WesWorld

1918 S Class Submarines

Ships in class; S1-S20

All ships sold to China 1938




S.20 , Italian Submarine laid down 1918

Displacement:
440 t light; 450 t standard; 502 t normal; 542 t full load

Operational diving depth ~210ft

Dimensions:
50.00 m x 6.00 m x 3.00 m
6 - 450 mm submerged bow torpedo tubes with 12 torpedoes

Machinery:
Diesel Internal combustion engines plus batteries,
Electric cruising motors plus geared drives, 1 shaft, 1,000 shp / 746 Kw = 14.61 kts submerged
Range 5,000nm at 10.00 kts

Complement:
26 - 34

Cost:
£0.041 million / $0.164 million

Relative margin of stability: 1.08

1918, B-Class

Ships in class; It is not known how many vessels remain in service

Surface displacement: 40tons

Length: 50ft
Beam: 7.5ft

Maximum surface speed: 6.9knts
Maximum submerged speed: 5knts

Complement: 5

Armament: 2x450mm torpedoes


NB The government has never officially admitted that this class exists.

1923, SX.01 Experimental submarine

Ships in class; SX.01



Notes; This submarine is powered by massive diesels for high speed. Speeds of over 23knts have been reached on trials.

SX.01 , Italian Experimental Submarine laid down 1923

Displacement:
500 t light; 512 t standard; 586 t normal; 643 t full load
Dimensions:
60.00 m x 6.05 m x 4.00 m
Armament:
1 - 37 mm gun in a single mount
2 trainable 450mm torpedo tubes on deck
2 hull-mounted 450mm torpedo tubes
Up to 8 torpedoes carried

Machinery:
Diesel Internal combustion generators plus batteries,
Electric motors, 2 shafts, 5,800 shp / 4,327 Kw = 22.81 kts
Range 7,000nm at 10.00 kts

Complement:
59 - 77

Cost:
£0.130 million / $0.521 million

Relative margin of stability: 1.00

SA Class, 1925

Ships in class; SA01, SA02, SA03, SA04, SA05, SA06, SA07, SA08, SA09




SA.1, Italian Submarine laid down 1925

Displacement:
439 t light; 451 t standard; 518 t normal; 571 t full load

Dimensions: Length overall / water x beam x draught
190.29 ft / 190.29 ft x 19.09 ft x 12.47 ft (normal load)
58.00 m / 58.00 m x 5.82 m x 3.80 m

Armament:
1 - 1.46" / 37.0 mm guns in single mounts, 1.55lbs / 0.70kg shells, 1925 Model
Breech loading gun in deck mount
on centreline amidships
Weight of broadside 2 lbs / 1 kg
Shells per gun, main battery: 2,000
6 - 17.7" / 450 mm submerged torpedo tubes

Machinery:
Diesel Internal combustion generators plus batteries,
Electric motors, 2 shafts, 5,413 shp / 4,038 Kw = 22.78 kts
Range 7,000nm at 10.00 kts
Bunker at max displacement = 120 tons

Complement:
53 - 70

Cost:
£0.131 million / $0.525 million

Distribution of weights at normal displacement:
Armament: 0 tons, 0.0 %
Machinery: 176 tons, 33.9 %
Hull, fittings & equipment: 188 tons, 36.3 %
Fuel, ammunition & stores: 79 tons, 15.2 %
Miscellaneous weights: 75 tons, 14.5 %


Stability (Unstable if below 1.00): 1.00

Operational Diving Depth=45m
Emergency Diving Depth=68m
Crush Depth=113m

Ships in class; Ettore Fieramosca



Italian Submarine laid down 1926

Displacement:
992 t light; 1,018 t standard; 1,285 t normal; 1,499 t full load

Dimensions: Length overall / water x beam x draught
229.66 ft / 229.66 ft x 22.97 ft x 16.40 ft (normal load)
70.00 m / 70.00 m x 7.00 m x 5.00 m

Armament:
2 - 0.79" / 20.0 mm guns (1x2 guns), 0.24lbs / 0.11kg shells, 1926 Model
Breech loading guns in deck mount
on centreline amidships
Weight of broadside 0 lbs / 0 kg
Shells per gun, main battery: 2,000
6 - 21.0" / 533 mm submerged torpedo tubes

