Question My Wife's Rig is No Longer Balanced. How Do I Add More Ditchable Weight?

[johndiver999]

@johndiver999, she absolutely should wear the necessary weight. My concern was that we were getting into a situation where her rig was no linger Balanced and that I should be trying tonfind a means of including more ditchable weight. After some additional research based on the responses provided here, it doesn't sound like that part is much of a problem. She can wear as much lead as she needs to descend and to hold her safety stop.

I agree, the consensus is to just load the wife up with lead. Hell she can swim 15 lbs up from depth right? I read that on the internet so she must be able to do that during an emergency, right?

If it were my wife, she would be trying an elastic freedive belt that can be adjusted to fit most people comfortably and can be dropped if needed. 10-12 lbs is comfortable, practical and relatively inexpensive, plus putting all that lead on her rig would make it more of a beast to handle on the boat. The danger is not in wearing 3 lbs more lead than the absolute minimum, but rather the robustness of her exit plan should she have a BC failure. Make sure you rank the various priorities properly when choosing a configuration.

 

[rx7diver]

Thanks everyone.

... @rx7this was also a concern for me. I'm not certain if we'll be diving steel or aluminum in Icrland . . . and, I had been hoping to take our carbon fiber backplates to reduce luggage weight by not packing steel. That drops her weight down by twleve pounds, forcing her to rely on trim pockets for almost all of it. (We can still get 30 pounds across all the weight pouches, but just. If we're diving steel tanks, I guess that will help some, but you're right, she will need more practice.) ...

When I first got my drysuit (for Great Lakes diving), I would dive it using a single cylinder and a 3rd-gen Scubapro Stab Jacket (orange, taco-pocket model; has a blow-molded plastic backpack) and a rubber weight belt with solid Pb weights. I would also thread a 3 to 4 lb solid Pb weight through the tank strap. Scubapro Jet Fins. Worked fine. No issues.

Of course, I was wearing a steel cylinder (first a PST 3,500 psig HP80, and then a PST 3,500 psig HP100), and my suit was compressed neoprene rather than tri-lam (so, not nearly as buoyant), and I wasn't wearing near the thickness of underwear layers that you describe your wife wearing.

Still, I had no issues whatsoever.

I used this same configuration for a dive I made in Puget Sound, except using an Al 80, and I was taken completely by surprise by the amount of additional Pb I needed! Salt water and an Al cylinder!!

rx7diver

 

[happy-diver]

I incorporate into my busy schedule artistic lead shaping

I found a great roll, of thick lead, in my neighbours yard

It's okay, not that neighbour, this neighbour was with me

 

[steinbil]

I agree, the consensus is to just load the wife up with lead. Hell she can swim 15 lbs up from depth right? I read that on the internet so she must be able to do that during an emergency, right?

If the extra weight is because of heavy undergarments, she won't be more negative in the water. Even in a completely flooded suit the undergarments are very buoyant. So the amount of lead is irrelevant as long as she's properly weighted. So the only weight she'll be swimming up is the weight of the gas + 1-2lbs for comfort air in the drysuit. Not to mention, with redundant buoyancy, the chances of having to swim up any weight at all is close to 0.

 

[Ryan Neely]

@happy-diver like that. If only there was more time to do all ofbthe things.

 

[Ryan Neely]

@steinbil and @johndiver999, out of curiosity (because I haven't taken an official tech course; I've only read a handful of books), I've seen some folks diving with a steel twinset and a v-weight.

If my (admittedly limited) online research is correct, a pair of steel HP80s would be almost 26.5 lbs negative in salt water when full and about 14.5 lbs negative when empty.

Assuming all I needed to descend was the 26 lbs from the cylinders and gas at the beginning of the dive, I should only need to carry enough weight to offset the gas usage by the end of the dive. Right?

So, if my thinking is correct (and please correct me if I'm wrong), let's assume I add 12 pounds to a v-weight to compensate for that gas. None of this weight is ditchable, but according to my understanding of the conversation in this thread, that shouldn't be a problem so long as my wing and my drysuit can both, independently, lift that amount of weight. (e.g., If there is a catastrophic wing failure or total drysuit flooding, one or the other of them should be able to offset the weight . . . in tandem with breathing buoyancy and loft from finning).

I mean, this is all theoretical for me. Om not doing this kind of diving. I'm just trying to understand the differences in viewpoints expressed here.

