Dumpable weight vs trim

[Ayisha]

If someone is wearing a thick wetsuit, then they can not just swim up if the BC fails.

That is not true. Being able to swim up a rig with a non-functioning BCD is part of the definition of a "Balanced Rig".

BTW, I wear a 2 piece 7 mm wetsuit. So a total of 14 mm at the core. No problem at all.

 

[johndiver999]

That is not true. Being able to swim up a rig with a non-functioning BCD is part of the definition of a "Balanced Rig".

BTW, I wear a 2 piece 7 mm wetsuit. So a total of 14 mm at the core. No problem at all.

OK then, you are clearly a much better swimmer than I am.

 

[Ayisha]

...For #2, yes you can kick, like what you do to begin a normal ascent when you have no problems...

You may begin a normal ascent by kicking. I begin a normal ascent by inhaling while my feet are stationary, but we have different training.

 

[Ayisha]

...What people are saying is that if you go OOA while diving and are neutrally buoyant, it will take little or not effort to start your ascent. Once you start your ascent, the expanding air in the BCD will do the job without any more effort on your part.

The problem you describe would require two unrelated major failures (OOA and BCD bladder failure) to occur at precisely the same time. For many people, the possibility of two unrelated major failures to occur simultaneously is so remote that it does not need to have to be considered.

Thank you for explaining it so clearly.

 

[lairdb]

The problem you describe would require two unrelated major failures (OOA and BCD bladder failure) to occur at precisely the same time. For many people, the possibility of two unrelated major failures to occur simultaneously is so remote that it does not need to have to be considered.

And if unbalanced enough that you can’t swim it up, and OOG, then ditching the entire rig is an option.

ETA: if I was able to think clearly enough I might try to grab the SMB or the survivalpak, but in this scenario I’m way down the incident pit already.

 

[TMHeimer]

So what it seems to boil down to is that several disagree that dropping weights should ever be done, either as a necessity (say from 130' depth and no gas) or as a better option-- buoyant ascent as opposed to a properly weighted person just making a normal ascent doing the things you should do for that. Ie.-- there is no benefit in ever dropping one's weights, not even the extra speed it would give you to get up from 130'. Thus there is no need for any ditchable weight.

Then I guess PADI (and others?) should be advised, so the buoyant ascent can be dropped from all manuals-- like buddy breathing was. I'm not sure that was a good idea, though admit I'm not really qualified to give reasons for saying that.

 

[Bierstadt]

I won't address what has already been well-covered, but I am also very leg-heavy and (after trying multiple options) I use hard weights tied with bungee cord. It is very secure, can be adjusted slightly, and I can cut one or both free with a flick of my dive knife if need be (although that is very far down the contingency tree, so it's not like I have practiced it).

 

[Barnaby'sDad]

So what it seems to boil down to is that several disagree that dropping weights should ever be done, either as a necessity (say from 130' depth and no gas) or as a better option-- buoyant ascent as opposed to a properly weighted person just making a normal ascent doing the things you should do for that. Ie.-- there is no benefit in ever dropping one's weights, not even the extra speed it would give you to get up from 130'. Thus there is no need for any ditchable weight.

Then I guess PADI (and others?) should be advised, so the buoyant ascent can be dropped from all manuals-- like buddy breathing was. I'm not sure that was a good idea, though admit I'm not really qualified to give reasons for saying that.

My answer would be “it depends.” I’m generally not in favor of planning to dump weight. I’ll defer to previous comments to that effect rather than piling on and beating a dead horse.

However, I have experienced dives where keeping the contingency of dropping weights in the back of your mind is a good idea. Ex. While an extremely non-standard scenario for most... I’ve completed dives where the local standard is to dive well overweight (Cooper River, SC) to give you a better chance of being firmly planted on the river bottom while fossil hunting, given the strong current.

In that scenario...again...extremely non-standard, you want the ability to quickly ditch weight, if necessary. Why? In the scenario in question...you actually have to add gas to your wing/BC to ascend. If your wing/BC bladder fails during your ascent or while you’re on the surface waiting to get picked up (I’ve read accounts of the latter happening), the only way that you’ve got a chance to get to the surface or stay on the surface is to drop a good amount of the weight that you’re carrying.

 

[TMHeimer]

My answer would be “it depends.” I’m generally not in favor of planning to dump weight. I’ll defer to previous comments to that effect rather than piling on and beating a dead horse.

However, I have experienced dives where keeping the contingency of dropping weights in the back of your mind is a good idea. Ex. While an extremely non-standard scenario for most... I’ve completed dives where the local standard is to dive well overweight (Cooper River, SC) to give you a better chance of being firmly planted on the river bottom while fossil hunting, given the strong current.

In that scenario...again...extremely non-standard, you want the ability to quickly ditch weight, if necessary. Why? In the scenario in question...you actually have to add gas to your wing/BC to ascend. If your wing/BC bladder fails during your ascent or while you’re on the surface waiting to get picked up (I’ve read accounts of the latter happening), the only way that you’ve got a chance to get to the surface or stay on the surface is to drop a good amount of the weight that you’re carrying.

Good points. Maybe these ideas should be presented when listing buoyant ascent as a last ditch way up. In your intentional overweighted scenario (even in a river and not down 100'), you still have to have tank air to add some to ascend. Of course you probably have at least some in your BC which would expand-- if you can kick hard enough to get started with the extra weight.
I know previous posts are talking about divers who are properly weighted. But this scenario may be one reason "bouyant ascent" has not been eliminated?

 

[lairdb]

So what it seems to boil down to is that several disagree that dropping weights should ever be done, either as a necessity (say from 130' depth and no gas) or as a better option-- buoyant ascent as opposed to a properly weighted person just making a normal ascent doing the things you should do for that. Ie.-- there is no benefit in ever dropping one's weights, not even the extra speed it would give you to get up from 130'. Thus there is no need for any ditchable weight.

Then I guess PADI (and others?) should be advised, so the buoyant ascent can be dropped from all manuals-- like buddy breathing was. I'm not sure that was a good idea, though admit I'm not really qualified to give reasons for saying that.

Different agencies can legitimately have different SOPs and standards. The WRSTC standards do not mandate that buoyant emergency ascent be taught -- though they do mandate that "Surface operation of the quick release/emergency function of the weight system" (my emphasis) be taught. I haven't dug around -- perhaps some current instructors can weigh in -- but I suspect some other agencies do not, or never did, include buoyant emergency ascent.

ETA: In a brief skim of RAID's basic OW material, I don't see buoyant ascent discussed. The only references to discarding weight that I see are specifically at the surface.