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luis
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Deep dives with Argonaut Double hose (305 ft)

Tue Aug 30, 2022 10:04 pm

Deep dives with Argonaut Double hose

General dive descriptions:

I just got back about a week ago from the Dahab in the Red Sea, Egypt. We did a series of deep dives with two of them in the Blue Hole just north of Dahab. One dive was to just under 210 ft of depth and the las t one was to 305 feet.

We were using TriMix for the bottom gas and for the travel gas during the deepest dive.

My primary regulator for my bottom gas was my Argonaut mounted on my back cylinder. I carried my bottom gas mixture on my back cylinder and my right “side mounted” cylinder. A low pressure quick disconnect hose allowed me to select from breathing my back gas or from the right cylinder (with the same mix). The right cylinder had a Conshelf first stage with a long hose to a Scubapro 109 for gas sharing if needed.

I carried my deco cylinders on (Nitrox 32 and 100% Oxygen) on my left side. The Nitrox 32 was in an AL80 and the O2 was in an AL40 below it.

For the Nitrox32 I used another Conshelf with a Scubapro 109 second stage. For the Oxygen, I used an oxygen clean unbalanced piston (DGX brand) first stage with another Scubapro 109 second stage. The unbalanced piston regulators are IMO the best choice for higher O2 gas mixes specially for pure O2.

For the first dive in the Blue Hole, we were using TMx 18/30 (18% O2, and 30 helium). We did start with the Nitrox 32 as a travel gas down to 110 ft in order to save a bit on the cost of helium.

For the deepest last two dives, we were using TMx 13/50 (13% O2, and 50 helium). With that low oxygen content, we needed a travel gas and therefore we added a 5th cylinder with TMx 20/20.

Note: these are not standard gas mixes, but they were readily available at out support dive shop in Dahab. BTW, I already got plenty of friendly comments about the non-standard mixes… My answer is: that is not the only thing non-standard… 8)

We had surface support from the dive shop with personnel assistance that would actually carry all our side cylinders into the water. The assistance made for the easiest shore diving experience that I can think of.

The Blue Hole in Dahab has an arch at around 175 ft deep, with a fairly large opening going out to open ocean. The bottom of the Blue Hole has a steep slope, but just under the arch the depth is about 300 ft and continues down into the open ocean.

A lot of divers have attempted going through the Blue Hole under the arch using a single AL80 with air. Many unprepared divers have died attempting such a dive (over 200 documented).

A lot of people have asked me if I saw any bones at the bottom of the arch. The answer is no. If the bodies are not recovered shortly after the incident, they get swept out to sea. I have heard that some remains can be found down around 600 ft depth. Well beyond any depth of interest to me.


Equipment observations.

First, I was extremely pleased with the performance of my Argonaut. I have been diving this Argonaut now for many years and it is just super. I will get into some of the improvements I have done to my Argonaut in following posts, but I will say the second stage has been adjusted to the max-possible venturi assistance.

I have used this regulator down to 180 ft and the performance has always been outstanding. With my new DSV flow diverter I have taken the venturi flow performance to a new level. 8)

During these dives with the helium in the TriMix, the performance was just beyond outstanding… With 50% helium, I felt very comfortable and clearly remember every detail of the smooth performance.

Also, a very impressive observation was the drastic noise difference every time I switch from my side gas regulators (single hose) to my back gas. I have always known there is a difference, but the repeated switching created a contrast in noise level that was dramatic.

Some friends thought that maybe the noise just switched from front to back, but that is not exactly the case. One of the unique modifications I have been working on the last two years (since Covid) has been on my exhaust bubble silencer. More on that later, but it definitely works.

The position of the side cylinders needs some improvement, but they did their job without any issues. My right cylinder in particular needs adjustment, but both sides can use it.

The configuration I used is what I called mix-mount, it draws from side mount and back mount, but most of my testing and cylinder position tuning has occurred here in Maine with cold water equipment. The transition to 3mm shorty with aluminum tanks requires a bit more refinement.