1-2 aircraft

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 2,000 shp / 1,492 Kw = 15.49 kts
Range 17,100nm at 10.00 kts
Bunker at max displacement = 481 tons

Complement:
106 - 139

Cost:
£0.151 million / $0.604 million

Distribution of weights at normal displacement:
Armament: 0 tons, 0.0 %
Machinery: 64 tons, 5.0 %
Hull, fittings & equipment: 678 tons, 52.8 %
Fuel, ammunition & stores: 293 tons, 22.8 %
Miscellaneous weights: 250 tons, 19.4 %

Stability (Unstable if below 1.00): 1.05

Operational Diving Depth=77m
Emergency Diving Depth=123m
Crush Depth=193m

Ships in Class;

Brin Laid down 1927
Galvani Laid down 1927
Guglielmotti Laid down 1927
Archimede Laid down 1927
Torricelli Laid down 1927
Balilla Laid down 1927
Sciesa Laid down 1927
Toti Laid down 1927
Millelire Laid down 1927



RN Brin, Italian Submarine laid down 1927

Displacement:
1,000 t light; 1,029 t standard; 1,310 t normal; 1,535 t full load

Dimensions: Length overall / water x beam x draught
229.66 ft / 229.66 ft x 22.97 ft x 16.40 ft (normal load)
70.00 m / 70.00 m x 7.00 m x 5.00 m

Armament:
1 - 3.94" / 100 mm guns in single mounts, 30.42lbs / 13.80kg shells, 1927 Model
Quick firing gun in deck mount
on centreline amidships, 1 raised gun
2 - 0.54" / 13.7 mm guns (1x2 guns), 0.08lbs / 0.04kg shells, 1927 Model
Machine guns in deck mount
on side
Weight of broadside 31 lbs / 14 kg
Shells per gun, main battery: 150
8 - 21.0" / 533 mm submerged torpedo tubes

Machinery:
Diesel Internal combustion engines plus batteries,
Electric cruising motors plus geared drives, 2 shafts, 1,800 shp / 1,343 Kw = 15.01 kts
Range 18,050nm at 10.00 kts
Bunker at max displacement = 506 tons

Complement:
108 - 141

Cost:
£0.168 million / $0.672 million

Distribution of weights at normal displacement:
Armament: 4 tons, 0.3 %
Machinery: 57 tons, 4.3 %
Hull, fittings & equipment: 659 tons, 50.3 %
Fuel, ammunition & stores: 310 tons, 23.7 %
Miscellaneous weights: 280 tons, 21.4 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
519 lbs / 236 Kg = 17.0 x 3.9 " / 100 mm shells or 0.4 torpedoes
Stability (Unstable if below 1.00): 1.01
Metacentric height 0.6 ft / 0.2 m
Roll period: 12.9 seconds
Steadiness - As gun platform (Average = 50 %): 0 %
- Recoil effect (Restricted arc if above 1.00): 0.00
Seaboat quality (Average = 1.00): 0.00

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.530
Length to Beam Ratio: 10.00 : 1
'Natural speed' for length: 15.15 kts
Power going to wave formation at top speed: 41 %
Trim (Max stability = 0, Max steadiness = 100): 50
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: 0.00 ft / 0.00 m
- Forecastle (20 %): 0.00 ft / 0.00 m
- Mid (50 %): 0.00 ft / 0.00 m
- Quarterdeck (15 %): 0.00 ft / 0.00 m
- Stern: 0.00 ft / 0.00 m
- Average freeboard: 0.00 ft / 0.00 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 112.5 %
- Above water (accommodation/working, high = better): 0.0 %
Waterplane Area: 3,613 Square feet or 336 Square metres
Displacement factor (Displacement / loading): 309 %
Structure weight / hull surface area: 115 lbs/sq ft or 563 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 3.46
- Longitudinal: 2.18
- Overall: 2.44
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is extremely poor
Ship has quick, lively roll, not a steady gun platform
Caution: Lacks seaworthiness - very limited seakeeping ability

Operational Diving Depth=73m
Emergency Diving Depth=117m
Crush Depth=183m

Ships in Class;

Leonardo da Vinci Laid down 1928
Marconi Laid down 1928
Torelli Laid down 1928
Baracca Laid down 1928



