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"B" submarines (B1) (11, 1904 - 1906)


B2 1900s


Name No Yard No Builder Laid down Launched Comp Fate
B1 I21   Vickers, Barrow 1903 25.10.1904 4.1904 sold 8.1921
B2     Vickers, Barrow 1904 30.10.1905 12.1905 collision 4.10.1912
B3 I23   Vickers, Barrow 1904 31.10.1905 1.1906 sold 12.1919
B4 I24   Vickers, Barrow 1904 14.11.1905 1.1906 sold 4.1919
B5 I25   Vickers, Barrow 1904 14.11.1905 2.1906 sold 8.1921
B6, 8.1917- S6 I26   Vickers, Barrow 1904 30.11.1905 3.1906 patrol boat 8.1917, sold 1919
B7, 8.1917- S7 I27   Vickers, Barrow 1904 30.11.1905 3.1906 patrol boat 8.1917, sold 1919
B8, 8.1917- S8 I28   Vickers, Barrow 1905 23.1.1906 4.1906 patrol boat 8.1917, sold 1919
B9, 8.1917- S9 I29   Vickers, Barrow 1905 24.1.1906 4.1906 patrol boat 8.1917, sold 1919
B10 I20   Vickers, Barrow 1905 23.3.1906 5.1906 sunk 9.8.1916
B11, 8.1917- S11 I00   Vickers, Barrow 1905 21.2.1906 7.1906 patrol boat 8.1917, sold 1919

Technical data

Displacement standard, t 
Displacement normal, t

287 / 316

Length, m


Breadth, m


Draught, m


No of shafts



1 Vickers petrol engine / 1 electric motor

Power, h. p.

600 / 290

Max speed, kts

12 / 6

Fuel, t

petrol 16

Endurance, nm(kts)1000(8.7) /

2 - 450 TT (bow, 4)



Diving depth operational, m30


<i>B2</i> 1900s
B2 1900s

Project history

The successors to the 'A' class were very similar, the main improvements being the provision of a more substantial deck casing to improve surface performance and a bigger reserve of buoyancy. They were also fitted with a pair of hydroplanes at the forward end of the conning tower to improve underwater handling. This innovation was not repeated in subsequent classes, but 50 years later it was reintroduced in US nuclear submarines for the same reason.


1917, S6-9, 11: were converted to surface patrols, electric motors were removed; + 1 x 1 - 76 12pdr 12cwt QF Mk.I/II

Naval service

The six boats went to the Mediterranean were not employed after the autumn of 1915 for lack of spares, and in order to make better use of them the Admiralty arranged with the Italian Navy to rebuild them as surface patrol boats at Venice in 1917. This involved removing the electric motors and batteries and building up the bow casing to form a forecastle. A small wheelhouse was provided, and 2 platform for a 12pdr gun. No note survives about their torpedo armament but presumably the tubes were not used. As S6-11 these patrol craft were employed in the Adriatic, and the survivors were sold at Malta in 1919.     B2 was sunk in collision with SS Amerika in the Dover Strait 4.10.1912. B10 was sunk in Venice DYd while undergoing conversion to surface patrol boat 9.10.1916, by Austrian bombing attack. B11 was sent to the Mediterranean late in 1914, and on 1 December negotiated Turkish minefields and nets to sink the coast defence ship Messudieh.