"Safe" weight distribution? Weight ditching question.

[Storker]

Not being able to swim to the surface without dropping weights in case of loss of buoyancy means you are overweighted.

I know it's not a high-probability scenario, but what if the drysuit floods? Even when my drysuit is "completely empty" (which it isn't in reality, since that would mean I was so squeezed that I wouldn't be able to move), my undersuit traps quite a bit of air and it provides a pretty decent amount of buoyancy.

I haven't done the experiment, though, so I don't really know how much buoyancy I'd lose in a full DS flood. And that's simply because if I did it in my winter undersuit at the time of the year my winter undersuit is approriate, there'd probably be a pretty decent risk that I'd get a serious case of hypothermia.

 

[Patoux01]

I haven't done the experiment, though, so I don't really know how much buoyancy I'd lose in a full DS flood.

I'm actually considering doing an on-purpose full flood (think vertical in water and letting water in through the neck seal until no air comes out), just so I know, but seeing I'm a solo diver that's not really the smartest move. I'm still not considering my weights as ditchable though, even if they technically are (weightbelt under the harness), nor do I feel a need to have them ditchable (and I dive a small-ish twinset and drysuit).

I consider one failure to be enough to plan for, especially for buoyancy. If my suit fails, I'm going up on the wing. If the wing fails, I'm going up on the suit. I consider it unlikely enough to have the second buoyancy source fails within 20 minutes of the first one to not plan for it.

 

[Storker]

I consider one failure to be enough to plan for, especially for buoyancy. If my suit fails, I'm going up on the wing. If the wing fails, I'm going up on the suit.

Totally agree. I'm rather thinking that if my DS floods completely, will I be able to become sufficiently buoyant? Particularly on the surface.

Swimming up while somewhat negative is one thing. Staying on the surface while somewhat negative is another. Particularly if I'm shore diving and surface a bit out in some chop.

I consider it unlikely enough to have the second buoyancy source fails within 20 minutes of the first one to not plan for it.

I'm not quite following you here. "within 20 minutes"? On a couple of occasions my - or my buddy's - BCD wouldn't hold air. We thumbed the dive there and then since we had planned to have redundant buoyancy.

 

[Patoux01]

If it fails as I start my ascent, I may be up to 20 minutes away from the surface. Typically it's less than 5 minutes away.

My diving also does not allow me to just ascend and assume it's safe their. Once on the surface I'm in for a good swim because I'm shore diving.

 

[Storker]

If it fails as I start my ascent, I may be up to 20 minutes away from the surface.

Ah. I forgot about deco obligations. My bad.

 

[Patoux01]

Yeah I sort of realized afterwards this is basic discussion, but it's my reasoning for my view on it, and with no deco it should point even further in the direction of "there doesn't seem to be a need for it".

 

[Edward3c]

I know it's not a high-probability scenario, but what if the drysuit floods? Even when my drysuit is "completely empty" (which it isn't in reality, since that would mean I was so squeezed that I wouldn't be able to move), my undersuit traps quite a bit of air and it provides a pretty decent amount of buoyancy.

I haven't done the experiment, though, so I don't really know how much buoyancy I'd lose in a full DS flood. And that's simply because if I did it in my winter undersuit at the time of the year my winter undersuit is approriate, there'd probably be a pretty decent risk that I'd get a serious case of hypothermia.

I've had divers return to the surface with completely flooded suits. Whilst the suit is in the water its not too big a deal (providing there is proper lift capability in the wing/BC). The only way to recover them into the boat was to open the zip and parbuckle them in. I've seen shore divers cut their suit at the ankle so they can get out of the water. The question is how much water can fit in your suit with you? It's more than you might think.

Interesting, but not what the OP asked.

 

[Storker]

What is "proper lift capacity" for a diver with a flooded suit? I don't know, so I prefer to be able to dump some lead if SHTF.

Interesting, but not what the OP asked.

Well, for me at least a flooded suit should be considered when I decide on whether or not I want some of my weight to be ditchable

 

[decompression]

Read up on accident reports. A sizable number of the victims are found with their weights in place. A sizable number of the victims manage to surface before they go under again. Simple physics tell us that the more positively buoyant you are, the higher you'll ride on the surface and the less is the risk that you'll sink back below the surface.

Those simple facts make me believe that it might be a good idea to have some ditchable weight. For me, hard data trump (pun not intended, I'm not using a capital "T") speculation and rationalization. As always, YMMV.

Besides, being able to hand up a few kilos to the boat tender before climbing aboard IS rather nice...

I would tend to believe a majority of those victims could be considered "vacation divers" using rental equipment. Removing your weights once in an open water class several years ago might be a contributing factor.

 

[decompression]

A catastrophic failure of a drysuit will usually still allow some air to be retained for some buoyancy. It requires a bit of body language but is still effective. Regardless, a total suit flood (I've had several, both accidental and on purpose), does not result in negative buoyancy, just a lost of warmth/dexterity and "some" buoyancy. That is yet another reason the wing is for buoyancy and the suit is for exposure protection.