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USS KEY WEST SSN-722 Build Log 2020-02-18: HULL-Diver Box Mounting

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  • USS KEY WEST SSN-722 Build Log 2020-02-18: HULL-Diver Box Mounting

    One thing I discovered about using the “Diver Boxes” as opposed to the ubiquitous cylinder is the methodology for mounting them within the hull. Granted the cylinder is straightforward, a minimum of two saddles and something to strap it down. It can be as simple as a set of rubber bands or Velcro, or as elaborate brass metal straps. Quick and easy, so no argument here.

    The boxes do need something a tad more robust, considering you’re opening it within the hull by popping the two latches for access, because you don’t need to remove it unless you want to perform maintenance or testing/troubleshooting on the bench. Also, while you can of course create a set of saddles and fix it’s location within the hull, I found a double, tube “rail” mounting design more practical, and just as easy to install. You can relocate the boxes easily fore and aft, for whatever reason (trim, functionality, ease of access, etc) and simply remove them with two thumb nuts.

    I had something of the sort, yet very rudimentary in my “test platform” SHARK. I also discovered one can use the rails to strap down an appropriately sized Ballast tank. Another bonus I serendipitously found was since the compartmental “box” design requires external electrical runs, I can use the rails (with cable ties) to run electrical wiring harnesses, pneumatic plumping, etc from box to box or to whatever. Keeping everything clean and organized.

    So in the photos below, you can see the prototype 3D printed “proof of concept” tube rail “mounts” and box “hold-down” brackets. Originally I was going with a rounded, more “organic” look, but settled on a “geometric” style, just preference giving it a more “industrial” look. The tubing is ”, thick wall, aluminum.

    The plan is to mold these 3D prints, then cast from Alumilite. The hull mounted supports will have the tube guides drilled and tapped for 6-32 set screws. These supports can be fixed to the hull in any manner one chooses. Quantity, location and depth below the waterline is of course dependent upon the boat and it’s size.

    Each box gets two rail “rail bed” saddles (one fore, one aft), which have an 8-32 stud coming up from the center. The rail “hold-down” bracket has the accommodating hole for the stud in it’s center, and is used to clamp the box to the rail with a thumb screw.

    So to remove a box for service, repair, replacement, undo it’s electrical and mechanical connections, and two thumbscrews. Done! Yet it will hold fast enough to pop the two latches on the box to open the lid.

    Here you see the “rail” concept using two ” brass tubes. The diver box to the left is inverted of course, and has its four associated parts laying on it, two “rail bed” saddles and two “hold-down”brackets. To the immediate left of that are two 4’ Al tubes, which constitute the “rails”

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    A closeup of the “rail” mount. The 6-32 set screw will be located at the center of each outboard, upper angled face. One for each “rail”, so two per mount. This will hold the tube fast along the axis of the boat.

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    Viewed as if you were beneath the box, this gives you an idea of how the two “rail beds” will be permanently affixed to the box, and the two “hold-downs” clamp the rails to the box with a thumb screw.

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    Now that you have an idea on how this works, here you can see the “proof of concept” being fitted on 722. They’re a bit high with respect to the keel at the moment because I’ll need to remove some material from two or three of the old bulkheads to fit low where I want it. Note the ”faux” ballast tank.

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    Unless of course the rail mounts themselves are removable from the hull, don’t plan on one long set of rails, that would be difficult to remove the tubes after installation. Always design and build for easy access and repair. The beauty of this is you can have one long set, or two or three smaller sets of rails if you have different sized boxes or an overly sized ballast tank, or wish to affix the mounts permanently.

    If you do go this route and make sets for yourself, insure the 8-32 stud is long enough that you can pre-install the “hold-down” brackets, then simply place the box on the rails, and rotate the brackets into place and tighten. Done

    Now that I’m happy with how this will work, I’m going to fabricate the molds and start pumping these out. After this DeBoer 688 hull, I have the venerable DeBoer 571 to do!

    v/r "Sub" Ed

    Silent Service "Cold War" Veteran (The good years!)
    NEVER underestimate the power of a Sailor who served aboard a submarine.