Type IA U-Boats

Dimensions: 72.4 metres x 6.2 metres x 4.3 metres (draught)

Displacement: 862-tons (983-tons dived)

Complement: 4 officers, 39 crew.

Rated Diving Depth: 330 feet.

Armament: 4 x 53.3cm (21?) torpedo tubes at bow below the designed waterline. 2 x 53.3cm (21?) torpedo tubes at stern below the designed waterline.
14 x torpedoes or 28 TMA (42 TMB) mines.
1 x 10.5cm SKC/36 deck cannon (150 rounds) on the forward deck.
1 x 2cm/30-37 AA cannon (2,000 rounds) on the conning tower.

Propulsion: 2 x MAN 8-cylinder, 4-stroke, M8 V 40/46 unsupercharged diesels, in compartment two.
2 x BBC GG UB 720/8 double electric motors, maximum 530 ehp, in compartment two.
2 x 62-cell AFA 36 MAK 740 batteries in battery boxes without rubber shock absorbers (9620 amp hours) below compartments three and five.

Speed: 18.6 knots surfaced/8.3 submerged.

Endurance: 8,100 miles (diesel electric surfaced) @ 10 knots.
7,900 miles (surfaced, cruising) @ 10 knots.
136 miles (submerged) @ 2 knots.
78 miles (submerged) @ 4 knots.

The Type IA was not a successful submarine for the Kriegsmarine. Based heavily on the Gür, designed for the Turkish navy by a German construction team, they were created as a awy of providing the new German submarine construction with a heavy ocean-going type of U-boat.

The first completed Type IA, U25, was launched by AG Weser (Bremen) on 14 February 1936, the second, U26, following one month later. Heavily armed they were unfortunately found to have unsatisfactory seakeeping qualities: unstable both above and below the surface, slow to dive and difficult to manoeuvre underwater. They were also found to be extremely unreliable mechanically, several wartime patrols cancelled due to myriad small defects. The boats were so troublesome that Dönitz wrote in his War Diary on 20 December 1939:

"U25, the boat, that has only managed a short patrol since the war's beginning and spent the rest of its time in the shipyard, must again break off its trip and return to the yard."

By the end of August 1940 they had both been sunk while in service with the 2nd U-Flotilla.