New to Double Hose Diving

[Ed Palma]

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.

...

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.

Thanks Luis, for bringing up that point There's this article I read by Jack Kellon, "The true work of breathing in rebreathers" Immersed:1998. p.30-33 that to a degree illustrates the difference between what we perceive as easy breathing versus true work of breathing.

Here's an excerpt:

I agree with you that this topic is indeed very relevant to the topic of DH diving.

 

[Luis H]

Thanks Ed,

I have been looking for that kind of information for a while. I have talked to several re-breather instructors and researchers, but I have not found good studies on this subject.

 

[DB12]

Wow guys thanks for the warm welcome and thanks for the load of interesting information you have put out here :cool2:
Still need to receive the VDH confirmation e-mail for the account but hopefully it will come.

@Airleron: If all goes according to plans I should be in Daytona Beach, FL from then onwards, would definitely appreciate to do a test dive before spending a lot of cash ! I'll be sure to start ordering a few books though in the meantime so I can start to read up on some things about DH regs. (I suspect all that reading will make me very impatient though )

@Luis & Ed: Would you then say that diving a PRAM on a modern BC such as the Halcyon Eclipse (without mods.) would be something possible ?

Cheers
HOOT

 

[Airleron]

Ed, thanks for posting the diagram above....kind of an eye opener that I hadn't really thought much about, until I started using double hose regs. Very very relevant.

Hey now, I am letting those regs live in my house and when they retire, they'll have a nice comfy shelf to live on. Of course, they aren't retiring any time soon!

 

[Ed Palma]

Hoot, it is definitely possible to do that. Halcyon BC, safe 2nd, dry suit - the PRAM will deliver. If one minor change could be made to improve WOB, loosen the shoulder straps, and tighten the crotch strap. Of course, the optimum config for DH use would be a plain harness to bring the cans close to the lung centroid, but for me, the difference isn't enough to deter me from using a regular BP/W if need be (that said, I do have a simple harness which I use with my Mistral for totally fun diving...)

 

[duckbill]

So are we to infer from these studies presented that a double hose regulator will beathe more easily or seem to breathe more easily if brought up on the back toward the "eupneic centroid" near the base of the ears instead of down closer to the center of the lungs? Experience hasn't borne this out for me.

 

[Ed Palma]

Interesting point you bring up DB. I had to go back to the article to see how you inferred that, and I think I found the pertinent section:

"This explains why a diver thinks that a single-hose regulator breathes better than a double-hose regulator in the upright position. A second stage regulator diaphragm located at the mouth is obviously closer in the water column to the eupneic centroid than is a double-hose regulator located halfway down the back."​

Kellon, J. : Immersed​

​

I think I will try a little experimentation with my PRAM in the vertical (gasp!) position next week to determine the veracity of this statement. At the moment, I will agree with you that this doesn't seem to be borne out of experience. I think anyone who's had their cheeks inflated by having a DH lower in the WC will testify that it breathes better closer to the lungs.

 

[knowone]

Doc Ed!


Your insurmountable enthusiasm regarding all things diving is blessed, to the soul.

Your willingness to experiment or achieve, to post fact is also far beyond the usual.


I envy your aquaman dimensions.

 

[Luis H]

Interesting point you bring up DB. I had to go back to the article to see how you inferred that, and I think I found the pertinent section:

"This explains why a diver thinks that a single-hose regulator breathes better than a double-hose regulator in the upright position. A second stage regulator diaphragm located at the mouth is obviously closer in the water column to the eupneic centroid than is a double-hose regulator located halfway down the back."​

Kellon, J. : Immersed​

​

I think I will try a little experimentation with my PRAM in the vertical (gasp!) position next week to determine the veracity of this statement. At the moment, I will agree with you that this doesn't seem to be borne out of experience. I think anyone who's had their cheeks inflated by having a DH lower in the WC will testify that it breathes better closer to the lungs.

Yes, I think there is something wrong in that statement (he may be referring about exhalation in that statement), but we will never know for sure because he passed away.

He designed some very interesting re-breathers (AFAIK the predecessor to the Halcyon, etc.)

The precision of some of his statements has and can be question, but I tend to agree with the over all concept.

Note: I just found out about this article when Ed post it, but I have been doing a bit of research about Jack Kellon after reading this article.



While searching about Kellon, I also found other relater article by Capt. Edward D. Thalmann, MD. It looks like Dr. Thalmann did a lot of research related to work of breathing with re-breathers (among all the other research he did while at NEDU and later with DAN). I am going to try to find if more of his research is related to this subject.