The late Combat Models made an assortment of very exotic 1/72 vacuformed submarine & aircraft kits. These submarine vacuformed kits came in a form of thin plastic styrene like sheets with the section halves of clear hulls formed and a plan sheet. The smooth hull sections have to be cut out from a styrene sheet and glued together. The hardest part is to keep the panels straight which tend during construction to warp out, and thus inner bulkheads and structures are a must the maintain the hulls integrity. The S class kit came with two towers, each in halves. One to make a late tower and the other an early pre WWII tower. The late tower was more workable and so I went with the late AA platform tower.
I followed the combat model plans and many overall different S boats for details. The hand full of boats that were refitted with the late tower the deck gun platform structure was widened funneling outward. This is not represented on the plan. The skeg ( the skinny upper blade like structure that attaches the stern upper deck to the rudder) is a common characteristic of early Holland S boats. However The skegs would rust out and favorably not be replaced by COs. This in turn would leave a tear drop shaped hull on the stern.. In lieu of the skeg , safety hatches were placed on the sterns, This policy may have also resulted from the near tragic loss of the S5 on August 20, 1920. Briefly , The S5 stern protruded 17 ft out of the water and the crew were rescued by a passing freighter by using the freighters machinist drill to cut a hole in the stern. The crew luckily escaped their stricken submarine. Some of the late S boats like the S43 had a skeg like rear deck structure but it was rounder and was not as long as the skeg to the rudder and some other variants differed again. The generic model I made from the Combat Model S class submarine kit has an early S body with a late war tower. Unknown to me if any skegged submarines made it to the late war ,1944 refits, odds are against it. The deck is made of basswood strips, the rounded long hull blisters (common with these old subs) I used a plastic strip that came scaled to the correct shape and size. The stern planes are all movable, the metal bow planes pivot & retract, all fittings were scratch, some resin, some brass. The torpedo doors shutters are in the open position, inside is the inner torpedo tube hatches & hinges made from brass. These kits come smooth so I added riveting to the frame areas. The completed S Boat in 1/72 sizes up to the ROG Type VII U-boat hull. The subs deck gun is the WWII US Submarine1/72 scale 4"/50 cal deck gun it is now a kit and is offered from http://ibs.eastcoastarmory.com . Combat Models creator & owner sadly passed away a few years ago, but the kits are still attainable from Rosemont Hobbies in PA, http://rosemonthobby.swiftsite.com/ .