Irish Fast Minelayer 1920(ish)

[snip]

An idea for a fast minelayer to "aggressively supplement" the current large minelayers.

Aideen Class, Irish Fast Minelayer laid down 1920 (Engine 1912)

Displacement:
   1,808 t light; 1,866 t standard; 1,991 t normal; 2,091 t full load

Dimensions: Length overall / water x beam x draught
   335.02 ft / 325.00 ft x 32.00 ft x 14.00 ft (normal load)
   102.11 m / 99.06 m x 9.75 m  x 4.27 m

Armament:
      3 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1920 Model
     Breech loading guns in deck mounts
     on centreline, all forward, 1 raised mount
      16 - 0.98" / 25.0 mm guns (8x2 guns), 0.48lbs / 0.22kg shells, 1920 Model
     Machine guns in deck mounts
     on side, evenly spread
   Weight of broadside 332 lbs / 150 kg
   Shells per gun, main battery: 100

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   0.70" / 18 mm   243.75 ft / 74.30 m   6.79 ft / 2.07 m
   Ends:   Unarmoured
     Main Belt covers 115 % of normal length
     Main belt does not fully cover magazines and engineering spaces

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1.00" / 25 mm   0.25" / 6 mm            -
   2nd:   0.50" / 13 mm         -               -

   - Armour deck: 0.50" / 13 mm, Conning tower: 2.00" / 51 mm

Machinery:
   Coal and oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 14,555 shp / 10,858 Kw = 25.00 kts
   Range 3,000nm at 10.00 kts
   Bunker at max displacement = 225 tons (90% coal)

Complement:
   148 - 193

Cost:
   £0.441 million / $1.764 million

Distribution of weights at normal displacement:
   Armament: 41 tons, 2.1 %
   Armour: 125 tons, 6.3 %
      - Belts: 47 tons, 2.4 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 8 tons, 0.4 %
      - Armour Deck: 63 tons, 3.2 %
      - Conning Tower: 7 tons, 0.3 %
   Machinery: 632 tons, 31.7 %
   Hull, fittings & equipment: 784 tons, 39.4 %
   Fuel, ammunition & stores: 183 tons, 9.2 %
   Miscellaneous weights: 225 tons, 11.3 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     1,548 lbs / 702 Kg = 14.3 x 6.0 " / 152 mm shells or 0.5 torpedoes
   Stability (Unstable if below 1.00): 1.12
   Metacentric height 1.1 ft / 0.3 m
   Roll period: 12.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.44
   Seaboat quality  (Average = 1.00): 1.90

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.479
   Length to Beam Ratio: 10.16 : 1
   'Natural speed' for length: 18.03 kts
   Power going to wave formation at top speed: 57 %
   Trim (Max stability = 0, Max steadiness = 100): 37
   Bow angle (Positive = bow angles forward): 25.50 degrees
   Stern overhang: -2.00 ft / -0.61 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      21.00 ft / 6.40 m
      - Forecastle (10 %):   19.00 ft / 5.79 m
      - Mid (40 %):      19.00 ft / 5.79 m (13.10 ft / 3.99 m aft of break)
      - Quarterdeck (15 %):   13.10 ft / 3.99 m
      - Stern:      13.10 ft / 3.99 m
      - Average freeboard:   15.54 ft / 4.74 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 130.6 %
      - Above water (accommodation/working, high = better): 135.3 %
   Waterplane Area: 6,798 Square feet or 632 Square metres
   Displacement factor (Displacement / loading): 102 %
   Structure weight / hull surface area: 51 lbs/sq ft or 250 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.86
      - Longitudinal: 4.14
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is cramped
   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

200 tons Mines
25 tons long range wireless

Comments and/or suggestions?

[maddox]

1) fast minelayer.... A 1938 class fast minelayer.  Knock of 10 kts, and you have a fast 1920 minelayer.

2) Why the 6" guns?

