CSA Minesweeper Design

[Guinness]

This is built under merchant standards, but I put 2 diesel engines in her, so I think I need mod approval to build her.

The CSA sees a need to develop dedicated minesweeping vessals. Consensus was quickly found to build a new class using the hull and general design of the successful S-01 class sloops, but substituting minesweeping gear for some armament, and introducing a 2 screw diesel powerplant.

MS-01, CSA Minesweeping Sloop laid down 1912 (Engine 1909)

Displacement:
   200 t light; 207 t standard; 260 t normal; 302 t full load

Dimensions: Length overall / water x beam x draught
   185.00 ft / 175.00 ft x 18.00 ft x 5.58 ft (normal load)
   56.39 m / 53.34 m x 5.49 m  x 1.70 m

Armament:
      3 - 2.25" / 57.2 mm guns in single mounts, 5.70lbs / 2.58kg shells, 1912 Model
     Breech loading guns in deck mounts
     on centreline, evenly spread, all raised mounts
     Aft Main mounts separated by engine room
      4 - 1.00" / 25.4 mm guns in single mounts, 0.50lbs / 0.23kg shells, 1912 Model
     Breech loading guns in deck mounts
     on side, all amidships, all raised mounts - superfiring
   Weight of broadside 19 lbs / 9 kg
   Shells per gun, main battery: 150

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   0.50" / 13 mm     81.00 ft / 24.69 m   9.00 ft / 2.74 m
   Ends:   Unarmoured
     Main Belt covers 71 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.50" / 13 mm         -               -
   2nd:   0.25" / 6 mm         -               -

   - Armour deck: 0.25" / 6 mm

Machinery:
   Diesel Internal combustion motors,
   Direct drive, 2 shafts, 706 shp / 527 Kw = 15.00 kts
   Range 5,250nm at 10.00 kts
   Bunker at max displacement = 95 tons

Complement:
   32 - 42

Cost:
   £0.014 million / $0.054 million

Distribution of weights at normal displacement:
   Armament: 2 tons, 0.9 %
   Armour: 28 tons, 10.8 %
      - Belts: 16 tons, 6.2 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 2 tons, 0.8 %
      - Armour Deck: 10 tons, 3.8 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 32 tons, 12.4 %
   Hull, fittings & equipment: 128 tons, 49.2 %
   Fuel, ammunition & stores: 60 tons, 22.9 %
   Miscellaneous weights: 10 tons, 3.9 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     815 lbs / 370 Kg = 143.1 x 2.3 " / 57 mm shells or 0.8 torpedoes
   Stability (Unstable if below 1.00): 1.00
   Metacentric height 0.4 ft / 0.1 m
   Roll period: 12.2 seconds
   Steadiness   - As gun platform (Average = 50 %): 100 %
         - Recoil effect (Restricted arc if above 1.00): 0.31
   Seaboat quality  (Average = 1.00): 2.00

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.517
   Length to Beam Ratio: 9.72 : 1
   'Natural speed' for length: 13.23 kts
   Power going to wave formation at top speed: 46 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 18.45 degrees
   Stern overhang: 5.00 ft / 1.52 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      15.00 ft / 4.57 m
      - Forecastle (20 %):   14.50 ft / 4.42 m
      - Mid (50 %):      14.00 ft / 4.27 m (6.00 ft / 1.83 m aft of break)
      - Quarterdeck (15 %):   6.00 ft / 1.83 m
      - Stern:      8.00 ft / 2.44 m
      - Average freeboard:   10.37 ft / 3.16 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 52.6 %
      - Above water (accommodation/working, high = better): 124.5 %
   Waterplane Area: 2,132 Square feet or 198 Square metres
   Displacement factor (Displacement / loading): 214 %
   Structure weight / hull surface area: 24 lbs/sq ft or 119 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.82
      - Longitudinal: 7.44
      - Overall: 1.02
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is excellent
   Ship has slow, easy roll, a good, steady gun platform
   Excellent seaboat, comfortable, can fire her guns in the heaviest weather

10 tons misc weight for various minesweeping gear
Armored deck represents 1" thick armored fuel tank

**** Note: twin engined ****

Costs:
$1.4*0.25=0.35 (hull)
72 tons of military equipment = 0.072 BP and $0.072
Totals: 0.072 BP and $0.422

[Borys]

Ahoj!
The 2" guns are useless - 2 3" or 3,5" guns can make an impression, but not those peashooters.

