Plus sized women and bouyant capacity

[DivingDoc]

I am trying to figure out how being a plus -sized woman affects which BC you use and how much bouyant lift capacity you need.

I should think it would mean that you need LESS boyant lift capacity becuse if you have a higher body fat percentage, you are more bouyant. Or does is mean that you need more BLC because you need to carry more lead???

 

[Dee]

Getting a BC to fit you properly is important. If you are more bouyant, you'll carry more weight and will need more lift. I don't want to say that you shouldn't worry about the lift of your BC but unless you wear extremely thick neoprene or a dry suit with lots of lead to need lots of lift, most BCs 'off the rack' have plenty of lift for recreational diving.

I'm sure one of the more techno-minded will get into a deep discussion of pounds of lift for every single item you have on you but it's just not one of the things I've really worried about! My Zeagle Concept has 44# of lift. I bought it because of the way it fit me. My weights fluxuate between #2 in the summer with steel tanks to #18 in the winter with full wetsuit and alum. tanks and my BC handles it all very well.

 

[ladycute1]

Well, DivingDoc... I'm not sure if this will help you...

But, as a plus size woman, for me, the important thing is to get a bc to fit... If it doesn't fit, it doesn't matter how much lift it has. I have a US Divers Sonic 2 -- I typically wear about 20 - 22 lbs when diving with the equivalent of a dive skin.


Last year when I was doing my rescue diver class, I had to hold my instructor's weight belt and the 'victim's' weight belt -- another 14 pounds -- with no problem.

Liz

 

[DivingDoc]

Originally posted by ladycute1
Well, DivingDoc... I'm not sure if this will help you...

But, as a plus size woman, for me, the important thing is to get a bc to fit... If it doesn't fit, it doesn't matter how much lift it has. I have a US Divers Sonic 2 -- I typically wear about 20 - 22 lbs when diving with the equivalent of a dive skin.


Last year when I was doing my rescue diver class, I had to hold my instructor's weight belt and the 'victim's' weight belt -- another 14 pounds -- with no problem.

Liz

And how much lift capacity does your BC have?

 

[ladycute1]

Doc,

I don't know how much my bc is rated for... -- that's why I gave you the name and model...

But, I've also been thinking about this some more... and I'm not sure I see why a plus size woman would require more lift.... Yes, I wear more weight, but I only wear enough weight to make me neutrally bouyant.... so I don't see how the amount of lift I need would be any different than a slender person... At least for recreational diving... I suppose it might be an issue in ultra deep diving.

 

[DivingDoc]

Originally posted by ladycute1
Doc,

I don't know how much my bc is rated for... -- that's why I gave you the name and model...

Here are the specs for your BC's BLC:

Lift capacities: x-small - 21 lbs, small - 25 lbs, medium - 29 lbs, large - 35 lbs, x-large - 43 lbs


I'm confused about why I might need more BLC too. The owner of my LDS keeps saying that most women's BC's don't have enough BLC. But the BLC you need is the CHANGE in your bouyancy during the dive. I should think that for most rec divers, that number is only 5# -- the number of pounds that the air in your tank weighs. And that's a negative number in terms of
BLC -- you would need less BLC coming up than going down.

For plus sized women, I should think it wouldn't make a difference -- the extra buoyancy caused by a higher body fat percentage is of necessity counterbalanced by the lead that the diver has to wear. Am I thinking right here?

 

[ladycute1]

Doc --

Let me kind of 'think out loud' as I muddle through your question... Perhaps I can serve to muddy the waters even more!!

As I understand it, the BC's lift capacity is important for three (i think) reasons... first, having the ability to assist with lifting you to the surface if you were to have a problem (or if you needed to help another diver); second, to hold you afloat at the surface, and third, to provide you with enough bouyancy at depth to counter the lead you are wearing so that you can maintain neutral bouyancy (you need to be slightly negative to begin your descent, and then the amount you are 'negative' increases with depth.)

OK, now, let's also keep in mind, that if you were to have a problem, you could always dump your weights, and then you are back to your bouyant self.

Generally speaking, plus size women are more bouyant, so they need to wear more lead to make them initially slightly negative.

But, it seems to me, that as long as you add weight slowly, carefully doing bouyancy checks until you find the right amount, the lift capacity of the BC is of little importance.

No matter how much lead you are wearing, as long as you are neutral to ever so slightly bouyant on the surface, your own bouyancy is compensating.

