How much lift is really needed or is too much?BCD?

[jplacson]

But lack of proper training shouldn't excuse a diver from learning what to do in an emergency. If you're properly weighted, swimming up against your rig shouldn't be a problem at all...even for a beginner. Unless your BC fails at the very start of a dive, when your tank is full, you'd be swimming up about 1-2# only. And I'm not talking about a small BC leak... I'm talking about a complete rupture.

If you're not properly weighted, and rely on the 'additional safety' of more lift from your BC, and your BC fails... now you're swimming up against 8-10# more! That's something a beginner will have a harder time doing.

All agencies teach proper weighting. If done according to the text book (regardless of agency) everyone would be neutral at 10-15' with an almost empty tank, and a deflatted BC. If this is the case, the only weight you'd have would be at the beginning of the dive, which would be your air... about 3-4#. Should your BC fail at any point during the dive, you'd only be 1-2# negative... annoying, but it's actually possible to still continue the dive.

Now, if you are properly weighted, and still feel the need for more lift... there's nothing inherently wrong with more lift... it's the drag that comes with it. If surface buoyancy is all you'e after, get a surface flotation device. It offers more safety since it will serve as a back-up should your BC fail.

 

[IndigoBlue]

But lack of proper training shouldn't excuse a diver from learning what to do in an emergency. If you're properly weighted, swimming up against your rig shouldn't be a problem at all...even for a beginner. Unless your BC fails at the very start of a dive, when your tank is full, you'd be swimming up about 1-2# only. And I'm not talking about a small BC leak... I'm talking about a complete rupture.

If you're not properly weighted, and rely on the 'additional safety' of more lift from your BC, and your BC fails... now you're swimming up against 8-10# more! That's something a beginner will have a harder time doing.

All agencies teach proper weighting. If done according to the text book (regardless of agency) everyone would be neutral at 10-15' with an almost empty tank, and a deflatted BC. If this is the case, the only weight you'd have would be at the beginning of the dive, which would be your air... about 3-4#. Should your BC fail at any point during the dive, you'd only be 1-2# negative... annoying, but it's actually possible to still continue the dive.

Now, if you are properly weighted, and still feel the need for more lift... there's nothing inherently wrong with more lift... it's the drag that comes with it. If surface buoyancy is all you'e after, get a surface flotation device. It offers more safety since it will serve as a back-up should your BC fail.

The issue is not about proper training, the issue is about proper lift capacity determination for a B/C.

The training issue is related to advanced training to compensate for minimal lift capacity as in MemPilot's case, or even inadequate lift capacity as in ScubaRon's case.

 

[jplacson]

But your BC basically just need to counter the weight you need to sink... which is more or less the buoyancy of your exposure suit.

Higher lift capacities (60# and up) are generally used for cold water diving due to the additional lead needed to sink thicker wetsuits, or drysuits and undergarments.

When I used to use a stab jacket, I spread my lead out to make each part of my rig neutral. I wore just enough on my belt to keep me neutral at the surface (PADI style, full breath-hold, eye level) without my BC... just my suit, fins, etc. Then I would dunk my rig in the water with an empty tank, and add just enough lead to sink it about a foot underwater. This worked for me back then and it made a huge difference for my diving experience. I needed less energy to fin, used up a lot less air (less buoyancy adjustments), and it was a LOT easier to lug my rig around with less weight.

Since I shifted to a BP/W rig, I dropped even more lead. And even though the normal 6# SS BP was recommended... I went out of my way to borrow an AL plate and check my buoyancy with my instructor. I currently dive with a total of 4# (2# AL plate, 2# trim)

Like I said earlier, if properly weighted, even the 18# Halcyon "Batwing" would be enough flotation on the surface. The larger lift capacities are meant to compensate for exposure suit compression at depth... with thicker suits this accounts for a lot of loss.

 

[IndigoBlue]

But your BC basically just need to counter the weight you need to sink... which is more or less the buoyancy of your exposure suit.
..

That is the precise issue that we are all debating, and you have erroneously assumed it away as a given. Then once you have assumed away the original issue, then you affirm the consequent with your incomplete analysis.

Your assumption is partially correct, for drysuit applications, with caveats, which I mentioned earlier, and which DA Aquamaster also stated.

