Retcon Alert: 1911 CSA Minelayer

[Guinness]

One of the most mysterious items Carthaginian left for me was 3 450t minelayers he was building when I took over. As near as I can find, there wasn't a publicized design for them. So I decided to flesh out their back story and do a SS. If this proves sane, I'll probably whip up at least a waterline rendering of her too.

Backstory: when designing the class of Torpedo Rams that would become the TR-200 class, the Navy put out to private firms for competing designs. One which was submitted and lost was chosen for further development as an experimental minelayer. Both designs used the same 12,000 SHP, single screw powerplant, but the loser in the competition displaced less for more speed, had longer range, but had much less freeboard and carried a lighter main armament.

As a minelayer, the design was stripped of all torpedoes and all but one 3.5" gun, and instead carries 12 mines and related handling gear, including mine rails from the main mine storage amidships to the stern.

3 ships were contracted to be built in navy yards, Minelayers #1 - #3.

Minelayer Number 1, CSA Minelayer laid down 1911 (Engine 1909)

Displacement:
   450 t light; 463 t standard; 544 t normal; 608 t full load

Dimensions: Length overall / water x beam x draught
   226.00 ft / 220.00 ft x 18.50 ft x 9.54 ft (normal load)
   68.89 m / 67.06 m x 5.64 m  x 2.91 m

Armament:
      1 - 3.50" / 88.9 mm guns in single mounts, 20.00lbs / 9.07kg shells, 1911 Model
     Breech loading gun in deck mount
     on centreline aft, 1 raised gun
      4 - 1.00" / 25.4 mm guns in single mounts, 0.50lbs / 0.23kg shells, 1911 Model
     Breech loading guns in deck mounts
     on centreline ends, evenly spread, all raised mounts - superfiring
   Weight of broadside 22 lbs / 10 kg
   Shells per gun, main battery: 200

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

   - Conning tower: 0.50" / 13 mm

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 1 shaft, 12,000 shp / 8,952 Kw = 27.73 kts
   Range 5,110nm at 10.00 kts
   Bunker at max displacement = 145 tons

Complement:
   56 - 73

Cost:
   £0.058 million / $0.233 million

Distribution of weights at normal displacement:
   Armament: 3 tons, 0.5 %
   Armour: 2 tons, 0.4 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 1 tons, 0.2 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 1 tons, 0.1 %
   Machinery: 286 tons, 52.5 %
   Hull, fittings & equipment: 141 tons, 26.0 %
   Fuel, ammunition & stores: 94 tons, 17.3 %
   Miscellaneous weights: 18 tons, 3.3 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     142 lbs / 64 Kg = 6.6 x 3.5 " / 89 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.33
   Metacentric height 0.7 ft / 0.2 m
   Roll period: 9.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 56 %
         - Recoil effect (Restricted arc if above 1.00): 0.14
   Seaboat quality  (Average = 1.00): 1.12

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.490
   Length to Beam Ratio: 11.89 : 1
   'Natural speed' for length: 14.83 kts
   Power going to wave formation at top speed: 69 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 12.10 degrees
   Stern overhang: 3.00 ft / 0.91 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      14.00 ft / 4.27 m
      - Forecastle (20 %):   13.00 ft / 3.96 m
      - Mid (50 %):      9.00 ft / 2.74 m
      - Quarterdeck (20 %):   9.00 ft / 2.74 m
      - Stern:      9.00 ft / 2.74 m
      - Average freeboard:   10.48 ft / 3.19 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 177.5 %
      - Above water (accommodation/working, high = better): 87.7 %
   Waterplane Area: 2,579 Square feet or 240 Square metres
   Displacement factor (Displacement / loading): 48 %
   Structure weight / hull surface area: 20 lbs/sq ft or 97 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 3.36
      - Overall: 0.60
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is cramped

Range at max speed: 300nm or 10.8 hours

Misc Weights:
6t: mine handling gear
12t: mines

[Guinness]

The final design of this ship, including illustration, can be found here:

http://www.navalism.org/index.php?topic=2458.msg30881#msg30881

[The Rock Doctor]

Looks like a handy ship.  You will (hopefully never) find it useful in time of war...

