Hello Folks
Here we're back with new stuff for our Mare Island project.
Sometimes ago I posted pictures of my trials to build a Gato submarine structural sections we wanted to put in our slip.
Our concept was good, but assembly proved troublesome, with no efficient way to obtain regular spacing for frames.
I designed a special jig to fulfill this delicate task (remember we're working on a 72mm long hull section with 68 frames spaced 1.01mm with central section spaced .87mm!), but this proved too difficult to handle.
We redesigned our jig in last August and I tried "the assembly" this month.
First I spent hours on official Gato blueprints (from the Floating Drydock) to get structural shape of each frame : some are plain, some are only lattice frames, some with round holes, oval holes, etc... This was a long but rather easy task from the blueprints. I issued a resumee I sent to Jean who drew the 68 frames, keel sections, longitudinal stiffeners... and the jig, of course.
And I etched the corresponding 250x100mm nickel-steel sheet.
Following is a description of the assembly of a structural Gato hull.
Reminder : we wanted to obtain this :
Here is our special designed jig which can hold each frame at its right position and spacing until we've pushed the cylindrical watertight compartment. Of course, our jig is... photo etched. Frame numbering is relief etched and high lighted with white paint for ease.
The jig ready for work. Note movable clamps which are used to hold the keel during assembly.
Here comes the keel assemblies (we wanted one complete keel from frame 35 to 108 as well as two smaller sections, thus making three different keels):
Each keel section is made of four parts : two external, relief etched and two internal, making a total thickness of .4mm:
First the four parts are put together and adjusted with the jig's clamps:
Then they're glued with super fluid CA glue which bonds the four layer assembly.
Here's the "main keel" being glued:
Let's start with the large keel : this is clamped in the jig to exactly match the side slots:
The end frame (#35 from bow) is glued on the tip of the keel : it's inserted laterally through the positioning slots:
Then each of the following 67 frames is inserted and simultaneously a 6mm brass tubing (the central watertight compartment) is gently pushed through. At this stage each frame is glued to the keel only with a tiny drop of CA glue:
Note the sliding top clamps which prevent the jig from opening and allow enough visibility to work inside:
Assembly under progress:
Three hours and 68 frames later, the aft end frame is glued:
Now is the turn of the two longitudinal top girders which are clamped into the frames at the top of the ballasts:
The assembly is now "secure" and the jig can be opened to work on mid longitudinal girders:
The hull is almost finished. Now come the end bulkheads:
Some details are added externally, such as part of plating, pipes... etc.:
Now comes the painting. Most period pictures are B&W, making difficult to know the real colours. We planned a red lead or grey shades... until we discovered on the NARA colour slides collection a beautiful series of the assembly of USS Bergall (SS-320), a Balao class sub which showed... zinc chromate primer frames (Plane fans will be delighted). Of course, this may not have been the only/ standard colour, but this is a proof it has been used at last for some ships, and this will add a touch of live colour in our grey-blue-green diorama...
Original colour pictures may be found here:
http://www.historylink101.com/ww2_navy/ ... index.html
USS Bergall pictures are located between #15062 and 15157.
Now the paint is drying� more pictures tomorrow !
PS : in the meantime, Jean is working on another addition� but I can�t tell about : he could kill me. Just have stolen a picture :
(Reminds of Mars Attacks, hu ?)
Bruno
) which has never been done before... but this is a surprise, so we won't tell you more or post pics of this until the prototype is done. All I can tell now is I simply fell on the floor, speechless, when I received the film masters... 
