Don class river monitor, laid down 1918
Length, 51.0 m x Beam, 8.9 m x Depth, 1.9 m
539 tonnes normal displacement (518 tonnes standard)
Main battery: 1 x 23.4-cm
Secondary
battery: 1 x 7.6-cm
AA battery: 2
x 3.7-cm
Light battery: 4 x 1.3-cm
Weight of broadside: 185 kg
Main belt, 2.5 cm; bow and stern, 2.0 cm
Upper belt, 2.5 cm
Armor deck, average 1.0 cm
Conning tower, 3.0 cm
Battery armor:
Main, 3.0 cm shields
/ secondary, 3.0 cm shields
AA, 2.5 cm shields / light guns, 3.0
cm shields
Maximum speed for 397 shaft kw = 12.00 knots
Approximate cruising radius, 1200 nm / 10 knots
Typical complement: 56-73
Estimated cost, $498,000 (£125,000)
Remarks:
Relative extent of belt armor, 85 percent of 'typical' coverage.
Ship has slow, easy roll; a good, steady gun platform.
Good seaboat; rides out heavy weather easily.
Cramped ship; poor crew accommodation, limited working space.
Distribution of weights:
Percent
normal
displacement:
Armament ......................... 51 tonnes
= 9 pct
Armor, total .....................
101 tonnes = 19 pct
Belt
67 tonnes = 12 pct
Deck
26 tonnes = 5 pct
C.T.
2 tonnes = 0 pct
Armament
6 tonnes = 1 pct
Machinery ........................ 21 tonnes
= 4 pct
Hull and fittings; equipment .....
301 tonnes = 56 pct
Fuel, ammunition, stores .........
66 tonnes = 12 pct
Miscellaneous weights ............
0 tonnes = 0 pct
-----
539 tonnes = 100 pct
Estimated metacentric height, 0.3 m
Displacement summary:
Light ship:
473 tonnes
Standard displacement: 518 tonnes
Normal service:
539 tonnes
Full load:
554 tonnes
Loading submergence 332 tonnes/metre
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Estimated overall survivability and seakeeping ability:
Relative margin of stability: 1.17
Shellfire needed to sink: 341 kg = 1.9 x 23.4-cm shells
(Approximates weight of penetrating
shell hits needed to sink ship,
not
counting critical hits)
Torpedoes needed to sink: 0.6
(Approximates number of 'typical'
torpedo hits needed to sink ship)
Relative steadiness as gun platform, 70 percent
(50 percent is 'average')
Relative rocking effect from firing to beam, 0.41
Relative quality as a seaboat: 1.20
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Hull form characteristics:
Block coefficient: 0.62
Sharpness coefficient: 0.44
Hull speed coefficient 'M' = 6.28
'Natural speed' for length = 12.9 knots
Power going to wave formation
at top speed: 45 percent
Estimated hull characteristics and strength:
Relative underwater volume absorbed by
magazines and engineering spaces: 85 percent
Relative accommodation and working space: 77 percent
Displacement factor: 98 percent
(Displacement relative to loading factors)
Relative cross-sectional hull strength: 1.13
(Structure weight per square
metre
of hull surface: 315 kg)
Relative longitudinal hull strength: 2.26
(for 1.95 m average freeboard;
freeboard
adjustment -0.62 m)
Relative composite hull strength: 1.21
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[Machine-readable parameters: Spring Style v. 1.2.1]
167.28 x 29.19 x 6.23; 6.40 -- Dimensions
0.62 -- Block coefficient
1918 -- Year laid down
12.00 / 1200 / 10.00;
Turbine, coal fired -- Speed / radius / cruise
0 tons -- Miscellaneous weights
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1 x 9.21; 0 --
Main battery; turrets
Central positioning of guns
Gun-shields
:
1 x 2.99; 0 --
Secondary battery; turrets
Gun-shields
:
2 x 1.46 -- Tertiary (QF/AA) battery
Gun-shields
:
4 x 0.51 -- Fourth (light) battery
0 -- No torpedo armament
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0.98 / 0.79 / 0.98
/ 0.00; 85 -- Belt armor; relative extent
0.39 / 1.18 -- Deck / CT
1.18 / 1.18 / 1.00 / 1.18 -- Battery armor
(Note: For portability, values are stored in Anglo-American units)
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