When to ditch weight?

[stuartv]

Not at the beginning of the dive, but at the bottom with a dead BC.

As I said, it may not be the right number, but I believe you would have to add the weight belt (or attached weight) that is used to make you neutral at the safety stop after the use of the air and re expansion of the wetsuit. At the point you have a full tank and crushed wetsuit it is just added weight on you.


Bob

I specified HP120, 7mm wet suit, AND BEING PROPERLY WEIGHTED.

That last part means, by definition, you are neutral at your safety stop, with an almost empty tank and an empty wing.

If you are neutral with an empty wing and an almost empty HP120 and a 7mm wet suit at 15', then that means you have whatever weight on your belt that you have, and when you roll time back to having a full tank you are 9 - 10 pounds negative. And with that full tank, when you go to the bottom and lose (guesstimate) 75% of the buoyancy that your suit provides at the surface (guesstimate lose 75% of 20#), you are another 15# negative.

So, 25# negative at the start of the dive, at the bottom, with an empty BCD. Not 45#.

IF you are properly weighted, then your worst case is being negative by the weight of your gas (~10 pounds for an HP120) plus the loss from wet suit crush (guessing 15# for this made-up example). If you're more negative than that, it's because you are over weighted. If you're 45# negative, you are carrying 20# of extra weight for no reason.

 

[Bob DBF]

Let me think about this a bit, I'm quite busy moving, and I'll get back to you here or on a PM. I've got something stuck in my head about this and have to clear it out and rethink it all.

On a side note, I have enjoyed your posts since day 1.


Cheers

Bob

 

[stuartv]

Let me think about this a bit, I'm quite busy moving, and I'll get back to you here or on a PM. I've got something stuck in my head about this and have to clear it out and rethink it all.

On a side note, I have enjoyed your posts since day 1.


Cheers

Bob

Thanks, Bob!

 

[LariatAdvance]

During our OW, we were taught how to ditch weight. After learning how to dive and completing so many dives, the more I am lost about when or what situation warrants ditching one's weight.
One situation I can think is jumping into the water with the tank close. However, this has happened to me before and it was easy to kick to the surface, blow air into the BCD with the mouthpiece and take time to open the tank. Even with no air in the BCD, one just does not sink quickly downward.

Did you happen to read the OW manual? It's page 74.
"It is never wrong to drop your weights at the surface." and "Dropping weights underwater risks an uncontrolled accent, so only do so if you're unsure you can reach the surface any other way."

Why are you negatively buoyant at the surface? If you "jump in the water" you should be there floating until you release the air from your BCD to start your decent. Since you're supposed to be positively buoyant on surface, why would there be a need to drop weights if you realize your tank valve is closed? Being buoyant on surface gives you that few minutes to make sure your reg is working, make sure your buddy is there, make sure you tank valve is on, your computer is working, etc. I'd know within 10~15 seconds after "jumping in" that I wasn't getting air from my reg, and I'd still be floating on surface when I realized that. Also how would you give the "OK" sign that you are trained to give if you sink like a rock as soon as you jump in?

I guess it may vary by school or something, but we were taught to jump in, or back roll in, slightly buoyant, (you're bobbing on the surface now) give the "OK" hand signal to the guy on the boat, back off a bit so your buddy doesn't jump in on top of your head, make sure he's OK, check everything is working as it should, then raise the BC relief valve and submerge together as a pair, assuming everything and everyone checked out OK.

10 feet under and sinking is a bad time to realize you forgot to turn the tank valve on in my opinion. LOL

It's a lot easier to just say, "Hey Fred, turn my tank on, man, I forgot." at the surface than it is to try to communicate with a dive buddy with hand signals underwater to do it........."Oh, the deceased was signaling "turn my tank valve on?" I thought he was signaling "Hey look at that cool starfish over there."

 

[Storker]

1. If underwater and you feel that you may pass unconscious in the immediate future or if you assess that it's the only way to attain neutral/positive buoyancy.
2. At the surface, if in distress.

Re: #2: A lot of diving fatality victims are found still wearing their weights. Quite a few fatalities involve not being able to secure positive buoyancy at the surface. Which indicates that far too many are too reluctant to drop their weights if they're experiencing problems on the surface.

 

[stuartv]

Being buoyant on surface gives you that few minutes to make sure your reg is working, make sure your buddy is there, make sure you tank valve is on, your computer is working, etc.

Sitting/standing on the boat/dock/shore gives you even more time to do all that stuff.

10 feet under and sinking is a bad time to realize you forgot to turn the tank valve on in my opinion. LOL

In the water at all is not the best time to realize you forget to turn on the tank valve.

BTW, some dives almost require you to drop in negative and start sinking immediately.

 

[Premo83]

I considered once ditching weights. It happened last April at Roca Partida. I was around 5m deep, low on air but already did my safety stop. Just when I shot the SMB I got caught in a horizontal vortex and started spinning with the line wrapped around me. I waited a little bit to see if the momentum would carry me out of the vortex. It didn't happen and I kept spinning. I inflated my BCD and got out of it easily. But if inflating the BCD and kicking wouldn't have been enough my next move would probably have been ditching the weights as I was already low on air, didn't have much time to sit it out and I wasn't very deep.

 

[Don Quixote]

Why are you negatively buoyant at the surface? If you "jump in the water" you should be there floating until you release the air from your BCD to start your decent. Since you're supposed to be positively buoyant on surface, why would there be a need to drop weights if you realize your tank valve is closed? Being buoyant on surface gives you that few minutes to make sure your reg is working, make sure your buddy is there, make sure you tank valve is on, your computer is working, etc. I'd know within 10~15 seconds after "jumping in" that I wasn't getting air from my reg, and I'd still be floating on surface when I realized that. Also how would you give the "OK" sign that you are trained to give if you sink like a rock as soon as you jump in?

The day that it happened, it was even worst. We did went through our BWRAF but I actually just kind of called through it without actually doing the actions. The LP inflator was not connected to the BC. Then, I jumped in with no regulator in my mouth. All this with the tank closed. That is how bad it is. One does not really sink like a rock.

But really, about negative entry, we are asked to do it many times in fast currents from a dinghy or boat.

 

[MAKO Spearguns]

The day that it happened, it was even worst. We did went through our BWRAF but I actually just kind of called through it without actually doing the actions. The LP inflator was not connected to the BC. Then, I jumped in with no regulator in my mouth. All this with the tank closed. That is how bad it is. One does not really sink like a rock.

But really, about negative entry, we are asked to do it many times in fast currents from a dinghy or boat.

I applaud your honesty and willingness to share with everyone, It is stories like these that reinforce my decision to market weight belts to the scuba community and to offer a free replacement offer for ditched and lost weight belts.

dive safe!
Dano