Over breathing

[nemrod]

I was reading in an ancient scroll, OK, just a very old dive book and the subject of over exertion was brought up. It said that the diver must be carefull not to over exert because the Aqualung cannot supply enough air for the over exerted diver leading to panic! Well now I think they were using Aqualung in a generic sense as we Southerners call all soft drinks a coke! lol. So my question, has anyone of normal size and condition actually been able to exceed the breathing capacity of their double hose? I came pretty close during the vintage dive in the Blue Spring thanks to my trying to push a large camcorder agaisnt the current while being under weighted and some what tired from the swim/walk to the spring. I had to roll over (on my back) and take a breather on a ledge out of the current. I was diving my very nice DA on this dive. I do not believe this would have happened had I been using my Royals but of course being head down fighting a current in vintage Voit Skindiver fins, under weighted, with drag inducing camcorder is not a great position concerning the dynamics of a double hose this being one of the more "hard" breathing positions--head down.
Advertisements of the era state that all Aqualungs can supply 12 cf per minute minimum or something like that without exceeding Navy limits of breathing resistence. Back when I was into marathons and tri stuff I am certain I could exceed an uptake of 12 cf per minute while exerting myself during competition but that was at an extremely high level of fitness which sadly I will never have again. I should think that airflow capability should be sufficient for normal exertion and normal fitness levels of average size persons. James

[Broxton Chuck]

The whole key to the problem is " UNDERWEIGHTED"! You can wear yourself out just trying to "STAY DOWN" regardless of what regulator your using. I always go low and slow, but even in the current of the blue spring its EASY to drop from ledge to ledge with the correct weight. Us vintage guys need to remember that with no BC we need to get our weight dialed in just perfect. Always a hair heavy at the start, but once that tank is getting low, still have enough ballast to hold you nuetral so you can finish your dive comfortably. I dont use a weight belt on land, gravity is the dependable soloution there.

[sea.explorer]

With the IP set to "factory standards" (about 110psi) I have found that at depth or under heavy exertion the delivery is typically a little lacking and I must focus on slowing my breathing rate. I also regularly dive at altitudes in excess of 10,000' and the thin air makes these issues more extreme. I am a big advocate of raising the IP beyond the 110 psi. My Royal Aqua-master is set at about 145 and there is definitely no shortage of air delivery under even extreme conditions in my experience. Since the Aqua-master is unbalanced the IP will not be stabilized at all tank pressures but you can still crank it up. I suppose that it should be said that adjusting a regulator beyond factory specs should classify it as experimental. I think of it like aviation. Homebuilt airplanes and planes modified beyond factory specifications are classified as "experimental" by the FAA. They still fly and often outperform factory built planes but they are considered to be a different beast. Dive safely and have fun. -Ryan

Chuck hit the nail on the head, most divers don't take the time to dial in their weighting and this leads to over exertion. The effects of overweighting can be magnified when diving without a BC. Another challenge is that vintage divers are often changing gear configurations regularly, different wet suit different tank set etc. It is fun after all, to dive all of our toys. I have put together several weight belts for different configurations and I grab the one that fits the set-up I am diving. I also log weight and equipment in my log book for reference.

[SeaRat]

I was reading in an ancient scroll, OK, just a very old dive book and the subject of over exertion was brought up. It said that the diver must be carefull not to over exert because the Aqualung cannot supply enough air for the over exerted diver leading to panic! Well now I think they were using Aqualung in a generic sense as we Southerners call all soft drinks a coke! lol.

Actually, I think this ancient scroll was describing a single unit, the "DA Aqualung" by USD. And I think they were correct, as I have seen much the same language describing hard breathing is some other texts (look at Fred Roberts Basic Scuba for a description of troubleshooting the DA Aqualung).

The basic problem is that the DA Aqualung cannot supply enough air under exertion to meet the diver's requirements. I did the same swimming against the current in about 40 feet of water in Clear Lake some years age, and had to swim on my back to get anywhere near enough air to come out of the DA Aqualung I was using. That is the last time I used that regulator on an actual dive.

John

[nemrod]

John, if your not using a DA then what are you using? If your using a RAM then do you also find it that much superior to the DA as I have?
Well, I do still use my DA, plan a small dive trip in a couple of weeks to Table Rock Lake, well, actually we are just going boating but I will bring some dive gear. Anyway, I planned to use the DA as I intend nothing deep. At least with my regulators at no tank pressures, high or low, does my DA ever approach the performance of my RAMs for whatever reasons.
Yes, after reviewing the ancient scroll I suspect you are correct in that the DA was the subject regulator.
James

[broxton chuck]

Why are we bastardizing our old reliable friend the Aquamaster. Sure they breathe better upside down, and on and on, but this is the type of regulator we enjoy in our sport. They ALL breathe with the same characteristics, its part of the game.I dive a 54 BROXTON, and its no comparison to an aquamaster, or a ROYAL, but its more than adequate for me. I have had it to 125 feet, and it works fine. If you tune up an aquamaster, and carefully get everything tweaked just right, they are super easy breathing, and are more than adequate for the vintage guy or gal! Were not in the olympics, were sport divers doing our thing. The indianapolis 500 is a different route than the freeway we drive everyday. Lets not RUSH to judgement!

[swimjim]

If I understand it correctly, a DA Aqualung is the predessor of the DA Aquamaster and they are two different regs. The AquaMaster is, from what I've read, is a far better breather then the original Aqualung.

Jim

PS They both probably do better then my Dacor diving lung with its relatively thin hoses and mouth piece.

