WesWorld

Minelayers of the Japanese Navy.

Data here is the data released to the public

Ri Ichi Class
R-1 to R-27

Dimensions: 220.00 ft x 28.00 ft x 7.00 ft
Standard Displacement: 550 tons
Armament: 6 - 10.5 cm / 50 cal Model 1914 guns
4 - 50 mm / 60 cal Model 1914 AA guns
12 - 25 mm / 60 cal Model 1914 light AA guns
Armour: Main gun shields 1.00", AA gun shields 1.00", Light AA gun shields 1.00"
Machinery: 3 Kanpon oil fired boilers, Brown Curtis geared,
Geared drive, 2 shafts, 2,600 shp = 17.00 kts
Range 5,000nm at 12.00 kts
Complement: 9 Officers, 74 other rank

Ri Ichi, Japan Minelayer laid down 1916
All scrapped in 1943

Displacement:
524 t light; 557 t standard; 678 t normal; 771 t full load
Loading submergence 118 tons/feet

Dimensions:
220.00 ft x 28.00 ft x 7.00 ft (normal load)
67.06 m x 8.53 m x 2.13 m

Armament:
6 - 4.13" / 105 mm guns
4 - 1.97" / 50 mm AA guns
12 - 0.98" / 25 mm guns
Weight of broadside 233 lbs / 106 kg

Armour:
Main gun shields 1.00" / 25 mm, AA gun shields 1.00" / 25 mm, Light gun shields 1.00" / 25 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 2,811 shp / 2,097 Kw = 18.50 kts
Range 5,600nm at 12.00 kts

Complement:
66 - 86

Cost:
£0.094 million / $0.376 million

Distribution of weights at normal displacement:
Armament: 29 tons, 4.3 %
Armour: 10 tons, 1.5 %
Belts: 0 tons, 0.0 %, Armament: 10 tons, 1.5 %, Armour Deck: 0 tons, 0.0 %
Conning Tower: 0 tons, 0.0 %, Torpedo bulkhead: 0 tons, 0.0 %
Machinery: 105 tons, 15.5 %
Hull, fittings & equipment: 305 tons, 45.0 %
Fuel, ammunition & stores: 154 tons, 22.7 %
Miscellaneous weights: 75 tons, 11.1 %

Metacentric height 1.0

Remarks:
Hull space for machinery, storage & compartmentation is adequate
Room for accommodation & workspaces is adequate

Estimated overall survivability and seakeeping ability:
Relative margin of stability: 1.19
Shellfire needed to sink: 974 lbs / 442 Kg = 27.6 x 4.1 " / 105 mm shells
(Approx weight of penetrating shell hits needed to sink ship excluding critical hits)
Torpedoes needed to sink: 0.6
(Approx number of typical torpedo hits needed to sink ship)
Relative steadiness as gun platform: 51 %
(Average = 50 %)
Relative rocking effect from firing to beam: 0.29
Relative quality as seaboat: 1.01

Hull form characteristics:
Block coefficient: 0.550
Sharpness coefficient: 0.38
Hull speed coefficient 'M': 7.65
'Natural speed' for length: 14.83 kts
Power going to wave formation at top speed: 55 %
Trim: 50
(Maximise stabilty/flotation = 0, Maximise steadiness/seakeeping = 100)

Estimated hull characteristics & strength:
Underwater volume absorbed by magazines and engineering spaces: 95.5 %
Relative accommodation and working space: 103.6 %
(Average = 100%)
Displacement factor: 128 %
(Displacement relative to loading factors)
Relative cross-sectional hull strength: 1.00
(Structure weight / hull surface area: 49 lbs / square foot or 239 Kg / square metre)
Relative longitudinal hull strength: 1.75
(for 8.70 ft / 2.65 m average freeboard, freeboard adjustment -0.14 ft)
Relative composite hull strength: 1.05

Tsugaru, Japan Minelayer laid down 1942


Displacement:
3,658 t light; 3,791 t standard; 4,434 t normal; 4,949 t full load

Dimensions: Length overall / water x beam x draught
391.97 ft / 385.00 ft x 51.00 ft x 18.00 ft (normal load)
119.47 m / 117.35 m x 15.54 m x 5.49 m

