"Gold Standard" weight check

[BRT]

My idea of perfect weighting is when you can maintain your 15’ safety stop at the end of your dive with a near empty tank, no air in your BC, and control your stop with breathing alone.
This formula works with any configuration and/or any combination of exposure protection and the sum total/balance of all components.

This is the correct answer.

 

[BRT]

No the diver needs enough lead to control buoyancy while underwater. That means at a depth of one foot not 15. Also if the diver is going to deploy and smb from depth. They need additional lead to keep the end of the smb submerged and the remainder vertical. This obsessive compulsion to chase minimum lead/ballast is often of little practical value.

And just a little more to compensate for minor differences in tanks and for the breakfast burrito you ate.

 

[BRT]

For ocean diving (well Puget Sound, Strait of Juan de Fuca), I just take a 2-lb'er for my DSMB. That's enough to let it hang while keeping a 6' long Halcyon DSMB pointing out of the water to some degree.

For that diving with swells (I check the wind forecast), I'm not draining my cylinders down to 500 psi either.

Nice to say that you are not draining your cylinders down to 500 psi, but there will come a day when you are high on nitrogen and low on air. Not by plan, but it will happen and when it does swimming down to hold a safety stop is no fun. Been there, done that.

 

[wetb4igetinthewater]

but there will come a day when you are high on nitrogen and low on air.

On my rebreather?

I know you mean the general "you". That is always a possibility for recreational diving. However, in recreational diving the surface is theoretically always an option.

If you are technical diving and you run into this situation, something is seriously wrong somewhere, and I'd recommend looking at the system straight from the beginning as it won't be a single thing, but a number of things.

 

[rjack321]

so let me get this straight. Diver whips out their DSMB, finning to compensate for the additional lift of their DSMB when inflated. Once they release, then they add enough gas to be neutral?!?

Or they could just orally inflate their DSMB from a sufficient depth, hold their breath momentarily, until they release their DSMB to they maintain neutral buoyancy throughout the whole process.

Often overlooked... The really big ones need to be inflated from very deep or at the surface. You can't get them full at 6m depth without ending up on the surface yourself in the process.

 

[wetb4igetinthewater]

Often overlooked... The really big ones need to be inflated from very deep or at the surface. You can't get them full at 6m depth without ending up on the surface yourself in the process.

Oh that's certainly true. That's why I mark my DSMB's with depth ratings to be fully inflated at the surface. The bigger it is, the deeper I have to be.

 

[Eric Sedletzky]

That is true, but I'd use my lungs to negate that effect. If I need to descend, being a little heavy I could exhale and go down (note, I said I little heavy, not overweight). Vs if perfectly neutrally buoyant, it would be a little tougher to get down during the swell up. But then again, I like being a little heavy, you can neutralize extra weight with buoyancy in the water, but you cannot negate extra buoyancy in the water without assistance.

Or maybe that's another question - neutrally buoyant at 15' (or 20') empty bladder and empty tank - with lungs full? or lungs empty?

I don’t really know if it’s that hairline or not.
Yeah, I’ve weighted myself really light, as in start fighting to stay down at 20’ and I do this when I doing vintage type diving with no BC. I’ve even picked up rocks to stay down to finish my dive.
And then I do dives where I don’t go deeper than 10’ to 12’ and I need to be heavy to stay down so I can work. Those dives I add 4 or 5 lbs.
But if you find that 15’ empty bc/empty tank baseline then you can adjust accordingly to suit the particular dive. Wearing a drysuit for instance would be one scenario where you’d want a few extra lbs to keep from being shrink wrapped at 10’ or 15’ or 20’? Pick your poison.
But a lot of residual air in the BC just means more weight to drag around for the casual rec diver who doesn’t give this stuff a lot of thought.

 

[BRT]

On my rebreather?

I know you mean the general "you". That is always a possibility for recreational diving. However, in recreational diving the surface is theoretically always an option.

If you are technical diving and you run into this situation, something is seriously wrong somewhere, and I'd recommend looking at the system straight from the beginning as it won't be a single thing, but a number of things.

I am a recreational diver. I suspect you also dive open circuit on occasion. I have never needed to surface with my computer in deco, and have only gone into deco for kicks and grins so I know what it looks like. And only on a somewhat deep first dive. On a first dive if my Oceanic was showing a couple of minutes of deco at 115 feet I doubt I could swim up fast enough to surface with it in deco. However, after a long first dive, I have ended up on safety stop with 300 psi and my nitrogen level on the bar graph deep in the yellow. Didn't plan that, but it happened. More than once over the last 30 years since I bought a computer. No problem, sit at 15 feet and calmly breathe the tank down and the nitrogen down. But one time......I was light on lead. Swimming down to hold a stop is not the best way to get the most time out of a low tank. Yes, the surface is there. Yes, I have gone to the surface with my computer deep in the yellow. Yes, I had some problems with one of my hips that may have been related to that. I want enough lead that I can calmly breath my tank to the bottom at 15', at 10' and at 1'.