Da Vinci, Italian Ocean Going Submarine laid down 1928

Displacement:
1,000 t light; 1,030 t standard; 1,388 t normal; 1,675 t full load

Dimensions: Length overall / water x beam x draught
229.66 ft / 229.66 ft x 22.97 ft x 19.69 ft (normal load)
70.00 m / 70.00 m x 7.00 m x 6.00 m

Armament:
1 - 3.94" / 100 mm guns in single mounts, 30.42lbs / 13.80kg shells, 1928 Model
Breech loading gun in deck mount
on centreline amidships, 1 raised gun
2 - 0.79" / 20.0 mm guns (1x2 guns), 0.24lbs / 0.11kg shells, 1928 Model
Breech loading guns in deck mount
on side, all raised guns
Weight of broadside 31 lbs / 14 kg
Shells per gun, main battery: 150
8 - 21.0" / 533 mm submerged torpedo tubes

Machinery:
Diesel Internal combustion engines plus batteries,
Electric cruising motors plus geared drives, 2 shafts, 4,200 shp / 3,133 Kw = 18.54 kts
Range 14,130nm at 12.00 kts
Bunker at max displacement = 644 tons

Complement:
113 - 147

Cost:
£0.216 million / $0.864 million

Distribution of weights at normal displacement:
Armament: 4 tons, 0.3 %
Machinery: 131 tons, 9.4 %
Hull, fittings & equipment: 665 tons, 47.9 %
Fuel, ammunition & stores: 388 tons, 28.0 %
Miscellaneous weights: 200 tons, 14.4 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
382 lbs / 173 Kg = 12.5 x 3.9 " / 100 mm shells or 0.3 torpedoes
Stability (Unstable if below 1.00): 1.05
Metacentric height 0.6 ft / 0.2 m
Roll period: 12.4 seconds
Steadiness - As gun platform (Average = 50 %): 0 %
- Recoil effect (Restricted arc if above 1.00): 0.00
Seaboat quality (Average = 1.00): 0.00

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.468
Length to Beam Ratio: 10.00 : 1
'Natural speed' for length: 15.15 kts
Power going to wave formation at top speed: 49 %
Trim (Max stability = 0, Max steadiness = 100): 50
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: 0.00 ft / 0.00 m
- Forecastle (20 %): 0.00 ft / 0.00 m
- Mid (50 %): 0.00 ft / 0.00 m
- Quarterdeck (15 %): 0.00 ft / 0.00 m
- Stern: 0.00 ft / 0.00 m
- Average freeboard: 0.00 ft / 0.00 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 136.5 %
- Above water (accommodation/working, high = better): 0.0 %
Waterplane Area: 3,416 Square feet or 317 Square metres
Displacement factor (Displacement / loading): 282 %
Structure weight / hull surface area: 110 lbs/sq ft or 536 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 2.97
- Longitudinal: 2.98
- Overall: 2.97
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is extremely poor
Ship has quick, lively roll, not a steady gun platform
Caution: Lacks seaworthiness - very limited seakeeping ability

Operational Diving Depth=89m
Emergency Diving Depth=142m
Crush Depth=222m

Antonio Sciesca Class Submarine

7 Units laid down 1930

Antonio Sciesa
Balilla
Domenico Millelire
Enrico Toti
Giovanni da Procida
Goffredo Mameli
Pier Capponi


Italian Ocean Going Submarine laid down 1930

Displacement:
1,500 t light; 1,548 t standard (sub); 2,203 t normal; 2,727 t full load

Dimensions: Length overall / water x beam x draught
259.19 ft / 259.19 ft x 25.92 ft x 21.65 ft (normal load)
79.00 m / 79.00 m x 7.90 m x 6.60 m

Armament:
2 - 3.94" / 100 mm guns in single mounts, 30.42lbs / 13.80kg shells, 1930 Model
Breech loading guns in deck mounts
on centreline, all amidships
1 - 1.00" / 25.4 mm guns in single mounts, 0.52lbs / 0.24kg shells, 1930 Model
Anti-aircraft gun in deck mount
on side, 1 raised gun
Weight of broadside 61 lbs / 28 kg
Shells per gun, main battery: 120
10 - 17.7" / 450 mm submerged torpedo tubes ( 6 fore, 4 aft )

