I.J.N. Submarines

O-1 (ex U-125)
O-2 (ex U-46)

by Yoya Kawamura (1739-LIFE-1991)


(continued from KTB #112)

After the end of WW I, the surviving German U-Boats were divided among the victorious powers. They were not to be commissioned in the respective navies, but were to be used for non-combat purposes, mainly research and development. Japan was allocated eight boats: U-125; U-43; U-55; UC-90; UC-99; UB-125 and UB-143. Of those, U-43 was scrapped in England. As for the rest, they were towed to Malta and from there, Japanese crew sailed them to Japan under their own power. They all arrived safely in Japan, and were given Japanese designations O-1 thru O-7.

O-1 (ex U-125)

Builder Blohm & Voss (Hamburg)
Displacement 1163/1468 tons
Length 82 meters (269 feet)
Beam 7.4 meters (24 feet 4 inches)
Draft 4.2 meters (13 feet 10 inches)
Machinery: twin-shaft MAN 4-stroke diesel and two SSW electric motors

Power

    (diesel) 2,400 hp
    (electric) 1,235 hp
Speed
    (diesel) 11.5 knots
    (electric) 8 knots
Fuel 220 tons
Radius
    (diesel) 11,470 miles @ 8 knots
    (electric) 35 miles @ 4.5 knots
Tubes
    (fwd) four tubes 50cm (19.7 inches)
    (aft) two mine tubes
    (carried 14 torpedoes - 42 mines)
Guns single 15cm (45 cal)
Depth of dive 82 meters (250 feet)
Crew 40

U-125 belonged to UE-III type; a large mine-laying submarine. It was fitted with a very modern mine-laying system; had a very large radius of operation with good seakeeping. I-21 Class mine-laying submarine IJN built later were almost an exact copy of U-125. O-1 was used in conjunction with the submarine-rescue vessel ASAHI as a dead weight to pull up a submarine in distress.

O-2 (ex U-46)

Builder Danzig
Displacement 725/940 tons
Length 65 meters (213 feet 3 inches)
Beam 6.2 meters (20 feet 4 inches)
Draft 3.7 meters (12 feet 3 inches)
Machinery: twin shaft MAN 6 cyl 4 stroke diesels, two SSW electric motors
Power

    (diesel) 2,400 bhp
    (electric) 1,200 hp
Speed
    (diesel) 15.2 knots
    (electric) 9.7 knots
Fuel 110 tons
Radius
    (diesel) 8,100 miles @ 8 knots
    (electric) 51 miles @ 5 knots
Tubes
    (fwd) two 50cm (19.7 inch)
    (aft) two same size)
    (carried 6 torpedoes)
Guns single 10.5cm (45 cal)
Depth of dive 53 meters (160 feet)
Crew 36

More History of the Japanese Submarine Navy

Back to KTB #114 Table of Contents
Back to KTB List of Issues
Back to MagWeb Master Magazine List
© Copyright 1999 by Harry Cooper, Sharkhunters International, Inc.
This article appears in MagWeb (Magazine Web) on the Internet World Wide Web. Other military history articles and gaming articles are available at http://www.magweb.com
Sharkhunters International, Inc., PO Box 1539, Hernando, FL 34442, ph: 352-637-2917, fax: 352-637-6289, www.sharkhunters.com