New to Double Hose Diving

[herman]

I am unaware of any vintage divers in Italy but ask on VDH, you never know. There are a good many vintage divers in northern Fla and southern Georgia so I am sure you can find someone to dive with you once you get there. You will find we are a small but fairly close community, a good many of us have traveled long distances to dive together.....still waiting on Ed to arrange a vintage dive.

The only functional difference between the RAM and DAAM (you might as well get use to our shorthand) is the RAM has a balanced first stage as opposed to the DA's unbalanced one. Since all the components are housed in the first stage nozzle, all you have to do to convert from a DA to a RAM ( or vise versa) is to remove the DA nozzle and replace it with a RAM nozzle (along with all the internal parts and the seat pin). Since the Phoenix conversion completely replaces the first stage nozzle it makes no difference wheather you start with a DAAM or RAM, so why spend the extra for a RAM. Go to the VDH sight and download the service and parts manuals for the regs, then you can get a better idea of their differences. The only other difference is the labels on the can and while I am on the subject, the only difference between the round label DA's and RAMs (1970 to 72 models) and the square label ones is the label and an indent on the exhaust can, internally they are exactly alike. And again, for some unknown reason the round label ones tend to sell for more than the square label ones....and personally, I prefer the square labels ones, to me they look better.
For a first reg, buying a complete reg with the Phoenix installed from Bryan (or one from other members of VDH) is a great way to go.

The Halcyon may work but you will have to readjust it. The cans (round metal part) must be low, between your shoulder blades. Most BCs will not allow the tank to be placed low enough, esp it it has double tank bands and even if you can, often times the top of the plate will hit the cans, stopping you from going any lower. You can usually extend the shoulder straps and tighten the crotch strap to move the cans down but at least on the ET, it makes the waist strap too low- which is why it has to be modified. Also, STA's (single tank adapters) are not acceptable as they raise the tank off your back. The objective is to get the cans as close as possible to your lungs. All these issues are basic to double hose design and the new Mistral and Mentor will have the same issues. I think this may have been one of the reasons modern divers did not like them, vintage divers had other reasons.

 

[captain]

VDH has a member in France, Scaph.

 

[Airleron]

Welcome to the Cult, HOOT! Ha!

Yes, diving and collecting DHer's is a disease and once you acquire one, before you know it, you'll have 5. And you'll SWEAR you NEEDED every one of them. Because they need good homes........(that's what I tell myself)

I agree with the rest of the crew, start off with a Phoenix from VDH, it eases you into "vintage" diving while still using all the safety gear you're use to. Double hoser's have nuances that need to be learned, and having the octo/spg/bc will give you the safety features you're use to. Read as much as you can about what to expect when diving with a DH, and how to clear, purge, etc. your reg. I read every blog and book I could for a year before I made my first purchase. That's extreme, but it was right for me. I don't mean to plug any one source, but buying a ready to go DHer from VDH is a great way to go.

Good Luck and welcome to the board!
Lisa

Edit: I'm in sort of South Florida 45 minutes north of Palm Beach (some of the best diving in Fla) if you happen to be in the area in Jan/Feb. Look me up, we'll go vintage diving. By that time I should have about 6,854 regulators to try! And I'll be living in a box.

 

[Airleron]

Good gawd, that's some right purty gear there, Gill!!! I particularly like the VOITs.....

 

[Ed Palma]

... I read every blog and book I could for a year before I made my first purchase. That's extreme, but it was right for me.

Lisa

... and once you started with one, they just kept on coming! At some point, at this rate, you'll have a collection like Karl's! (I wonder what his very first reg was...?)

 

[Airleron]

... and once you started with one, they just kept on coming! At some point, at this rate, you'll have a collection like Karl's! (I wonder what his very first reg was...?)

I bet it was a CG45 or some other Holy Grail of gear.....his collection is nothing short of amazing

 

[Ed Palma]

Just a few points about reg positioning. It cannot be denied that positioning the reg between the shoulder blades is one of the best possible position for a DH reg, but don't let that stop you from experimenting with various other rigs - if that's what gets you diving.

