Gunboats, Launchs, and Submarine Chasers

[The Rock Doctor]

Definition:

Small, low-endurance vessels designed for coastal protection duties.  Endurance likely limited to one or two days.  Unarmored.  Does Not include inland river units operated by the Force Publique.

Nomenclature:

Currently assigned numbers.

Note:

The concept of "Submarine Chaser" has not occurred to the Belgians; I'm simply tacking it in to the title so I don't need to fight with it in 1910 or 1914.

[The Rock Doctor]

G-1 Class Gunboat

A batch of basic patrol units, the first few built in Britain, the last ones being built entirely in Belgium.

The low endurance is a problem for transfers; those units deployed to Liberia and the Congo Free State were actually towed there, and one unit, G-11, was almost lost in a squall this way.

G-1 to G-4, laid down 1897
G-5 to G-8, laid down 1898
G-9 to G-12, laid down 1899

Gunboat, laid down 1897

Displacement:
   124 t light; 128 t standard; 136 t normal; 143 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (98.43 ft / 98.43 ft) x 16.40 ft x (4.92 / 5.12 ft)
   (30.00 m / 30.00 m) x 5.00 m  x (1.50 / 1.56 m)

Armament:
      1 - 2.24" / 57.0 mm 45.0 cal gun - 5.71lbs / 2.59kg shells, 150 per gun
     Breech loading gun in deck mount, 1897 Model
     1 x Single mount on centreline, aft deck aft
      3 - 0.31" / 8.0 mm 45.0 cal guns - 0.02lbs / 0.01kg shells, 15,000 per gun
     Machine guns in deck mounts, 1897 Model
     2 x Single mounts on sides amidships
     1 x Single mount on centreline, aft deck centre
      Weight of broadside 6 lbs / 3 kg

Machinery:
   Coal fired boilers, complex reciprocating steam engines,
   Direct drive, 2 shafts, 600 ihp / 448 Kw = 14.56 kts
   Range 600nm at 10.00 kts
   Bunker at max displacement = 15 tons (100% coal)

Complement:
   19 - 25

Cost:
   £0.014 million / $0.057 million

Distribution of weights at normal displacement:
   Armament: 1 tons, 0.8 %
      - Guns: 1 tons, 0.8 %
   Machinery: 68 tons, 50.0 %
   Hull, fittings & equipment: 48 tons, 35.4 %
   Fuel, ammunition & stores: 12 tons, 8.7 %
   Miscellaneous weights: 7 tons, 5.1 %
      - Hull above water: 7 tons
        -5 t:  Short-term accommodation for 5 troops/customs personnel
        -2 t:  Weight reserve / deck cargo

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     84 lbs / 38 Kg = 14.9 x 2.2 " / 57 mm shells or 0.1 torpedoes
   Stability (Unstable if below 1.00): 1.46
   Metacentric height 0.6 ft / 0.2 m
   Roll period: 8.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.05
   Seaboat quality  (Average = 1.00): 1.50

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.600 / 0.605
   Length to Beam Ratio: 6.00 : 1
   'Natural speed' for length: 9.92 kts
   Power going to wave formation at top speed: 68 %
   Trim (Max stability = 0, Max steadiness = 100): 47
   Bow angle (Positive = bow angles forward): 0.00 degrees
   Stern overhang: -1.64 ft / -0.50 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  7.87 ft / 2.40 m,  7.87 ft / 2.40 m
      - Forward deck:   30.00 %,  7.87 ft / 2.40 m,  7.87 ft / 2.40 m
      - Aft deck:   35.00 %,  7.87 ft / 2.40 m,  7.87 ft / 2.40 m
      - Quarter deck:   15.00 %,  7.87 ft / 2.40 m,  7.87 ft / 2.40 m
      - Average freeboard:      7.87 ft / 2.40 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 169.8 %
      - Above water (accommodation/working, high = better): 93.2 %
   Waterplane Area: 1,181 Square feet or 110 Square metres
   Displacement factor (Displacement / loading): 66 %
   Structure weight / hull surface area: 21 lbs/sq ft or 103 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.79
      - Longitudinal: 8.05
      - Overall: 1.00
   Cramped machinery, storage, compartmentation space
   Adequate accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform
   Good seaboat, rides out heavy weather easily