Lotsa Weight

[TMHeimer]

Eric's point about BC not completely deflating may not be wrong. When attempting to completely deflate at depth I use the optimum position (LPI way up, tilt to the right), and am not really sure every bit of air is out. Maybe there is a pocket of air somewhere. I bought the BC used 11 years ago and can't recall how old it was when I bought it. I appreciate the other suggestions, but covering all of those, I just don't have the money right now to make any equipment changes. I sold the steel 120 due to too many long walks with that, and the steel 72 due to not enough gas. But as mentioned, going back to a steel tank and bp/w only redistributes the weight anyway. I could do the weight tests as suggested, but maybe pointless since at least for now I'm stuck with the equipment I have.

 

[Eric Sedletzky]

All the talk about doing weight checks at the beginning of the dive being at eye level etc. is pretty standard but not always the most accurate. That's what I thought too when I started scuba which is different from freedive weighting. They wanted us to be able to sink feet first on scuba by dumping weight and exhaling. I would have never done this freediving which I did for years before scuba. I finally read something once about getting your weight right down to the oz. and it made sense.

It went something like this,
"For scuba diving the end goal is to ideally weight yourself so that at the end of your dive when your tank is almost empty [300 to 500 psi] you can ascend to 15 feet and completely empty your BCD bladder and hold a perfect safety stop controlling your depth with your breath control alone. If you can manage to experiment with your ballast combinations to be able to achieve this then you have achieved perfect weighting.
It doesn't matter at that point what your weight characteristics are at the biginning of the dive because the issue is moot, it's at the end of the dive holding your final 15' safety stop is when it matters."
This made perfect sense to me so I experimented and realized I was dragging around about 10 lbs of excess weight that didn't need to be there. It took me about three dives.
From there I knew about what to expect when changing different cylinders and plates etc. because I had a baseline to work from.
It also so happens that I dive in a 7mm wetsuit complete with booties gloves hood etc.
For me to be perfectly weighted doing the afore mentioned method means I have to actually tip forward at the beginning of the dive and swim down. I will float on the surface with an empty wing and a full tank, that's just how it works out. But I can hold my final stop with an empty tank
At 15' with an empty wing so I know I'm right there.
I also think it's safer this way too. I'm a little leary of having so much weight on that all that's keeping me on the surface is my inflated BC. To me that's abusing something that was originally invented to be used only at depth to take the edge off. I think people who use their BC in this manner are button happy elevator divers, part of the new age of training that is even further removed from where scuba started and totally gear dependant.

 

[TMHeimer]

Eric, Interesting view. Everyone agrees that you do your weighting so you are neutrally buoyant at a 15' safety stop. I haven't heard of doing the stop with a completely empty BC, though not saying I disagree with you--just haven't heard it before. So when you have to tip forward and swim down at the start of the dive (such as in free diving, and not what we all were taught--yet I have done it myself and of course pulled myself down anchor lines head first), you have no problem descending? By floating on the surface with full tank and empty wing (BC) does that mean horizontally, or feet down and water at eye level while holding a normal breath, like the regular weight check? If the latter, why would you have to tip forward and swim down when exhaling would let you descend feet first if you wanted to?
I can see how this works for you, and don't disagree when you say it's better to have less weight if possible for safety reasons--so you're not depending soley on the BC to offset it, etc. But it would seem that by traditional means, you are positively buoyant starting the dive, which doesn't sound right. I'm not sure how your weighting method may work for most of my normal dives, which frequently jump back & forth from 10 to 30'. I do know that with less weight than what I'm using, it becomes "rock-holding" time for me at those depths. You've studied this a lot more than me, so I'm keeping an open mind here. What think others?

 

[Eric Sedletzky]

To answer your questions about swim down descents just like freediving.
Okay So, with the way I'm weighted I mentioned I can float on the surface at the beginning of the dive and I actually have to work to get down. At about 10' or so There is enough squeeze on the suit that it becomes neutral and easier with each kick as I go deeper. I don't have to start adding air to my wing until I hit probably 30', and then it's only a shot or two. This is the product of lightening up the load to the max. I've even been known to lighten it up to where I myself am grabbing rocks at 20' at the end trying to offset lightness.

