Wing lift?

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stuartv

Seeking the Light
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I just completed the confined water portion of my OW cert class.

It seems that the normal procedure for getting properly weighted results in the diver being negatively buoyant, when the BC is empty and the tank is full, by something like 6 to 10 pounds, maybe? Whatever the amount is, it's not a big amount.

I've been reading up on dive equipment to help me better understand the stuff I'm being issued to use and also to help know exactly what I want when I eventually get around to buying gear. In reading, I've seen that the BP/W setup is popular here. And that wings are generally rated from anywhere around 20'ish to 40 or so pounds of lift.

My question is, why would anyone ever need a wing with 40 pounds of lift? If you're weighted to be roughly negative 10 pounds buoyant, it seems like 40 pounds of lift from a wing would be overkill?

Is it because 40 pounds of lift at the surface is that much less at deep depths? I'm up to speed on the chemistry and physics involved, I'm just too lazy to do the math. :)

Is it so that you have enough lift to carry things up from the bottom?

Thanks for any help.
 
two things factor into buoyancy, the rig, which is more negative with a full tank than it is empty by up to 12lb swing depending on size of the tank. LP104 is one of the biggest and most negative tanks, and is almost 16lbs negative when full. So using that
16lb tank
3lbs regulator
up to 11lbs for a bp/w *6lb plate, 2lb STA, 2lbs of cam bands, then about 1lb for d-rings, the webbing, and buckle
there's 30lbs right that, and that's just the rig. This is obviously worst case scenario

Dive is now wearing a 7mm farmer john because it's cold and they can't afford a drysuit. Those can be up to 40lbs buoyant. So you take of 15lbs from that because of the tank and bp/w, and you still need 25lbs of lead to sink. At the surface the wing is only keeping the 15lbs of the tank plus 12lbs of your noggin up, so it will be mostly full, but still able to keep you at the surface.

If the diver is diving shallow, they might be able to get away with a 40lb wing, but if they're diving any deeper than 70ft or so, a 40lb wing isn't actually enough to pick them up off of the bottom when the tank is full. At 70ft that wetsuit should still be about 20lbs positive, so you have 55lbs of ballast on between a full tank, the rig, and lead, less 20lbs of lift from the suit instead of 40, and you don't have the weight of your head, so you're at 35lbs of negative ballast at depth. That is where you need a 40lb wing.

Now, this is obviously the worst case scenario, drysuits are highly recommended at that level because the lack of buoyancy change with regards to depth is very useful for neutral buoyancy scenarios, and a cave filled LP104 isn't all that common of a single tank, though a Worthington 130 is, and those are 12lbs negative when full. Many people will use two different singles wings if they do warm water stuff and cold water stuff in single tanks, but typically if you're diving in cold water, you go to doubles and a drysuit so you aren't carrying lead around.

Same scenario above but in a drysuit. Rig is 30lbs negative, drysuit is 35lbs positive *made up number*, need 20lbs of lead for balance purposes. Get to the bottom, and you have 50lbs of ballast, against 35lbs of buoyancy when full, so you can get away with a smaller 30lb wing *still have to factor head at the surface*.

When you are carrying things up from the bottom you should always use lift bags if they are more than about 5lbs, anything more and it can cause serious problems for you on ascent and is dangerous. Lift bags are relatively cheap and you generally aren't picking things up from the bottom. This is why you inflate an unconscious divers bc to get them neutral for retrieval instead of your own. Not safe otherwise.
 
I just completed the confined water portion of my OW cert class.

It seems that the normal procedure for getting properly weighted results in the diver being negatively buoyant, when the BC is empty and the tank is full, by something like 6 to 10 pounds, maybe? Whatever the amount is, it's not a big amount.

I've been reading up on dive equipment to help me better understand the stuff I'm being issued to use and also to help know exactly what I want when I eventually get around to buying gear. In reading, I've seen that the BP/W setup is popular here. And that wings are generally rated from anywhere around 20'ish to 40 or so pounds of lift.

My question is, why would anyone ever need a wing with 40 pounds of lift? If you're weighted to be roughly negative 10 pounds buoyant, it seems like 40 pounds of lift from a wing would be overkill?

Is it because 40 pounds of lift at the surface is that much less at deep depths? I'm up to speed on the chemistry and physics involved, I'm just too lazy to do the math. :)

Is it so that you have enough lift to carry things up from the bottom?

Thanks for any help.
So a real question exists, as to what exposure suits you will wear....and how cold is the water you will dive most often in....
Here in S FlA, coldest we normally get is low 70's or sometimes high 60's.....Summer can be 85 degrees... My wife, who gets cold very easily, has a semi dry 7/8 by Aqualung, which is so hot she cant use it till the water is 70 degrees or colder....I think it would be very good for 50 to 55, and I have no idea how much colder it would be good for....the thing is, she uses a max of 24 pounds of lead, including the Stainless steel backplate/along with a steel 100. This is her January /February gear for the BHB Marine park, in 20 foot max depths, with her needing to be quite heavy for macro photogrphy of Nudiebranchs on the bottom. If she was doing an ocean dive in this suit, she would probably change to around 15 pounds of lead. Her Halcyon Wing is a 30 pound wing, and she would never consider the much larger drag of the bigger wings, and the de-stabilizing influence of using a monster wing, great big bubble of air inside, and ridiculous amounts of lead to compensate ( which is what many new divers actually do, as their instructors find it easier/quicker/expedient, to throw 20 pounds too much weight on them-- so they don't have to learn how to properly dump their BC for descent. This seems to be the norm in many large , high volume classes....