[Guinness]

Yeah, I like how it came out too. So much so, in fact, that I've been kicking around an idea for a follow on, 500t Torpedo Ram derivative.

This fixes some of the negatives of the TR-200 class, as well as the TRM-01 class, like the single screw, gets a bit more speed and range, and an extra 3.5" 20 pounder gun.

The question is: is it fast enough at 28.5 knots for a modern torpedo craft? In comparison, I'm also working on a new 1000 tonner that does 31 knots (at least according to SS2), carries 4x4" guns, 6 tubes, depth charges and fire control.

I suppose I could build that design as a leader and a bunch of these. Hmmm....

Small Torpedo Ram, CSA Torpedo Ram laid down 1914 (Engine 1912)

Displacement:
   500 t light; 521 t standard; 612 t normal; 685 t full load

Dimensions: Length overall / water x beam x draught
   229.22 ft / 223.00 ft x 19.33 ft x 10.14 ft (normal load)
   69.86 m / 67.97 m x 5.89 m  x 3.09 m

Armament:
      3 - 3.50" / 88.9 mm guns in single mounts, 20.00lbs / 9.07kg shells, 1914 Model
     Breech loading guns in deck mounts
     on centreline ends, majority aft, 1 raised mount aft
      4 - 1.00" / 25.4 mm guns (2x2 guns), 0.50lbs / 0.23kg shells, 1914 Model
     Breech loading guns in deck mounts
     on side, all amidships, all raised mounts - superfiring
      1 - 1.50" / 38.1 mm guns in single mounts, 1.75lbs / 0.79kg shells, 1914 Model
     Breech loading gun in deck mount
     on centreline amidships, 1 raised gun
   Weight of broadside 64 lbs / 29 kg
   Shells per gun, main battery: 220
   3 - 20.0" / 508 mm above water torpedoes

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 14,500 shp / 10,817 Kw = 28.48 kts
   Range 6,250nm at 10.00 kts
   Bunker at max displacement = 164 tons

Complement:
   60 - 79

Cost:
   £0.087 million / $0.347 million

Distribution of weights at normal displacement:
   Armament: 9 tons, 1.4 %
   Machinery: 311 tons, 50.9 %
   Hull, fittings & equipment: 166 tons, 27.2 %
   Fuel, ammunition & stores: 112 tons, 18.2 %
   Miscellaneous weights: 14 tons, 2.3 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     150 lbs / 68 Kg = 7.0 x 3.5 " / 89 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.10
   Metacentric height 0.5 ft / 0.2 m
   Roll period: 11.4 seconds
   Steadiness   - As gun platform (Average = 50 %): 71 %
         - Recoil effect (Restricted arc if above 1.00): 0.41
   Seaboat quality  (Average = 1.00): 1.07

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.490
   Length to Beam Ratio: 11.54 : 1
   'Natural speed' for length: 14.93 kts
   Power going to wave formation at top speed: 71 %
   Trim (Max stability = 0, Max steadiness = 100): 66
   Bow angle (Positive = bow angles forward): 12.10 degrees
   Stern overhang: 3.00 ft / 0.91 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      15.00 ft / 4.57 m
      - Forecastle (20 %):   12.66 ft / 3.86 m
      - Mid (49 %):      10.00 ft / 3.05 m
      - Quarterdeck (20 %):   10.00 ft / 3.05 m
      - Stern:      10.00 ft / 3.05 m
      - Average freeboard:   11.10 ft / 3.38 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 177.9 %
      - Above water (accommodation/working, high = better): 54.3 %
   Waterplane Area: 2,846 Square feet or 264 Square metres
   Displacement factor (Displacement / loading): 49 %
   Structure weight / hull surface area: 22 lbs/sq ft or 105 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 3.96
      - Overall: 0.61
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is cramped
   Ship has slow, easy roll, a good, steady gun platform

Range at max speed: 337nm or 11.8 hours
Range at 15 knots: 2325nm

Misc Weights:
3t: 3 torpedoes
4t 12 depth charges
7t: misc equipment and reserve

[Korpen]

The question is: is it fast enough at 28.5 knots for a modern torpedo craft? In comparison, I'm also working on a new 1000 tonner that does 31 knots (at least according to SS2), carries 4x4" guns, 6 tubes, depth charges and fire control.

