HMS Sentinel (BM-1929)
One class of vessel that had proved useful during WW1 had been the Monitor,
gunnery support vessels. At the end of the war the ones that had proved not so
good were hastily scrapped. This left only the two Erebus class ships as
effective units of the type (real timeline). The conversion of the two Lion class battlecruisers
to hybrid seaplane carriers left four twin 13.5" turrets that could be used to
build a new class of monitors. They were to be 7,000 ton vessels, and with a
maximum speed of 16 knots. Armour equivalent to a light cruiser was fitted. It was the armoured deck that was given full measure
with a 3" deck being fitted. Because of their speed, the four vessels were to be
spread around the Empire to provide support where necessary. The first unit HMS
Skirmisher was completed in 1928, the second HMS Sentinel in 1929, the third HMS
Saracen in 1931 and lastly HMS Scourge in 1932. One was to be based at Malta and
Singapore with the last two kept in home waters.
One of the main aims was to increase the range of the 13.5" guns from 23,000
yards at 20 degrees elevation, to 34,000 yards at 40 degrees elevation. This was
achieved by cutting enlarged holes in the hoods and dropping the floor of the
turret into the barbette which allowed the greater elevation and range. The guns
themselves were upgraded from the 1250 pound 'light' shell to the 1400 pound
'heavy' shell ammunition type. Shell stowage was increased to 150 rounds per gun
as it was considered that the monitors were likely to be in action longer per
day giving fire support to land units.
| Displacement | 7,200 tons std, 10,600 tons full load | |
| Length | 355 feet | |
| Breadth | 88 ft | |
| Draught | 14 ft | |
| Machinery | 2 shaft Steam turbines, 10,000shp | |
| Speed | 16 knots | |
| Range | 5,000 miles at 10 knots | |
| Armour | 3" side 3" deck, 9" to 4" turret | |
| Armament | As completed 2 x 13.5" (1x2) 4 x 4" AA (4x1) 8 x 2pd (2x4) |
World War Two 2 x 13.5" (1x2) 4 x 4" DP (4x1) 8 x 2pd (2x4) 12 x 20mm (12x1) |
| Complement | 240 | 256 |
| Notes | All four were lost during WW2: | |
| Skirmisher | sunk 1940 off the Dunkirk beaches, by Stuka dive bombers. | |
| Sentinel | sunk 1942 in support of the Dieppe landings by JU-88 bombers | |
| Saracen | sunk 1943 in support of the Anzio landings by glider bomb. | |
| Scourge | sunk 1942 trying to reach Australia through the Lombok Strait, torpedoed by Japanese destroyers. | |
By 1941 all the remaining ships had received the set of upgrades intended for
the class. Radar adorned the mast heads, while the 4" HACS unit and 2 pounder
pom poms had also received radar assistance.