Your assumption is totally unsafe in the case of a thick wetsuit, which changes buoyancy with various depths. In THAT case, your B/C has to counter ALL of your weights, AND the air in your tank(s) [0.08 lbs per cu ft], AND your gear (regs, camera, lights, etc.)

 

[IndigoBlue]

..., if properly weighted, even the 18# Halcyon "Batwing" would be enough flotation on the surface. The larger lift capacities are meant to compensate for exposure suit compression at depth... with thicker suits this accounts for a lot of loss.

The Halcyon configurations and gear were specifically designed by Jarrod Jablonski for his cave and shipwreck diving exploits. They are perfect for that application. The advanced training comes in when you try to adapt these configurations and this gear to non-cave & non-shipwreck applications.

And 18 lb "batwing" ... how funny! That might be fine for warm water diving with a 3mm or less wetsuit in the tropics. But I myself complain that most retail B/Cs with their 25 lb wings are too small for most thick wetsuit applications for single-tank diving.

I have friends who dive cold water WITHOUT a B/C nor wing. Anything is possible. That does not however make diving without a B/C nor wing, nor with an undersized B/C, safe or even sane.

 

[jplacson]

But even with a thick wetsuit... wouldn't your total weight (lead, air, regs, gear, etc) total to less than 50#? That would mean a 55# or 60# wing would be enough (which is supposedly the amount of lift needed for cold water dives)

*I have no experience with cold water diving, so I'm just asking*

On my remark about the 18# wing... I only meant surface flotation...not during the dive. If you're neutral at a 15' safety stop at the end of a dive (deflated wing), regardless of gear worn, any air in your BC would make up positive lift wouldn't it? So that being the case, at the beginning of any dive, you should technically just be negative due to the amount of air in your tanks. (Correct me if I'm wrong here)

 

[IndigoBlue]

But even with a thick wetsuit... wouldn't your total weight (lead, air, regs, gear, etc) total to less than 50#? That would mean a 55# or 60# wing would be enough (which is supposedly the amount of lift needed for cold water dives)

*I have no experience with cold water diving, so I'm just asking*

QUOTE]

...

On my remark about the 18# wing... I only meant surface flotation...not during the dive. If you're neutral at a 15' safety stop at the end of a dive (deflated wing), regardless of gear worn, any air in your BC would make up positive lift wouldn't it? So that being the case, at the beginning of any dive, you should technically just be negative due to the amount of air in your tanks. (Correct me if I'm wrong here)

The issue was HOW to calculate your needed lift capacity of your B/C, not what do you think would be adequate in a universal scenario. Have you ever seen a salvage diver's tool bag?

Your B/C lift capacity has nothing to do with how you are weighted at the beginning of a dive. Now you are mixing apples and oranges. LOL!

When putting a worm onto a hook, for fishing, the worm will squirm and wiggle. Debates often turn into that as well. It's called changing the subject.

I do not have a problem with ScubaRon diving a negative rig, and being able to swim-up a negative rig from depth. That is an advanced diving skill. I have a problem with him suggesting it on a universal basis to lesser experienced divers. I hope ScubaRon never runs OOA, because an ESA is based on the assumption that he is neutral at all times. Sure, he could always ditch his belt and EBA, but I would love to see him when he gets to the surface, after an EBA. Assuming, of course, that he makes it back. I have seen weight belts get caught up on gear, it actually happens more often than you think.

 

[firedogut]

WOW!!!!!!!!!!!!! talk about changing subjects....LOL.

i thank you for your input and here is what i have figured out...You are all CRAZY!!!!! but hell even a broken clock is right 2 times a day.

my new set up and the prices i am going to pay

Aeris Atmos 1 Console with compass 229.95
Viper America 159.95
Dacor Viper Octo 74.95
Zeagle Escape BCD 286.95

All of which is being bought at LDS (not in my city but do have stores) all are dealers. (i checked with dacor and zeagle)

what do you think? i'm going to start a new post on this also ...this post kinda is on a new topic

 

[ScubaRon]

Nice change of subject.
You are way too overweighted for your B/C in your thick wetsuit.
I strongly urge you to re-calculate.

...and how would you know that?
We are all in awe of your drysuit, but that really is not what this thread was about.
ScubaRon

 

[IndigoBlue]

WOW!!!!!!!!!!!!! talk about changing subjects....LOL.

that happens a lot here.