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"D" submarines (D1) (8, 1909 - 1912)


Name No Yard No Builder Laid down Launched Comp Fate
D1 I71   Vickers, Barrow 5.1907 16.5.1908 9.1909 sunk as target 23.10.1918
D2 I72   Vickers, Barrow 7.1909 22.5.1910 3.1911 sunk 25.11.1914
D3 I73   Vickers, Barrow 3.1910 17.10.1910 8.1911 sunk 15.3.1918
D4 I74   Vickers, Barrow 2.1910 27.5.1911 11.1911 sold 12.1921
D5 I75   Vickers, Barrow 2.1910 28.8.1911 1.1912 sunk 3.11.1914
D6 I76   Vickers, Barrow 2.1910 23.10.1911 4.1912 sunk 26.6.1918
D7 I77   Chatham DYd 2.1910 14.1.1911 12.1911 sold 12.1921
D8 I78   Chatham DYd 2.1910 23.9.1911 3.1912 sold 12.1921

Technical data

Displacement standard, t 
Displacement normal, t

D1: 483 / 595

D2: 489 / 603

D3 - 8: 495 / 620

Length, m

D1: 49.7

D2: 49.4

D3 - 8: 50.2

Breadth, m

D1: 6.10

D2: 6.25

D3 - 8: 6.23

Draught, m

D1: 3.18

D2: 3.29

D3 - 8: 3.48

No of shafts



2 6-cyl Vickers diesels / 2 electric motors

Power, h. p.

1200 / 550

Max speed, kts

14 / 9

Fuel, t

diesel oil: 35

Endurance, nm(kts)2500(10) / 45(5)

3 - 450 TT (2 bow, 1 stern, 6)



Diving depth operational, m30

Project history

Approved 1906, and were the first British submarines with an overseas patrolling capability. Apart from the introduction of diesels most of the improvements stemmed from the big increase in displacement. More internal volume and a bigger crew lightened the work-load on a long patrol. The diesel engines also helped by eliminating the dangerous petrol vapour which had caused numerous explosions in the early boats. The adoption of saddle tanks increased internal space, while twin screws gave greater manoeuvrability. Earlier submarines had been fitted to receive radio messages but the 'D' class could transmit as well for the first time, an extendable mast being rigged by hand when needed. Although contemporary references suggest that the entire class were fitted with guns, and many with 2-12pdr, only D4 had one, on a platform which folded down into the casing. This arrangement was not a success, and later the gun was given a fixed position on deck. With their larger conning tower, and full-length casings the 'D' class marked a clean break with the tiny 'A's, 'B's and 'C's. D1 was authorised under 1906-07 Estimates, D2 under 1908-09 Estimates and remainder under 1909-10 Estimates.



Naval service

D2 was sunk by German patrol boats off the Ems estuary 25.11.1914. D3 was sunk in error by a French airship in the Channel 15.3.1918. D5 was mined 3.11.1914 in the North Sea. D6 was torpedoed 26.6.1918 by German submarine UB73 off Northern Ireland.