With her 5 mil Aqualung semi dry, which she just went to this weekend... ( water 79 degrees) Sandra is using 6 pounds of weight on a belt, plus her steel backplate....and a 30 pound lift wing.
And, in ocean dives, you really DONT want to be 10 pounds too heavy...certainly never 10 pounds too heavy at the end of the dive with 750 psi in the tank--this would mean you are way too heavy for the whole dive, and having to fight with a huge air bubble inside the BC, that is constantly growing or shrinking on depth changes, and drastically altering your buoyancy....and screwing up your trim....
You want the tiniest air bubble possible inside the wing/bc....Best case at 70 feet down, you have this tiny little bubble you pushed in to it at the bottom, to get dead neutral.....( and if you were wearing lycra, far better still would be NO Air in the wing at all, because your buoyancy does not change from surface to bottom, and you can run neutral on the bottom the first 3/4ths of the dive with this no air in bc balance....as the tank gets more buoyant as it nears 1000 psi, you should be coming up anyway, and you can just apply a tiny amount of swimming force to counteract the tiny pull up the tank will offer as you approach the end of the dive....holding the stop just means some lazy finning with a slight push down during it.
We don't want any more weight than we need!!! Which is another reason we go with 30 pound lift or less BC's, in Florida.
I myself use the Halcyon 18 pound lift wing, whether using an 80 Aluminum, or a HP 120 for a 110 to 115 foot foot max depth dive, like the Castor....

[video=youtube_share;qHFkQrPtlJM]http://youtu.be/qHFkQrPtlJM?list=UUsM5Za9Kc3DbP7Qo3-Zmz9w[/video]
PLEASE WATCH ONLY AT 1080P--( gear icon lower right of player bottom)
This shows Sandra with her 30 pound lift Halcyon wing and 6 pounds of weight ( plus the backplate--she has the huge camera and the freediving fins)..and our dive buddy Bill Mee with a 30 pound halcyon wing ( Halcyon 30 pound wing, no added weights to backplate--just it's 6 pounds plus reg)..Bill has the bright Surface marker buoy clipped to his side... and is in-shot several times in the vid. You can see he needs very little air in the wing to be dead neutral---to just hang effortlessly in a horizontal position while watching big marine life..
The idea is to never have your BC causing you to work overtime to control it....we adjust ours at the bottom, and then pretty much have little to do with it until we are on our way up to the surface.....With too much weighty and a big BC, every time you go up or down 15 feet you would be turning on the elevator :)

When Sandra's screaming through her reg alerted me to the Manta Ray about 50 feet above us, I was able to swim fast and shoot, without any noticeable nonsense out of my wing getting too much lift---nothing I could not easily compensate for with fins.....OBVIOUSLY I needed both hands on the camera, and would not have wanted to have to pull a hand off the camera to deflate the wing with....it was easy to ignore, by design. Wings and BC's are not supposed to be elevators...they are there ONLY so that you can be neutral when you want to be....swimming is what gets you up to the surface, not an elevator :)
 
Dan, you always have to have the amount of air in the wing that the tank displaces, so in an AL80, you're at at least 6lbs when it's full, HP120 around 12lbs when it's full. 28lbs of ballast is about right for a woman with that suit and that gear configuration, 16lbs is about right for a 5mm as well. Fwiw if she was going deeper than 20ft, that wing would be pushing the envelope on its lifting capacity as the suit continues to compress. It would still hold her up, but it would be very full.

I use a 22lb wing regularly in single tank diving in a drysuit, but since I sink naturally I need a minimum 35lb wing if I'm in a 5mm fullsuit. Any less than that and it can't float me at the surface. That is wearing double 72's, a transpac, and no weight belt. So the rig is about 20lbs negative with regulators and bands plus my head at the surface.

He asked what the 40lb wings were for, they have a use and you can't dive 30lb wings in some farmer johns at depth, you also need them if you are diving the larger worthington tanks that 2lbs negative when empty and pushing 15lbs when full.
 
Dan, you always have to have the amount of air in the wing that the tank displaces, so in an AL80, you're at at least 6lbs when it's full, HP120 around 12lbs when it's full. 28lbs of ballast is about right for a woman with that suit and that gear configuration, 16lbs is about right for a 5mm as well. Fwiw if she was going deeper than 20ft, that wing would be pushing the envelope on its lifting capacity as the suit continues to compress. It would still hold her up, but it would be very full.

I use a 22lb wing regularly in single tank diving in a drysuit, but since I sink naturally I need a minimum 35lb wing if I'm in a 5mm fullsuit. Any less than that and it can't float me at the surface. That is wearing double 72's, a transpac, and no weight belt. So the rig is about 20lbs negative with regulators and bands plus my head at the surface.