I have written about this configuration in these threads and I may be adding more information in the future. I am very pleased with this setup.


https://scubaboard.com/community/thread ... nt.545511/

viewtopic.php?f=47&t=9260



I will be writing more about some of the work I have doing to the Argonaut (the exhaust silencer and my new DSV flow diverter, etc.), but for now here is the dive profile of a couple of my dives and below is a link to a video. I do not have any pictures of the dives. I don’t even have a camera housing rated to these depths.



Image


Image


Note: The breathing noise in this video is all from the diver holding the GoPro.



From looking at the videos I already established that I need to clip my side mount cylinders lower on my waist, not on the butt plate. This is particularly true with 50% helium. Even when it is full, the content in that cylinder is about 36% to 40% lighter. I would have made some corrections on the spot, but at the time it didn’t feel bad. I should have moved some weights… Oh well.

Most of the testing of my “mix-mount” set-up was done in cold water with a drysuit or heavy wetsuit. For the earlier dives I used small steel side cylinders, very heavy (worked great with a drysuit).
Luis

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couv
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Re: Deep dives with Argonaut Double hose (305 ft)

Wed Aug 31, 2022 12:48 pm

Fantastic!

Just to clarify. Did you physically exchange the DH mouthpiece (DSV) with each gas switch or did you continue to breathe off the DH loop using your mixed- manifold technique as described in other threads.

Cheers,

Robert
A sincere THANK YOU to all at VDH who make this wonderful resource available and to all the thoughtful contributors.

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luis
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Re: Deep dives with Argonaut Double hose (305 ft)

Wed Aug 31, 2022 2:55 pm

For these dives I only connected the regulators from the two cylinders with the same gas mixture. I did have a quick connect on my Nx32 and I could have switched to that, but that doesn't make it visually obvious which gas I am using to my buddy.

So I opted to just go the more standard way and switch regulators so that gas switches are more obvious to the buddy pair.

Breathing the wrong gas at depth is one of the more dangerous issues in this type of diving, therefore definitive buddy check during gas switching is considered a very important safety procedure.
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Re: Deep dives with Argonaut Double hose (305 ft)

Wed Aug 31, 2022 4:38 pm

Since I don't have any underwater pictures, I though I would share some of the top-side pictures.

Here is what the Blue Hole looks like from the surface.

Image


The free divers wake up much earlier than we do:


Image


And by the time we are getting out this is what the entrance looks like with all the snorkelers and the general tourist.
It can be a zoo trying to get out, but we had excellent surface support.


Image

Here are all the cylinders that two of us carried for the last deep dive.


Image


OK, I should not say that we carried them... I only carried my single back cylinder. The rest were brought to us into the water and we clipped them while standing in waist deep water.


Image


Here is the actual entrance with nice steps into the water.


Image


Here is our surface support assistance in his custom wetsuit. He was just awesome!
He actually hold the Guiness world record for the longest open water dive (over 6 days) and the largest underwater painting: Saddam Killany. And what a supper nice guy.


Image



Behind him you can see the Bedouin restaurants across from the Blue Hole.
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Re: Deep dives with Argonaut Double hose (305 ft)

Wed Aug 31, 2022 6:06 pm

Here is a sneak preview of my exhaust silencer 3D printed exhaust can.

This is the regulator I normally use, but I changed it to DIN fitting, removed the octopus, and added the cross-over LP hose, for the deep dives.

The exhaust silencer is made from 1000 tiny holes (OK, only 999 to be exact).

The sum of the exhaust gas flow area is several times that of the cross-sectional area in the exhaust hose or any of the exhaust gas path. So, I have done lots of calculations and lots of testing (properly instrumented and otherwise) and the flow impedance is barely measurable (or actually not at all).

The exhaust is broken down into tiny bubbles, which quiets it down to a much lower sound than the intake noise. I don’t have the instrumentation for acoustic testing, so all I can do is comparison testing.

I will have more info to follow, including some inside pictures. I made some really nice changes to the inside valve area also.

