WesWorld

Was fooling around with SS2 and decide to sim my RGBs (based on the British Una class):


Displacement, 20 tons
Dimensions, 50' x 12' x 2'
Armament, 1x47mm fow, 1x81mm mortar aft, 2x50cal MGs.
Speed, 10kts
Armor, 0.5"

And it actually worked!

Thoughts?


Mortar simed as 50mm muzzleloading gun.

RGB-1, Mexico River Gunboat laid down 1933

Displacement:
18 t light; 19 t standard; 20 t normal; 20 t full load

Dimensions: Length overall / water x beam x draught
50.00 ft / 50.00 ft x 12.00 ft x 2.00 ft (normal load)
15.24 m / 15.24 m x 3.66 m x 0.61 m

Armament:
1 - 1.85" / 47.0 mm guns in single mounts, 3.17lbs / 1.44kg shells, 1933 Model
Breech loading gun in deck mount
on centreline forward
1 - 3.19" / 81.0 mm Mortar in single mounts, 16.22lbs / 7.36kg shells, 1933 Model
Mortar in deck mount
on centreline aft
2 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1933 Model
Machine guns in deck mounts
on side, evenly spread
Weight of broadside 7 lbs / 3 kg
Shells per gun, main battery: 100

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 0.50" / 13 mm 50.00 ft / 15.24 m 4.00 ft / 1.22 m
Ends: Unarmoured
Main Belt covers 154 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.50" / 13 mm - -

- Conning tower: 0.50" / 13 mm

Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 56 shp / 42 Kw = 10.00 kts
Range 1,000nm at 5.00 kts
Bunker at max displacement = 1 tons

Complement:
4 - 6

Cost:
£0.008 million / $0.031 million

Distribution of weights at normal displacement:
Armament: 1 tons, 4.5 %
Armour: 4 tons, 21.5 %
- Belts: 4 tons, 18.9 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 0 tons, 2.2 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 0 tons, 0.4 %
Machinery: 2 tons, 8.4 %
Hull, fittings & equipment: 10 tons, 48.9 %
Fuel, ammunition & stores: 1 tons, 6.4 %
Miscellaneous weights: 2 tons, 10.2 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
57 lbs / 26 Kg = 17.9 x 1.9 " / 47 mm shells or 0.2 torpedoes
Stability (Unstable if below 1.00): 1.16
Metacentric height 0.3 ft / 0.1 m
Roll period: 9.6 seconds
Steadiness - As gun platform (Average = 50 %): 50 %
- Recoil effect (Restricted arc if above 1.00): 0.20
Seaboat quality (Average = 1.00): 1.00

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.570
Length to Beam Ratio: 4.17 : 1
'Natural speed' for length: 7.07 kts
Power going to wave formation at top speed: 66 %
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: 5.00 ft / 1.52 m
- Forecastle (20 %): 5.00 ft / 1.52 m
- Mid (50 %): 5.00 ft / 1.52 m
- Quarterdeck (15 %): 4.00 ft / 1.22 m
- Stern: 4.00 ft / 1.22 m
- Average freeboard: 4.68 ft / 1.42 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 73.4 %
- Above water (accommodation/working, high = better): 96.1 %
Waterplane Area: 427 Square feet or 40 Square metres
Displacement factor (Displacement / loading): 118 %
Structure weight / hull surface area: 14 lbs/sq ft or 70 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.79
- Longitudinal: 8.91
- Overall: 1.00
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is adequate

Looks good to me. Why'd you sim an 81 mm mortar as a 50 mm breachloader, rather than an 81 mm weapon?

Because if I simmed it as an 81mm gun the armament weight goes up to 4 tons wrecking the design.