Machinery:
Diesel Internal combustion engines plus batteries,
Electric cruising motors plus geared drives, 2 shafts, 4,000 shp / 2,984 Kw = 17.14 kts
Range 20,530nm at 12.00 kts
Bunker at max displacement = 1,179 tons

Complement:
159 - 208

Cost:
£0.317 million / $1.270 million

Distribution of weights at normal displacement:
Armament: 8 tons, 0.3 %
Machinery: 121 tons, 5.5 %
Hull, fittings & equipment: 971 tons, 44.1 %
Fuel, ammunition & stores: 703 tons, 31.9 %
Miscellaneous weights: 400 tons, 18.2 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,246 lbs / 565 Kg = 40.8 x 3.9 " / 100 mm shells or 0.6 torpedoes
Stability (Unstable if below 1.00): 1.00
Metacentric height 0.7 ft / 0.2 m
Roll period: 13.4 seconds
Steadiness - As gun platform (Average = 50 %): 0 %
- Recoil effect (Restricted arc if above 1.00): 0.00
Seaboat quality (Average = 1.00): 0.00

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.530
Length to Beam Ratio: 10.00 : 1
'Natural speed' for length: 16.10 kts
Power going to wave formation at top speed: 45 %
Trim (Max stability = 0, Max steadiness = 100): 50
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: 0.00 ft / 0.00 m
- Forecastle (20 %): 0.00 ft / 0.00 m
- Mid (50 %): 0.00 ft / 0.00 m
- Quarterdeck (15 %): 0.00 ft / 0.00 m
- Stern: 0.00 ft / 0.00 m
- Average freeboard: 0.00 ft / 0.00 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 88.0 %
- Above water (accommodation/working, high = better): 0.0 %
Waterplane Area: 4,601 Square feet or 427 Square metres
Displacement factor (Displacement / loading): 313 %
Structure weight / hull surface area: 123 lbs/sq ft or 600 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 3.01
- Longitudinal: 2.61
- Overall: 2.70
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is extremely poor
Ship has quick, lively roll, not a steady gun platform
Caution: Lacks seaworthiness - very limited seakeeping ability

Operational Diving Depth=80m
Emergency Diving Depth=130m
Crush Depth=200m

400t misc. weight = 300tons ballast tanks + 20x450mm torpedoes(20t) + 80tons extra stores for extended patrols

Date 1930
Ocean=1 Coast=0 1
misc wt 50
Gun cal cm 10
ElecHP 1500 Max Sub Spd 7.8

DieselHP 8000 Max Surf Spd 19.6

L 79.0
Beam 7.9
D 6.6
Crush depth 225
sigma 480
#TT 10
mines 0
Tons Oil 500.0
Tons Battery 150.0

Cruise speed 10
Submerged speed 4
Cruise Power 1064 Range 23494

CREW 65
D_body 4.6
SpaceK 26.0
T_sheet 2.2
Structure mass 704.2
wt gun 7.5
misc wt 50
wt TT 150
wt mines 0
wt motors 58
wt diesel 119

wt H2O2 0
wt fuel&batts 650
kerb wt 1739
disp 2060
res buoyancy 16%

Submgd power 199 Range 89

9 Laid down 1931

Argonauta, Fisalia, Jalea, Jantina, Medusa, Salpa, Serpente, Ametista, Anfitrite

10 Laid down 1932

Diamante, Galatea, Naiade, Nereide, Ondina, Rubino, Sirena, Smeraldo, Topazio, Zaffiro

Note: Submarines Salpa, Serpente and Sirena modified for use with Xa MAS along lines shown at bottom.