Image


The regulator on the right is my primary regulator. These are my two working prototypes.

More to follow. Note, the back cans are the original injection molded.


Image
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Re: Deep dives with Argonaut Double hose (305 ft)

Wed Aug 31, 2022 6:37 pm

What an interesting idea Luis! I can just imagine that in action! :D

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Re: Deep dives with Argonaut Double hose (305 ft)

Wed Aug 31, 2022 9:32 pm

Thanks Jim,

You can see my bubbles in the video. They start as tiny bubbles, but they grow fast as they move away and then sometimes reform into bigger bubbles about 3 feet or more away from me. When they get that far away there is no noise.

Most of the time the tiny bubbles just continue growing as they rise.
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Re: Deep dives with Argonaut Double hose (305 ft)

Wed Aug 31, 2022 9:35 pm

Here is a picture of the inside of one of the cans. I think the lighter color can.

The filler material I used is clear so you can see a lot of the 3D printed imperfections. But the final surface that clamps the diaphragm is all filled in and is sanded smooth.

I re-designed the exhaust valve to have a much wider landing to make it easier to fill and sand into a very smooth sealing surface. I also tilted the valve surface down 2 more degrees (away from the diaphragm) than before, and you can see the diaphragm stops.

The exhaust support spider is also different.

I am also having to use a sealer on the tube and sand that smooth.


The tiny holes look a lot bigger than they are because the 3D printing doesn’t do sharp edges. And I have to clean many of them with a tiny drill bit.


An interesting issue: the black can on the left is the last 3D printed can I will work on black. The material is so incredibly shiny and dark that it is very hard see what I am doing.

I like the one on the right the best, but I have not head back from the vendor that produced that can.

It has been over a year since the last time I was actually working on these cans and this project.


Image


I have two more printed cans that I put aside for a while, but I need to finish sanding and finishing them. It is not a lot of work, but I have to put time to do it.



The other huge improvement (IMHO) is my new DSV flow diverter and the amount of venturi assistance I am able to adjust into my HPR second stage... stay tuned... 8)
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Re: Deep dives with Argonaut Double hose (305 ft)

Thu Sep 01, 2022 5:06 pm

Interesting. Drager made an exhaust diffuser for a few of their nitrox rebreathers; the FGT, LAR (nitrox model VII) and Dolphin/Atlantis. It uses a foam dome in a cage. This one is made by Martin at TECME in Germany for the Dolphin.
Drager Bubble Diffuser.jpg
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luis
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Re: Deep dives with Argonaut Double hose (305 ft)

Thu Sep 01, 2022 6:07 pm

Yes, the concept is not new. The implementation is what becomes is a bit more of an issue.

In a semi-closed rebreather it is a bit easier because you are just dealing with about 1/3 of the exhaust on every breath... roughly...

I have copies of about 10 different patents for a number of exhaust silencers, from big attachments to even a hood where the exhaust is channeled into many little bubbles. Most of the patents are very old and none of them resemble what I am doing, but similar principle.

I do know of of at least one European Navy using a semi-closed rebreather with an exhaust silencer.


Thanks for the post.
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Re: Deep dives with Argonaut Double hose (305 ft)

Mon Sep 12, 2022 3:52 pm

Wow!

I was just watching a YouTube video about the Blue Hole and all of the divers who died trying to go under the arch with a single 80 cf tank. And here you are diving the same location... With an Argonaut! Of course I am relieved to see all of the redundancy, preparedness, and technical expertise you brought to it. The number of friends I have that could handle such an advanced dive I can number on less fingers than one full hand... And that's counting you! Congratulations on the accomplishment and on your recent retirement! :)

If you are able to get the bubble silencer and flow diverter produced I will certainly order them.
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Re: Deep dives with Argonaut Double hose (305 ft)

Sat Sep 24, 2022 7:17 pm

Awesome, thanks for sharing!

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luis
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Re: Deep dives with Argonaut Double hose (305 ft)

Tue Oct 18, 2022 4:38 pm

I have couple of more subjects related to my setup for these dives. I was going to take a long pause in light of Bryan’s passing, but I decided to post since I had most of the writing done from before.

