WesWorld

Quoted

Originally posted by BruceDuncan

Low-stowed cargo simmed as torpedo bulkhead
Velocity: 11

*whistles innocently*

Quoted

Originally posted by Hrolf Hakonson
What's with the massively thick torpedo bulkhead? I doubt the original had that.....

One of the methods I have seen used to sim cargo, particularly cargo carried below the waterline, is to sim it as armor. That is cited in the notes. This seems to better reflect the stability of a freighter, whereas miscellaneous weight seems to reflect cargo carried above the waterline; hence both values.

As Springsharp is not - as I understand it - intended to model cargo ships that well, I took this as a compromise position. If that is not the proper way to sim low-stowed cargo, point me to the proper way.

For SS2, it will probably work fine. SS3 allows you to designate misc. weight as being below the waterline (among other places).

I've made some modifications to the design to address some of the variances from the historical example and to address issues of stability. I feel I've gone about as far on the historical issues as I should. The question is whether I have achieved sufficient stability and yet have a margin of strength.

Your comments are most welcome.

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C-1 Rev B, TBD River-Sea Freighter laid down 1940

Displacement: 4,988 t light; 5,094 t standard; 5,300 t normal; 5,465 t full load

Dimensions: Length overall / water x beam x draught
308.40 ft / 282.15 ft x 44.95 ft x 19.52 ft (normal load)
94.00 m / 86.00 m x 13.70 m x 5.95 m

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Ends: Unarmoured

- Torpedo Bulkhead:
13.4" / 340 mm 196.85 ft / 60.00 m 22.97 ft / 7.00 m

Machinery: Diesel Internal combustion motors, Geared drive, 1 shaft, 1,353 shp / 1,009 Kw = 11.00 kts; Range 6,000nm at 10.00 kts; Bunker at max displacement = 371 tons

Complement: 30 - 40

Cost: £1.078 million / $4.311 million

Distribution of weights at normal displacement:

Armament: 0 tons, 0.0 %
Armour: 2,239 tons, 42.2 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 2,239 tons, 42.2 %
- Armament: 0 tons, 0.0 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 36 tons, 0.7 %
Hull, fittings & equipment: 1,712 tons, 32.3 %
Fuel, ammunition & stores: 312 tons, 5.9 %
Miscellaneous weights: 1,000 tons, 18.9 %

Overall survivability and seakeeping ability:

Survivability (Non-critical penetrating hits needed to sink ship): 2,264 lbs / 1,027 Kg = 21 x 6 " / 152 mm shells or 1.1 torpedoes
Stability (Unstable if below 1.00): 1.10
Metacentric height 1.8 ft / 0.6 m
Roll period: 14.0 seconds
Steadiness - As gun platform (Average = 50 %): 90 %
- Recoil effect (Restricted arc if above 1.00): 0.00
Seaboat quality (Average = 1.00): 2.00

Hull form characteristics:

Hull has raised forecastle
Block coefficient: 0.749
Length to Beam Ratio: 6.28 : 1
'Natural speed' for length: 16.80 kts
Power going to wave formation at top speed: 33 %
Trim (Max stability = 0, Max steadiness = 100): 45
Bow angle (Positive = bow angles forward): 40.00 degrees
Stern overhang: 6.43 ft / 1.96 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 23.62 ft / 7.20 m
- Forecastle (20 %): 20.34 ft / 6.20 m (13.12 ft / 4.00 m aft of break)
- Mid (50 %): 21.33 ft / 6.50 m
- Quarterdeck (15 %): 13.12 ft / 4.00 m
- Stern: 21.33 ft / 6.50 m
- Average freeboard: 18.11 ft / 5.52 m

Ship space, strength and comments:

Space - Hull below water (magazines/engines, low = better): 43.9 %
- Above water (accommodation/working, high = better): 112.7 %
Waterplane Area: 10,615 Square feet or 986 Square metres
Displacement factor (Displacement / loading): 160 %
Structure weight / hull surface area: 92 lbs/sq ft or 448 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.35
- Longitudinal: 5.92
- Overall: 1.57
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is adequate
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable, rides out heavy weather easily

Low-stowed cargo simmed as torpedo bulkhead
High-stowed cargo simmed as miscellaneous weight
Rev A - Total cargo - 1646+800 = 2446 vice Historical Deadweight 3900dwt
Rev B - Added stern overhang to adjust overall length
Rev B - Increased torpedo bulkhead, nodified miscellaneous weight to seek imporved stability - 2239+1000 = 3239 tons vice 3900 dwt
Rev B - Modified block coefficient by increasing displacement to historical 5300 tons

Final crew size and damage values divided by 10 for civilian ships