The SBoot 37mm Flak Cannon
(for the German S-100 Class Schnellboot)
There were are a number of weapons aboard the S100 boats, of which the largest gun was the 37mm Flak Cannon, (anything above 20mm is a cannon), and later in the war many were replaced by 40mm Bofors cannons. I have given dimensions below for the 1/20th scale.
This is a drawing of the barrel only, there were a number of mounts used for these cannons but for the S-100 we are only interested in the "wet mount" or the M42 mount.
Historical Photo
The 3.7cm Flak M42 was apparently manufactured by Rheinmetal-Borsig and was essentially an improved version of the older Kriegsmarine 3.7 cm cannon and had a much higher rate of fire. It was recoil operated, air cooled and used five-round ammunition clips. These guns were fitted with forward armoured shields to protect the gunners.
The design of this gun was based on ease of manufacturing, it was constructed of a monobloc barrel connected to the breech ring by a bayonet joint to allow easy replacement, it used a vertical sliding breech block, a hydraulic brake and a spring recuperator.
This was the marine version of the 3.7cm Flak 36/37 and used by the Kriegsmarine on surface ships and U-boats. The 3.7cm Flak used several types of mounts and entered service around autumn 1943, it was manned by a 3-man crew, with a fourth crew member operating as the clip loader.