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Modeling the UB I Type Coastal U-boat

by Tom Koehl with minor edits from Tony Lovell

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My interest in the UB I class submarine goes back some forty years to 1959, when the Saturday Evening Post serialized a novel by Jack Finney, “The U-19’s Last Kill” (six parts, Aug 22 through Sept 26), the story of six ex-submariners who raise and restore a WWI U-boat to a minimal operating condition and proceed to rob the Queen Mary on the high seas. Jack Finney’s description of the boat, the restoration efforts and the voyage captured my imagination then, just as it does today. It’s a story of big boys playing with the ultimate toy! The book, published as Assault On A Queen, was later made into a forgettable movie, with Frank Sinatra in the protagonist role and the boat updated to a Hollywood facsimile of a WWII type VII, much to my disappointment.

The UB I class of Unterseeboot has been largely relegated to the background by chroniclers of the naval action of World War I. Perhaps because they lacked the impressive size and tonnage scores of their larger relations, but just as probably because they were comparatively few in number and operated in the more restricted waters of the Black Sea, Aegean, Adriatic and North Seas. Recent publications have brought out some of the quantitative data relative to their operations, but is is the more obscure narratives, a few of which have recently been reprinted, that really tell the story of the diminutive UB I boats and their minelaying derivative, the UC I class.

To quote Eberhard Rössler, one of the leading authorities on U-boat development, “The period preceding 1918, with few exceptions, was devoid of essential U-boat documentation. And the paucity of material from the Technical Office of the U-boat Inspectorate is the harder to bear in the light of the fact that those involved in the U-boat development of that era are no longer alive. Apart from the three famous publications dating back to 1919/20 and 1922 from Dr. Techel, Dr. Werner and Schurer on particular aspects of German submarine construction and the comprehensive work in tabular form of Erich Groner on German warships, very little additional information on German U-boat development has come from the archives.”

While researching a naval project at the Library of Congress in 1988, I stumbled upon the two illustrated articles in the German periodical Schiffbau, by Drs. Werner and Schurer, which described the development of the coastal UB boats and their minelaying cousins, the UC boats. Seeing the UB I was like a flashback and I photocopied as much as I could, but someone had preceded me and razored out several of the key pages from the text. I found two other important texts as well: Dr. Hans Techel’s early technical volume on U-boat development, and a difinitive two-volume work on submarines of the Imperial Austro-Hungarian Navy. Since the Library of Congress is not a lending library, I cross-referenced the inter-library exchange network and found the texts at several university libraries, whereupon I promptly requested loan copies for further study.

Building the UB I Type Submarine Model

Preparing the Plans

I compiled a significant collection of texts pertaining to German U-boats, most in English, but several in the original German, published between 1919 and the present. Sadly, much of the archival source material pertaining to WWI boats perished during the strategic bombing campaign of WWII, but materials which had been published in the international press survived in other countries. The UB I plans available consist of inboard profiles and hull sections of the AG Weser boats, although Techel’s book has a simplified illustration of the early Germaniawerft design. At first I believed it to be a rough sketch, but after careful examination of the available photographs, particularly those of the boats in the Austro-Hungarian Navy, it became readily apparent that there were actually two versions of the boats: the Germaniawerft, with more angular casing lines, pointed stern, large elliptical limber holes, and a higher conning tower; and the AG Weser design, with a curved after deck casing, smaller limber holes, drooped stern, and a lower-profile conning tower. The variations seem to derive from three factors: the designs were probably prepared independently by each yard in conformance with strict performance and equipment specs, but not in detail as to externals; the AG Weser design, under construction at a later stage of the evolutionary process, may represent refinements to correct deficiencies uncovered during the first months of service life for the Germaniawerft boats; and lastly, each yard may have made changes which reflected their experience, tooling and manufacturing processes.

With a background in naval intelligence and photo interpretation, I began to study the photos in detail, deciding to build a Germaniawerft boat as I regarded it as a pure, unrefined example of early sub design and the functional simplicity and efficiency of the mechanical systems fascinated me. Using Dr. Techel’s accurate sketch as a springboard, I began to compare the photos, sketching the visible components, searching for shadowy details and looking at the sub as a collection of purely functional systems. For dimensioning and making proportional sketches there were plenty of sailors pictured on the decks, and by scaling from the human figure and the existing inboard profile plans I was able to gradually develop an accurate set of drawings. I prepared an exterior profile, deck plan, and hull sections from which I could begin building, and as I built each section I compared it to the available photos for proper proportions. The model took approximately 300 hours, spanning a five month period in the Fall of 1990. I completed it just before being recalled to active duty for Desert Storm.

