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Argonaut mix-mount… a variation on side-mount

Discussion in 'Sidemount Diving' started by Luis H, Jun 4, 2017.

  1. Luis H

    Luis H Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Maine
    Argonaut mix-mount… a variation on side-mount

    Here are some pictures of my second dive with this configuration.

    I am calling it mix-mount because it uses some side-mount components, but I am also using a 30 cuft pony bottle on my back as a mount for my double hose regulator. The regulator also doubles up as a LP gas manifold block for all three cylinders.

    The back gas is only used as a third redundancy reserve and as a possible transition gas when switching between cylinders.

    The availability of the back gas is automatic. It is controlled by IP differential between the side mount cylinders and the back mount.

    There is a lot more information and pictures on these threads, but I thought I would share this over here.
    Argonaut Mix-mount or Tri-mount… as opposed to side-mount
    Vintage Double Hose • View topic - Argonaut Mix-mount or Tri-mount… as opposed to side mount

    There are some pictures showing the hose connection details.

    This has been an interesting experiment and I expect that there will be several situations where this configuration is going to come in handy. I have been using a double hose regulators in extended rage diving (AKA technical diving) for a while, but this is the first time I try this configuration.

    I will be glad to answer any questions and I appreciate any comments.












    The three cylinders I am using are small. The aluminum back-gas is an AL30 (diameter = 5 1/4”, by 20” tall).

    The steel cylinders are 61 cuft at 3300 psi (diameter = 6”, by 22” tall). This are good testing cylinder up here because they are very heavy in the water.





    This is more complicated than a single tank, but it does open the door to many possibilities. It is just another set of tools that can be used for some challenging dives or just for fun. :wink:
    Last edited: Jun 4, 2017
    macado, couv and northernone like this.
  2. northernone

    northernone Great White Rest in Peace ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Currently: Cozumel, from Canada
    • I love this from the perspective of an underwater photographer. All the stability and extra gas of sidemount combined with the advantages of dual hose regarding bubbles.
    • Would be great ice diving too.
    Anything preventing you from using a skinny 6cf tank as the backmounted cylinder if one wanted to copy your design for cave diving where a thinner profile would be advantageous?

    Great to see a quality design. Well done on the redundancies and flexibility you've built in.
  3. Luis H

    Luis H Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Maine

    You could use any size cylinder for back gas. I don’t own a 6 cuft, but I do have a 30 cuft and a 19 cuft.

    The difference in the cylinder radius from a 30 cuft down to a 6 cuft is only about 1 inch. I mention radius, because in this case, the separation between your back and the center of the cylinder is going to be driven by the regulator. The only gain by reducing the cylinder size is on the outer radius.

    The way I am thinking about it, the small diameter cylinder actually protects the BC bladder in an over head environment. I personally don’t really want to ever place myself in such a tight overhead environment where one inch will make the difference.

    In a hard overhead environment I would definitely use DIN connections.

    Added: I should point out that I am not a cave diver.
    Last edited: Jun 4, 2017
    couv and northernone like this.
  4. Luis H

    Luis H Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Maine
    Here is a short video from yesterday.

    I was checking to see how well I could back-kick with the side tanks and I also tried rolling to see how the tanks would behave at my side. I also tested in several other positions, like on my back, etc. The tanks do move, but they do behave ok and they return to their position. It all worked out well.

    The only issue I had was a small air leak from my right tank valve. I just need to replace an O-ring on the convertible DIN valve.

    This was the second time I tried this rig.

    couv likes this.
  5. Luis H

    Luis H Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Maine

    I missed that comment.

    Yes, a double hose regulator is not normally affected by cold temperatures. Both the first and second stage are normally dry.

    They used the Royal Aqua Master in Antarctica 20 years after they were out of production, because of their cold water performance and their resistance to freezing. AFAIK, they quit using them when they couldn’t get parts anymore and were having maintenance issues.

    With my new DSV (closing) mouthpiece the Argonaut is always very dry. Much dryer than with just the one-way valves in the mouthpiece.

    I haven’t taken the Argonaut under the ice since I designed the DSV mouthpiece, but I have used one of my early Argonaut prototypes under the ice and never had any issues. I intentionally tried to get the Argonaut to freeze and it didn’t happened.
    northernone likes this.

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