There is a cooling factor to the suit and a long duration squeeze and rebound factor to wetsuits also. When a suit is cooled the gas bubbles get smaller and the suit will lose buoyancy. This may not happen right as the suit hits the water, it could be several minutes into the dive and will increase as the dive time progresses. The suit will also lose buoyancy from sustained crushing at depth. Suits don't rebound right away as you ascend, it takes a while for them to come back. So applying this to the mathematics of weighting, it's not just the loss of gas that affects overall weighting, it's also the physics of wetsuit material both with temperature and pressure.
That's how I can get away with weighting myself so light and still being able to hold the 15' stop at the end of the dive. Those other factors help me.

A lot of the reason for the light weighting is because where we dive there is lot of hiking, sometimes on goat trails and paths to get to the water, and perhaps a little bit of a cliff/ rock slab crab crawl at the waters edge. So we have a lot of reasons why we like to pack as little weight as needed. That's also why North Coast divers who hunt and hike to desolate dive spots very rarely use drysuits, and why we use light steel tanks like steel 72's, because we can get over 80 cf with a fat fill. And then a lot of times we are hiking back up the hill to our trucks with a load of fish, scallops, and a few urchins so that's even more weight. So yeah, every ounce counts.
Like I mentioned above, I have weighted myself so light that I start fighting it at 20'. My thought originally was that I was going to be dragging around a few Lings and a load of scallops, so that would have been "integrated" ballast at that point. But most of the time that I do that in preparation I get skunked and end up carrying around rocks anyway. 'Ain't that the way it goes?
This is kind of in line with how they used to dive with no BC in the old days. If they tried to weight themselves like the standard out of OW is these days they couldn't do it. No BC to keep them afloat.

One of the biggest lessons about weighting came to me crystal clear when I dived for the first time with no BC. I went to grab for the inflator and there wasn't one. Time to rethink weighting to make this work!
It sounds kind of draconian and sadistic, but I've heard it said that the best way to teach someone proper buoyancy is to take away their BC.
That would be a crash course for sure...literally!

So now in your case where you need to stay down at 10' to do your work, then yeah add the weight you need.

 

[Doby45]

@TMHeimer do not take this the wrong way. I am amazed that you are a Divemaster with 500-999 dives and the thought process of proper weighting is eluding you. That right there literally baffles me. You state you have never heard that on your 15' safety stop you should be able to hold that with an empty wing? I mean if you are posing these questions simply as a point of discussion I can see the value in that and carry on good sir but I personally have seen posts from you on this forum where you discuss proper training and your history as a DM. I can not fathom how one could be a DM and not understand the weighting concept.

 

[turnburglar]

@TMHeimer i am 6'1" and ~185, so pretty close in body comp to you. I was diving an older aqua lung solafx 8/7 and switching to a brand new suit had to add 4 pounds almost too the weight belt. With a Steel BP/W and AL80 I'm looking right at 20 pounds on the weight belt. I think the big difference between our suits is the FJ style of neoprene stacking. I know you said you can't afford any new gear, but maybe to reduce the weight belt you could find a warmer/thinner suit?

 

[TMHeimer]

Eric, I understand all that. It's a good procedure that works well in your situations.

Doby45, No, I haven't heard of that on a 15' safety stop. To be honest, I have only taken 20-30 charters in total and have had no problems (save maybe the first time) at 15'. But I also don't know exactly how much/little air is still in my jacket BC at the stop--just that it works fine. All my actual ocean DM experience was 20-30' checkout dives. I certainly understand all that Eric talks about--wetsuit compression, delay in that, etc. and how to do a PADI proper weight check. So what process of proper weighting are you talking about?

turnburgler, Good idea, but a different suit also costs money.

 

[Doby45]

Doby45, No, I haven't heard of that on a 15' safety stop. To be honest, I have only taken 20-30 charters in total and have had no problems (save maybe the first time) at 15'. But I also don't know exactly how much/little air is still in my jacket BC at the stop--just that it works fine. All my actual ocean DM experience was 20-30' checkout dives. I certainly understand all that Eric talks about--wetsuit compression, delay in that, etc. and how to do a PADI proper weight check. So what process of proper weighting are you talking about?

Go to a 15'-20' platform with a tank around 500psi, carry all the weight you could possibly want. Once on that platform, empty your BCD, when you are sitting there stuck on that platform start taking weight off a pound or two at a time. When you get to where you can hold your hover you should be pretty much dead nuts on your weight. This is the LEAST amount of weight you should need to be able to maintain a safety stop at the end of your dive.