In this theoretical situation, we have almost 38.5 pounds of weight at the beginning of a dive that is non-ditchable. (And I do understand that tje 1w pounds to accommodate for gas loss could go somewhere other than a v-weight to make it ditchable; I chose that example for this exact purpose.) If I understand correctly, I should be able to swim up at least ten pounds (I can attest that yes, I can; I have done this). A full lung volume should be able to compensate for five pounds (I cannot attest to this, but I'll go along for the sake of theory). That would mean that, at the beginning of the dive, if either my wing or my drysuit fails, the other would need to be capable of lifting the remaining 23.5 lbs.

A 30-lb wing should be capable of that. A drysuit is much larger than the wing, so it should also be capable of that (though it may be harder to control).

Am I thinking about this correctly, or have I completely misunderstood? What other methods would there be in a situation like the one presented here?

 

[steinbil]

Assuming all I needed to descend was the 26 lbs from the cylinders and gas at the beginning of the dive, I should only need to carry enough weight to offset the gas usage by the end of the dive. Right?

In theory, yes. In practice I find it much more reliable to just check your weighting at 3m with 30bar left in the tank and as much air as you want in your drysuit. Do it at the end of a dive if you can pass some weights to a buddy to check, or just dive in somewhere shallow with leftover gas from a previous dive and purge until you hit 30 bar. Empty all gas from wing and exhale and see if you can sink to the bottom (3m/10ft) and if you're able to lift off the bottom with a full inhale. Start with a couple of kg/a few pounds overweight and pass off to a buddy or leave weights on the bottom.

So, if my thinking is correct (and please correct me if I'm wrong), let's assume I add 12 pounds to a v-weight to compensate for that gas. None of this weight is ditchable, but according to my understanding of the conversation in this thread, that shouldn't be a problem so long as my wing and my drysuit can both, independently, lift that amount of weight. (e.g., If there is a catastrophic wing failure or total drysuit flooding, one or the other of them should be able to offset the weight . . . in tandem with breathing buoyancy and loft from finning).

And in practice all doubles wings or any drysuit will be able to lift enough.

A 30-lb wing should be capable of that. A drysuit is much larger than the wing, so it should also be capable of that (though it may be harder to control).

Yes. The reason why a 40lbs wing is standard for doubles is for extra lift on the surface.

 

[steinbil]

In this theoretical situation, we have almost 38.5 pounds of weight at the beginning of a dive that is non-ditchable.

This is where you're tripping up. The actual negative weight you're carrying on its own is not relevant. If you want to calculate you also need to account for the positive buoyancy of your body and all your exposure protection. Also for a full calculation you should include the negative weight of your regulators, backplate, batteries and lights ++

It's the total negative buoyancy in the water that matters. And the easiest way to find that out is just to do a weight check.

If you're properly weighted the only weight you should ever have to swim up is the weight of the gas. And a complete failure to contain any gas in both drysuit and wing is highly unlikely. In the worst case you could even breathe down or purge some gas to lose some weight, but these are not very realistic scenarios.

 

[inquis]

Assuming all I needed to descend was the 26 lbs from the cylinders and gas at the beginning of the dive, I should only need to carry enough weight to offset the gas usage by the end of the dive. Right?

This suggests you're neutral with empty wing and 26 lbs of "ballast" (anything that is negatively buoyant, including gas). Exhale and you descend. Great. The goal is to be neutral with empty tanks/wing, so you're right that you need an additional 12 lbs to offset the gas you will be losing during the dive. That means you are a net 12 lb negative at the start (with empty wing), so you just inflate the wing enough to compensate.

At this point the wing is supporting +12 and the suit +26, and you're neutral. Yes, if you lose either, the other needs to handle the additional load (a maximum of 38 lb). As pointed out, a completely flooded suit still has the inherent buoyancy of the undergarments, so you won't lose all 26 lb attributed to the suit, but we assume we will as a worst case.

Another 12 lb by the suit if the wing dies is no problem. A wing that is physically large enough to extend outside a pair of doubles will have at least 40 lb of lift, so also no problem if the suit floods.

 

[inquis]

If you're properly weighted the only weight you should ever have to swim up is the weight of the gas.

If both suit and wing die (agreed, odds are low), without any other compensation device you will have to swim up more than the weight of the gas. The inherent buoyancy of undergarments helps but not completely. However, you would likely have a DSMB which would hopefully take you all the way to neutral.