There's this old graphic from from Bill Barada, "Let's Go Diving" U.S. Divers Co. 1962, page 29. Some of the concepts are worthy of debate:

Although getting the regulator between the shoulder blades is theoretically the best position it can be, there are I believe some instances where it wouldn't really matter if in the horizontal position - as the reg diaphragm remains at a consistent level relative to the center of the lungs. I believe this has been posited before by Nemrod. At any rate, I decided that for BP diving, the slight perfomance drop of the DH when used with the backplate was relatively okay.

I resized and positioned these photos in such a way for me to compare the difference between using a harness alone and my BP without a STA. Its about a half-inch drop in performance when horizontal, but maybe a bit more in the vertical position (which I'm usually not in anyway...)

Just some points to ponder...

 

[Luis H]

Thanks for the pictures Ed. Those illustrate true body position on the water column, better than the classical drawings from Bill Barada.

I agree with Nemrod and your statement that moving the regulator diaphragm in a horizontal pale would not make any difference if we were only talking about horizontal planes in the water column.

The picture on the left is the most common position when a diver is looking forward.

First a theory of mine that I have discussed in the past and I have ran it by a couple of medical doctors and they seem to agree.

The work of breathing is without question done by the muscles associated with the lungs and the thoracic cavity. Therefore the work required to take a breath is influenced by the position of your lungs in the water column, but you have no immediate sensation of this work. If you are on the surface with a snorkel you don’t feel any difference when you breathe in a horizontal position (right on the surface) or you are vertical with only your head on the surface.

On the other hand pressure differential sensations are measured in our inner ear. When you fly on an airplane (or driving on the mountains) your inner ear has to equalize because it is very sensitive to minute pressure changes. This is the same reason why putting a single hose regulator with the diaphragm near your inner ear tends to diminish the difference in sensation with diver position. It doesn’t totally eliminate because if you look up the regulator diaphragm is higher than the inner ear by several inches.

So my point is that the sensation of how hard a regulator breath and the actual work that it takes to take a breath are not exactly the same thing. Therefore, the diver on the left picture with the regulator in the same horizontal plane as his inner ears feel that his regulator breathes great and it does.

Even on the picture on the left I would move the tank/ regulator a bit lower, but mostly so it won’t hit you on the back of the head. Diving in that position will provide great performance to a DH regulator.

I am sure you know as a doctor that human sensations get fooled more often than not. Our perceptions are influenced by way too many factors.


BTW, you sometimes feel some pressure differential right on the cheeks of your mouth, but this tends to be a secondary sensation. When you roll with a DH regulator and your mouthpiece is higher than the regulator you can sometimes feel this sensation.


I hope this does not derail this thread, but this is general information about the physics (and interaction with human physiology) behind all scuba regulators but it is particularly noticeable when diving double hose regulators.

 

[Luis H]

Just to expand on a coupe of points.

The difference between a DA Aqua Master and a Royal Aqua Master in only in the first stage, but that is a big difference. The balanced first stage makes a huge difference in performance, but if you are going to replace the first stage to the Phoenix then it doesn’t matter.

The Phoenix is a balanced first stage with the same mechanical parts as the first stage of the RAM, but with a slightly improved aerodynamic flow path.

The balanced first stage not only provides a constant intermediate independent of tank pressure, but it also has substantially larger flow orifices.

The performance of a DA Aqua Master comes close to a RAM with low tank pressure and in relatively shallow water and/or low work load. The RAM first stage will outperform when high flow rates are required and with full tank pressures.

When I designed the Phoenix Mod-II (the one now available) I also designed it to improve on the performance of the RAM. The difference is small between the PRAM and the RAM, but I have some test data and multiple observations that confirm that there is some difference.

I also have some test data from the regulator labs in Panama City from test performed on the Phoenix Royal Aqua Master, the new Mistral, and a few other regulators. The inhalation breathing resistance of the PRAM outperformed all the others.

The Mentor is not only, not available to the public; they only build something like 200 or 300 of them back around 2003. They were basically hand made and I don’t think they will ever make more.

 

[DrunkenParrot]

... and once you started with one, they just kept on coming!

Aint that the truth....