Armament:
4 - 5.00" / 127 mm guns (2x2 guns), 55.12lbs / 25.00kg shells, 1942 Model
Dual purpose guns in deck mounts with hoists
on centreline ends, evenly spread
16 - 0.52" / 13.2 mm guns (4x4 guns), 0.09lbs / 0.04kg shells, 1942 Model
Machine guns in deck mounts
on side ends, evenly spread, all raised mounts - superfiring
Weight of broadside 222 lbs / 101 kg
Shells per gun, main battery: 350

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 2.00" / 51 mm - -

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 29,860 shp / 22,275 Kw = 28.00 kts
Range 10,000nm at 15.00 kts
Bunker at max displacement = 1,158 tons

Complement:
271 - 353

Cost:
£1.678 million / $6.710 million

Distribution of weights at normal displacement:
Armament: 31 tons, 0.7%
Armour: 19 tons, 0.4%
- Belts: 0 tons, 0.0%
- Torpedo bulkhead: 0 tons, 0.0%
- Armament: 19 tons, 0.4%
- Armour Deck: 0 tons, 0.0%
- Conning Tower: 0 tons, 0.0%
Machinery: 780 tons, 17.6%
Hull, fittings & equipment: 1,578 tons, 35.6%
Fuel, ammunition & stores: 776 tons, 17.5%
Miscellaneous weights: 1,250 tons, 28.2%

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
6,012 lbs / 2,727 Kg = 96.2 x 5.0 " / 127 mm shells or 1.2 torpedoes
Stability (Unstable if below 1.00): 1.05
Metacentric height 2.0 ft / 0.6 m
Roll period: 15.1 seconds
Steadiness - As gun platform (Average = 50 %): 51 %
- Recoil effect (Restricted arc if above 1.00): 0.11
Seaboat quality (Average = 1.00): 1.24

Hull form characteristics:
Hull has a flush deck
and transom stern
Block coefficient: 0.439
Length to Beam Ratio: 7.55 : 1
'Natural speed' for length: 23.13 kts
Power going to wave formation at top speed: 62 %
Trim (Max stability = 0, Max steadiness = 100): 41
Bow angle (Positive = bow angles forward): 15.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 26.00 ft / 7.92 m
- Forecastle (20%): 18.00 ft / 5.49 m
- Mid (50%): 18.00 ft / 5.49 m
- Quarterdeck (15%): 18.00 ft / 5.49 m
- Stern: 18.00 ft / 5.49 m
- Average freeboard: 18.64 ft / 5.68 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 94.1%
- Above water (accommodation/working, high = better): 163.1%
Waterplane Area: 12,894 Square feet or 1,198 Square metres
Displacement factor (Displacement / loading): 144%
Structure weight / hull surface area: 72 lbs/sq ft or 352 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.89
- Longitudinal: 2.95
- Overall: 1.00
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent
Good seaboat, rides out heavy weather easily

700 tons for mines and rails.
25 tons for seaplane.
25 tons for crane and catapult.
100 tons for electronics.
400 tons for various stuff.

Hashima (ex-Hatsushima), Japan Minelayer/Cable layer laid down 1942


Displacement:
1,284 t light; 1,317 t standard; 1,534 t normal; 1,707 t full load

Dimensions: Length overall / water x beam x draught
266.81 ft / 252.00 ft x 35.50 ft x 12.00 ft (normal load)
81.33 m / 76.81 m x 10.82 m x 3.66 m

Armament:
1 - 3.00" / 76.2 mm guns in single mounts, 12.00lbs / 5.44kg shells, 1942 Model
Dual purpose gun in a deck mount with hoist
on centreline aft
2 - 0.52" / 13.2 mm guns (1x2 guns), 0.09lbs / 0.04kg shells, 1942 Model
Machine guns in deck mount
on centreline aft, all raised guns - superfiring
Weight of broadside 12 lbs / 6 kg
Shells per gun, main battery: 350