He asked what the 40lb wings were for, they have a use and you can't dive 30lb wings in some farmer johns at depth, you also need them if you are diving the larger worthington tanks that 2lbs negative when empty and pushing 15lbs when full.
Hi Tbone,
Sorry, I did not mean to make it seem like I was disagreeing with you.
We are both talking about sides of this issue....an issue that has a lot involved with it.. :)

I used to love using steel 72's....awesome almost neutral tanks.....I WOULD use them today instead of Al 80's , if they were easy to get, and in full hydro and VIP ...I pretty much used the 6 that I had to death, in the 80's and 90's ::wink:
 
72's are still my favorite tanks. Only ones that could replace them are if I could find a set of 45's or 50's cheap and cave fill them. I have them for doubles and sidemount, don't dive single tank backmount unless I have to.

Just wanted to clarify that the wing still needs to carry the amount of air needed to compensate for the buoyancy change at depth of the suit plus the full weight of the air you are carrying. That total amount is what the bare minimum number is, and you generally want/need a 10lb minimum safety factor for your noggin at the surface.
 
It seems that the normal procedure for getting properly weighted results in the diver being negatively buoyant, when the BC is empty and the tank is full, by something like 6 to 10 pounds, maybe? Whatever the amount is, it's not a big amount.

I've been reading up on dive equipment to help me better understand the stuff I'm being issued to use and also to help know exactly what I want when I eventually get around to buying gear. In reading, I've seen that the BP/W setup is popular here. And that wings are generally rated from anywhere around 20'ish to 40 or so pounds of lift.

My question is, why would anyone ever need a wing with 40 pounds of lift? If you're weighted to be roughly negative 10 pounds buoyant, it seems like 40 pounds of lift from a wing would be overkill?


At it's most basic level, the minimum you need is enough lift to make you neutral with a full tank and nearly complete loss of buoyancy from your wetsuit due to compression from depth.

This will probably put you somewhere around 20 pounds of lift in the tropics with a single AL 80 cylinder and a thin wetsuit.

However, if you're diving in colder water with a thicker wetsuit, you'll need more lift.

If you want more "altitude" on the surface, you'll need more lift.

If you plan on needing to rescue someone who's drowning on the surface and want to get their head out of the water while you figure out what's wrong and what to do, you'll need more lift.

That said, you read a lot about BP/W on SCUBABoard, not because of any overwhelming advantage, but because its proponents are very vocal. You might or might not like it and it might or might not be appropriate for your diving. Don't buy one just because "all the cool kids have one". BP/W is still a niche market, accounting for less than 10% (less than 5% IIRC) of BC sales.

flots.
 
And for deep, like 140 feet to 165 ( transitional stuff some recreational divers will pull off), or tech deep, like 200 to 300 feet deep, I don't see wetsuits as a solution any longer...as Tbone says, the buoyancy shift is immense, along with the need for larger and heavier tanks, making a bad problem, worse!
Add to that, as the very thick wetsuits compress at even as shallow as 150 feet, they are now about as warm as 3 mil suits, if that...and practically of no thermal value at 200 and beyond. Deep is for Drysuits, if the water is much colder than 80 degrees....In the past, we have had months in summer where at 300 it was still 80 degrees, and where you could dive lycra....and that was nice....but inversions and thermoclines would screw the pooch too many times to count, causing an abort for the dive with the surprise 50 degree water and the diver not feeling anything from the knee down--feet knumb from cold in about 30 seconds.....I.E, Lycra is not a really good solution for most deep dives either :)


I will use my TLS 350 drysuit for tech dives, but HATE it for recreational depths, as the drag from a dry suit makes it feel like I have a sea anchor attached. There is too much surface area that water pulls on with a dry suit....so if you are in a situation, were you need to cover a wide distance...an expanse to the next reef, or to a wreck in the distance...or, where you need to swim after a Manta Ray or a goliath....you just don't want the dry suit...it is a liability. On deep dives, we just don't really have the option of big long swims, or fast blasting after sea life....so the compromise of a Dry suit is ok for deep.... Just my 2 cents....
 
My question is, why would anyone ever need a wing with 40 pounds of lift? If you're weighted to be roughly negative 10 pounds buoyant, it seems like 40 pounds of lift from a wing would be overkill?

At it's most basic level, the minimum you need is enough lift to make you neutral with a full tank and nearly complete loss of buoyancy from your wetsuit due to compression from depth.
Or due to DS flooding on the surface.

I dive a drysuit and a single tank setup with a 40lb wing. When I'm correctly weighted for my winter undergarments, my rig is between 10 and 15 kg (25 to 35 lbs) negative with a completely deflated wing, depending on the type of tank I'm using, and I've got 12 lbs on my belt. Even a 40 lb wing isn't enough to make me neutral with a totally flooded suit unless I ditch my weights. A 30lb wing would be marginal even after ditching my belt. Also, when diving from a small boat, I sometimes like to doff my rig before climbing out of the water, and haul it up after getting aboard myself. With a 30lb wing, my rig would sink while I was climbing aboard.

Methinks a 40lb wing is about the right size for me...
 
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