WesWorld

Patrol Boats will appear here once built.

RPB-1, Japan River Police Boat laid down 1928
Built: 10.

Displacement:
142 t light; 149 t standard; 168 t normal; 183 t full load

Dimensions: Length overall / water x beam x draught
141.41 ft / 140.00 ft x 30.00 ft x 2.00 ft (normal load)
43.10 m / 42.67 m x 9.14 m x 0.61 m

Armament:
1 - 2.95" / 75.0 mm guns in single mounts, 13.00lbs / 5.90kg shells, 1921 Model
Dual purpose gun in deck mount
on centreline forward
8 - 0.98" / 25.0 mm guns (4x2 guns), 0.57lbs / 0.26kg shells, 1926 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
Weight of broadside 18 lbs / 8 kg
Shells per gun, main battery: 300

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 2.00" / 51 mm 1.00" / 25 mm -
2nd: 1.00" / 25 mm - -

- Conning tower: 3.00" / 76 mm

Machinery:
Oil fired boilers, steam turbines,
Direct drive, 2 shafts, 848 shp / 632 Kw = 15.00 kts
Range 2,800nm at 10.00 kts
Bunker at max displacement = 34 tons

Complement:
23 - 30

Cost:
£0.040 million / $0.159 million

Distribution of weights at normal displacement:
Armament: 2 tons, 1.2 %
Armour: 6 tons, 3.5 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 4 tons, 2.4 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 2 tons, 1.2 %
Machinery: 26 tons, 15.7 %
Hull, fittings & equipment: 108 tons, 64.1 %
Fuel, ammunition & stores: 26 tons, 15.4 %
Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
718 lbs / 326 Kg = 55.8 x 3.0 " / 75 mm shells or 0.8 torpedoes
Stability (Unstable if below 1.00): 1.30
Metacentric height 1.3 ft / 0.4 m
Roll period: 11.0 seconds
Steadiness - As gun platform (Average = 50 %): 51 %
- Recoil effect (Restricted arc if above 1.00): 0.02
Seaboat quality (Average = 1.00): 0.71

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.700
Length to Beam Ratio: 4.67 : 1
'Natural speed' for length: 11.83 kts
Power going to wave formation at top speed: 53 %
Trim (Max stability = 0, Max steadiness = 100): 72
Bow angle (Positive = bow angles forward): 10.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 8.00 ft / 2.44 m
- Forecastle (10 %): 6.50 ft / 1.98 m
- Mid (50 %): 6.50 ft / 1.98 m
- Quarterdeck (15 %): 6.50 ft / 1.98 m
- Stern: 6.50 ft / 1.98 m
- Average freeboard: 6.56 ft / 2.00 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 63.1 %
- Above water (accommodation/working, high = better): 181.2 %
Waterplane Area: 3,366 Square feet or 313 Square metres
Displacement factor (Displacement / loading): 223 %
Structure weight / hull surface area: 28 lbs/sq ft or 137 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.94
- Longitudinal: 2.04
- Overall: 1.02
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is excellent
Poor seaboat, wet and uncomfortable, reduced performance in heavy weather


RPB-1, Japan River Police Boat laid down 1928 (1945 refit)

Displacement:
142 t light; 149 t standard; 168 t normal; 183 t full load

Dimensions: Length overall / water x beam x draught
141.41 ft / 140.00 ft x 30.00 ft x 2.00 ft (normal load)
43.10 m / 42.67 m x 9.14 m x 0.61 m

Armament:
1 - 2.95" / 75.0 mm guns in single mounts, 12.00lbs / 5.44kg shells, 1945 Model
Dual purpose gun in deck mount
on centreline forward
8 - 0.98" / 25.0 mm guns (4x2 guns), 0.57lbs / 0.26kg shells, 1945 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
Weight of broadside 17 lbs / 8 kg
Shells per gun, main battery: 300

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 2.00" / 51 mm 1.00" / 25 mm -
2nd: 1.00" / 25 mm - -

- Conning tower: 3.00" / 76 mm

Machinery:
Oil fired boilers, steam turbines,
Direct drive, 2 shafts, 848 shp / 632 Kw = 15.00 kts
Range 2,800nm at 10.00 kts
Bunker at max displacement = 34 tons

Complement:
23 - 30

Cost:
£0.040 million / $0.159 million

Distribution of weights at normal displacement:
Armament: 2 tons, 1.2%
Armour: 6 tons, 3.5%
- Belts: 0 tons, 0.0%
- Torpedo bulkhead: 0 tons, 0.0%
- Armament: 4 tons, 2.4%
- Armour Deck: 0 tons, 0.0%
- Conning Tower: 2 tons, 1.2%
Machinery: 26 tons, 15.7%
Hull, fittings & equipment: 108 tons, 64.2%
Fuel, ammunition & stores: 26 tons, 15.3%
Miscellaneous weights: 0 tons, 0.0%

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
719 lbs / 326 Kg = 55.9 x 3.0 " / 75 mm shells or 0.8 torpedoes
Stability (Unstable if below 1.00): 1.30
Metacentric height 1.3 ft / 0.4 m
Roll period: 11.0 seconds
Steadiness - As gun platform (Average = 50 %): 51 %
- Recoil effect (Restricted arc if above 1.00): 0.02
Seaboat quality (Average = 1.00): 0.71

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.700
Length to Beam Ratio: 4.67 : 1
'Natural speed' for length: 11.83 kts
Power going to wave formation at top speed: 53 %
Trim (Max stability = 0, Max steadiness = 100): 72
Bow angle (Positive = bow angles forward): 10.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 8.00 ft / 2.44 m
- Forecastle (10%): 6.50 ft / 1.98 m
- Mid (50%): 6.50 ft / 1.98 m
- Quarterdeck (15%): 6.50 ft / 1.98 m
- Stern: 6.50 ft / 1.98 m
- Average freeboard: 6.56 ft / 2.00 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 63.0%
- Above water (accommodation/working, high = better): 181.2%
Waterplane Area: 3,366 Square feet or 313 Square metres
Displacement factor (Displacement / loading): 223%
Structure weight / hull surface area: 28 lbs/sq ft or 137 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.94
- Longitudinal: 2.04
- Overall: 1.02
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is excellent
Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

PBR, 1931 (Patrol Boat Riverine; not to be confused with the Japanese RPB which stands for River Police Boat)
Built: 101.
Displacement: 6.8 tons light, 8.1 tons full load
Length: 32 feet
Beam: 11 2/3 feet
Draft: 2.5 feet
Propulsion: 2 KHI 6V53N diesels, 220 hp, 2 water jets, fuel - 160 gal.
Speed: 28 knots
Range: 4 or 5 (enlisted)
Crew: 4 or 5 (enlisted)
Weapons: 1 twin 13.2 MGs (center forward), 1 single 13.2mm MG (center aft), 2 7.7mm MGs (sides aft) + personal weapons of the crew


Refitted in 1945