Depends on what you intend to use them for...
For costal operations vs. its equals 28 kts should be enogh, if the intention is to engage full-size warships it should be faster.

[Guinness]

I'm thinking of it as a sort of second line destroyer/escort vessel. I agree though, that I'd want it to be faster. For coastal work, I'm already very happy with my 250t design.

Sadly, I think ~28 knots is as fast as you can get something that will fit in a type 0 drydock at this point in time.

[Korpen]

I'm thinking of it as a sort of second line destroyer/escort vessel. I agree though, that I'd want it to be faster. For coastal work, I'm already very happy with my 250t design.

Sadly, I think ~28 knots is as fast as you can get something that will fit in a type 0 drydock at this point in time.

Not really, cutting range will give you 30kts:
Seakeeping is pratically identical to your 28,5kts design (1,11 at 28,5kta)

Enter ship name, Enter country Enter ship type laid down 1912

Displacement:
   500 t light; 517 t standard; 583 t normal; 635 t full load

Dimensions: Length overall / water x beam x draught
   229,66 ft / 229,66 ft x 19,69 ft x 9,02 ft (normal load)
   70,00 m / 70,00 m x 6,00 m  x 2,75 m

Armament:
      3 - 3,46" / 88,0 mm guns in single mounts, 20,79lbs / 9,43kg shells, 1912 Model
     Quick firing guns in deck mounts
     on centreline ends, majority forward, 1 raised mount
   Weight of broadside 62 lbs / 28 kg
   Shells per gun, main battery: 150
   3 - 19,7" / 500 mm above water torpedoes

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 17 351 shp / 12 944 Kw = 30,00 kts
   Range 3 000nm at 12,00 kts
   Bunker at max displacement = 118 tons

Complement:
   59 - 77

Cost:
   £0,067 million / $0,269 million

Distribution of weights at normal displacement:
   Armament: 8 tons, 1,3 %
   Machinery: 309 tons, 53,0 %
   Hull, fittings & equipment: 174 tons, 29,8 %
   Fuel, ammunition & stores: 82 tons, 14,1 %
   Miscellaneous weights: 10 tons, 1,7 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     145 lbs / 66 Kg = 7,0 x 3,5 " / 88 mm shells or 0,2 torpedoes
   Stability (Unstable if below 1.00): 1,21
   Metacentric height 0,6 ft / 0,2 m
   Roll period: 10,5 seconds
   Steadiness   - As gun platform (Average = 50 %): 52 %
         - Recoil effect (Restricted arc if above 1.00): 0,29
   Seaboat quality  (Average = 1.00): 0,96

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0,500
   Length to Beam Ratio: 11,67 : 1
   'Natural speed' for length: 15,15 kts
   Power going to wave formation at top speed: 73 %
   Trim (Max stability = 0, Max steadiness = 100): 54
   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:      16,40 ft / 5,00 m
      - Forecastle (30 %):   13,12 ft / 4,00 m
      - Mid (40 %):      9,84 ft / 3,00 m
      - Quarterdeck (15 %):   9,84 ft / 3,00 m
      - Stern:      9,84 ft / 3,00 m
      - Average freeboard:   11,38 ft / 3,47 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 183,3 %
      - Above water (accommodation/working, high = better): 59,0 %
   Waterplane Area: 3 012 Square feet or 280 Square metres
   Displacement factor (Displacement / loading): 40 %
   Structure weight / hull surface area: 22 lbs/sq ft or 106 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,50
      - Longitudinal: 3,96
      - Overall: 0,61
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is cramped
   Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

[Guinness]

interesting. What's the range at full speed though?