Now, let me through in a caveat -- if you are doing dry suit diving and require a VERY large amount of weight, then perhaps something changes... (I don't know since I don't dive with a dry suit) ---

I still go back to the idea that the important thing is having a bc that fits properly and then using only enough weight to make you neutral to slightly negative.

I think (warning opinion here that your LDS may be confused, or maybe wants to sell you what they have in stock? It makes no sense.... but, frankly, if your LDS can't explain this to you in a way that you can understand, then I wouldn't feel overly trustworty of them.

If you want to try and get some more 'expert' advice... you might try posting this in the 'gear' forum .....

On another note, how would you like to join a group of plus size women diving in Hawaii?

 

[Zept]

I've been watching this one go round, and now I'm intrigued. Doesn't seem as if anyone has a definitive answer to a pretty obvious question.

Here's my thruppence worth...

The bouyant lift has to do three things:

1) Compensate for the change in bouyancy of your tank. That's around 4 to 7lbs for a single tank, depending on its size. Size of the diver is irrelevant.

2) Compensate for the change in bouyancy of your wetsuit, which will compress at depth. Size of the diver and thickness of the suit are both relevant, since it's the total volume of neoprene that matters. With a skin, there's no change in bouyancy. With a 7mm wetsuit on a large person, it could be 10lbs or more, at a guess (Rodale's says a large men's 7mm fullsuit is 14-20lbs bouyant. I'm guessing it will lose at least half of that at the depth). A larger diver will need more lift than a smaller one if they are diving in cold water.

3) Hold you up at the surface. My guess is that a larger person will need slightly more lift than a smaller one, because they'll have more mass in their head and shoulders. I wouldn't expect the difference to be huge, though. There's also the question of whether you might want extra lift to, say, support another diver -- although arguably in that situation you'd drop your weights.

I don't think anyone has answered your question (in the other thread) about whether there's a downside to having too much lift. The only thing I can think of is that you might have excess material flapping around, making you less streamlined -- but it would depend on the cut of the BC. I'm a long way from being an expert, though -- maybe someone else can help here?

Seems to me that it's nice to have some spare capacity... it lets you use more neoprene or float a bit higher when the sea is choppy. You don't have to use it when you don't need it. On the other hand, if you find yourself wanting more lift than your BC provides, you can't pop down to the dive shop for another 10lbs (exception: if you have a BC with interchangeable wings, you can buy a new wing).

One final thought: BCs vary, and you don't always get the lift that the manufacturer claims. And usually you'll get a bit of water in the bladder, which reduces the lift -- so don't cut it too fine!

I still think the only way you're going to get a definitive answer is by trying some rental BCs. We could do physics all afternoon, but it's just too hard to tie down all the variables.


Zept

 

[DivingDoc]

Originally posted by ladycute1
Doc --

Let me kind of 'think out loud' as I muddle through your question... Perhaps I can serve to muddy the waters even more!!

No matter how much lead you are wearing, as long as you are neutral to ever so slightly bouyant on the surface, your own bouyancy is compensating.

I think (warning opinion here that your LDS may be confused, or maybe wants to sell you what they have in stock? It makes no sense.... but, frankly, if your LDS can't explain this to you in a way that you can understand, then I wouldn't feel overly trustworty of them.

On another note, how would you like to join a group of plus size women diving in Hawaii?

I have been to 3 LDS's and at least 2 of them want to sell me a really complicated BC -- one wants to sell me a Zeagle Ranger and the other one wants to sell me a Zeagle 911! I am suspicious that they both want to sell me the most expensive BC they've got!

I would love to go to Hawaii some time. But we are already scheduled to go to Coz in June.

 

[DivingDoc]

Originally posted by Zept

3) Hold you up at the surface. My guess is that a larger person will need slightly more lift than a smaller one, because they'll have more mass in their head and shoulders.

Yes, but larger people are generally a higher fat percentage and therefore carry their own increased buoyancy. I suppose big muscular, large boned men with low body fat would require more BLC for their "largeness," but we are talking about plus sized women here.

I don't think anyone has answered your question (in the other thread) about whether there's a downside to having too much lift.

One final thought: BCs vary, and you don't always get the lift that the manufacturer claims. And usually you'll get a bit of water in the bladder, which reduces the lift -- so don't cut it too fine!
Zept

Too much lift = less streamlining in the water. Zeagle makes interchangeable bladders -- also Halcyon with their BP and wing config. I suppose that might be the way to go.