Weight repartition on w/integrated BC

[Srrh]

Hello y'all,

Is there a rule of thumb when it comes to distributing weight in the 4 pockets of a weight-integrated BCD ?

To figure the correct amount of weight is easy enough: I empty my bc and I add weight until the water line reaches about 50% of my mask.
Then depending on the size and material of the bottle i add 2.5-5 pounds of additional weight... and voila!!

But where do I put this wieght ?
1/3 in each both front pockets (thus 2/3) and 1/6 in the back triming pocket ?
1/4 in each four of them ?

I use to dive with a weight belt...if I didn't like the weight distribution, I could always fiddle with it underwater...but with my new BCD, no more...

Of course I can always adjust for later dives...but I'd like to know if anyone has a good general rule of thumb for this ?

thank-you...

 

[TSandM]

We've put between 1/4 and 1/3 of the total weight in the upper trim pockets, but it's going to be very individual and probably depend a great deal on how much total weight you're talking about. When I dive wet with a 3 mil suit, I only use six pounds and put it all on the cambands. When I dive dry with a single tank, I have eight pounds on my back and 18 on a weight belt.

 

[rakkis]

It depends on your individual muscle/fat distribution and the type of cylinder.

A rule of thumb I generally start people out with is:
steel - 70/30 front/back split
aluminum - 60/40

Start there and tweak it to fit you

 

[LowVizWiz]

Because my legs are usually trying to sink I keep most of my weight in the back non-ditchable pockets of my BCD. I also dive a steel tank which helps me stay horiziontal. If I were to use the 70/30 split I'd have a hard time staying horizontal.

I think it really depends on what helps YOU have propper trim.

 

[Srrh]

It depends on your individual muscle/fat distribution

Muscle ?? where ?
lol

Thanks all...

 

[Charlie99]

Stop all motion while horizontal and neutral. If your legs go up you have too much of the lead in the shoulder pockets. If your legs sink, you need to move some lead up to the shoulder pockets.

Shift a couple pounds at a time and repeat as necessary until you stay pretty close to horizontal when not finning. What is important in getting horizontal trim is not that the pockets are in the front and the back, but that the rear shoulder level pockets are closer to the head/further from the feet.

Everyone is a bit different. I'm just a slight airhead, so I only use 1 pound in each of my shoulder pockets; and either 8 or 14 in the lower pockets depending upon whether I have 3/2mm or 5mm wetsuit. AL80 in both cases.

 

[Srrh]

I keep most of my weight in the back non-ditchable pockets of my BCD.

Waaaiiiittttt a minute...

What do you do in case of emegency ?

Aren't you supposed to be able to ditch your weights at any time to attain instantenious buyancy ?

I thought that, at the very least, my back/trim weight (non ditchable) were supposed to allow me to be slightly positively bouyant...and that, if all else failled, I could always ditch the rest..

Follow-up question:
Do you all use standard weights or did you DIY ? Pockets full of rocks perhaps ?
I think I am going to use zip-locks full of steel-shots...I could calibrate it to the nearest gr...
Is that a good idea ? i was going to use salt...
;-)

 

[TSandM]

If you do a search on ditchable weight, you'll read more than you want to about the arguments for and against maintaining ditchable weight. Each person has to decide for himself how important ditchable weight is.

For me, having the weight distributed so that I can remain horizontal and still is the primary goal. Keeping a balanced rig (meaning I can swim it up from depth in the event of a wing failure or drysuit flood) is also important. I need ditchable weight with my doubles, because I would have trouble swimming them up from depth in the event of a catastrophic buoyancy failure at depth, so I wear a weight belt with some of the weight there (and that also happens to trim me out properly, as well).

Ditching weight is primarily an issue for getting buoyant at the surface. Most people would agree that ditching significant weight at depth is a truly last ditch measure, as it will not permit you to control your ascent at all once it is done.

 

[Srrh]

If you do a search on ditchable weight, you'll read more than you want to about the arguments for and against maintaining ditchable weight. Each person has to decide for himself how important ditchable weight is.

I need to learn more in this 'debate' cause that Flies in the face of everything I learned in OW...

But touché on the 'that ditching significant weight at depth is a truly last ditch measure'...couldn't agree more...

Still, how would one ditch his 'un-ditchable' on the surface ?
Buddy ?

BTW: you use both a weigth integrated BC AND a weight belt ? sorts of defeat the purpose, no ?

 

[Charlie99]

I need to learn more in this 'debate' cause that Flies in the face of everything I learned in OW...

It just breaks down to considering the various risks involved.

1. You don't want to do an uncontrolled ascent. Dropping weights, either on purpose or by accidentally ditching them can lead to an uncontrolled ascent. Very, very dangerous if you have significant N2 loading. In the case of a diver with many minutes of mandatory decompression obligation, it could be life threatening. Even with a lightly loaded diver still within NDL limits, there is always the possibility of embolism/AGE or lung barotrauma.

2. OTOH, you don't want to get stuck to the bottom and unable to ascend if your BCD or wing fails. If you are at depth and your BCD fails you will be negatively buoyant by 1) the weight of the air in your tank + 2) any wetsuit compression due to depth + 3) any excess lead or overweighting. Most divers can handle, for the short time of an ascent at least, the 6 pounds of air in an AL80 and perhaps another 10 pounds of wetsuit compression. As you ascend, the wetsuit gains buoyancy and it gets easier to continue swimming up.

3. If are on the surface, you shouldn't be more negative than roughly the weight of air in your tank. About 6 pounds for 80 cubic of air. If you want to float on the surface for a long time, and your BCD isn't working then you would like to dump some weight. You might also like to dump a bit of weight, if you do the far to common mistake of entering the water to start a dive with no air in the BCD and the tank valve turned off.

====================

It's a balance between being able to ditch some weight to assist in an ascent or to stay on the surface vs. having weight very securely attached so you don't do an unintended rapid ascent.

A good check to perform sometime is to do an ascent from fairly deep with your BCD empty. Or at least make sure that you can swim up off the bottom with no air in your BCD. Doing this near the beginning of a dive, while you have a full tank, is the best test.

Personally, I find that for my style of diving a good tradeoff between having some weight to dump and lessening the risk of accidental dumping is to put 3 or 4 pounds into each ditchable pocket (6 or 8 pounds total). The rest of the weight is either in my shoulder pockets, or just sits inside my zippered BCD storage pocket.

=================

Some other divers decide to put some weight in the pockets of a weight integrated BCD, and some on a weightbelt. The reason is that, if for some reason, you ever try to remove your BCD and all of your lead is in the BCD, you will find that the wetsuit makes you buoyant and want to go up, while the lead in the BCD has it headed for the bottom. Moving some weight to a weightbelt reduces this problem.

Think about the alternatives. Choose wisely.

Charlie Allen