Argonauta, Italian Submarine laid down 1931

Displacement:
449 t light; 462 t standard; 535 t normal; 593 t full load

Dimensions: Length overall / water x beam x draught
164.04 ft / 164.04 ft x 16.40 ft x 13.12 ft (normal load)
50.00 m / 50.00 m x 5.00 m x 4.00 m

Armament:
1 - 3.94" / 100 mm guns in single mounts, 33.07lbs / 15.00kg shells, 1931 Model
Quick firing gun in deck mount
on centreline amidships, 1 raised gun
2 - 0.98" / 25.0 mm guns in single mounts, 0.52lbs / 0.24kg shells, 1931 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
Weight of broadside 34 lbs / 15 kg
Shells per gun, main battery: 100
4 - 21.0" / 533 mm submerged torpedo tubes

Machinery:
Diesel Internal combustion engines plus batteries,
Electric cruising motors plus geared drives, 2 shafts, 1,000 shp / 746 Kw = 14.46 kts
Range 8,000nm at 10.00 kts
Bunker at max displacement = 131 tons

Complement:
55 - 72

Cost:
£0.101 million / $0.405 million

Distribution of weights at normal displacement:
Armament: 4 tons, 0.7 %
Machinery: 30 tons, 5.6 %
Hull, fittings & equipment: 315 tons, 59.0 %
Fuel, ammunition & stores: 86 tons, 16.0 %
Miscellaneous weights: 100 tons, 18.7 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
184 lbs / 84 Kg = 6.0 x 3.9 " / 100 mm shells or 0.2 torpedoes
Stability (Unstable if below 1.00): 1.00
Metacentric height 0.3 ft / 0.1 m
Roll period: 12.0 seconds
Steadiness - As gun platform (Average = 50 %): 0 %
- Recoil effect (Restricted arc if above 1.00): 0.00
Seaboat quality (Average = 1.00): 0.00

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.530
Length to Beam Ratio: 10.00 : 1
'Natural speed' for length: 12.81 kts
Power going to wave formation at top speed: 47 %
Trim (Max stability = 0, Max steadiness = 100): 50
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: 0.00 ft / 0.00 m
- Forecastle (20 %): 0.00 ft / 0.00 m
- Mid (50 %): 0.00 ft / 0.00 m
- Quarterdeck (15 %): 0.00 ft / 0.00 m
- Stern: 0.00 ft / 0.00 m
- Average freeboard: 0.00 ft / 0.00 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 120.3 %
- Above water (accommodation/working, high = better): 0.0 %
Waterplane Area: 1,843 Square feet or 171 Square metres
Displacement factor (Displacement / loading): 280 %
Structure weight / hull surface area: 102 lbs/sq ft or 498 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 3.93
- Longitudinal: 3.18
- Overall: 3.35
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is extremely poor
Ship has quick, lively roll, not a steady gun platform
Caution: Lacks seaworthiness - very limited seakeeping ability

Operational Diving Depth=100m
Emergency Diving Depth=160m
Crush Depth=250m


Date 1931
Ocean=1 Coast=0 0
Gun cal cm 10
ElecHP 750
DieselHP 2000
wt fuel&batts 94
kerb wt 449
disp 513
res buoyancy 12%
Max Surf Spd 16.8
Max Sub Spd 8.5

L 50.0
Beam 5.0
D 4.1
Crush depth 180
sigma 480
#TT 4
mines 0
Tons Oil 50.0
Tons Battery 44.0

Cruise speed 10 Cruise Power 418 Range 5976
Submerged speed 4 Submgd power 79 Range 63

10 Vessels laid down late 1932

Adua, Alagi, Aradam, Ascianghi, Axum, Beilul, Dagabur, Dessié, Durbo, Gondar

10 Vessels laid down 1935

Aluminio, Amianto, Attinio, Azoto, Bario, Bromo, Cadmio, Cernia, Corbonio, Cromo

A smaller type more useful for operations in the Eastern Med. and Red Sea

Because of the need for operations in confined waterspaces close to land this class is considerably different. The hull is not strengthened to the same extent as previous, crush depth being 125m instead of the previous 180m. The hull is more streamlined with no deck gun being carried. For operations close to land it was thought better to remain submerged. The 1600hp electric motors and batteries have been taken from the previous Antonio Sciesca Class. This large increase in power and the more streamlined hull gives a faster underwater speed of 16knts. Nearly enough to avoid escorting vessels. A 750hp Fiat Diesel is used for surface propulsion and to charge the batteries. For the first time the Mililiter device will be fitted to a class as a whole after succesful trials from 1925 onwards onboard S3. This will help again in having the submarines remain underwater and undetected. 4x533mm torpedo tubes are fitted forwards with 8 torpedoes carried. A D3 sonar set is carried forwards to help with ranging and early warning.

