Upgrading AL DA Aqua Master

[Nemrod]

I don't think I made a negative statement about BC-less diving. The fact is you have to compensate for the weight of the gas; one way or the other, you're going to be either heavy at the beginning or light at the end, or some combination like herman. I'm sure you can do it just fine. But you can't be truly neutral throughout the whole dive. Not that it matters too much, I'm sure you have the technique to deal with a few extra pounds of gas weight.

I guess the only way to really measure the actual loss in buoyancy of a wetsuit would be to get neutral at the surface, descend, and start handing weights to your buddy until you're neutral again. The typical 'sink your wetsuit' test only measures the total buoyancy of the suit.

I apologise, I did not choose my words accurately, what I meant was that you don't understand, quote:

"But, I don't see how you can comfortably maintain neutral buoyancy throughout the dive with a 5-6lb swing in gas weight"

I tiried to explain how it is done, sorry if it did not help.

N

 

[Nemrod]

Onre more and then I will be bow out since I don't think I am helping here.

The problem with trying to explain diving sans BC to a modern divers is they expect perfection, they think in terms of REQUIRED safety stops etc. I could go on and on on the subject, you are on the wrong side of the glass, you are looking in, I am looking out. I don't expect to be neutral at the end of the dive and in fact it is proper to be slightly positive at the end of the dive. We did not do safety stops (but I can if I need to) and we are mostly talking about shallow, no deco diving here BTW. As well, in the time before a BC, we did have a surface float usually which we depended upon for self rescue (should you get sucked a mile offshore from your entry), a paddle board, inner tube. We did not wear as much exposure protection as is in vogue now, I guess we were just tougher, lol. We did not generally dive huge double tanks, we did not have an octo or double regulators or all of that type of equipment added to our rig to guess for weighting on.

No, you cannot dive the way you were taught minus a BC, it will not work, you have to re-learn, the New Science of Skin and Scuba Diving, 1968 CR is a good reference. More than once the old trick of picking up a rock to get negative has been repeated by the vintage diver.

Additionally, by weighting to be slightly positive at the end of the dive if you do have a problem and jettison your weight belt you should now be quite bouyant. We had to be profiecient at Doff and Don which in addition to learning to remove and replace your gear, it is instrumental in observing and learning about bouyancy changes with and without gear and when breathing compressed air.

One other thing, this is key, we did not drift up and down in the water column like an aquatic hot air balloon as almost ALL divers do now, we SWIM down, we SWIM around and then we SWIM up.

Well, anyways, way off topic now, good luck.

N

 

[rstofer]

Well, anyways, way off topic now, good luck.

N

Not at all off topic. In fact, I need to read your post a few more times until I start to understand how this works.

I, too, had the question about compensating for tank contents and wetsuit buoyancy. I'm still not sure I get it. But, then, I haven't really thought it through or tried it in the water.

I do remember Sea Hunt (in fact, I just bought the entire 128 episode DVD set) and Mike Nelson wore a wetsuit and a massive weight belt (by appearance). No BC, no octo, nothing else except a harness and tank/regulator. I'm assuming that SOME of the photography wasn't faked so it must have worked.

I think I better start at the beginning of this thread and try to absorb the comments of experts.

Thanks!
Richard

 

[duckbill]

As well, in the time before a BC, we did have a surface float usually which we depended upon for self rescue (should you get sucked a mile offshore from your entry), a paddle board, inner tube.N

This is a key point that is sadly lacking in most encouragements to try diving without a BC.

 

[DA Aquamaster]

What matters is to be neutrally buoyant with about 500 psi in the tank at the end of the dive at 10ft to 20 ft. I was taught that way when I learned to dive and still configure that way for modern or vintage diving. Wether you have a BC or not is irrelevent.

Prior to scuba diving I was a free diver (called skin diving at the time). We weighting ourselves so that in just the exposure suit and weightbelt we floated at eye ball level at the surface with full lungs and sank when we exhaled. It was the same concept as it left us neutral with full lungs at 20-30 ft in the average wet suit. It meant you did not fight an excessive amount of buoyancy descending, were not overly negative at depth and would float the last 20 feet to the surface if you sufferred a shallow water black out.

