Confederate Ship Designs: 1919 and Beyond...

[Carthaginian]

Well, the subs are kinda 'generic'- you use the chart and come up with one.
I'll admit, I moved one of the aft tubes to the forward set so I could build something 'unique,' but other than that it's just some historic dimensions and the chart to give me some rough idea of how powerful I can build a sub within the rules.

[Logi]

Well the submarine isn't really a design issue so much as BP issue.

[Sachmle]

tis only 1 BP

[TexanCowboy]

I'm still in favor of using the WW sim rules....

[Carthaginian]

A part of the storyline recently begun...

The Confederacy, unhappy with the sudden return of the Brethren and insecure after the death of their leader, has begun a crash program in border and maritime security. Plans for the activation of a reserve army formation and the construction of a powerful coastal patrol network are underway.
The sloops operated by the Navy are too large and too short-ranged for the kinds of work envisioned by this new force. As a result, the Border Guards are forced to seek outside designs for their use. A civilian trawler company offered to modify one of their offshore fishing designs to mount some light armament, and the result is the Alpha class of cutters. Designed for long range, high endurance at sea and very good relative handling characteristics, these small but sturdy ships are fast enough that most merchants can be caught, and armed heavily enough that any vessel considering running should think twice.

*NOTE: The miscellaneous weight includes 1 ton of small arms, enabling the crew of the ship to divide off into boarding parties as needed. The ship itself can be operated by as few as 10 men as long as the guns aren't manned... though no one is getting any sleep in this situation.

PC-01, Confederate States Boarder Guards Cutter, Patrol laid down 1920

Displacement:
   250 t light; 262 t standard; 375 t normal; 466 t full load

Dimensions: Length overall / water x beam x draught
   135.00 ft / 125.00 ft x 20.00 ft x 10.00 ft (normal load)
   41.15 m / 38.10 m x 6.10 m  x 3.05 m

Armament:
     2 - 2.75" / 69.9 mm guns in single mounts, 10.00lbs / 4.54kg shells, 1920 Model
     Quick firing guns in deck mounts
     on centreline ends, evenly spread
     4 - 1.00" / 25.4 mm guns in single mounts, 0.50lbs / 0.23kg shells, 1920 Model
     Machine guns in deck mounts
     on side, all amidships, all raised mounts - superfiring
   Weight of broadside 22 lbs / 10 kg
   Shells per gun, main battery: 300

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

Machinery:
   Diesel Internal combustion motors,
   Geared drive, 2 shafts, 2,370 shp / 1,768 Kw = 18.02 kts
   Range 8,150nm at 12.00 kts
   Bunker at max displacement = 204 tons

Complement:
   42 - 55

Cost:
   £0.054 million / $0.215 million

Distribution of weights at normal displacement:
   Armament: 3 tons, 0.8 %
   Armour: 1 tons, 0.4 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 1 tons, 0.4 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 83 tons, 22.1 %
   Hull, fittings & equipment: 116 tons, 30.8 %
   Fuel, ammunition & stores: 125 tons, 33.3 %
   Miscellaneous weights: 48 tons, 12.7 %
      20t - extra food, water, etc
        1t - small arms and ammunition
        1t - 2 collapsible life rafts
      26t - hull reenforcement for weapons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     507 lbs / 230 Kg = 48.8 x 2.8 " / 70 mm shells or 0.4 torpedoes
   Stability (Unstable if below 1.00): 1.15
   Metacentric height 0.6 ft / 0.2 m
   Roll period: 11.0 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.11
   Seaboat quality  (Average = 1.00): 1.32