Date custom
Ocean=1 Coast=0 0
Gun cal cm 0
ElecHP 1600
DieselHP 750
CREW 24
wt fuel&batts 160
kerb wt 355
disp 396
res buoyancy 10%
Max Surf Spd 12.8
Max Sub Spd 16.1

L 44.0
Beam 4.5
D 4.0
Crush depth 125
#TT 4
Tons Oil 20.0
Tons Battery 140.0

Cruise speed 2778nm@10knts
Submerged speed 757nm@4knts

laid down 1933

Displacement:
365 t light; 373 t standard; 396 t normal; 414 t full load

Dimensions: Length overall / water x beam x draught
144.36 ft / 144.36 ft x 14.76 ft x 13.12 ft (normal load)
44.00 m / 44.00 m x 4.50 m x 4.00 m

Armament:
1 - 0.98" / 25.0 mm guns in single mounts, 0.48lbs / 0.22kg shells, 1933 Model
Anti-aircraft gun in deck mount
on centreline amidships
Weight of broadside 0 lbs / 0 kg
Shells per gun, main battery: 2,000
4 - 21.0" / 533 mm submerged torpedo tubes

Machinery:
Diesel Internal combustion engines plus batteries,
Electric cruising motors plus geared drives, 1 shaft, 547 shp / 408 Kw = 12.80 kts
Range 2,800nm at 10.00 kts
Bunker at max displacement = 41 tons

Complement:
43 - 57

Cost:
£0.071 million / $0.285 million

Distribution of weights at normal displacement:
Armament: 0 tons, 0.0 %
Machinery: 16 tons, 4.0 %
Hull, fittings & equipment: 282 tons, 71.2 %
Fuel, ammunition & stores: 31 tons, 7.9 %
Miscellaneous weights: 67 tons, 16.9 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
81 lbs / 37 Kg = 170.8 x 1.0 " / 25 mm shells or 0.1 torpedoes
Stability (Unstable if below 1.00): 1.01
Metacentric height 0.3 ft / 0.1 m
Roll period: 11.5 seconds
Steadiness - As gun platform (Average = 50 %): 0 %
- Recoil effect (Restricted arc if above 1.00): 0.00
Seaboat quality (Average = 1.00): 0.00

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.496
Length to Beam Ratio: 9.78 : 1
'Natural speed' for length: 12.01 kts
Power going to wave formation at top speed: 42 %
Trim (Max stability = 0, Max steadiness = 100): 50
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: 0.00 ft / 0.00 m
- Forecastle (20 %): 0.00 ft / 0.00 m
- Mid (50 %): 0.00 ft / 0.00 m
- Quarterdeck (15 %): 0.00 ft / 0.00 m
- Stern: 0.00 ft / 0.00 m
- Average freeboard: 0.00 ft / 0.00 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 156.4 %
- Above water (accommodation/working, high = better): 0.0 %
Waterplane Area: 1,358 Square feet or 126 Square metres
Displacement factor (Displacement / loading): 399 %
Structure weight / hull surface area: 112 lbs/sq ft or 547 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 4.76
- Longitudinal: 5.00
- Overall: 4.78
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is extremely poor
Ship has quick, lively roll, not a steady gun platform
Caution: Lacks seaworthiness - very limited seakeeping ability

Perla Class



Evolution over Argonauta Class better suited to prolonged operations. Different hull reflects increased emphasis on seakeeping and handling. 4x533mm torpedo tubes are fitted forwards with 8 torpedoes carried. A D3 sonar set is carried forwards to help with ranging and early warning. All boats fitted with mine laying equipment, 28 mines maximum.

10 Vessels laid down in 1933
20 Vessels laid down in 1934
10 Vessels laid down in 1935

10 Ships Sold to Thailand 1940

P1 - P40

Date 1933
Coastal
Armament 1x 100/35, 2x 25
ElecHP 600
DieselHP 1000
CREW 25
wt fuel&batts 65
kerb wt 375
disp 423
res buoyancy 11%
Max Surf Spd 13.9
Max Sub Spd 8.2

L 46.0
Beam 4.6
D 4.0
Crush depth 180
#TT 4
mines 28
Tons Oil 20.0
Tons Battery 45.0