 

[mainedvr]

I may have asked this before. I usually dive with 7 mil farmer john wetsuit, hood, boots, etc. and need 43 pounds with my new (used) wetsuit. Prior to the new suit I used as little as 37 with the old beat up suit. I know that the integrity of the newer suit causes it to be more buoyant. Obviously, I know how to do a proper weight check and have done them countless times with OW students. One instructor friend said he uses a similar amount when diving wet. Another from a different shop said I should be wearing 20-25 pounds, as we are similar in size. I tried 37 pounds when I switched to the newer suit and no way ever I could descend, with BC deflated. On SB, I read of people using way less weight than me with the same wetsuit. Years ago I took PPB and the instructor was amazed that I was correct in needing all the weight I showed up with. I have swam my unit up from 15-20' with 43 pounds and BC empty without drawing a deep breath. Everyone's buoyancy differs, but are there just a very few of us that need that much weight? Bone density? What?

Lets see I dive typically a 5mm Henderson aqua lock and a 3/5 hooded vest, I use 8lbs of weight in weight pockets, I have a BP that is I believe 6lbs, I dive typically a 100 HP steel Fabre, F1 fins, my harness and two scout lights, So I guess I am around18-20 lbs maybe a little more. I started off with like 35lbs OW. I am 6 1 265lbs. I have no problem with decending or accending safely and can hold a safety stop fine at 15' or less with tank even below 500psi. Not sure how that equates but what I think is it is just an individual thing and if your not sinking like a rock or stuck at the bottom and cant swim your gear to the surface you are probably where you need to be especially if you have done a real weight check. I know when I dove a jacket style bc I was always getting air trapped and that may be why I had to use more weight but as I learned more and got more dives in that may be why I was able to reduce weight.

 

[Diving Dubai]

From my perspective, if I were assisting @TMHeimer, I would divide the process into 3 steps.

STEP 1 The Descent.

For the first dive of the day you exposure suit is dry and nicely buoyant so in the water you need to flood it or burp the air out. Also you need to consider the initial shock of rolling in to cold water. We are used to it momentarily taking our breath away, but what's not recognised is that our diaphragm drops increasing our lung volume. Thus until we relax we are even more buoyant. If we have problems descending this again causes our lungs to expand as we're not in a relaxed state

What I would encourage Tom to do would be to wait on the surface and compose himself and then test his descent. You want only enough weight with a full tank that a full exhale allows you to sink. Just press the inflator and descend (or try to) in a vertical manner, at least for the first 3 feet. I personally move to horizontal at 3 feet and carry on the descent. Once you can manage this, at say 6-10' take a big inhale, you should be able to stop your descent but not shoot to the surface.

This should get you a maximum weighting you need. Remember that you'll be probably ingrained and have adapted yoru technique to account for lots of weight.

STEP 2 - 15' SS

Get your self to 15' with 500psi in the vertical position i (for ease of dumping air) and deflate your BCD holding a normal breath if you start descending take a bit of weight off. Don't fin (cross your feet) or get agitated otherwise your diaphragm will drop again causing increase lung volume. Repeat as necessary. Ideally you should have a little bit of air in your BCD no more than a couple of lbs at the SS just to give you some leaway (if you're not relaxed for instance and still need to hold the SS)

To "visualise" a normal breath, think of your lungs as a car fuel tank. Normal breathing is between 1/4 full and 3/4 full leaving 1/4 in reserve at either end for adjustments. so you want to hold your breath at the 1/2 full position. When at home try to visualise the position of your chest during normal breathing - as divers we tend to over exaggerate breathing underwater.

STEP 3

Keep analysing your weight on every dive. Ask yourself if you are feeling too heavy? As you become more practiced and comfortable with the adjustment I assure you a little more lead will come off.


The final steps to be only carried out with a friend is to get your tank to 250-300 psi and check you can hold t he stop (the friend should have air. When mentoring I tend to drain the persons tank and let them breath off my long hose so there is no chance of them running out of air. You just want to ensure you can still hold a stop at this level.

My weighting is without a pony, I don't bother adjusting for a pony, because I want to ensure I can hold a stop with it empty, and a few lbs of extra weight doesn't bother me. The same with any other kit. all weighting without hit as I want to know I can hold a safety stop with the bare minimum rig.