Machinery:
Coal fired boilers, complex reciprocating steam engines,
Geared drive, 2 shafts, 3,871 ihp / 2,887 Kw = 18.00 kts
Range 3,000nm at 15.00 kts
Bunker at max displacement = 390 tons (100% coal)

Complement:
122 - 159

Cost:
£0.503 million / $2.011 million

Distribution of weights at normal displacement:
Armament: 2 tons, 0.1%
Machinery: 233 tons, 15.2%
Hull, fittings & equipment: 431 tons, 28.1%
Fuel, ammunition & stores: 250 tons, 16.3%
Miscellaneous weights: 618 tons, 40.3%

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,790 lbs / 812 Kg = 132.6 x 3.0 " / 76 mm shells or 0.7 torpedoes
Stability (Unstable if below 1.00): 1.06
Metacentric height 1.2 ft / 0.4 m
Roll period: 13.7 seconds
Steadiness - As gun platform (Average = 50 %): 54 %
- Recoil effect (Restricted arc if above 1.00): 0.01
Seaboat quality (Average = 1.00): 1.64

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.500
Length to Beam Ratio: 7.10 : 1
'Natural speed' for length: 15.87 kts
Power going to wave formation at top speed: 52 %
Trim (Max stability = 0, Max steadiness = 100): 33
Bow angle (Positive = bow angles forward): 30.00 degrees
Stern overhang: 5.00 ft / 1.52 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 17.00 ft / 5.18 m
- Forecastle (25%): 17.00 ft / 5.18 m
- Mid (30%): 10.00 ft / 3.05 m
- Quarterdeck (15%): 10.00 ft / 3.05 m
- Stern: 10.00 ft / 3.05 m
- Average freeboard: 11.93 ft / 3.63 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 94.4%
- Above water (accommodation/working, high = better): 95.8%
Waterplane Area: 5,961 Square feet or 554 Square metres
Displacement factor (Displacement / loading): 140%
Structure weight / hull surface area: 45 lbs/sq ft or 218 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.92
- Longitudinal: 2.17
- Overall: 1.00
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is adequate
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

75 tons for electronics.
depth charges
543 tons for depth charges, Type 92 remotely controlled mines or 20,000 m submarine cable.

Sokuten, Japan Minelayer laid down 1942


Displacement:
584 t light; 600 t standard; 682 t normal; 747 t full load

Dimensions: Length overall / water x beam x draught
240.00 ft / 240.00 ft x 26.00 ft x 8.50 ft (normal load)
73.15 m / 73.15 m x 7.92 m x 2.59 m

Armament:
1 - 3.00" / 76.2 mm guns in single mounts, 12.00lbs / 5.44kg shells, 1942 Model
Dual purpose gun in a deck mount with hoist
on centreline forward
8 - 0.52" / 13.2 mm guns (4x2 guns), 0.09lbs / 0.04kg shells, 1942 Model
Machine guns in deck mounts
on side, evenly spread
Weight of broadside 13 lbs / 6 kg
Shells per gun, main battery: 350

Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 3,446 shp / 2,571 Kw = 20.00 kts
Range 4,000nm at 14.00 kts
Bunker at max displacement = 147 tons

Complement:
66 - 86

Cost:
£0.220 million / $0.879 million

Distribution of weights at normal displacement:
Armament: 2 tons, 0.3%
Machinery: 90 tons, 13.2%
Hull, fittings & equipment: 244 tons, 35.8%
Fuel, ammunition & stores: 98 tons, 14.4%
Miscellaneous weights: 248 tons, 36.4%

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,018 lbs / 462 Kg = 75.4 x 3.0 " / 76 mm shells or 0.6 torpedoes
Stability (Unstable if below 1.00): 1.05
Metacentric height 0.7 ft / 0.2 m
Roll period: 12.8 seconds
Steadiness - As gun platform (Average = 50 %): 50 %
- Recoil effect (Restricted arc if above 1.00): 0.04
Seaboat quality (Average = 1.00): 1.47