Range 2663@10knts
Underwater range 75@4knts

laid down 1933

Displacement:
390 t light; 400 t standard; 423 t normal; 441 t full load

Dimensions: Length overall / water x beam x draught
147.64 ft / 147.64 ft x 15.09 ft x 13.12 ft (normal load)
45.00 m / 45.00 m x 4.60 m x 4.00 m

Armament:
1 - 3.94" / 100 mm guns in single mounts, 30.51lbs / 13.84kg shells, 1933 Model
Quick firing gun in deck mount
on centreline amidships
2 - 0.98" / 25.0 mm guns in single mounts, 0.48lbs / 0.22kg shells, 1933 Model
Anti-aircraft guns in deck mounts
on side, all amidships
Weight of broadside 31 lbs / 14 kg
Shells per gun, main battery: 100
4 - 21.0" / 533 mm submerged torpedo tubes

Machinery:
Diesel Internal combustion engines plus batteries,
Electric cruising motors plus geared drives, 1 shaft, 773 shp / 577 Kw = 13.90 kts
Range 2,700nm at 10.00 kts
Bunker at max displacement = 41 tons

Complement:
46 - 60

Cost:
£0.095 million / $0.380 million

Distribution of weights at normal displacement:
Armament: 4 tons, 0.9 %
Machinery: 23 tons, 5.3 %
Hull, fittings & equipment: 293 tons, 69.1 %
Fuel, ammunition & stores: 33 tons, 7.8 %
Miscellaneous weights: 71 tons, 16.8 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
68 lbs / 31 Kg = 2.2 x 3.9 " / 100 mm shells or 0.1 torpedoes
Stability (Unstable if below 1.00): 1.02
Metacentric height 0.3 ft / 0.1 m
Roll period: 11.5 seconds
Steadiness - As gun platform (Average = 50 %): 0 %
- Recoil effect (Restricted arc if above 1.00): 0.00
Seaboat quality (Average = 1.00): 0.00

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.506
Length to Beam Ratio: 9.78 : 1
'Natural speed' for length: 12.15 kts
Power going to wave formation at top speed: 47 %
Trim (Max stability = 0, Max steadiness = 100): 50
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: 0.00 ft / 0.00 m
- Forecastle (20 %): 0.00 ft / 0.00 m
- Mid (50 %): 0.00 ft / 0.00 m
- Quarterdeck (15 %): 0.00 ft / 0.00 m
- Stern: 0.00 ft / 0.00 m
- Average freeboard: 0.00 ft / 0.00 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 177.5 %
- Above water (accommodation/working, high = better): 0.0 %
Waterplane Area: 1,437 Square feet or 133 Square metres
Displacement factor (Displacement / loading): 287 %
Structure weight / hull surface area: 112 lbs/sq ft or 546 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 4.52
- Longitudinal: 4.58
- Overall: 4.52
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is extremely poor
Ship has quick, lively roll, not a steady gun platform
Caution: Lacks seaworthiness - very limited seakeeping ability

T - Class

5 vessels laid down in 1936

T1, T2, T3, T4, T5

Date 1936
Oceanic
Armament 1x 100/35, 1x 25
ElecHP 1600
DieselHP 3600
CREW 44
wt fuel&batts 230
kerb wt 851
disp 1062
res buoyancy 20%
Max Surf Spd 17.2
Max Sub Spd 11.5

L 60.0m
Beam 6.0m
D 5.0m
Crush depth 250
#TT 8x 450mm
Tons Oil 130.0
Tons Battery 100.0

Range 9200@10knts
Underwater range 190@4knts

U-Class

4 vessels laid down 1937

U-1, U-2, U-3, U-4

4 vessels laid down 1940

U-5, U-6, U-7, U-8

Date 1937
Oceanic
Armament 1x 100/35, 1x 25
ElecHP 1600
DieselHP 3600
CREW 51
wt fuel&batts 380
Light weight 1150
kerb wt 1410
disp 1656
res buoyancy 15%
Max Surf Spd 15.5knts
Max Sub Spd 10.4knts (1hr rate)

L 70.0m
Beam 8.6m
D 5.5m
Crush depth 250
#TT 10 x 533mm (6 bow, 4 stern)
Tons Oil 260.0
Tons Battery 120.0

Surface Range 13500@10knts
Underwater range 170@4knts