R/C'ing the Revell 1/72 GATO Class Static Submarine Kit, Part-9

A Report to the Cabal:

At the Subcommittee site I found an excellent drawing prepared by Scott Trosper. Scott adapted what appears to be a version of the Docking Plan (GATO class, I hope?) to the specifics of the 1/72 Revell GATO kit. He indicates on his drawing two vital and easy to identify transverse datum lines unique to the kit: the forward and after radial breaks between main hull and the bow and the stern of the kit. Scott's drawing is vital if you are to faithfully (best generally available source to date) represent the many main ballast and fuel ballast tank flood and drain openings as well as auxiliary sea chest openings on the bottom of the boat. And he's made it an easy matter to scale the drawing up to the size of your model -- clearly marked one-inch conversion scales litter the face of his drawing. Or, you can do what I did and determine the ratio of the models and the drawings datum lines. Estabilishing that ratio permits you to convert your drawing measurements to those of the models employing either math or proportional dividers (the simplest of analog computers).

I suggest you follow the SC board thread that deals with Scott's work. You'll find it here: http://www.subcommittee.com/SubComm/member_homepages_search.cfm? MemberID=154

Study that discussion and you'll find that Scott was assisted by Crazy Ivan in this adaptation of government drawings to a document that is Revell GATO specific. I made extensive use of this plan as I established on the model the location, size and shape of the many holes that penetrate the bottom of this submarine kit. Good work, Scott.

And, by the way, there are variations as to the placement of the bottom penetrations between GATO/BALAO and TENCH class boats. May I suggest that Scott's drawing, my document of choice on this particular build, be regarded as an interim or generic representation of the bottom holes in the hull, not the final, definitive answer for all boats of the three classes. TENCH class boats, for example, had a much different flood/drain hole arrangement than what is presented in Scott's drawing, so you TENCH conversion candidates, take note! Also, post war conversions of GATO and TENCH boats that underwent GUPPY upgrades: some of them saw the deletion of some ballast tanks, those spaces converted into storage areas or other service.

See ... the Internet is useful every once in a great while.

Ellie read my last Report (someone out there ratted me out!) and was not amused ... said I had to play nice for at least the next five installments.

Man ...!

Before I could launch into marking off location and punching holes to represent the main ballast tank and fuel ballast tank flood/drain holes I had to finish the job of re-contouring of the hull bottom with screed-blade applied Evercoat Metal Glaze filler to get rid of that concave warp encountered earlier, followed by the installation of brass keel rub plates.

The slightly raised keel rub plate on the bottom of the hull extends from the bow to the stern. Here I'm building up masking tape dams left and right of the stern rub plate, which has to be built up slightly with filler to match the increased height caused by the re-contouring of the models bottom hull, work done to correct the concave warp. Multiple layers of masking tape were laid down till the edge of the tape damn stood almost a sixteenth inch tall. That done I was ready to apply catalyzed filler within the tape dam.

Filler is applied within the masking tape dam and leveled off with the putty knife. Do it right here and you will hardly have any touchup work to do later with sanding block and file. It took about three applications to get the filler to the height of the tape dam edges.

The masking tape dam pulled away and the top (bottom) of the Evercoat Metal Glaze stern keel rub plate given a few licks with a sanding block and I'm ready to dress the sides of the rube plate. Similar work had to be done at the bow, to match the brass keel rub plate to the plastic one molded within the bow piece.

Very carefully, with a flat file edge, I smoothed the sides of the stern keel rub plate.

A screeding blade was cut and sanded to capture the mean curvature of the hull at the bottom. A notch in the blade engages the outboard edge of the keel rub plate. The screed is pulled along after brushing down some filler, the blade working to force the filler to adapt the correct hull contour. As long as I hold the notch of the screed blade tight into the edge of the keel rub plate, keep the blade perpendicular to the keel, and keep the blade pushed into the hull as I pull it along, I get a nice, smooth, even layout of the filler.

This screed blade is cut from a commercial auto-body filler application tool, sometimes called a 'card.' Its flexible plastic yields slightly when pressed into the work, letting you change the blade geometry as you drag it along. Also, the plastic of these tools will not adhere to the filler. So, if you forget to wipe it clean after use you can later chip the hardened filler off it without too much difficulty.

