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FIGHTING SHIPS OF THE WORLD
UNITED KINGDOM
SUBMARINES
"improved H" submarines (H21) (23(9), 1918 - 1920)


Photo



H27 1919

Ships


Name No Yard No Builder Laid down Launched Comp Fate
H21     Vickers, Barrow 3.1917 20.10.1917 1.1918 sold 7.1926
H22     Vickers, Barrow 3.1917 14.11.1917 11.1918 sold 2.1929
H23     Vickers, Barrow 3.1917 29.1.1918 4.1918 sold 5.1934
H24     Vickers, Barrow 3.1917 14.11.1917 5.1918 sold 5.1934
H25     Vickers, Barrow 3.1917 27.4.1918 7.1918 sold 2.1929
H26     Vickers, Barrow 3.1917 15.11.1917 3.1918 sold 4.1928
H27     Vickers, Barrow 3.1917 25.9.1918 1.1919 sold 8.1935
H28 28H, N28   Vickers, Barrow 3.1917 12.3.1918 6.1918 sold 9.1944
H29     Vickers, Barrow 3.1917 8.6.1918 9.1918 foundered in dock 9.8.1926
H30     Vickers, Barrow 3.1917 9.5.1918 10.1918 sold 8.1935
H31 31H, N31   Vickers, Barrow 4.1917 16.11.1918 2.1919 sunk 24.12.1941
H32 32H, N32   Vickers, Barrow 4.1917 19.11.1918 5.1919 sold 10.1944
H33 33H, N33   Cammell Laird, Birkenhead 11.1917 24.8.1918 5.1919 BU 10.1944
H34 34H, N34   Cammell Laird, Birkenhead 11.1917 5.11.1918 9.1919 BU 7.1945
H35     Cammell Laird, Birkenhead 1917 --- --- cancelled 10.1917
H36     Cammell Laird, Birkenhead 1917 --- --- cancelled 10.1917
H37     Cammell Laird, Birkenhead 1917 --- --- cancelled 10.1917
H38     Cammell Laird, Birkenhead 1917 --- --- cancelled 10.1917
H39     Cammell Laird, Birkenhead 1917 --- --- cancelled 10.1917
H40     Armstrong, Elswick 1917 --- --- cancelled 10.1917
H41     Armstrong, Elswick 1917 26.7.1918 --- cancelled 1918
H42     Armstrong, Elswick 10/1917 21.10.1918 5/1919 collision 23.3.1922
H43 43H, N43   Armstrong, Elswick 10.1917 3.2.1919 11.1919 BU 11.1944
H44 44H, N44   Armstrong, Elswick 10.1917 17.2.1919 3/1920 BU 2.1945
H45     Armstrong, Elswick 1917 --- --- cancelled 10.1917
H46     Armstrong, Elswick 1917 --- --- cancelled 10.1917
H47     Beardmore, Dalmuir 11.1917 19.11.1918 2.1919 collision 9.7.1929
H48     Beardmore, Dalmuir 11/1917 31.3.1919 6/1919 sold 8.1935
H49 49H, N49   Beardmore, Dalmuir 7.1917 15.7.1919 9.1919 sunk 27.10.1940
H50 50H, N50   Beardmore, Dalmuir 1.1918 25.10.1919 2.1920 BU 7.1945
H51     Pembroke DYd 10/1917 15.11.1918 9/1919 sold 6.1924
H52     Pembroke DYd 1.1918 31.3.1919 12/1919 sold 11.1927


Technical data


Displacement standard, t 
Displacement normal, t

423 / 510

Length, m

52.4

Breadth, m

4.80

Draught, m

4.03

No of shafts

2

Machinery

2 NLSE diesels / 2 electric motors

Power, h. p.

480 / 620

Max speed, kts

11.5 / 10.5

Fuel, t

diesel oil 16

Endurance, nm(kts)

2975(7.5) / 130(2)

Armament

4 - 533 TT (bow, 6 - 8)

Complement

22

Diving depth operational, m30


Standard scale images


<i>H28</i> 1939
H28 1939


Graphics


<i>H27</i> 1919
H27 1919


Project history

In January 1917 an order was placed with Vickers for 12 boats similar to the 'H' class but with 533mm TT. Engines, main motors and major fittings were obtained from the United States. In June 1917 a second batch was ordered, 6 from Cammell Laird, 8 from Armstrong Whitworth, 4 from Beardmore, 2 from Pembroke DYd and 2 from Devonport DYd, using engines and motors made in England to US designs, but otherwise identical to those in H1-20 and H11-32. The order was cut back when it was decided in October 1917 to build 12 'R' class (using many of the H21 class components). Another was cancelled shortly after the Armistice, so only 22 out of 34 were completed. The main differences between these and the earlier 'H' class resulted from fitting 533mm TT; the hull was 6.4m longer but the diameter of the pressure hull was the same. Displacement went up by 16%. Despite their small reserve of surface stability, inherent in a single-hulled design, they were most successful and some survived to serve in the Second World War, although nominally restricted to training duties.

Modernizations

1922 - late 1920s, some survived: + type 113 sonar

1942- 1944, survived: + type 286W or type 291W radar

Naval service

Н49 was sunk 18.10.1940 by German trawlers UJ116 and UJ118 off Dutch coast. Н31 was lost for the unknown reason in Bay of Biscay 24.12.1941. H29 foundered 9.8.1926 in dock at Devonport, raised and sold in October 1927. H42 collided with destroyer Versatile 23.3.1922 off Gibraltar and sunk. H47 collided with L12 and sunk 9.7.1929.