Construction Materials

I build my models in sheet styrene plastic, buying large 40x70 inch sheets in .010, .020, .040, and .060 from Cadillac Plastic, a national wholesale supplier. For cement I use carbo-trichlor (Parks #2915), available from most hardware stores in 32 oz. cans. I decant it into a smaller 6 oz. dispenser for use and apply it with a fine sable brush. I’m still using the brush I started with over ten years ago, and when the styrene parts are properly shaped and mated, I’ve yet to have a seam separate. The plastic is literally welded together. It is easy to laminate to build large blocks for shaping with a Dremel sanding drum, it will take a curve, can be vacuum formed, sands to a perfectly smooth finish, and can be textured and painted to represent virtually any material. The only drawback is that styrene reacts to lacquer paints, and I always test paints on a scrap before committing it to the model!

Building the Conning Tower

I began the model as I do with all submarines - I built the conning tower first. It constitutes a small model in itself, allows me to warm up to the project, and looking at it gives me motivation I need when I get frustrated with the hull! My technique is hardly new, using .040 and .020 styrene for the formers and skin, respectively. For the UB I, however, because of the delicate triple vent holes in the top of the tower and the steps on the port side aft, I cut away the thicker .020 skin in this area and wrapped a very thin predrilled .010 skin over the entire tower. The periscope is telescoped brass tubing, as are the wireless telegraph antenna supports. The cutaway on each side which exposes part of the inner pressure vessel was sanded out from fore to aft with a dowel wrapped with sandpaper, a properly curved .020 skin was fitted, and when firmly cemented in place it was given its final trimming. The small portion of the tower pressure vessel was shaped from two separate piece of styrene, one from .040 to give the proper curvature front to rear, and an outer skin of .020 trimmed to fit into the cutout. The deadlight rims were added, and the completed pieces were cemented into place in the cutaway. The top hatch is built up from styrene disks of different diameters, with a domed top cut from a Leggs panty-hose egg (white, not the chromed ones which seem to be too brittle) and small hinges added from sheet styrene scraps. The hatch wheel is an O-Gauge boxcar brake wheel.

The fairings at the rear of the tower (which support the wider navigation deck) were built up from styrene scraps, cemented to the underside of the deck and shaped prior to cementing the upper deck onto the tower. The navigation light housings were laminated from styrene sheet with a cutout at the forward end to take the light lenses. The faceted lenses are stock ship model supplies, as are the cleats on the side of the tower to which the antenna lines are secured. The hatches for access to fuel valves, pressure lines, and deck equipment are sheet stock with hinges of styrene “boards” and rods (Evergreen Plastic). The compass stand, helm, and telescoping antenna trunk on the starboard side are built up from styrene scraps and rods. The whistle on the forepeak of the tower is shaped from a small brass tube and the air pressure lines and side rails are brass wire. I have yet to make the safety rails for the top of the tower, as I’m debating whether to solder them up from brass rod or to have them photo-etched.

Building the Pressure Hull

To begin the pressure hull I started with a center section of 3.75 inch diameter ABS plastic tube. The thick wall of this tubing makes a good anchor for the mounting fixtures and a stable, rugged basis for building the bow and stern conical sections. I wrapped the tube with a skin of .040 styrene after heating it in a warm oven for about 20 minutes. It doesn’t make the skin maliable so much as it allows it to take and hold a curve without having to resort to straps, clamps, etc. When cementing it on, ABS compatible cement must be used (Plastruct is a good example), and since it takes longer to set, I used large hose clamps to hold the styrene in place. Once set, the skin was trimmed at each end flush with the tube. I marked the centerline of the hull, and then cut sheet profiles of the bow and stern portions from .040 to which I added hull half-sections at critical points to define the conical sections. The bow cap and stern cone were built up separately: the stern cone from many laminations of .040 styrene, and shaped with the Dremel to match the outer dimensions of the hull, and the bow cap framed and skinned like the conning tower. More will be said about this later.

The stern and bow sections were wrapped with two layers of .020 styrene, reinforced on the inner surfaces with strips of scrap to stiffen the shell. To the rear bulkhead of the front section and the front bulkhead of the rear section I cemented a 1/2” thick styrene disk turned to match the inner diameter of the center section’s ABS tube. Because the model is three feet long it was more practical
to do most of the finish work on the bow and stern sections individually before attaching them to the center section, just as the real boats were transported in three main sections to their operating bases.

