BCD question.

[lowlysubaruguy]

Because I had to know I dove my wife’s 18 pound wing with 100HP steel tank single 14 pounds of weight and had no issues at any point in the dive even at 90 feet floated me with great buoyancy control and minimal effort through out the dive and floated me at the surface without being fully inflated. I’m 5’8 210 pounds if it matters.

 

[happy-diver]

and you sir have your best buoyancy calculator of them all

 

[rnln]

Looks like I used the Excel sheet wrong. My result of "recommendations" turned out to between 15 to 38 lbs lift lol

Ayisha,
My plan right now is only up to 60' deep. I don't know when I can go deeper. Base on my freediving experience, I will wear 3mm-3.5mm in summer and 5mm in winter. I am 200lbs. On my last dive, I wore 7mm farmer john, with 32lbs of lead and still felt I need more because once in a while I automatically blow up slowly even with empty bladder.

On tank, I most likely will use 1 single rental tank, which I think is aluminum 80 or 100 cf.
So, I should need between 30 to "less than 40"?

Thanks Ayisha

 

[rnln]

Because I had to know I dove my wife’s 18 pound wing with 100HP steel tank single 14 pounds of weight and had no issues at any point in the dive even at 90 feet floated me with great buoyancy control and minimal effort through out the dive and floated me at the surface without being fully inflated. I’m 5’8 210 pounds if it matters.

Let me use the best knowledge that I've been consumed by reading...You wear 14 lbs lead. That should = 14 + 11 = 25 lbs of lead if you are wearing aluminum tank. I read somewhere steel tank is 11 lbs heavier than aluminum.
I wonder what the "lift capacity" of a BCD/wing bases on?... well, anyway....

questions. Hope you don't mind.
Were you in warm water or cold water?
What thickness of wetsuit you were wearing?

Talking to friends, someone thinks (he confirmed that this is just talk, might not be accurate) between thickness of wetsuit, every time he came down 2mm, he can reduce 4 lbs of lead. So If I go from 7mm to 3mm, I should take off maybe around 8 lbs. So, I should be around 26 lbs on 3mm wetsuit. Closed to what you said above.
Your and my height/weight are similar.

So, base on your experiment, 18 lbs lift capacity wng will work. Base on Ayisha, 30 is a set number for it. Can I say, between 25-30 lbs lift capacity is safe number I should look for?

Thanks lowlysubaruguy.

 

[rnln]

2 more questions hope everyone don't mind.

Can any backplate go with any backplate-hardness, and can also go with any kind of wing, or there are some can not go with some other?

The other question is if all I need for a BCD is a backplate, a backplate-hardness, and a wing/blader... or is there anything else I don't know yet?

Thanks everyone in advance.

 

[rongoodman]

Let me use the best knowledge that I've been consumed by reading...You wear 14 lbs lead. That should = 14 + 11 = 25 lbs of lead if you are wearing aluminum tank. I read somewhere steel tank is 11 lbs heavier than aluminum.

That doesn't sound right, except maybe for some oddball steel tanks. A five or six lb difference seems more reasonable, but it will be up to you to do a proper weight check with the tank you're using.

Can any backplate go with any backplate-hardness, and can also go with any kind of wing, or there are some can not go with some other?

If you're using an STA any combo should work, since the 11" spacing of the bolt holes is standard. If not, the slots for the cambands in the wing and plate will need to align.

 

[lowlysubaruguy]

Sorry I did not post the whole equation on the 18 wing

3/2 long wetsuit 78 degree water I was probably heavy on weight a couple pounds with the steel tank but it was good to be heavy to know it had plenty of lift. It was plenty of lift. 210 pound 5’ 8” I’m big boned not fat not skinny my fins are slightly positive

For a fact i would feel comfortable and safe with an 18 pound wing her bcd is an apex and it is very streamlined. Watching her in the water it’s very compact with that wing.

While I read that cold water dry suit diving you need more lift I question that, I do dive cold water very cold at times have a high tides 8mm dry suit I don’t even use my bcd for lift unless I’m sitting on the surface for a while and even then my dry suit can float me. While I can’t speak of other types of dry suit it takes a lot of weight just to sink me in that dry suit to begin with I bet the 18 pound wing would be enough but I don’t know My bcd has a 30 pound wing.

And then there’s other factors that general stats don’t calculate for. We all have different buoyancy my son sinks like a rock he probably needs a little more floatation but he’s also smaller so he needs less lift maybe they cancel each other out 30 pounds should lift anyone under 250 pounds in a 4/3 or thinner full wet suit. For single tank recreational diving anyway I bet an 18 wing will lift anyone in that class as well. Not saying it’s right I just think it will. And in reality you only have to have just enough lift to equalize easily and to float you if you suffer a catastrophic event at depths and have to be floated without your own input as far as floatation on the surface I’ve been in BCD’s that floated you so face first they were unsafe as floatation devices on any level if your unconscious or impaired so surface floatation is really a complete different factor in my opinion. Not that I’d want to dive in something that would not float me on the surface but there’s some poorly designed BCD’s and popular brands as well.

Another factor for me is lobster diving I might want to be a bit extra weighted a 30 pound wing may provide faster momentary lift if needed so I will most likely stick with my 30. But I do plan on trying the wife’s gear for that if it’s ever available when I’m lobster diving or spearfishing just to know. The advantage of that small wing is packing for travel and its got to be more efficient in the water it’s like having nothing on your back it shrinks down very small in the water .

 

[tursiops]

Because I had to know I dove my wife’s 18 pound wing with 100HP steel tank single 14 pounds of weight and had no issues at any point in the dive even at 90 feet floated me with great buoyancy control and minimal effort through out the dive and floated me at the surface without being fully inflated. I’m 5’8 210 pounds if it matters.

What thickness wetsuit? That is the missing information. Was your 14 pounds on your waist or in the BCD?

 

[lowlysubaruguy]

In the weight pockets every thing else was answered in my second response

 

[yle]

Thanks everyone for quick answer and document. About the other discussion, manual, and Excel, OMG haha. It would take me many free days to understand. Many terminologies I don't even know what it means yet

Of course I will need to read more and more, but for right now can someone from SoCal tell me the proximate least lift capacity of a BCD or Wing/blader most people get? Should it be possible?

I'm in So Cal. We wear 7mm wetsuits, usually with boots, hood and gloves, year round. So the lift required due to wetsuit compression, especially at depths of around 100 ft, can be significant. The neoprene I wear has a buoyancy at the surface of around 18 lbs, but it loses about 12 lbs of that at depth. Which means even if I'm correctly weighted at the surface, I need 12 lbs of lift from my BCD at depth just to compensate for wetsuit compression.

I can't speak for everyone in So Cal, but my educated guess is that the typical BCD you will see on a So Cal diver has a lift capacity of 35 lbs, give or take 5 pounds.

As others have posted here, as a bare minimum you want to make sure your gear can float by itself at the surface. A full AL80 tank is 3lbs negative, and a typical So Cal diver might have 20 lbs in their weight pouches (although some have more.) Which means you would need at least 23 lbs lift from your BCD just to keep your gear at the surface (actually more than that, due to the weight of your regulator, etc.) Add a safety factor of 50%... and you're at 35 lbs lift for your BCD.

Also keep in mind that the bladder of your BCD is collapsible (i.e. it stays flat if you're not using it), so there not much downside to having too much lift capacity. There's a potential serious downside to having too little lift capacity.