Near disaster; dropped weights - what to do?

[The Chairman]

I am with CyborDolphin... what BC were you using? I can almost gaurantee that the weights were secured via velcro. Gawd, I hate Velcro in a weight system! My OMS IQ uses that, and I do hate them. I must check them out a dozen times BEFORE I descend. Make sure all of the velcro is clean and try not to over stress them. Find ways of attaching your weight onto different areas so that you have an absolute minimum in the ditchable areas.

While I almost always dive with a buddy, I make it a point to NEVER have to rely on one. I have had no need of a guardian guide, but then I refrain from tech diving as well. I am always a little overweighted, but not much. I definately like to sink with ease, and do not mind finning to the surface if needed. If I were to loose either side of my weights, I would still have just enough to be able to stay under. I would have to swim downward, but I could manage it.

 

[Louie]

Hello again,

In answer to the questions about equipment, I was using:

Seaquest Diva BC (yes, with the velcro pockets)
5mm full wetsuit
Weights - 2 pockets (3lbx1 and 6lbx1) plus 3lb in a non-ditch pocket at the back - I weigh about 115lb

I am now conscious of the possibility of loosened weights and check my pockets frequently during a dive.

 

[Louie]

Oh, also

The entire dive was done using air.

 

[Bob3]

Sounds like you may have been just a tad overweighted.
I'm just guessing, but 21 lbs of lead with that small of a wetsuit seems to be a bit much.
You should be neutral at your safety stop with an "empty" tank & zero air in your BC, meaning you'll be a couple lbs positive at the surface (at the end of the dive).

On the topic of being able to fin back down to catch your own lead, you'll need a stout set of flippers for that one.

 

[Lost Yooper]

I've seen that happen (and heard of it happening) so many times with those type of W/I BC's, it's not funny anymore. You're incident is a prime example of what the buddy system is all about. You owe him a beer or two (or three)!!

That was a warning shot acrossed your bow. I would seriously consider forgetting about those pouches and go with a double buckle weight belt and disperse some weight in other areas. That type of scenario is simply not an option for those type of dives -- don't allow it to happen again, eh!

Take care.

Mike

 

[Se7en]

Originally posted by Bob3

You should be neutral at your safety stop with an "empty" tank & zero air in your BC, meaning you'll be a couple lbs positive at the surface (at the end of the dive).

I tried... but I couldn't ignore one of my pet beefs.

Bob3, not trying to pick on you - but what is the basis for the absurd bit of dogma you are quoting?

FACT: The greatest pressure change vs distance occurs close to the surface (ie from the safety stop to the surface)

FACT: Even on so called 'non decompression' dives, this is the most critical part of the decompression

Good Practice is to make the last few metres of your ascent as slow as possible to aid with offgassing.

As far as I'm aware, the accepted procedure in the event of a problem (such as exceeding planned bottom time) is to spend as much time as possible at a safety stop before exiting the water, then ascend from there at a rate of 1m per minute or less.

How can you do any of the above if you are neutral at 5m safety stop, and then positive from there up? That tired bit of recieved wisdom is actually advocating an uncontrolled ascent from 5m.

Think about it, and then weight yourself so you can do a controlled (NOT BOYANT) ascent from the bottom, to the surface.

Repetative winge over.

Mike

 

[Campana]

I've dived with others who put their weights in their velcro pockets correctly and still lost them, on several occasions. This was in Genesis BC's (Athenas). I have also seen lost weight pockets on Aqualung Cousteau's with the little plastic post and clip.

I use Halcyon weight pockets with a buckle. You are not going to lose weight pockets with one. Scubapro is starting to put buckles on their BC weight pockets as well. Why? Because you need the buckles to keep the weights in. In my opinion the velcro system is inferior and dangerous. If I had a BC with Velcro pockets, I'd get rid of it. Failing that, I'd wear a weight belt.

 

[fredk]

i have seen weights drop out of the pockets on zeagle bcd's as well, if it were to happen to me from a depth like you were at i would definetly flare to slow my ascent, but i would also breathe some o2 upon surfacing be monitered very closely and stay dry for several days saftey pays dividends sometimes. i witnessed enough cases of dcs that could have easily been avoided by basic diving protocol. i volunteered in a chamber for a year and have seen every basic rule of diving either broken or seriously pushed the limits.

 

[Rick Murchison]

Originally posted by Se7en
FACT: The greatest pressure change vs distance occurs close to the surface (ie from the safety stop to the surface)

Sorry,
That statement isn't "fact" at all - it is false. The pressure change per foot depth water is a constant 1/33 (average for salt water) ATM. That's why we can convert depth to atmospheres with a simple division formula.
The fact you're after is that the "greatest change in pressure relative to the total pressure" (greatest delta "P" over "P") per unit depth occurs near the surface. The implications of *this* fact are what makes the final few feet of the ascent the most critical for bubble growth, with all its associated problems.
Rick
By the way, you can find that "greatest pressure change" in a disturbing number of "authoritative" documents and even scuba texts - but that doesn't change the real laws of physics, or make it any less false.

 

[devjr]

Overweighted? I calculate that Louie was wearing 12 pounds of lead which sounds about right for a 115 lb diver if the tank itself was slightly negative. I weigh 200, and with a similar tank and wetsuit would be wearing 18 pounds of lead to be neutral at 10 feet.

Before continuing, let's pause to consider SE7's argument about whether to rig for neutral weight at the surface instead of 10 (or 15 feet) depth. The argument in favor of neutral buoyancy at the surface seems to be based on a concern that the diver not be allowed to become positively buoyant when approaching the surface as would occur with the diver who configures his end ballast to become neutral at some point below the surface.

Where I need 18 pounds to be neutral at about 10 feet depth, approx 21 pounds is used to be neutral at the surface. Thus, the maximum amount of upward thrust when rising from 10 feet would be the difference, three pounds lift at the surface with the average being 1 1/2 pounds over 10 feet of travel. Because of inertia, drag and the short distance involved it hardly seems likely that the rather minor lift of 1 1/2 pounds average would be a safety concern if a stop has already been performed. There is such a thing as "too cautious". On the other hand, not all ballast problems are the same for all people.

Although she didn't say, I suspect that "Louie" lost her 6 pound weight which would be fully half of her lead ballast. That's a lot and tough for a 115 pound woman to overcome. Nevertheless, the weight only fell 20 feet, and venting of air plus some determined swimming would probably have allowed her to fetch it. Of course, a novice diver might not take this rather desparate measure, especially if help were at hand. Fortunately, things worked out OK.