[SeaRat]

Jim is correct, I'm NOT talking about the DA Aquamaster. The original scuba from France, and subsequently manufactured by US Divers, was called the DA Aqualung. The horseshoe was different, the nozzle was different, and the air was directed directly against the case, and not up the intake hose; e.g. there was no venturi with this reg. I'll look and get a diagram here about it later tonight.

The DA Aquamaster is a great regulator, but not quite to the standard of the Royal Aquamaster.

John

[nemrod]

That makes more sense that it was a precursor to the DA that the scroll spoke of. They did say Aqualung and not Aquamaster and I originnnaly took it as being generic.
I started this thread to see if someone knew how much air a working diver consumed at depths and actually how much air the DA could supply and have they actualy found themselves needing more and not to bash the DA which as I hve said I enjoy using. The old magazines I have state the Aquallung regulators can supply 12 cfm, that does not seem like a very high number to me and wondered if there were any perspectives on this. James

[Broxton Carol]

Am I a dummy? I need to learn to read the fine print, but at my age I cant see it. Just when your swimming along with your DA AQUALUNG getting plenty of air, some moron comes up and cuts your hose! By the way my instructor said that if a inhale hose got torn off, or was disabled, immediatly dump your tank, rip off the hose, and breathe from the port on the regulator as you surface. I never tried it, but it sounded scary!

[SeaRat]

Nemrod,

I have a publication called Science Diving International, Proceedings of the 3rd Scientific Symposium of C.M.A.S., published by the World Underwater Federation (C.M.A.S.) and the British SubAqua Club (B.S.A.C.) from 1975. It it is a paper titled "An Attempt to Link Objective and Subjective Performance of Sport Divers' Regulators", by R.J. Nyman and J.G. Van Der Walt of the South African Under-water Union. They did a bunch of tests on then-current regulators (not the DA Aquamaster or DA Aqualung, however). They ran their tests at flows of 100, 200, 300 and finally 400 liters per minute. 400 liters per minute is about 14 cubic feet per minute. To get these flow rates on two hose regulators (Nemrod Snark III, Spiro Mistral, Spiro Royal Mistral, Seibe-Gorman Mistral, and Drager PA 61/II) they needed suction efforts which were very high (up to 30 cm of water). They also did it at various inlet pressures (40, 90, 140, and 150 atm). This is a 19 page document with charts and graphs of their findings. But I thought you would like to know the flow rates used.

By the way, my comments on the DA Aqualung are a result of my trying to get mine to perform anywhere near what I would call "fair" and it did not happen. I even reversed the setting of the valve in the box, so that the opening pointed toward the intake hose (I actually saw one like this on e-bay, and decided to try it--it probably was the forerunner of the DA Aquamaster), and was not able to get it to perform where I would take it into open water. Broxton Chuck, I'd like to know what you've done for yours that makes it perform, the interstage pressure, etc.

John

[nemrod]

Uhhhhh, you might not want to put the outlet port of the regulator into your mouth!!!!!!!!directly!!!!!!!!!!!!!!!. This could cause an embolism while you try it sittng in your living room couch. Do not put a venturi straight into your lungs---bad--bad. This was discussed on another thread here and I can confirm that it is a very bad thing--trust me! James

[SeaRat]

James,

That scenario of breathing directly off the intake port of a two-hose reg is not a good idea. It would be like breathing off a valve, and there have been fatal embolisms from that (kids, trying to breath helium). It would give this thread's name a bit more of a message.

John

[Broxton Chuck]

Hi John:I have several BROXTONS and 3 navy type DA's, and a DA NAVY approved. They alll work fine. When I overhaul one, heres what I do. First, get a kit from bryan, and start with all new supple gaskets. I always keep the original diaphragm in the 1st/second stage assy, as its formed to fit the pad. Next I clean out the nozzle and inspect the seat and the little pin that activates the seat. Heres a little trick I learned in the shop.... Get a magnifying glass and observe the height of the pad, when placed in the nozzle with the pin in place. A WORN seat will have an indent from the pin, in the brass in the center, and this will reduce the height of the pad. If tolerances are like new, the pad will stick up out of there a noticable distance. Thats what you want. A worn seat will let the pin only hold the pad off from flush a little bit. This adds up to volume of air delivered........ get me?!!! I had some old pins from the shop that were over length, that you could cut to fit. That sounds crazy BUT it works. Just dont go overboard. Next, set the midrange to about 110 psi. Thats just fine. If you use one of BRYANS LP seats, they work great. Turn your screws out 1 1/2 turns like the book says, and at 110 psi you will have a tight reg, free of air leaks. Next, use the CORRECT diaphragm, the one that rests on the fingers of the horse shoe. Most of these were changed over the years. The originals were BLACK and sat flat compared to the late ones. I have heard these are military but I dont believe it. With the correct diaphragm, in there your reg will work perfect as it was designed to. You can of course use a late type diaphragm, but these will sit up off the fingers, and you will have to draw a lot of air before the reg will feed. Once you get in the water though, the reg will function as the water will get the diaphragm in position on the horse shoe, and all you have to do is smile, let the water do its work, and you will get all the air you need.

[Broxton Carol]

I just proof read my above comments, and would like to add: That when you put the pin in the horse shoe, I NEVER bend it over. Doing so destroys it. They are extremely hard to find. The originals were brass wire. The Da navy types were stainless wire, as the DA NAVY approved. I have been diving mine that way, and I stick the pin in from the top, through the screws, and the tension of the springs holds it right in there. Also I wouldnt sweat breathing off the port of a reg. I do that all the time to test function before closing up the cans. It would just free flow until you stuck your mouth over it. The hose and mouthpiece are just an extention of that port. I would inhale off that port just like taking a swig of old hawk whiskey straight from the bottle.