Safety question about BCD lift capacity and weights

[Tatsubon]

Grateful for everyones input into this matter. I have taken your replies in with considerable consideration, and re-evaluate my conditions.

Had a chat with my dive mentor during the weekend, and was also told that I can get my weights down to low 20# or even below, with proper breath control and locked legs (stop finning). He also emphasized in getting all the air out in the drysuit. (Have to work on a better scrunch technique). Do any of you have any tips? Should try to see if I can get more air out in the water. Have a feeling air might be trapped in the upper forearms or neck area. Taking my time to be calm as possible in the water and listen at what my rig has to say. Trimming is going to be the next hurdle ahead, but I will take it one step at a time.

Many thanks again for your support. Today I will be going to the pool to fine tune my buoyancy.

I will strive to minimize my weight.

Tatsubon

 

[Tatsubon]

Update from my pool session!

It was a great surprise to find that I now only need 20 lbs to dive with my drysuit in fresh water (wish I could have taken some more time to test 18#). Started at 26# then slowly started shaving off 2# at a time untill I found my sweet spot at around 20# with a tank at 800psi. Once my tanks pressure had droped to 600 I found myself too bouyant to stay down anymore. (this is actually a good thing before you ever find yourself OOA) A secondary safety sign telling you to double check your air and head up.

I also had noticed that once down below a certain depth I lost a little more bouyancy and had to add a little air in my drysuit to be neutral. This was a nice relief of drysuit squeeze with that little extra air. Now I can't wait to head out for some OW test next. Will try out 22# in salt to see if it can work out.

Tatsubon

 

[Steve50]

Update from my pool session!
Now I can't wait to head out for some OW test next. Will try out 22# in salt to see if it can work out.

Tatsubon

for salt water you will need this much more weight

(your weight + all your equipment including weights) x 2.5%

for most folks 4-8 lb. more

 

[hokie_diver]

By my calculations: 10% of body weight + 10# for shell drysuit + 5# for tank = 32#

I'm interested if this rule is some sort of standard... I've never heard it before and maybe it only makes sense for drysuit diving? Otherwise it has you wearing 22lb in warm water with no suit on...

Granted, I'm not Captain Experienced Diver, but that formula doesn't check out to me.

 

[Colliam7]

Your initial question started out asking about safety issues with exceeding a BCs stipulated weight capacity. But, it sounds like you have moved on to address the bigger issue of weight management in the DS environment, so I will add my 0.02 along those lines. Sounds like you are experiencing an odyssey similar to what many of us went through, both as newer divers and then as newer drysuit divers (need LOTS of weight to start, but gradually find ways to pare it down). Like you, I started out ‘needing’ ~33 lbs in my DS, but dropped considerably over time, with technique and gear changes. Mine included:
1. Simply trying less weight and finding that I really didn’t ‘need’ so much. That was a big revelation in itself and reflected my diving inexperience. I systematically tried using less weight, in increments, as you have now done in the pool and found that I didn’t need 33 pounds to begin with.
2. Better expulsion of air from the DS prior to getting in the water, again as you are apparently now working on. I was going in comfortable. Once I started going in with more of a 'shrink-wrap' approach, I didn’t need as much weight. I coupled this with keeping a little more squeeze in the suit while underwater. Not so much to be uncomfortable, but I found I really didn’t need so much air in the suit, and consequently lead in my BC, to be comfortable.
3. Better breathing control, as your mentor has already helped you identify.
4. Better finning technique, to avoid adding a vertical propulsion vector to my kicks, which made it appear that I was light.
5. Changing from Mares Quattros to more negative ScubaPro Jetfins.
6. Moved to a BP / W. I started out in a Ranger – a wonderful (weight-integrated) BC, but all that padding and material (including the little pouches used for the soft weights) adds to the need for more lead. Moving to a SS BP not only moved weight from my waist to my back, it allowed me to drop total weight as well.
7. Refining my undergarments. I started out using cotton / wool undergarments, which were also thicker than I needed. Once I switched to synthetics – I use REI MTS or Patagonia capilene underwear – I dropped some more weight, and I still have good insulation.
8. Moved to a steel tank. Started out with an AL80. Moved to a HP steel 120. Again, this moves weight from the belt / pocket to the back.

Don’t know if any of this helps or not – it is just my experience. But, it appears you are already moving in the right direction. (FWIW, I ended up going in a tec direction, and doubling my HP steel 120s. Now, I need no added weight in saltwater. Of course, those d@&$ double 120 tanks weigh a ton! )

 

[Gil57usa]

Ever dive in an XL 2 piece 7mm wetsuit with 5mm hood, boots, and gloves? It used to take 36# on my belt to get neutral with an AL80.

Yep, Dove with a 2 piece 7 mil farmer john for a number of years with an aluminum 80. I had 20 # on the belt. Same hood, gloves, etc.

Now, in a drysuit with doubles, bp/w, no weight at all.

 

[String]

Once my tanks pressure had droped to 600 I found myself too bouyant to stay down anymore. (this is actually a good thing before you ever find yourself OOA)

No, thats a very bad thing. That means if you get out of air or even low on air you'd be too buoyant to control and ascent or hold a stop meaning you'll be ascending too quickly, out of control and if you have stops to do, will miss them as well.
If you cant stay down with 600, at zero sharing air with a buddy it'll be impossible.

You're underweighted if this is happening and thats dangerous.

You need to be comfortable able to hold a stop with 500psi with a little bit of air left in a BC. That means if the tank is empty you can still control things.

 

[String]

I'm interested if this rule is some sort of standard... I've never heard it before and maybe it only makes sense for drysuit diving? Otherwise it has you wearing 22lb in warm water with no suit on...

Its an ill informed guesstimate that ignores body composition, sizing of exposure protection and so on. Very rarely is it accurate for anyone at all. Its best ignored.

With me for example it would have me massively overweighted even in my big drysuit with 4 layers of undergarments.

 

[hokie_diver]

Its an ill informed guesstimate that ignores body composition, sizing of exposure protection and so on. Very rarely is it accurate for anyone at all. Its best ignored.

With me for example it would have me massively overweighted even in my big drysuit with 4 layers of undergarments.

Makes sense. I've never dove a drysuit before so I wasn't sure where that rule came from. As far as I can recall, it was never presented in my OW class (YMCA).

In any scenario I have experience with (up to 7mm w/ hood in cold-ish water) that "rule" would have me drastically heavy.

 

[String]

Padi mention it in the peak performance speciality book. Its worthless though.