On the fast train or slow on?

[Warhammer]

What’s your opinion on proper weighting and ditchable weight? Do you think you should weight yourself so that, after dropping your weights in an emergency, you’d still be slightly negative buoyant at depth? In that case you’d have to actually swim up to a certain point before you’d become positive buoyant. Or do you think you’d be better off too just dump all your weights, become positive buoyant, and take your chances with AGE and DCS on your ride up? Or should you have 2 ditchable systems that you can ditch independantly depending on the situation? Assume these are wetsuit dives, so you will have to buoyancy of the wetsuit to contend with.

 

[ericfine50]

I would go with the idea of weighting yourself so after you ditch, you are posative. That does not mean rocket to the surface, but you can swim your single tank up w/o effort.

Eric

 

[Walter]

........are to be neutrally buoyant at either the surface or at 15 ft with about 500 PSI in your tank. Personally, I favor being neutrally buoyant at the surface. That way you can adjust to be neutral at all depths, including 15 ft, and you can easily make a slow ascent from 15 ft. If you are weighted for 15 ft, the ascent from there to the surface can be difficult to control.

WWW™

 

[raffles]

I think that if you're ditching your weights at depth you're in enough trouble to need to get to the surface in a hurry, that being the case AGE and DCS will probably be the least of your worries. Otherwise ditching should not be an option.

Raffles

 

[o2diver]

Good question, Friends have been discussing this very subject. We hecided it depends on your weight system. If you have intergrated weights that are not on a rip-cord, then you can drop one side and control your accent. If you just have a weight belt, then we agree with Eric. Kicking to the surface means work load, and that leads to DCS.
My .02
o2diver

 

[Warhammer]

I agree with you, Walter, but that isn’t what I meant. I too perfer to be weighted neutral @ 500PSI and on the surface.

Let me give you an example. With my full, shorty, and hood, I require 30 to 32lbs of lead in salt water with an AL80. Let’s break that down. The suits and hood have positive buoyancy of 22lbs on the surface, I have a positive buoyancy of 6lbs when breathing normally, and the AL80 has a positive buoyancy of approximately 3lbs when at 500PSI. Add those up and you get 31Lbs, which is the amount of lead needed. Suppose I had all this lead in my BCs weight integration system and with my Ranger, a single pull dumps it all. Ok, I’m diving a wreck at 100fsw, to the sand, and I inadvertently back into a sharp object and puncture my BCs bladder badly. It won’t hold any air, and I have around 1000PSI left in my tank. At 100fsw my wetsuits would have been compressed and they will have approximately 5.5/6Lbs of positive buoyancy at 100fsw. The tank would be approximate 2Lbs positive, I’m still 6Lbs positive, and I have 32lbs of lead. So I’d actually be 18Lbs (6 + 2 + 6 – 32 = -18lbs) negative at this point. So with no BC, I’d be firmly planted to the bottom. Not sure if I could swim up the –18lbs or not, never really tried it. But I’m in no immediate danger, I’m calm, have air, and ain’t going any deeper, so the situation is manageable, but I need to get to the surface safely. If I were to drop all 32lbs, I’d become 14lbs positive at 100fsw, the wetsuits would decompress as I ascended and I’d pick up 16 more pounds of buoyancy from them along the way, making me +30lbs by the time I got to the surface. Would it not be safer to drop only part of the weight, say 12Lbs, which would make me a negative 6Lbs after dropping the weight, which I should be able to swim up pretty easy. As I ascended I’d still gain the buoyancy of the suits (16lbs) making me +10lbs when I got to the surface. Don’t you think this would be safer than dropping them all in this situation? Would you not be moving rather fast with +30lbs of buoyancy, and probably be bent when you reached the surfaced?

 

[WetDane]

Warhammer,

I tend to agree with you - I woudl prefer not to dump all my weight at once - that's a guaranteeed disaster.
Assuming that one is calm and able to control the situation, I want to go slow - thank you very much.

I dive 18 lbs on a belt and 12 lbs in ditchable pockets - the way I figured it is that the belt is NEVER coming of - if I have to ditch to get up - I can drop 6 lbs at a time - this shoudl be plenty to get me started in the right direction!
On a sidenote - I had a friend get a ditch handle caught at 90 feet - lost half of his weight - Needless to say - He didn't like that much...

Cheers,
Terkel

 

[herman]

I see 2 other possible solutions to the situation. First, there has got to be an anchor line some where near by and a hand over hand acent up it seems to be the best exit. Lifting even the 30 lbs would not be difficult, safety stops would be no problem and then weights could be dropped at the surface in necessary. The other is your buddy still has a working bc, there is no reason that you could grab on to him ( with his co-operation ) and use his bc to accomplish the accent. Matter of fact, we did just that in one of the "rescues" in my rescue diver coarse. My Ranger has 44 lbs of lift and I dive with 20-25lb with a full wetsuit (7mm)in SW so I would still have 20 lbs or so of reserve, plenty to do the job even if some swimming to get it started was needed. In any case, I doubt that I would dump the majority of my weights at first. And there is always the option of opening the weight pouches and dropping a couple of weights by hand. It would be my absolute last resort to drop all my weight if I had the air and time to make a better/safer choice. At 30+ positive accent would not be pretty. A 3rd choice just came to mind, drop just enought to allow you to get off the bottom, find the anchor line and follow it up, you might have to hold on to stop your accent, but it sure beats rocketing to the surface.

 

[Warhammer]

Herman, that makes sense and 1 of those 3 things would be my first choices in that situation. If the first two options weren't available, in that situation, I could calmly take out weights one by one until I could swim the rig up or get to the anchor line if available. But even in a critical situation where I was still capable of swimming but didn't have time to selectively dump weights individually, I would think with that much bouyancy to contend with, separate dumping systems would be better than all or nothing in any situation that requires ditching. I'd also think that alot of divers faced with my senario would panic when they became planted on the bottom and would ditch the whole load, if it was all in one spot, while in panic mode. And I just can't think of any situation where that would be the best decision. Even if unable to swim, surely if I was able to release 1 set of weights, I'd be able to release 2. So I've come to the conclusion that 2 ditchable weight systems is better than one, espeacially when contending with that much buoyancy. Would you agree?

 

[WetDane]

I agree with you Warhammer.

I dive the Transpac with independent pockets, so my belt has 18 lbs that I have no intention of ever leaving behind, I have the 6 lbs on each side though that will lighten me enough to do what herman proposed - that's what I had in mind - good words Herman!

Terkel