Lightship design (Merchant)

Professional

Tuesday, March 2nd 2010, 5:29pm

(Great Thanks to BrockPaine for the SIM!!)

Lightship, Chile, Peru, Etc Lightship laid down 1938

Displacement:
462 t light; 478 t standard; 784 t normal; 1,029 t full load

Dimensions: Length overall / water x beam x draught
193.50 ft / 181.50 ft x 28.00 ft x 12.00 ft (normal load)
58.98 m / 55.32 m x 8.53 m x 3.66 m

Machinery:
Oil fired boilers, complex reciprocating steam engines,
Geared drive, 1 shaft, 598 ihp / 446 Kw = 12.00 kts
Range 15,000nm at 12.00 kts
Bunker at max displacement = 552 tons

Complement:
73 - 96

Cost:
£0.117 million / $0.469 million

Distribution of weights at normal displacement:
Armament: 0 tons, 0.0 %
Machinery: 33 tons, 4.2 %
Hull, fittings & equipment: 249 tons, 31.7 %
Fuel, ammunition & stores: 322 tons, 41.1 %
Miscellaneous weights: 180 tons, 23.0 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
2,226 lbs / 1,010 Kg = 20.6 x 6 " / 152 mm shells or 1.6 torpedoes
Stability (Unstable if below 1.00): 1.12
Metacentric height 0.9 ft / 0.3 m
Roll period: 12.3 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.00
Seaboat quality (Average = 1.00): 2.00

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.450
Length to Beam Ratio: 6.48 : 1
'Natural speed' for length: 13.47 kts
Power going to wave formation at top speed: 38 %
Trim (Max stability = 0, Max steadiness = 100): 35
Bow angle (Positive = bow angles forward): 25.12 degrees
Stern overhang: 4.50 ft / 1.37 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 16.00 ft / 4.88 m
- Forecastle (20 %): 12.00 ft / 3.66 m
- Mid (50 %): 9.00 ft / 2.74 m
- Quarterdeck (15 %): 11.00 ft / 3.35 m
- Stern: 13.00 ft / 3.96 m
- Average freeboard: 11.17 ft / 3.40 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 40.0 %
- Above water (accommodation/working, high = better): 82.4 %
Waterplane Area: 3,089 Square feet or 287 Square metres
Displacement factor (Displacement / loading): 318 %
Structure weight / hull surface area: 40 lbs/sq ft or 195 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.95
- Longitudinal: 5.27
- Overall: 1.13
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is cramped
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable, rides out heavy weather easily

368 tons ballast simmed as bunker fuel