One subject, is the performance improvements I have been working on, by optimizing the venturi flow (including the new flow diverter in the DSV and the improved venturi adjusting blocks). My last planned subject will be the cross-over connection and how I controlled my back-gas (using pneumatic lock).

When I designed the HPR second stage part of the design considerations was flexibility and adjustability, as well as backwards and forward compatibility with vintage DAAM, RAM and the future 2 stage replacement (now known as the Argonaut Kraken). At the time we didn’t have a mouthpiece with a flow diverter, therefore we had to limit the amount of venturi flow assistance, but I always planned on incorporating a new mouthpiece with a flow diverter. I needed the ability to adjust the mount of venturi flow.

From another post:
There is a reason why I called it the second stage HPR (High Performance Regulator).

With the HPR you have the ability of making three independent adjustments: the lever height, the spring tension (which can control cracking effort), and the amount of venturi assistance.

I am just about to write some more details on how to adjust all three, but here is a little advance information. I have shared most of it in other posts, but I will add more.
Note: I just designed a new flow diverter for my DSV design, that allows me to take full advantage of the maximum venturi flow.

1) The lever height adjustment is kind of intuitive. You use the nut on the seat carrier to adjust it.

2) The spring tension can be reduced by backing (unscrewing) the HPR body in increments of half turns (180 degrees). Cracking effort is fine-tuned by balancing the spring pressure against the IP. In the Argonaut, I typically adjust the cracking effort to about 0.6 inWC (to 0.7inWC max). Anything lower and it will free-flow when the top edge of the exhaust valve is higher than the center of the demand valve.

3) The venturi flow can be adjusted, by changing the ratio, of the amount of air in the jet pointing down the horn, to the amount of bleed-air going into the can. The adjustment is done by blocking the side bleed-air ports to the desired amount. I will expand on this.

From the early design stages I tried to make the HPR a very adjustable second stage with ability to push the performance...


Now we have my new DSV and I now have optimized the flow diverter for the DSV. Therefore, I can push the limits on the venturi flow assistance.

Below are pictures of my new flow diverter. The new flow diverter does not allow any blow-by past the mouthpiece, therefore allowing the maximum possible venturi flow assistance.

The flow diverter actually seals around the perimeter of the inner tube and it has a vane directing all the flow to the diver. The designed called for an interference fit, therefore to assemble it into the DSV it required a flexible material. The 3D printed units are made out of TPU (a flexible plastic, almost like an elastomer).


Image


Image


Inlet side of DSV and flow diverter.

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Exhaust side of diverter.

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Some 3D printed flow diverters, before I installed them.


Image


Here are pictures of my new 3D printed bleed-air port blocking device. Notice they can be turn around to allow more or less (down to zero) bleed-air out of the side ports.

I am using a tapered hole and counter sunk screws. The holes are offset just enough so that tightening the countersunk screw creates wedge effect due to the ramp in the hole and the screw. When tighten the screws, the stop pushes sideways against the second stage locking and sealing the bleed-air ports.


This is the configuration I use for maximum venturi flow. Notice that both bleed air ports are fully blocked. The notched ramps are facing out.


Image


Image


This is the configuration I would use with the old stock flow diverter to provide a manageable venturi flow. It is not the optimal, but it is good for must divers. Notice the one open bleed-air port.

Image


This is looking into the horn. Notice both bleed air ports are fully blocked.

This configuration provides exceptional venturi flow. This configuration can only be used with the new flow diverter installed in the DSV. With any other mouthpiece, the venturi flow will produce a lot of gas blow-by and out the exhaust. With the vintage curve mouthpiece (no flow diverter) it would often produce an uncontrollable free-flow out the exhaust.

With the new flow diverter, the combination makes for a sweet breathing regulator at any depth.


Image


Next, I will talk about the cross-over connection and how I controlled my back-gas (using pneumatic lock).
Luis

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