As to the shape of the three styles of flood/drain holes, I settled on fifty-degree ellipsoids which were traced off a standard drafting stencil onto a piece of brass sheet, and holes drilled and shaped to outline The brass piece with holes would become my scribing stencil, used to mark off the hull with deeply engraved lines within which I would drill, grind and file out the holes needed.

Later I'll produce a cast resin stencil to accompany the WTC-2.5/GATO units I sell. That and other items will constitute the 'GATO Enhancement package.' I'm still looking for exacting documentation as to hole shape, type, as well as other items that need to be engraved on the Revell 1/72 GATO kit hull.

By using the easily identifiable radial bands on the model (the bow and stern section seam lines) and Scott's drawing, I was able to quickly identify the location and approximate size of the flood/drain holes on the hull. Some of the preliminary work, using Scott's drawing, pictured above.

So, it's an easy matter for you, the lazy unaccomplished kit-assembler, to print out a copy of Scott's drawing; work out the enlargement factor between drawing and model; use that number (or, as I have, a pair of proportional dividers, which is produces a mechanical analog to the selected ratio) to convert drawing measurements; and to loft that dimension to the model.

To determine the enlargement factor you simply measure the distance, in inches, between the two perpendicular lines (indicated on the Scott Trosper drawing as, "stern/bow separation of 1/72 revell gato model") on the plan, and divid that into the distance measured between these points on the model kit. I got 9.125" off the plan and 35.25" off the model, which produces a conversion number of 3.863. From that point on all you have to do is multiply a dimension off the plan by 3.863 and you have it scaled up to fit the kit.

Of course, the size of your printed drawing is likely to be different, so work up your specific ratio between plan and model kit -- the ratio and conversion number I came up with is likely unique owing to computer and printer software and file size.

I experience no problem at all grinding through both the Evercoat filler and the kits styrene plastic underneath, no chipping issues at all. I suspect that there are both cohesive and adhesive mechanisms of bond at work with the polyester based filler on the polystyrene substrate of the kit. Bondo, Evercoat and other polyester based fillers are excellent re-contouring and seam filling mediums for this type plastic kit -- just insure that you have a well scratched surface before applying these catalyzed fillers to the work.

Here are some of the tools used to punch the holes. From left to right: The scribing stencil, this is used to guide the scribing tool (a modified rattail file) as I engrave the appropriate penetration outline onto the hulls filler and styrene substrate -- I've made the openings in the stencil the appropriate distance from two edges, this way I can push the stencils edge against the edge of the brass keel rub plate, using the keel as a datum line; next is a special sanding tool, a wood dowle cut to an oval section and wrapped with sandpaper -- I use it to dress the shape of the big ballast tank flood/ drain holes; the scribing tool; a 3/16" diameter round file used for final shaping; a bastard rattail file used for initial shaping; a bigger bastard round file; and an 1/8" straight burr bit in a Moto-Tool used for the initial opening up of each hole.

Here's the process: First you scribe in a deep engraved outline of the hole onto the bottom of the hull, using the stencil and scribe, the stencil positioned transversely in relation to the keel rub plate and longitudinally by pencil marks who's position was lofted off the Scott Trosper drawing. The initial hole is punched out with the Moto-Tool burr, working from center to nearly to the engraved line. The hole is finished up using first the bastard, then the second, and single cut round files, in the case of the big ovals I dress out the hole with the special sanding block. The work goes very quickly.

I made a special oval shaped sanding 'block' by shaping a length of 3/4" wooden dowle down on the sanding belt till it was a very sloppy fit in the big main ballast tank flood/drain holes. Wrapped with #240 sandpaper, which was glued in place with CA, this tool was used to refine the final shape of the big holes in the hull.

I fully realize that the shape of the holes I'm punching into the bottom of this 1/72 Revel GATO kit are not the final answer, and that more authoritative drawings will likely surface, necessitating my creation of new stencils and tools later, but that's fine with me: I had to get holes into this thing fast so I could press on with other jobs. I take solace in the fact that if I don't have the hole shape and positions exactly right, I have them damn close.