably too big for the 7L tanks. The 40lb size range wing will probably work for the 7L, it may or may not work for the 12L. Not something you are going to be able to conclusively figure out on the internet. You'll just have to try something in that size range to know.

I used an AGIR 38 with double 130's and 2 40's as deco bottles (in Salt with 18/55 backgas) without problems. Its touch and go with 130's with nitrox (and same deco bottles) in fresh water.

But then again, maybe I don't mind floating low in the water. ????

 

[dsteding]

I used an AGIR 38 with double 130's and 2 40's as deco bottles (in Salt with 18/55 backgas) without problems.

It is a miracle you are still with us.

 

[cool_hardware52]

So far I have determined:

40 pound wing, double 130's, 2 Al40's -- not a good idea unless you can drink seawater
40 pound wing, double 130's, 1 AL40, 1AL80 + video camera -- same

You have not provided any info as to what your suit buoyancy is, but I'll assume 22 lbs.

Double 130 will hold about 21 lbs of gas. Add 22 lbs of suit buoyancy and a few more lbs to allow for suit inflation at the shallow stop and you have 21 + 22 + 3 = 46 lbs. I'm not surprised that you found a 40 lbs wing insufficient.

Keep in mind that 46 lbs also represents the total ballast you need. You need 22 to simply offset the buoyancy of your suit, + 21 more to be negative by the weight of your gas + 3 more for extra inflation.

Your tanks are -1 each, empty. Plate and harness about -6, regs about -5, bands and manifold about -5, can light about -2 That totals -20 lbs. You need another 26 lbs of ballast. Lets say you choose to add 8 lbs of lead to your rig, and carry the rest of the 26 -8 = 18 in a belt. Your rig will now be -49 lbs with full tanks. That's another argument against using a 40 lbs wing.

It's easy to see that you need the 55 lbs wing for this rig, with or without the camera and or stages.

Tobin

 

[rjack321]

I used an AGIR 38 with double 130's and 2 40's as deco bottles (in Salt with 18/55 backgas) without problems. Its touch and go with 130's with nitrox (and same deco bottles) in fresh water.

But then again, maybe I don't mind floating low in the water. ????

Or you have a bouyant butt :mooner:

 

[JeffG]

Or you have a bouyant butt :mooner:

at 6' and 166 lbs, I kinda doubt it.

 

[rjack321]

at 6' and 166 lbs, I kinda doubt it.

400gm undie? As much as I'd like one, I'm still freezing in my 200gm.

 

[JeffG]

400gm undies? As much as I'd like one, I'm still freezing in my 200gm.

Yes, 400gm undies. You won't find me in the water with less (sometimes I add electrical heat.)

 

[limeyx]

If you throw your undergarment in the water it will saturate and sink, same for your shell suit, the materials they are made of have a specific gravity of greater than 1.0

If OTOH we put you in the undies and in the suit and at teh surface vent all the gas possible from your suit you will be buoyant. Depending on the size of the dive, and type of undies 16-30 lbs is pretty typical.

Why? Because the suit and undies are trapping gas, even when you have vented all you can at the surface.

What are effects of a suit flood on buoyancy? Very little, as long as the suit can still trap the ~1/3 of a cuft of gas that is creating the ~20 lbs of buoyancy. This is analogous to a wing that has some water in it. As long as there is enough volume left for the required gas water in your wing has no effect on buoyancy.

A total suit failure is another matter. For the sake of this example think of jumping off the boat with your zipper open, or having your neck seal fail catastrophically, i.e. the suit can no longer trap any gas. It will no longer be buoyant, just like a wing could no longer provide buoyancy if you ripped off the corrugated hose.


Tobin

Interesting, I wasn't aware that a flooded d/suit would operate quite like that.
I am definitely not willing to try it in 54F water right now though

So to get this straight, you are saying that with a TLS350 drysuit (essentially incompressible -- and I guess doesn't have much inherent buoyancy), and say 200G thinsulate u/garments.

Assume that I measure them to be 20 pounds buoyant with me in it, and I dump all available gas.

Now, open the zipper completely. Now the buoyancy I have is what? 20 pounds less ?(minus my inherent personal buoyancy generated from eating too many pies at christmas)