With a full tank and vintage gear, you are indeed 5 pounds negative with a full single tank at 10-20ft. However you are still not overly negative unless you have a thick wetsuit and go fairly deep.

Toward the end of the dive, you are again neutral with full lung volume at around 20 feet and are again buoyant enough to float at eyeball level at the surface.

Where a BC (horsecollar or otherwise) is nice to have is where you are diving doubles (10-12 lbs swng weight) or are diving deep with a thick wet suit.

 

[duckbill]

We weighting ourselves so that in just the exposure suit and weightbelt we floated at eye ball level at the surface with full lungs and sank when we exhaled.............would float the last 20 feet to the surface if you sufferred a shallow water black out.

For some reason, I always thought that in a blackout situation the body would go limp, causing one to exhale a good part of a lung full of air. If this is the case, how would one float to the surface from 20 feet, if exhaling at the surface would cause one to sink? Have I been wrong? Do blacked out divers continue to hold back lungs full of air by some type of reflex?

 

[John C. Ratliff]

For some reason, I always thought that in a blackout situation the body would go limp, causing one to exhale a good part of a lung full of air. If this is the case, how would one float to the surface from 20 feet, if exhaling at the surface would cause one to sink? Have I been wrong? Do blacked out divers continue to hold back lungs full of air by some type of reflex?

Duckbill,

I haven't gone through this whole thread yet, but saw this and must comment. I haven't been on here in a while, due to loosing my password and being very busy between work and school (I'm in finals week, took one final today, have one more on Sunday, and a lab due Friday--and in seven days will turn 63 years old ). Anyway, getting back to the subject, I've had shallow water blackout on a deep free dive, and did not loose my lung full of air. I came back to consciousness on the surface, after a dive to about 60 feet in the Vancouver BC area, many, many years ago. I've also had shallow water blackout due to an underwater swimming contest when I was on a high school swim team. In this case, there was no pressure gradient, but I had hyperventilated so much that I blew off most of my CO2 in my system, and the body's "must breath" signal is triggered by the rise in CO2, not the lowering of oxygen.

In my case, in the pool, I had to beat Tom's previous best a few minutes before of 4 lengths of a 20 yard pool underwater. I hyperventilated for about a minute, then dove in and for the first two lengths was feeling wonderful. The third length, I could start feeling it, and on the fourth length, I was hurting. I told myself that I would get to the end of the fourth length, take my turn, do one stroke (breast stroke) underwater, surface and swim to the side of the pool. And that's exactly what I did. The only thing is that I don't remember anything after the turn. I was told that I took my one stroke, surfaced and swam to the side of the pool, where I regained consciousness.

I have read years ago of several underwater swimming contest deaths where the swimmer continued to swim underwater, presumably after blacking out, until hitting the far side of the pool, where he (usually they were boys) became motionless. After being pulled out, they were unable to be revived, probably because of the brain being without oxygen for up to four minutes before being pulled out of the water.

I was very, very lucky. If I had not pre-programmed those actions, I could also have been a fatality.

One other point, since I'm pretty familiar with wearing thick wet suits (always 1/4 inch suits around here). They do compress, but mostly in the top 30 feet of the dive. I tried to be slightly buoyant at the surface for a free dive, so that I would be neutral at about 15 feet. I could get to 15 feet with a good surface dive. But that would not guarantee that we would be completely buoyant upon returning, even if blacking out. So one technique we had was to remove and hold our weight belt if we had a long, deep dive. Upon blacking out, the weight belt would then be gone--I never had that happen, but I did remove it a time or two.

SeaRat

 

[duckbill]

Thankyou, John. I, too, have weighted to be neutral at around 15 feet during the little freediving I have done, out of concern regarding shallow water blackout. I had no idea that one would continue holding his breath like that. Interesting stuff.

Sorry about the detour, gents, but I just had to ask. Curiosity satisfied. Now, about those double hosers....

 

[DA Aquamaster]

John covered it. One thing to add is that if you black out in a vertical ascent and are near neutral you will still gain a few more feet just due to momentum and then buoyancy will hopefully take care of the rest. It does not mean you will surface face up, but it does make it easier for your buddy find you and render assistance.

 

[duckbill]

...if you have a buddy!

Thanks again.