H21 1918
H28 1939
| Name | No | Builder | Laid down | Launched | Comp | Fate |
| H21 | Vickers, Barrow | 3/1917 | 20/10/1917 | 1/1918 | BU 7/1926 | |
| H22 | Vickers, Barrow | 3/1917 | 14/11/1917 | 11/1918 | BU 2/1929 | |
| H23 | Vickers, Barrow | 3/1917 | 29/1/1918 | 4/1918 | BU 5/1934 | |
| H24 | Vickers, Barrow | 3/1917 | 14/11/1917 | 5/1918 | BU 5/1934 | |
| H25 | Vickers, Barrow | 3/1917 | 27/4/1918 | 7/1918 | BU 2/1929 | |
| H26 | Vickers, Barrow | 3/1917 | 15/11/1917 | 3/1918 | BU 4/1928 | |
| H27 | Vickers, Barrow | 3/1917 | 25/9/1918 | 1/1919 | BU 8/1935 | |
| H28 | 28H - N28 | Vickers, Barrow | 3/1917 | 12/3/1918 | 6/1918 | BU 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 | BU 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 | BU 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 23/2/1922 | |
| 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 | BU 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 | BU 6/1924 | |
| H52 | Pembroke DYd | 1/1918 | 31/3/1919 | 12/1919 | BU 11/1927 |
|
Displacement standard, t |
|
|
Displacement normal, t |
423 / 510 |
|
Length, m |
52.4 |
|
Breadth, m |
4.80 |
|
Draught, m |
4.00 |
|
No of shafts |
2 |
|
Machinery |
NLSE diesels / electric motors |
|
Power, h. p. |
480 / 620 |
|
Max speed, kn |
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, m | 30 |
Ship project history: Boats were single-hulled and had small reserve of surface stability and buoyancy. Operational diving depth was 30m, maximal 90m.
Submarines of 2nd series were built by various yards directly in the Great Britain in 1917-1919. Engines, main electric motors and major fittings were obtained from USA. 12 first subs were ordered from Vickers in January 1917, 22 later boats with British-made machinery were ordered in June. In October 1917 it was decided to build 12 "R" class submarines instead of "H" and order was cut back.
Modernizations: None
Naval service: Six submarines (Í13, Í16-H20) are transferred to Chile 3/7/1917 as compensation for requisitioned Chilean ships. Í49 was sunk 18/10/1940 by German trawlers UJ116 and UJ118 in the North Sea. Í31 was lost for the unknown reason in bay of Biscay 24/12/1941.
H27 1919
© Ivan Gogin, 2008-10