NAVYPEDIA

Photo

M16 1915

Ships

Name	No	Yard No	Builder	Laid down	Launched	Comp	Fate
M15		865	Gray, Tees	3/1915	28.4.1915	6.1915	sunk 11.11.1917
M16		866	Gray, Tees	3/1915	3.5.1915	6.1915	sold 1.1920
M17		871	Gray, Tees	3.1915	12.5.1915	7.1915	sold 5.1920
M18		872	Gray, Tees	3.1915	15.5.1915	7.1915	sold 1.1920
M19		597	Raylton Dixon, Tees	3.1915	4.5.1915	6.1915	sold 5.1920
M20		598	Raylton Dixon, Tees	3.1915	11.5.1915	7.1915	sold 1.1920
M21		599	Raylton Dixon, Tees	3.1915	27.5.1915	7.1915	sunk 20.10.1918
M22, 12.1925- Medea		600	Raylton Dixon, Tees	3.1915	10.6.1915	8.1915	minelayer 1919, TS 1.1937, sold for BU 12.1938
M23		601	Raylton Dixon, Tees	3.1915	17.6.1915	7.1915	RNVR drillship Claverhouse 12.1922, BU 4.1959
M24		602	Raylton Dixon, Tees	3.1915	9.8.1915	10.1915	sold 1.1920
M25		603	Raylton Dixon, Tees	3.1915	24.7.1915	9.1915	scuttled 16.9.1919
M26		604	Raylton Dixon, Tees	3.1915	24.8.1915	10.1915	sold 1.1920
M27		605	Raylton Dixon, Tees	3.1915	8.9.1915	11.1915	scuttled 16.9.1919
M28		606	Raylton Dixon, Tees	3.1915	28.6.1915	8.1915	sunk 20.1.1918

Technical data

Displacement normal, t	540
Displacement full, t	650
Length, m	54.0
Breadth, m	9.40
Draught, m	2.00 - 2.10
No of shafts	M15 - 17, 21, 22: 2 M18 - 20, 23 - 28: 4
Machinery	M15 - 17, 21, 22: 2 VTE, 2 boilers M18 - 20, 23, 25, 28: 4 4-cyl. Bolinder semi-diesels M24: 4 4-cyl. Campbell paraffin engines M26, 27: 4 2-cyl. Bolinder semi-diesels
Power, h. p.	M15 - 17: 800 M18 - 20, 23 - 25, 28: 640 M21: 600 M22: 650 M26: 480 M27: 560
Max speed, kts	M15 - 17: 11 M18 - 28: 9
Fuel, t	45 oil
Endurance, nm(kts)	1440(8)
Armour, mm	turret: 152
Armament	M15 - 18: 1 x 1 - 234/47 BL Mk X, 1 x 1 - 76/50 12pdr 18cwt QF Mk I, 1 x 1 - 57/40 6pdr Hotchkiss Mk I (AA) M19 - 23, 25, 28: 1 x 1 - 234/32 BL Mk VI, 1 x 1 - 76/50 12pdr 18cwt QF Mk I, 1 x 1 - 57/40 6pdr Hotchkiss Mk I (AA) M24: 1 x 1 - 190/50 BL Mk IV, 1 x 1 - 76/50 12pdr 18cwt QF Mk I, 1 x 1 - 57/40 6pdr Hotchkiss Mk I (AA) M26, 27: 1 x 1 - 152/40 QF Mk II, 1 x 1 - 76/50 12pdr 18cwt QF Mk I, 1 x 1 - 57/40 6pdr Hotchkiss Mk I (AA)
Complement	69