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.525
   Length to Beam Ratio: 6.25 : 1
   'Natural speed' for length: 11.18 kts
   Power going to wave formation at top speed: 72 %
   Trim (Max stability = 0, Max steadiness = 100): 38
   Bow angle (Positive = bow angles forward): 21.05 degrees
   Stern overhang: 5.00 ft / 1.52 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      13.00 ft / 3.96 m
      - Forecastle (20 %):   11.00 ft / 3.35 m
      - Mid (50 %):      10.00 ft / 3.05 m
      - Quarterdeck (20 %):   10.00 ft / 3.05 m
      - Stern:      10.00 ft / 3.05 m
      - Average freeboard:   10.51 ft / 3.20 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 92.4 %
      - Above water (accommodation/working, high = better): 79.2 %
   Waterplane Area: 1,704 Square feet or 158 Square metres
   Displacement factor (Displacement / loading): 158 %
   Structure weight / hull surface area: 28 lbs/sq ft or 136 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.76
      - Longitudinal: 11.83
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is adequate
   Room for accommodation and workspaces is cramped
   Good seaboat, rides out heavy weather easily

PS: I have no illusions of these guys getting out of coastal waters. It'd be an adventure on par with bringing the Pinta across the Atlantic during hurricane season. The huge fuel capacity is to allow for multiple long pursuits during a long duration patrol rather than long distance oceanic cruising.

[Guinness]

Excuse my mixed units here, and someone check my math but...

1 english ton of fuel oil is a little bit more than 1000 liters. 1000 liters occupies 1 cubic meter. So this ship will be hauling 204 odd cubic meters of fuel. The entire under the waterline volume by my calculations is 372 cubic meters. This is total enclosed volume, and fails to take into account structure, etc. etc. Also the geared diesels won't take up a ton of space, but the engine spaces are still going to be at least 15 or 20% of waterline length, so let's say 74 cubic meters or so.

Even if using diesel, that only saves you a few cubic meters (if at all).

So all that fuel is going to leave precious few places to stash other stuff.

[Carthaginian]

Excuse my mixed units here, but...

1 english ton of fuel oil is a little bit more than 1000 liters. 1000 liters occupies 1 cubic meter. So this ship will be hauling 204 odd cubic meters of fuel. The entire under the waterline volume by my calculations is 372 cubic meters. This is total enclosed volume, and fails to take into account structure, etc. etc. Also the geared diesels won't take up a ton of space, but the engine spaces are still going to be at least 15 or 20% of waterline length, so let's say 74 cubic meters or so.

So all that fuel is going to leave precious few places to stash other stuff.

Yes, Guinness... Springsharp is unrealistic. We are well aware of this. We have NOT found a way to accurately adjust for it. Half the fuel capacity if it makes you feel better. QUARTER it if it makes you happy. I'm not pretending that this ship won't have sausages hung in the hallway and moldy loaves of bread hiding in every available corner, not to mention the guys aboard being limited to two changes of clothes and one shower a week and having to take those showers on deck with a firehose because the shower is crammed full of mason jars.

I'm not trying to 'rape the system'... the system just puts out like a sorority girl at a rush party.
Offer a workable solution and I'm all for it.

[Carthaginian]

OK... using some really bad fuel economy, we will say that these diesels get one nautical mile per gallon. 8150 gallons gives me 30.85 cu. m. and some small change (using Convert). Now, that's only about 10% of the ship's overall volume. Even if we say that the ship is getting 0.25 n. mi. per gallon, we don't come up with your massive number.

I think it's a bit safe to say that Springsharp is overestimating the weight of fuel oil, but underestimating the diesel's performance.

Penalize it as you will.

The ships are for storyline reasons, anyway.

[Desertfox]

If you intend to take out pirate ships with that little boat, you are going to need more firepower. That boat will be seriously outgunned by any pirate, and pirate ships will be able to take hits by those popguns a lot better than that ship will be able to take hits from the pirates. And if its going to operate only near the shore, it will have to be faster, otherwise it wont be able to catch smugglers.

[Nobody]

Excuse my mixed units here, and someone check my math but...

1 english ton of fuel oil is a little bit more than 1000 liters. 1000 liters occupies 1 cubic meter. So this ship will be hauling 204 odd cubic meters of fuel. The entire under the waterline volume by my calculations is 372 cubic meters. This is total enclosed volume, and fails to take into account structure, etc. etc. Also the geared diesels won't take up a ton of space, but the engine spaces are still going to be at least 15 or 20% of waterline length, so let's say 74 cubic meters or so.

