Weighting for Neutral Buoyancy

[rongoodman]

I can complete most dives with no air, or very little air, in my bladder. That's with 3mil or less and using the head awash at the beginning of the dive method. I don't have any issues at my safety stop,

So you compensate for the change in buoyancy due to the use of your breathing gas only with your lungs?

 

[The Chairman]

So you compensate for the change in buoyancy due to the use of your breathing gas only with your lungs?

Of course. The elbow on my bladder was broken over two years ago and I removed it. I haven't replaced it since then. I do carry a sausage to allow me to float easily on the surface after a dive. I have written often about learning breathing techniques that would easily allow this. They're not hard, but you do have to educate yourself.

 

[Rollin]

If anything, I'm just a touch heavy.

Then you should be neutral at 0 psi, empty bladder. Not at 500psi.

I get it with the lungs, I started diving without bcd 35 years ago. But it is sometimes not very comfortable when in current. Also, when doing deco, I prefer to inhale and exhale deep every once and a while. Breathing at the top of my lungs just for that 500g of lead.... and it's the language barrier probably, but why this amount of lead makes a controlled ascent difficult, I don't understand very well.
You never ascend with 1000 psi then?

 

[scubadada]

Then you should be neutral at 0 psi, empty bladder. Not at 500psi.

I get it with the lungs, I started diving without bcd 35 years ago. But it is sometimes not very comfortable when in current. Also, when doing deco, I prefer to inhale and exhale deep every once and a while. Breathing at the top of my lungs just for that 500g of lead.... and it's the language barrier probably, but why this amount of lead makes a controlled ascent difficult, I don't understand very well.
You never ascend with 1000 psi then?

I don't think we basically disagree about anything. We're talking about 1 lb/450 g of weight difference from being absolutely neutral at the safety stop or the last deco stop at 500 psi vs. 0 psi in an AL80. You're not going to have an opportunity to do the weight check at 0 psi, but being a touch heavy takes care of it.

Nobody always ends up at the last stop with the same amount of gas. I often end up with more than 500 psi and am a little on the heavy side. Especially when drift diving in SE Florida, I not infrequently surface with less than 500 psi, no less than in the 200s psi. I have no trouble with the stop or final ascent.

Neither of us is in bad shape, many divers never even do a proper weight check at their safety stop

 

[SmashMonkey]

This is great! Appreciate all the comments, even the OT ones. I asked this question because I was reading the Peak Performance Buoyancy Specialty Course thread and rather than hijack that thread I thought I would start my own. Just completed AOW and I didn't really learn anything about buoyancy on that dive. Although I did get the plastic so I can do the more challenging dives without having to explain my life story every time.

I think I like the 2 step procedure of 1) establishing pre-dive neutral buoyancy on the surface with a full tank, then + 5-6 lbs for the gas in the tank(s); then, 2) fine tune at 15-20 ft SS by +/- 1-2 lbs after accounting for the 500-1,000 psi left in the tank.

Erring on the side of being slightly overweighted works for me. I wear 12 lbs +/- 1 or 2 lbs for tropical diving and 6-8 is usually ditchable. I always have my DSMB for backup buoyancy. I totally forgot to think about exposure suit mostly because nowadays I only dive with a rashguard or Polartec. Although I am planning to venture deeper and darker where neoprene might be an option.

 

[Rollin]

I don't think we basically disagree about anything.

I agree. ;-)

But I don't use a 500 psi tank at the end of a dive to weigh myself. When using new gear or setup, I go to 3m or 10ft with full tanks and empty wing. I find our how many kg/pound of lead I need and just add the weight of the gas in my tanks (or even some more depending on current or video equipment).
For me at least, that's the only way to go to be sure from the beginning.

 

[scubadada]

I had been using the same amount of weight for quite a long time for either my 3, 5, or 7 mm full suit, with or without a 5/3 hooded vest. I bought a new 3 mm full wetsuit. On the first dive, I was quite light at the safety stop. I added a lb, much better but could just hold the stop and was light on the ascent to the surface. Added another lb and all was well, just a touch heavy. Now I know what I need to this wetsuit too

 

[MCR112]

Just joined the board today but will comment. Back when I started diving there were no BCD's so we weighted our selves to be a little negative at the end of our dive. Saying this we would rocket to the bottom at the start. I still struggle with being over weighted. DM's have worked we me on this but I don't feel comfortable having less weight. I have learned to be just barely negative by airing up the BCD . So it doesn't matter to me how much my gear weighs or if my suit floats I adjust my trim accordinly.

 

[gqllc007]

I also don't over think it...In Key Largo I used 16 pounds which was about 2 pounds heavy than needed to be...we were shallow around 30-40 feet....I just adjusted as needed. On the second dive I told the DM that I needed 8 pounds...I was wearing a SS BP/W so 4pounds in each pocket was 8 plus the Dive Rite SSBP and STA was around 8 more equaling 16 pounds total. He gave me 8 pounds for the left pocket and 8 pounds for the right pocket...I wasn't even thinking so I put the weights in the pockets....I was about 8 pounds too heavy on that dive...I just adjusted my buoyancy accordingly...

 

[Nemrod]

You might want to not under think your over weighting either, just saying. It can be dangerous especially if a significant portion of it cannot be jettisoned. N