Graphics

Project history

The program of monitor construction had virtually exhausted the stock of heavy gun mountings by early 1915 but Lord Fisher wanted further heavily armed vessels for the amphibious operations planned. There were a number of 234mm guns in stock, mainly Mk.VI type in Edgar class cruisers, as well as a few Mk.X mountings held as spares for Drake and Cressy classes. The four Edgar class being prepared for Dardanelles service were given a uniform armament of 152mm guns, thus releasing 8 guns, and as Gibraliar was to become a depot ship a further 2 guns became available. There were also 4 spare Mk.X guns and Mk.V mountings for Drake class, but only two ships left, Drake and Leviathan, had the Mk.V mounting, so four more monitors could be armed with 234mm guns. There was a considerable difference between the two mountings. The Mk.VI gun was a low-velocity short weapon on an old Vavasseur hand-worked mounting, capable or ranging to only 10km. The Mk.X, in contrast was a high-velocity gun with a range of 14km and capable of four times the rate of fire. The Elswick Ordnance Co was able to modify both mountings to permit elevation to 30°, increasing the range of the Mk.VI to 14.8km and 20km for the Mk.X (22.7km with 4crh shells).     The requirements of the design were basic: draught aboul 1.8m, speed 12kts and the simplest construction. Fisher was still anxious to get diesel engines into service, and he pressed for the use of the same Bolinder 'semi-diesel' as had been recommended for the large programme of 'X-lighter' landing barges. Only six of the 4-cylinder 'M' type were available and so two were given four of the 2-cylinder type. One ship received four paraffin engines by the Campbell Gas Co and the rest received conventional steam engines. The guns were allocated as follows: 2 from Edgar into M19 and M26; 2 from Theseus into M21 and M27; 2 from Grafton into M23 and M28; 2 from Endymion into M24 and M25; 2 from Gibraltar into M20 and M22. One spare Mk.X gun and its mounting was held at Malta, and a second had been sent out there before the Gallipoli landings, so M15 and M16 were sent out to be armed there; the other mountings were held at Portsmouth and were sent by road to Hartlepool.     In service their worst feature was their lively motion, which seriously impaired their ability to carry out accurate bombardments. As there was a serious shortage of heavy artillery on the Western Front, Admiral Bacon, commanding the Dover Patrol, ordered the 234mm guns to be taken out from M25 (the only monitor then in service in September 1915) and the three (M24, 26 and 27) still fitting out at Middlesborough. Early in 1916 all four were sent to Portsmouth to receive lighter guns .The 190mm guns were spares for Triumph, but when her sister Swiftsure began Atlantic patrols one of her spare guns was allocated to M26. The two 152mm guns had been removed from Redoutable.

Protection

Only the turret was armoured.

Modernizations

M15 and M16 received their 234mm guns at Malta in 7.1915

early 1916, M25: - 1 x 1 - 234/32; + 1 x 1 - 190/50 BL Mk IV

later M26: - 1 x 1 - 152/40; + 1 x 1 - 190/50 BL Mk III

later M27: - 1 x 1 - 152/40; + 1 x 1 - 152/45 BL Mk VII

1916 - 1918, M16: - 1 x 1 - 76/50, 1 x 1 - 57/40; + 1 x 1 - 76/45 20cwt QF Mk I

1916 - 1918, M18, M19, M20, M22: - 1 x 1 - 76/50; + 1 x 1 - 76/45 20cwt QF Mk I

1916 - 1918, M21, M25: - 1 x 1 - 57/40; + 1 x 1 - 76/45 20cwt QF Mk I

1916 - 1918, M23, M24, M26, M27: - 1 x 1 - 57/40; + 1 x 1 - 76/45 20cwt QF Mk I, 2 x 1 - 40/39 2pdr QF Mk II

1917, M21, M23: - 1 x 1 - 234/32; + 1 x 1 - 190/50 BL Mk III

1919, M23: - 2 x 1 - 40/39; + 2 x 1 - 47/50 3pdr Vickers Mk I

1919, M24, M26: - 1 x 1 - 76/50; + 1 x 1 - 76/45 20cwt QF Mk I

1919, M25: + 2 x 1 - 47/50 3pdr Vickers Mk I

1919, M27: - 1 x 1 - 152/45, 1 x 1 - 76/50; + 1 x 3 - 102/45 BL Mk IX, 1 x 1 - 76/45 20cwt QF Mk I

1919-1920, M22: unarmed, can carry 44 mines

Naval service

M15 was torpedoed by submarine UC38 off Gaza 11.11.1917. M21 struck two mines off Ostend 20.10.1918, was towed back to Diver and sank about a mile from West Pier that day. M25 and M27 were blown up and scuttled 16.9.1919 by own crews in Dvina River in Northern Russia because evacuation was unavailable. M28 was 20.1.1918 sunk by gunfire of German cruisers Goeben and Breslau at Imbros (Aegean).

M19 was badly damaged by gun explosion 4.12.1915. M22 was converted to minelayer in 1919-1920, sold for BU in 1938 and wrecked off Cornwall Coast 2.1.1939.

Many thanks to Wolfgang Stöhr for additional information on this page.