Weight question: none and trim.

[redrover]

I seem to be confused, maybe just inexperienced.

I was under the impression we divers wanted to carry weight. To have ditch able should unfortunate events occur. Also weight distribution assisting trim.
I’m not carrying any with a light wetsuit and it was making me nervous. I’m thinking of doing a small set of doubles and worrying about being heavy.
I’m seeing in a doubles question thread with people not carrying extra weight.

As a beginner was I mislead, for a good reason? Have I got it wrong? Is there a variable rule when becoming more experienced? Other than the being able to swim up gear, is there no problem? With no weight to distribute how do you get that lovely horizontal trim?
Mahalo

 

[spectrum]

There are some configurations that back you into the corner of having no ditchable weights.

Doubling aluminum cylinders can sometimes be a balance point since they will go positive and can offer a need for weight.

Having redundant buoyancy in the form of a dual bladder BC, lift bag or a drysuit are other options.

Pete

 

[TSandM]

There's a concept called a balanced rig, which means that, at the beginning of the dive (when your tanks are as negative as they will be) and at enough depth to have lost any buoyancy from your exposure protection, you can swim your rig to the surface. If you can't, you need ditchable weight and/or redundant buoyancy, because a catastrophic loss of buoyancy at that point would pin you to the bottom. That's why people who dive big steel doubles usually wear dry suits, and often also carry SMBs or lift bags for additional redundant lift.

Weight distribution IS a problem, if you don't require any additional weight with your tanks, and your balance with your tanks alone makes you head or feet heavy. This is one of the reasons that people in wetsuits do well with Al80s as doubles. You actually have to pack on a bit of weight to sink the tanks alone, and it helps your trim.

I carry two pounds with my 3 mil suit and an Al80, and I carry it on the cambands. It doesn't worry me not to have ditchable weight. I can swim the tank up easily, and I can stay on the surface with no air in the wing if I have to. (After a while, I'd sure want something to lean on, but I also carry an SMB on almost all dives.)

 

[RJP]

I seem to be confused, maybe just inexperienced.

I was under the impression we divers wanted to carry weight. To have ditch able should unfortunate events occur. Also weight distribution assisting trim.
I’m not carrying any with a light wetsuit and it was making me nervous. I’m thinking of doing a small set of doubles and worrying about being heavy.
I’m seeing in a doubles question thread with people not carrying extra weight.

As a beginner was I mislead, for a good reason? Have I got it wrong? Is there a variable rule when becoming more experienced? Other than the being able to swim up gear, is there no problem? With no weight to distribute how do you get that lovely horizontal trim?
Mahalo

Couple things at work here...

Do you need weight at all?

- Only if you can't sink when exhaling. Carrying it just to ditch it doesn't make sense. If you have it and need to ditch it, that's fine. But don't carry it just to be able to ditch it.


Do you need weight to adjust trim?

- Not necessarily. Especially dependent on answer to first question above. If you DO need weight, then moving it around to adjust trim is fine. But if you DON'T need weight at all, you don't need to add it to adjust trim.


How can you adjust trim without having weights to move around?

- Easy. Easiest and often most effective way is to adjust tank position. Feet heavy? Slide tank up. Swimming head down? Slide tank the other way. Even minor adjustments of tank position can have a significant impact.


Doubles and bouyancy/trim?

- I believe you said you're diving a BCD, so chances are you won't be diving doubles in that set up; you'll probably need to switch to BP/W. Which will likely add weight or at least remove some bouyant material. Typically you want to be diving a drysuit to have some redundant bouyancy/lift to offset the weight of doubles in the event your wing fails. You can however go with a redundant wing.



I have a few other thoughts, but need to run to do a class.

 

[Rick Inman]

The only time I can think I would need to ditch weights is if I don't have a balanced rig and I jump in without turning my regs on and my BC is empty and I can't reach my valves. In which case, it really wasn't my day to dive.

I can never imagine a time to ditch weights underwater unless it's a body recovery. In any real scenario I can think of, a quick ride to the surface will only make things worse. Even it you lose your buddy and you're suddenly OOG, unless you are so negative that you're crawling around on the bottom, just a few kicks upward will start the gasses in your BC/drysuit expanding, and off you go.

 

[TSandM]

Rick: Heavy steel doubles, light wetsuit, and you rip a huge tear in your wing crawling around inside the wreck. Absent a lift bag, and assuming you CAN'T just swim the rig up, what do you do now? (And of course, I know the answer . . . My buddy is now my redundant buoyancy )

 

[Wildcard]

There is what we are taught when we start and what we learn as we go. I have no ditchable weights when diving my 3mm. My 7 gets a few lbs extra on a weight belt that CAN be ditched but why? Same for the drysuit. Alot has to go wrong to have to ditch weights and then your in for an uncontroled ride to the surface/chamber.
Yes you can dive doubles with a regular BC. No big deal. Millitantmedic has the adapter for sale cheap if you want it. I don't think you need it though, esp for what your trying to do...Have you ever dove a steel tank? That may be the answer you seek. OTH what your doing works for you so why change? Ya have your nice little tanks, well greased , and your SAC is good. Dont make problems where none exsist.

 

[redrover]

Ah ha. Looks like I’ve been mentally overemphasizing – ditch your weights - it does get mentioned frequently.
I wasn’t thinking about a lift bag, Mahalo.
Nor remembering how some people do exposure protection etc., keep forgetting a drysuit is adjustable. LOL Don’t think I’m getting one of those tho.

Actually I’ve got a BC that can do doubles but still waffling about a lot of things besides that. Trying to figure out how to do what I want (heck, if can!) and hitting a wall each time I got to weight and trim issues. Thanks I needed this to get over that wall and thinking again.

Brian, you’re always good for a snort out loud from me. It’s those little AL50’s I’m thinking of doubling, a little self-redundancy. (I'm afraid that's all the extra weight I can manage.) Steel tanks are my friends, they live in my truck for now.:blinking:

 

[redrover]

There are some configurations that back you into the corner of having no ditchable weights.

Doubling aluminum cylinders can sometimes be a balance point since they will go positive and can offer a need for weight.

Having redundant buoyancy in the form of a dual bladder BC, lift bag or a drysuit are other options.

Pete

Oh dear, I’ve really been trying to figure this stuff out for myself but…
Would a dual bladder be one zipped into another? The more protected wings – also increased buoyancy?

 

[Rick Inman]

Rick: Heavy steel doubles, light wetsuit, and you rip a huge tear in your wing crawling around inside the wreck. Absent a lift bag, and assuming you CAN'T just swim the rig up, what do you do now? (And of course, I know the answer . . . My buddy is now my redundant buoyancy )

Heavy steel doubles + light wetsuit <> balanced rig.

Yeah, unbalanced rig, no lift bag, no buddy... time to go to your spare air and your double bladder, bungeed wing.