Hull form characteristics:
Hull has rise forward of midbreak
Block coefficient: 0.450
Length to Beam Ratio: 9.23 : 1
'Natural speed' for length: 15.49 kts
Power going to wave formation at top speed: 52 %
Trim (Max stability = 0, Max steadiness = 100): 34
Bow angle (Positive = bow angles forward): 0.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 15.00 ft / 4.57 m
- Forecastle (15%): 14.50 ft / 4.42 m
- Mid (25%): 14.50 ft / 4.42 m (8.00 ft / 2.44 m aft of break)
- Quarterdeck (15%): 8.00 ft / 2.44 m
- Stern: 8.00 ft / 2.44 m
- Average freeboard: 9.66 ft / 2.94 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 85.1%
- Above water (accommodation/working, high = better): 102.6%
Waterplane Area: 3,980 Square feet or 370 Square metres
Displacement factor (Displacement / loading): 154%
Structure weight / hull surface area: 35 lbs/sq ft or 173 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.93
- Longitudinal: 1.95
- Overall: 1.00
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is adequate
Good seaboat, rides out heavy weather easily

60 tons for electronics.
140 tons for mines and rails or anti-submarine nets or capture nets.
48 tons for depth charges, Type 94 depth charge projector and depth charge throwers.

MA-1, Japan Minelayer laid down 1942


Displacement:
149 t light; 154 t standard; 162 t normal; 168 t full load

Dimensions: Length overall / water x beam x draught
110.95 ft / 100.00 ft x 21.00 ft x 6.00 ft (normal load)
33.82 m / 30.48 m x 6.40 m x 1.83 m

Armament:
1 - 2.95" / 75.0 mm guns in single mounts, 12.00lbs / 5.44kg shells, 1942 Model
Dual purpose gun in a deck mount with hoist
on centreline forward
2 - 0.52" / 13.2 mm guns (1x2 guns), 0.09lbs / 0.04kg shells, 1942 Model
Machine guns in deck mount
on centreline aft, all raised guns - superfiring
Weight of broadside 12 lbs / 6 kg
Shells per gun, main battery: 300

Machinery:
Diesel Internal combustion motors,
Geared drive, 1 shaft, 113 shp / 84 Kw = 9.50 kts
Range 2,000nm at 9.50 kts
Bunker at max displacement = 14 tons

Complement:
22 - 29

Cost:
£0.044 million / $0.178 million

Distribution of weights at normal displacement:
Armament: 2 tons, 1.0%
Machinery: 3 tons, 1.8%
Hull, fittings & equipment: 64 tons, 39.6%
Fuel, ammunition & stores: 13 tons, 8.2%
Miscellaneous weights: 80 tons, 49.4%

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
279 lbs / 127 Kg = 21.7 x 3.0 " / 75 mm shells or 0.5 torpedoes
Stability (Unstable if below 1.00): 1.06
Metacentric height 0.5 ft / 0.2 m
Roll period: 12.1 seconds
Steadiness - As gun platform (Average = 50 %): 50 %
- Recoil effect (Restricted arc if above 1.00): 0.08
Seaboat quality (Average = 1.00): 2.00

Hull form characteristics:
Hull has rise forward of midbreak
Block coefficient: 0.450
Length to Beam Ratio: 4.76 : 1
'Natural speed' for length: 10.00 kts
Power going to wave formation at top speed: 45 %
Trim (Max stability = 0, Max steadiness = 100): 25
Bow angle (Positive = bow angles forward): 15.00 degrees
Stern overhang: 8.00 ft / 2.44 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 11.00 ft / 3.35 m
- Forecastle (10%): 11.00 ft / 3.35 m
- Mid (20%): 11.00 ft / 3.35 m (5.00 ft / 1.52 m aft of break)
- Quarterdeck (15%): 5.00 ft / 1.52 m
- Stern: 5.00 ft / 1.52 m
- Average freeboard: 6.20 ft / 1.89 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 68.7%
- Above water (accommodation/working, high = better): 64.1%
Waterplane Area: 1,276 Square feet or 119 Square metres
Displacement factor (Displacement / loading): 164%
Structure weight / hull surface area: 32 lbs/sq ft or 156 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.08
- Longitudinal: 4.95
- Overall: 1.26
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is cramped
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

20 tons for electronics.
60 tons for mines and rails.