Questions about wing sizing (how much lift for specific environment,gear, etc.)?

[Mark IV]

Thanks bro, I'll check that Nomad XT. But, what is "open water cenote diving" ? Ain;t that a contradiction in terms ? We weren't just dog-paddling around in the cavern area, we were boogying way down south, hoping to connect two well-known systems, so we needed all that gas......and more!
And I agree about the redundancy, that's already on my radar ( and it's been a lot of years, so I can't recall for sure, but it seems like I was running redundant bladders on my Dive Rite back in the late 90's).
And I do realize this "triple" tank system I describe isn't typical, it just sort of evolved on it's own out of necessity and convenience, and I got really comfortable with it. Back in the day (pre-nitrox and all that), I didn't own or have access to any manifolded tanks, and Cozumel (where we lived and dived) wasn't the cave-mecca that the mainland was. But, we did have access to steel 120's, kindly rented to us by Aldora for $2 each ! (and I was already well used to simultaneous back and side-mount on deep ocean dives).
So that's how all that came about.
Now, years later, I'm leaning towards a similar system, which would mean hauling down 3 new 120's, which are much easier to manhandle individually than a manifolded set of them.
Anyway, thanks for the heads-up........

 

[Ontwreckdiver]

Sub Gravity makes a 44lb single tank wing. Paragon 44 - Subgravity

 

[NAM001]

the purpose for a wing is multi fold
it is to be able to hold up your gear if you take it off in the water
it has to have enough lift to hold your head out of the water with a full tank of gas
It has to be able to carry the weight presented with a full tank and no wet/dry suit lift

you start a dive with an al80 7# neg your head takes 10# to hold out of he water thats 17# lift minimum with no other gear attached.
you float the same gear and that means 7# min lift with no other gear attached.
you have a full tank -7 with a wet suit on that is +8 with lead -8 that needs 15 lift because of suit squeeze. 100 ft 90% of suit lift is lost from compression.
if your buddy has a wing problem you need 2 times your needed lift t lift you both to the surface so that makes about a 30# wing being perfect. Now switch to a thicker wet suit and you need more lead and you need more wing. if you had a thick suit that needed say 20# lead then that with steel tanks and 9# of gas will push the 30-32 # wing to the max. The amount it is being pushed dampens as you breath down the gas at 8# per 100 cuft.

A 22-32# wing is for the most part the right size range you will probably not need more. the min size allows the air bubble to be more constrained than with say a 50# wing

Its not unusual to have doubles divers using an up to 60# wing. It sounds strange but here are the numbers. packing doubles that empty is -4# and over filled carrying 300 cuft gas for 24# of air. you are already at 30# and the dry suit is not in play yet in the event of a suit flood. My DS took just short of 40# lead depending what under garments I was wearing.

bigger is not better because the air bubble in the partially filled wing, as you tilt down or up will run to the highest point and mess up your trim making you go radical head light or feet light. My 30 and 32 works good but the 40 is starting to have bubble run issues. A awing is not just something you pick off the shelf because it goes with the color of your fins. there are doughnuts horse shoes all designed to work with your weighting placement and amount.

 

[Mark IV]

Thanks again for all the replies, advice, and info. But, (in a peripheral conversation) I think I've been talked into joining the 21st century, and am seriously reconsidering back-mounted alu80 doubles. Among other advantages over the expensive, heavy, corrosion-prone steel tanks, is that this would sidestep this wing-size question, and I could go right to a normal doubles wing from a wide range of manufacturers.
So that's where I'm at right now. Thanks again........

 

[loosenit2]

My thinking is very different from previous posts on this thread. I routinely dive HP 100 doubles and a dual 45 lb bladder is the right wing for that configuration when diving wet. HP 120# are 5 lbs heavier, per tank, so 15 lbs heavier.

I would argue you likely need a double bladder 55-60 lb wing to dive 3 HP 120s wet.