[Korpen]

interesting. What's the range at full speed though?

210nm @ 30kts, 250nm@28,5kts

[Guinness]

This would be a pretty capable ship for torpedo sweeps, and that sort of thing. Might be valuable during the invasion of Cuba (just kidding).

For general fleet work though, I think it's legs might be a little bit short.

Small Torpedo Ram, CSA Torpedo Ram laid down 1914 (Engine 1912)

Displacement:
   500 t light; 519 t standard; 583 t normal; 635 t full load

Dimensions: Length overall / water x beam x draught
   229.22 ft / 223.00 ft x 19.00 ft x 9.83 ft (normal load)
   69.86 m / 67.97 m x 5.79 m  x 3.00 m

Armament:
      3 - 3.50" / 88.9 mm guns in single mounts, 20.00lbs / 9.07kg shells, 1914 Model
     Breech loading guns in deck mounts
     on centreline ends, majority aft, 1 raised mount aft
      4 - 1.00" / 25.4 mm guns (2x2 guns), 0.50lbs / 0.23kg shells, 1914 Model
     Breech loading guns in deck mounts
     on side, all amidships, all raised mounts - superfiring
      1 - 1.50" / 38.1 mm guns in single mounts, 1.75lbs / 0.79kg shells, 1914 Model
     Breech loading gun in deck mount
     on centreline amidships, 1 raised gun
   Weight of broadside 64 lbs / 29 kg
   Shells per gun, main battery: 180
   3 - 20.0" / 508 mm above water torpedoes

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 17,500 shp / 13,055 Kw = 29.96 kts
   Range 4,500nm at 10.00 kts
   Bunker at max displacement = 116 tons

Complement:
   59 - 77

Cost:
   £0.086 million / $0.345 million

Distribution of weights at normal displacement:
   Armament: 9 tons, 1.5 %
   Machinery: 308 tons, 52.9 %
   Hull, fittings & equipment: 171 tons, 29.4 %
   Fuel, ammunition & stores: 83 tons, 14.2 %
   Miscellaneous weights: 12 tons, 2.1 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     135 lbs / 61 Kg = 6.3 x 3.5 " / 89 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.08
   Metacentric height 0.5 ft / 0.1 m
   Roll period: 11.5 seconds
   Steadiness   - As gun platform (Average = 50 %): 60 %
         - Recoil effect (Restricted arc if above 1.00): 0.41
   Seaboat quality  (Average = 1.00): 0.93

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.490
   Length to Beam Ratio: 11.74 : 1
   'Natural speed' for length: 14.93 kts
   Power going to wave formation at top speed: 73 %
   Trim (Max stability = 0, Max steadiness = 100): 64
   Bow angle (Positive = bow angles forward): 12.10 degrees
   Stern overhang: 3.00 ft / 0.91 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      15.00 ft / 4.57 m
      - Forecastle (20 %):   12.66 ft / 3.86 m
      - Mid (49 %):      10.00 ft / 3.05 m
      - Quarterdeck (20 %):   10.00 ft / 3.05 m
      - Stern:      10.00 ft / 3.05 m
      - Average freeboard:   11.10 ft / 3.38 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 184.2 %
      - Above water (accommodation/working, high = better): 53.6 %
   Waterplane Area: 2,798 Square feet or 260 Square metres
   Displacement factor (Displacement / loading): 40 %
   Structure weight / hull surface area: 22 lbs/sq ft or 108 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 4.29
      - Overall: 0.62
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is cramped
   Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

Range at max speed: 201nm or 6.7 hours
Range at 28.5 knots: 244nm or 8.5 hours
Range at 15 knots: 1685nm
Seakeaping at 28.5knots: 1.08

Misc Weights:
3t: 4 torpedoes
4t 12 depth charges
5t: misc equipment and reserve