The bow cap is complicated by the exposed torpedo tube channels, but it is built up similar to the conning tower. A center longitudinal profile was cut in .040 styrene, and transverse half-frames were attached at 1/2” intervals. The cap was skinned with an upper deck piece, port and starboard upper plates, and a set of lower skin plates cut away for the torpedo tube channels. The channels were skinned first, conforming to the cutouts in the transverse frames, then the outer skin plates were attached and carefully cut away to the edges of the channels. I should note here that I mix a styrene putty by dissolving styrene scraps in a baby-food jar of carbo-trichlor until it is the consistency of jam. It can be brushed on or applied with a small spatula or scrap of styrene. It dries quickly but needs curing time, so it is best to apply it sparingly to structures and set aside for several days to cure.

The stern cone is built up from many laminations of .040 styrene, cemented into place and then trimmed and shaped to match the contours of the hull. The next step is to attach the bow and stern sections to the center to complete the hull, fitting the plugs into the center tube and aligning the centerline markings. The upper deck casing is built up over frames just as in the real boats, using .040 frames and .020 skin. The two side skins were rough-cut overly long and cemented together at the very ends so that the two could be final shaped and drilled for the limber holes simultaneously. The large elliptical limber holes were drawn onto the plastic using a master template aligned to the bottom edge of the plating. Starter holes were drilled and then the openings were individually shaped with needle files until uniform and smooth.

Once the side plating is cemented to the frames, the deck plating is traced out onto .020 sheet and cut out slightly oversize. The deck hatches were cut out, small edge flanges cemented to the underside of the openings fore and aft, and then the deck was cemented to the upper casing. A sanding block was used to properly dress the top edges of the casing. The hatches are built up from .020 sheets edged with thin .010 reinforcing strips, the latch openings are cut out, then once the hatches are cemented into the openings, the hinges are attached just like the conning tower side hatches.

The large keel is built up like the deck casing, but with laminated blocks at each end to blend it into the hull. The cut outs are water inlets for the ballast tanks and as with the deck casing sides, the port and starboard side pieces were cut at the same time. The curved bow reinforcements are merely pieces of .020 sheet, as are the longitudinal reinforcing plates just below the bottom edge of the deck casing. A thin lip of strip styrene was added to the bottom edge.

The bow net cutter was built up from styrene strips, the fixed bow planes were shaped from .020 sheet with .020 attachment plates cut out to fit around the fins, and the rudder and stern planes are doubled .040 sheets shaped to give a more streamlined cross section. The propeller is a plastic one that has been cut down to size and shaped to resemble the ones in the photos, however a brass prop would be a more pleasing addition. The brass pulley blocks for the wireless antenna and the mooring chocks are the only other stock fittings used.


I air-brushed my model in a paint scheme which appears on UB8 in the Adriatic: red anti-fouling bottom, medium gray sides, black decks and light gray conning tower. The boats appear to have been overall medium gray when delivered, but dazzle-painted boats were common in the Flanders Flotilla, and several AG Weser boats show this. UB1, after it was ceded to the Austro-Hungarian Navy as U-10, was fitted with a sheet metal conning tower spray shield, which actually gave it more of the appearance of a larger boat. After relegated to training duties it was painted with a dark blue hull and deck with a light gray conning tower to better blend into the bright blue coastal waters of the Adriatic.

I mounted my model to an oak base with beech keel blocks and used two self tapping screws through the keel into the thick center section tube. With a bit of epoxy for good measure, and the keel blocks bedded in a sand and shell mixture (white-glued into place, like model railroad ballast) th emodel was done. The officer in turtleneck and sea boots was added as an afterthought to give a sense of size to the diminutive submarine!


  1. Aichelburg, (Unk) Die Unterseeboote Osterreich-Ungarns. Akademische Druck-u., Graz, 1981.
  2. Bennett, Geoffrey. Naval Battles of the First World War. Charles Scribner’s Sons, New York, 1968.
  3. Gray, Edwyn A. The Killing Time. Charles Scribner’s Sons, New York, 1972.
  4. Preston, Antony. U-Boats. Bison Books, London, 1978.
  5. Rossler, Eberhard. The U-Boat. Translated by Harold Erenburg. Naval Institute Press, Annapolis, 1981.
  6. Schurer, Friedrich. Deutsche Unterseeboote fur Kustengewasser. Schiffbau, 18/1919.
  7. Techel, Hans. Der Bau von Unterseebooten auf der Germaniawerft. Verein Deutscher Ingenieure, Berlin, 1922.
  8. Weir, Gary E. Building the Kaiser’s Navy. Naval Institute Press, Annapolis, 1992.
  9. Werner, Franz. Deutsche Unterseeminenleger fur Kustengewasser. Schiffbau, 1/1919.