WesWorld

1916, RD Class Minesweeper/layer

Ships in class; RD1, RD2 , RD3 , RD4 , RD5 , RD6, RD7, RD8 , RD9 , RD10 , RD11, RD12 , RD13 , RD14 , RD15




MS-16 , Italian Minesweeper/layer laid down 1916

Displacement:
840 t light; 859 t standard; 922 t normal; 969 t full load
Loading submergence 119 tons/feet

Dimensions:
223.10 ft x 26.25 ft x 9.19 ft (normal load)
68.00 m x 8.00 m x 2.80 m

Armament:
1 - 57 mm gun in a single mount
4 - 20 mm guns in single mounts
Weight of broadside 7 lbs / 3 kg
105tons of minesweeping/laying equipment

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 10,000 shp / 7,530 Kw = 24.00 kts
Range 4,000nm at 10.00 kts

Complement:
83 - 108

Cost:
£0.135 million / $0.542 million

Distribution of weights at normal displacement:
Armament: 1 tons, 0.1 %
Machinery: 376 tons, 40.8 %
Hull, fittings & equipment: 358 tons, 38.8 %
Fuel, ammunition & stores: 82 tons, 8.9 %
Miscellaneous weights: 105 tons, 11.4 %

Metacentric height 0.8

Remarks:
Hull space for machinery, storage & compartmentation is cramped
Room for accommodation & workspaces is excellent
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable and able to fight her guns in the heaviest weather

Estimated overall survivability and seakeeping ability:
Relative margin of stability: 1.07
Shellfire needed to sink: 754 lbs / 342 Kg = 133.4 x 2.2 " / 57 mm shells
(Approx weight of penetrating shell hits needed to sink ship excluding critical hits)
Torpedoes needed to sink: 0.3
(Approx number of typical torpedo hits needed to sink ship)
Relative steadiness as gun platform: 72 %
(Average = 50 %)
Relative rocking effect from firing to beam: 0.02
Relative quality as seaboat: 2.00

Hull form characteristics:
Block coefficient: 0.600
Sharpness coefficient: 0.38
Hull speed coefficient 'M': 7.00
'Natural speed' for length: 14.94 kts
Power going to wave formation at top speed: 70 %
Trim: 36
(Maximise stabilty/flotation = 0, Maximise steadiness/seakeeping = 100)

Estimated hull characteristics & strength:
Underwater volume absorbed by magazines and engineering spaces: 145.1 %
Relative accommodation and working space: 172.2 %
(Average = 100%)
Displacement factor: 107 %
(Displacement relative to loading factors)
Relative cross-sectional hull strength: 0.84
(Structure weight / hull surface area: 42 lbs / square foot or 204 Kg / square metre)
Relative longitudinal hull strength: 4.91
(for 18.04 ft / 5.50 m average freeboard, freeboard adjustment 8.64 ft)
Relative composite hull strength: 1.00

MAS 1 - 51 fitted with launching rails for 4 mines. Speed reduced to 22knts. 1x47mm gun as armament.

1934, RD51 - class

10 vessels laid down 1934

Displacement:
200 t light; 205 t standard; 211 t normal; 216 t full load

Dimensions: Length overall / water x beam x draught
126.99 ft / 114.83 ft x 19.03 ft x 6.56 ft (normal load)
38.71 m / 35.00 m x 5.80 m x 2.00 m

Armament:
1 - 3.00" / 76.2 mm guns in single mounts, 13.50lbs / 6.12kg shells, 1934 Model
Quick firing gun in deck mount
on centreline forward
4 - 0.98" / 25.0 mm guns in single mounts, 0.55lbs / 0.25kg shells, 1934 Model
Anti-aircraft guns in deck mounts
on side, all amidships
Weight of broadside 16 lbs / 7 kg
Shells per gun, main battery: 100

Machinery:
Diesel Internal combustion motors,
Geared drive, 1 shaft, 500 shp / 373 Kw = 13.47 kts
Range 1,000nm at 10.00 kts
Bunker at max displacement = 11 tons

Complement:
26 - 35

Cost:
£0.052 million / $0.209 million

Distribution of weights at normal displacement:
Armament: 2 tons, 0.9 %
Machinery: 14 tons, 6.8 %
Hull, fittings & equipment: 143 tons, 67.9 %
Fuel, ammunition & stores: 11 tons, 5.4 %
Miscellaneous weights: 40 tons, 19.0 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
548 lbs / 248 Kg = 40.6 x 3.0 " / 76 mm shells or 0.8 torpedoes
Stability (Unstable if below 1.00): 1.05
Metacentric height 0.5 ft / 0.1 m
Roll period: 11.9 seconds
Steadiness - As gun platform (Average = 50 %): 32 %
- Recoil effect (Restricted arc if above 1.00): 0.08
Seaboat quality (Average = 1.00): 1.28

