Germany (1935), 50 Submarines Types IIa, IIb, IIc, IId
In 1930, the false Dutch company NV Ingenieurskantoor voor Scheepsbouw den Haag (set up in the Netherlands to develop submarines for Germany after WW1) set out to design a new class of submarine as a means of coastal patrol and defense. This submarine was bought by the Finnish government and was called the CV-707 Vesikko
. This became the basis for the development of a new class of submarine for the German Kriegsmarine.
Finnish Vesikko, CV-707 prototype submarine in service and camouflage livery during the war.
In 1933, NV Ingenieurskantoor voor Scheepsbouw den Haag designed a new and improved CV-707 that would be built for the German navy at the Kiel shipyard. This class became the Type IIA, with the U-1 being the first built. It's primary roles were training of new crews and coastal defense.
The Type IIA had a length of 134 feet, a beam of 13 feet, and a draft of 12 feet, meaning that the sub was small and could only operate in coastal waters. A conning tower was located in the center of the boat and housed the periscopes that the sub would use to see while underwater. A single anti-aircraft gun may be mounted here.
Displacement for the Type IIA was 250 tons surfaced and 298 tons submerged. A test depth of 150 meters could safely be reached, although captains of submarines would regularly take their subs deeper than the test depth. With a crew of up to 25 men, the Type II was cramped and uncomfortable, although proportionate as other submarines such as the American Gato Class were 3 times the size and had 3 times the crew.
Cutaway plans of the U Boat type II
Armament of most Type II submarines was 3 533mm torpedo tubes, all forward facing, with 5 torpedoes carried in total. In addition, 1-2 20mm anti-aircraft cannons were carried. No deck gun or heavy anti-aircraft was carried.
In addition to the underwater and surface weapons, small arms such as MP-40 submachine guns and P-38 handguns were carried for self-defense and boarding.
Interestingly, all German submarine crews were also trained in land combat, so it can be assumed that the crews were at least somewhat skilled with their small arms.
German submarines, while having diesel and electric engines, were not true diesel-electrics. They used their louder diesel engines on the surface and their electric engines underwater.
Powering the Type II were 2 diesel engines and 2 electric motors allowing for up to 13 knots surfaced and 7 knots submerged.
Type IIA subs could travel 1,600 nmi at 8 knots while surfaced and 35 nmi at 4 knots while submerged.
Type IID subs could travel 5,650 nmi at 8 knots while surfaced and 56 nmi at 4 knots while submerged.
The first Type II submarines were completed in 1934, although most of the world did not know of their existence until 1935, when Germany and Great Britain signed a treaty allowing Germany to match England's submarine fleet.
Type II submarines would be used in the beginning years of the war as a training and coastal patrol boat until a shortage of U-Boats in 1942 and 1943 would see them supplementing the larger Type VII class in anti-ship roles. In total, there were at least 4 combat flotillas that operated the Type II. These included the 1st, 3rd, 5th, and 30th Flotillas. Most of these operated out of Kiel, with one notable exception.
Starting in 1942 with the formation of the 30th U-Boat Flotilla, Type IIBs would be used in the Black Sea, attacking Russian shipping and reinforcements making their way to the front line. The Flotilla was disbanded in 1944 after the destruction of all remaining U-Boats.
At the start of hostilities with France and England, the Type II was more used for coastal patrol and training, but as the war dragged on, it saw more combat in the English Channel. Eventually, the Type II was to be replaced by the Type XXIII "Elektroboot", although the Type II was never fully replaced in the Kriegsmarine.
U-37 entering Wilhelmshaven after a mission
U-Boat Type IIa waterline profile (1/400)
U-Boat Type IIc full profile for comparison
U1 in service with the Kriegsmarine before the war
U9, of the following IIb class.
The Vesikko preserved at Susisaari island in Suomenlinna near Helsinki as of today. It has been restored and opened as a museum in 1973