River Class, Denmark Patrol boat laid down 1924
K.D.M. Aabenraa
K.D.M. Arnaa
K.D.M. Bredeaa
K.D.M. Fladaa
K.D.M. Gelsaa
K.D.M. Gronaa
K.D.M. Holmeaa
K.D.M. Kongeaa
K.D.M. Sneumaa
K.D.M. Sonderaa
K.D.M. Vardeaa
K.D.M. Lydumaa
K.D.M. Hoveraa
Displacement:
237 t light; 250 t standard; 283 t normal; 308 t full load
Loading submergence 56 tons/feet
Dimensions:
150.00 ft x 25.00 ft x 7.00 ft (normal load)
45.72 m x 7.62 m x 2.13 m
Armament:
2 - 4.00" / 102 mm guns
4 - 2.24" / 57 mm guns
4 - 0.79" / 20 mm AA guns
8 - 0.51" / 13 mm guns
Weight of broadside 88 lbs / 40 kg
Armour:
Main gun shields 1.00" / 25 mm, 2nd gun shields 0.50" / 13 mm
AA gun shields 0.50" / 13 mm
Conning tower 1.00" / 25 mm
Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 1,623 shp / 1,211 Kw = 18.00 kts
Range 5,000nm at 10.00 kts
Complement:
34 - 44
Cost:
£0.077 million / $0.309 million
Distribution of weights at normal displacement:
Armament: 11 tons, 3.9 %
Armour: 4 tons, 1.5 %
Belts: 0 tons, 0.0 %, Armament: 3 tons, 1.2 %, Armour Deck: 0 tons, 0.0 %
Conning Tower: 1 tons, 0.3 %, Torpedo bulkhead: 0 tons, 0.0 %
Machinery: 53 tons, 18.9 %
Hull, fittings & equipment: 138 tons, 48.9 %
Fuel, ammunition & stores: 46 tons, 16.2 %
Miscellaneous weights: 30 tons, 10.6 %
Metacentric height 0.7
Remarks:
Hull space for machinery, storage & compartmentation is adequate
Room for accommodation & workspaces is adequate
Ship has slow, easy roll, a good, steady gun platform
Good seaboat, rides out heavy weather easily
Estimated overall survivability and seakeeping ability:
Relative margin of stability: 1.04
Shellfire needed to sink: 377 lbs / 171 Kg = 11.8 x 4.0 " / 102 mm shells
(Approx weight of penetrating shell hits needed to sink ship excluding critical hits)
Torpedoes needed to sink: 0.4
(Approx number of typical torpedo hits needed to sink ship)
Relative steadiness as gun platform: 70 %
(Average = 50 %)
Relative rocking effect from firing to beam: 0.28
Relative quality as seaboat: 1.21
Hull form characteristics:
Block coefficient: 0.377
Sharpness coefficient: 0.34
Hull speed coefficient 'M': 6.98
'Natural speed' for length: 12.25 kts
Power going to wave formation at top speed: 62 %
Trim: 58
(Maximise stabilty/flotation = 0, Maximise steadiness/seakeeping = 100)
Estimated hull characteristics & strength:
Underwater volume absorbed by magazines and engineering spaces: 103.1 %
Relative accommodation and working space: 99.4 %
(Average = 100%)
Displacement factor: 123 %
(Displacement relative to loading factors)
Relative cross-sectional hull strength: 0.85
(Structure weight / hull surface area: 39 lbs / square foot or 192 Kg / square metre)
Relative longitudinal hull strength: 4.33
(for 9.10 ft / 2.77 m average freeboard, freeboard adjustment 1.68 ft)
Relative composite hull strength: 1.00
4" guns, those reclaimed from scrapped vessels, are to be used in this class.