Borys

[The Rock Doctor]

And yet I'd say she's over-armed.  One medium caliber gun and a couple of machine guns would probably be sufficient - and about all there'd be room for.

[Guinness]

The 2.25" guns are really just there to make the crew feel better. :) And I suppose so she can do other stuff like revenue patrols in coast areas, help out the sloops on pirate patrols, etc.

[Borys]

One 3" and two MGs - historical Polish minesweeprs of similar size were armed that way.
Borys

[ledeper]

Try take a look at this:    
Re: Coastal-patrol and mine boat
« Reply #10

[P3D]

You need too large crew to operate 7 guns. 4 for each 6pdrs (historical), 2 for each 1"s. 1'd keep one 6pdr, and have two or three .50 Brownings. You need it only to shoot at the mines. If you are patrolling, then 1" is overkill.

[Guinness]

Yeah, at the moment the 1" AA is CSA standard equipment on all ships. I suppose it's not completely useless against some surface targets either. I probably need to develop a 50 cal. machine gun though, unless those are considered commodity items.

Right now I'm going with 1x3.50" and 2x1"AA. That 3.50" is also from my standard equipment list. I figure that gives here enough poke to at least go down fighting against a real naval combatant. The 1"ers would also be useful for shooting up small boats I imagine.

At any rate, final design and another goody about to show up in a new thread about the CSA's 2H1912 building program.

[Korpen]

I think she is a bit too slow; in the inter-war era Swedish minesweepers seemed to have considered 15kts to be the ideal speed for sweeping, faster then that did not increase the length of the sweep, lower and one got a shorter sweep that was less efficient at cutting mines. As the resistance of the sweeps will give quite a bit of drag, 2-3 knots more would probably be a good idea. At least something to keep in mind.

[Borys]

MG are commodity items. You declare you have them and you're done :)

[Guinness]

I think she is a bit too slow; in the inter-war era Swedish minesweepers seemed to have considered 15kts to be the ideal speed for sweeping, faster then that did not increase the length of the sweep, lower and one got a shorter sweep that was less efficient at cutting mines. As the resistance of the sweeps will give quite a bit of drag, 2-3 knots more would probably be a good idea. At least something to keep in mind.

Good tip. The CSA right now is very much in the nascent phase of mine warfare, between these ships and 3 minelayers Carthaginian started (which I can't find SS's for anywhere).

I expect that a good bit of operational practice with these ships may mean new concepts in minesweepers in the future. To a certain extent the CSA hedged its bets with this design as well, building it on the cheap, and in a hull already being used for patrol sloops anyway.

If we ever figure out what how to sweep mines, we might think about converting some old torpedo craft to the task as well, which would give us more speed.

[Sachmle]

Carth was never big on mines. Not sure why. I don't know if it was an ethics thing, like Rohan and not using subs because they think it's wrong to sneak attack (Looks at Japan), or because of his argument that ocean currents would pull any coastal mines he laid into the Gulf of, what do we call the Gulf of Mexico since there's no Mexico? Anyway, I'll see if I can get him to send me the SS reports on those minelayers, if I don't already have them somewhere.

[Borys]

Ahoj!
Carthaganian was not big on mines due to the Golfstrom. Yes, he was wrried that anything he dumps in the Gulf will end ip floating by his east coast.

Borys

[Guinness]

It's the Gulf of Texas.

I understand his worry about mines in the Gulf. I don't ever see the CSA laying a defensive field there. We might use them elsewhere defensively though. I think those three minelayers were more offensive in nature though.