Hull form characteristics:
Hull has rise forward of midbreak
Block coefficient: 0.515
Length to Beam Ratio: 6.03 : 1
'Natural speed' for length: 10.72 kts
Power going to wave formation at top speed: 59 %
Trim (Max stability = 0, Max steadiness = 100): 16
Bow angle (Positive = bow angles forward): 10.00 degrees
Stern overhang: 9.84 ft / 3.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 13.12 ft / 4.00 m
- Forecastle (20 %): 13.12 ft / 4.00 m
- Mid (20 %): 13.12 ft / 4.00 m (9.84 ft / 3.00 m aft of break)
- Quarterdeck (15 %): 6.56 ft / 2.00 m
- Stern: 9.84 ft / 3.00 m
- Average freeboard: 9.19 ft / 2.80 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 50.8 %
- Above water (accommodation/working, high = better): 85.5 %
Waterplane Area: 1,423 Square feet or 132 Square metres
Displacement factor (Displacement / loading): 251 %
Structure weight / hull surface area: 47 lbs/sq ft or 228 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.57
- Longitudinal: 17.22
- Overall: 2.00
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is cramped
Good seaboat, rides out heavy weather easily

A small minesweeper that can double as a coastal patrol vessel. The diesel-electric machinery is based off that on the Gabbiano Class corvettes.

RD61, RD62, RD63, RD64 Laid down 1938

Dragamine, laid down 1938

Displacement:
404 t light; 419 t standard; 511 t normal; 585 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(205.50 ft / 196.85 ft) x 24.61 ft x (8.20 / 9.01 ft)
(62.64 m / 60.00 m) x 7.50 m x (2.50 / 2.75 m)

Armament:
1 - 2.99" / 76.0 mm 62.0 cal gun - 14.75lbs / 6.69kg shells, 300 per gun
Anti-air gun in deck and hoist mount, 1938 Model
1 x Single mount on centreline, forward deck forward
2 - 1.46" / 37.0 mm 54.0 cal guns - 1.66lbs / 0.75kg shells, 1,000 per gun
Anti-air guns in deck mounts, 1938 Model
2 x Single mounts on sides, aft deck centre
2 raised mounts
4 - 0.98" / 25.0 mm 45.0 cal guns - 0.48lbs / 0.22kg shells, 150 per gun
Anti-air guns in deck mounts, 1938 Model
4 x Single mounts on sides amidships
Weight of broadside 20 lbs / 9 kg

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.18" / 30 mm 0.79" / 20 mm -

Machinery:
Diesel Internal combustion motors,
Electric cruising motors plus geared drives, 2 shafts, 4,000 shp / 2,984 Kw = 21.43 kts
Range 6,000nm at 12.00 kts
Bunker at max displacement = 166 tons

Complement:
53 - 69

Cost:
£0.151 million / $0.603 million

Distribution of weights at normal displacement:
Armament: 7 tons, 1.5 %
Armour: 4 tons, 0.8 %
- Armament: 4 tons, 0.8 %
Machinery: 118 tons, 23.1 %
Hull, fittings & equipment: 234 tons, 45.9 %
Fuel, ammunition & stores: 107 tons, 20.9 %
Miscellaneous weights: 40 tons, 7.8 %
- Hull above water: 20 tons
- On freeboard deck: 20 tons

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
950 lbs / 431 Kg = 70.9 x 3.0 " / 76 mm shells or 0.6 torpedoes
Stability (Unstable if below 1.00): 1.25
Metacentric height 0.9 ft / 0.3 m
Roll period: 10.8 seconds
Steadiness - As gun platform (Average = 50 %): 51 %
- Recoil effect (Restricted arc if above 1.00): 0.08
Seaboat quality (Average = 1.00): 1.29

Hull form characteristics:
Hull has a flush deck,
a normal bow and large transom stern
Block coefficient (normal/deep): 0.450 / 0.469
Length to Beam Ratio: 8.00 : 1
'Natural speed' for length: 16.42 kts
Power going to wave formation at top speed: 63 %
Trim (Max stability = 0, Max steadiness = 100): 39
Bow angle (Positive = bow angles forward): 20.00 degrees
Stern overhang: 3.28 ft / 1.00 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 15.00 %, 14.76 ft / 4.50 m, 11.48 ft / 3.50 m
- Forward deck: 30.00 %, 11.48 ft / 3.50 m, 9.84 ft / 3.00 m
- Aft deck: 40.00 %, 9.84 ft / 3.00 m, 9.84 ft / 3.00 m
- Quarter deck: 15.00 %, 9.84 ft / 3.00 m, 9.84 ft / 3.00 m
- Average freeboard: 10.53 ft / 3.21 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 84.9 %
- Above water (accommodation/working, high = better): 117.6 %
Waterplane Area: 3,209 Square feet or 298 Square metres
Displacement factor (Displacement / loading): 168 %
Structure weight / hull surface area: 40 lbs/sq ft or 194 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.98
- Longitudinal: 4.75
- Overall: 1.15
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is adequate
Good seaboat, rides out heavy weather easily

40tons minesweeping gear