Even if using diesel, that only saves you a few cubic meters (if at all).

So all that fuel is going to leave precious few places to stash other stuff.

Well that's why SpringSharp tells you the ship is cramped, why it calls the engine space adequate is a mystery though.
Anyway your are kind of comparing apples with pears (well thats what I would say, don't know whether you can say that in English as well).
NORMAL displacement is 375 t or 375 m³ (slightly depending on what kind of ton your are using and the water density), at this displacement SpringSharp gives you: "Fuel, ammunition & stores: 125 tons, 33.3 %"
The 204 t/m³ maximum bunker capacity are for FULL displacement of 466 t/m³.

So what can a dieseled powered ship do with 204 t of fuel? Well even the worst engine won't burn more than 300 g/hph, say 350 if we include auxiliaries (electricity). That means the ships engine burn ~0.83 t/h at full power - enough for 245 hours, or more than 10 days which gives a range of 4420 nm at 18 knots.
The engines weights about 35 kg/hp btw, which doesn't look unreasonable to me either, maybe a tad heavy but that depends on whether this figure includes props, shafts etc. or not.

[Guinness]

Ah true, I failed to take into account the difference between normal and full load. Normal would usually be 2/3 fuel, stores, etc. So at normal, we'd expect 204*.667 = 136 tons of fuel, or roughly 136 cubic meter all below the waterline. This seems more reasonable. I suppose we could expect this ship to carry "peace tanks" as well in the engine spaces, which might help too.

[maddox]

I guess that little patrol boat can be used for soft duty patrols for submariners.

On the comments concerning habitability. The sailing days of frigates ain't that long past....  I believe some of the crusty ancient ones will remark about the comfort these ships have.

[P3D]

A few notes.

There's a 5' draught difference between light and full ship.
The metacentric height is 0.6', so in light condition the ship might not even be marginally stable, requiring at least water as ballast in the fuel tanks. A partially full ship, OTOH, would be extremely lively and unhabitable.

While the ship has fuel for more than 30 days, It would not have the real endurance for more than 20 days I'd guess. A crew of 50 on less than 2000sqft above-water space is a  bit crowded (the engine spaces have to be 2 decks high due to the diesels).
You need at least a crew of 20 to man the weapons.

So, yes, cut endurance to third and instead of the 1" machine guns I'd use only 2x0.50"s
(much better against pirates and would not cause that much structural damage in ships), that'd reduce the necessary crew significantly.

[Carthaginian]

A few notes.

There's a 5' draught difference between light and full ship.
The metacentric height is 0.6', so in light condition the ship might not even be marginally stable, requiring at least water as ballast in the fuel tanks. A partially full ship, OTOH, would be extremely lively and unhabitable.

While the ship has fuel for more than 30 days, It would not have the real endurance for more than 20 days I'd guess. A crew of 50 on less than 2000sqft above-water space is a  bit crowded (the engine spaces have to be 2 decks high due to the diesels).
You need at least a crew of 20 to man the weapons.

So, yes, cut endurance to third and instead of the 1" machine guns I'd use only 2x0.50"s
(much better against pirates and would not cause that much structural damage in ships), that'd reduce the necessary crew significantly.

Hmmm... interesting notes that no one else has brought up, P3D.
I can definitely re-sim taking the whole '5' draft difference' thing into account, since the draft was never planned to be over 10'.

DF - Smugglers will not always be in rum-runner boats. Most smugglers use regular boats to bring in cargo, they just hide their stuff amongst legit cargo instead of relying on speed to get them past the authorities. You have to have some very high value, low weight cargo (like guns or alcohol) before a speed boat becomes useful.

Maddox -  You're right about habitability... the old Chiefs will be smacking kids around telling them about how bad things were when you had to pitch a hammock between the guns!

[mentat]

Where does the expertise on Smuggling come from ..... ;D