[snip]

1) Three words. Coal Fired Boilers

2) I figured it would be a good idea to give them something bigger with which to frighten DD's (they will be escorted, but with the numbers I have it might not be a bit one). Also there is the possibility of them being used for other roles than just minelaying (they would not be caring mines however)

[Sachmle]

Your belt is too short.

Your freeboard is really high for a <2,000t ship.

Your seakeeping is huge (1.90).

Cut freeboard until your seakeeping is like 1.35 then use the extra strength to add speed until you either run out of strength or your seakeeping drops below 1.10.

[snip]

Aideen Class, Irish Fast Minelayer laid down 1920 (Engine 1912)

Displacement:
   1,800 t light; 1,858 t standard; 1,983 t normal; 2,083 t full load

Dimensions: Length overall / water x beam x draught
   334.00 ft / 325.00 ft x 32.00 ft x 14.00 ft (normal load)
   101.80 m / 99.06 m x 9.75 m  x 4.27 m

Armament:
      3 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1920 Model
     Breech loading guns in deck mounts
     on centreline, all forward, 1 raised mount
      16 - 0.98" / 25.0 mm guns (8x2 guns), 0.48lbs / 0.22kg shells, 1920 Model
     Machine guns in deck mounts
     on side, evenly spread
   Weight of broadside 332 lbs / 150 kg
   Shells per gun, main battery: 100

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   0.60" / 15 mm   301.00 ft / 91.74 m   6.79 ft / 2.07 m
   Ends:   Unarmoured
     Main Belt covers 142 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1.00" / 25 mm   0.25" / 6 mm            -
   2nd:   0.50" / 13 mm         -               -

   - Armour deck: 0.50" / 13 mm, Conning tower: 2.00" / 51 mm

Machinery:
   Coal and oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 17,030 shp / 12,705 Kw = 26.00 kts
   Range 3,000nm at 10.00 kts
   Bunker at max displacement = 224 tons (90% coal)

Complement:
   148 - 193

Cost:
   £0.464 million / $1.854 million

Distribution of weights at normal displacement:
   Armament: 41 tons, 2.1 %
   Armour: 126 tons, 6.4 %
      - Belts: 48 tons, 2.4 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 8 tons, 0.4 %
      - Armour Deck: 63 tons, 3.2 %
      - Conning Tower: 7 tons, 0.3 %
   Machinery: 702 tons, 35.4 %
   Hull, fittings & equipment: 705 tons, 35.6 %
   Fuel, ammunition & stores: 183 tons, 9.2 %
   Miscellaneous weights: 225 tons, 11.3 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     1,176 lbs / 534 Kg = 10.9 x 6.0 " / 152 mm shells or 0.4 torpedoes
   Stability (Unstable if below 1.00): 1.11
   Metacentric height 1.1 ft / 0.3 m
   Roll period: 12.8 seconds
   Steadiness   - As gun platform (Average = 50 %): 65 %
         - Recoil effect (Restricted arc if above 1.00): 0.37
   Seaboat quality  (Average = 1.00): 1.30

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.477
   Length to Beam Ratio: 10.16 : 1
   'Natural speed' for length: 18.03 kts
   Power going to wave formation at top speed: 59 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 26.56 degrees
   Stern overhang: -2.00 ft / -0.61 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      18.00 ft / 5.49 m
      - Forecastle (10 %):   15.00 ft / 4.57 m
      - Mid (40 %):      15.00 ft / 4.57 m (12.00 ft / 3.66 m aft of break)
      - Quarterdeck (15 %):   12.00 ft / 3.66 m
      - Stern:      12.00 ft / 3.66 m
      - Average freeboard:   13.32 ft / 4.06 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 142.4 %
      - Above water (accommodation/working, high = better): 115.3 %
   Waterplane Area: 6,786 Square feet or 630 Square metres
   Displacement factor (Displacement / loading): 92 %
   Structure weight / hull surface area: 52 lbs/sq ft or 255 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.90
      - Longitudinal: 2.60
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is adequate
   Good seaboat, rides out heavy weather easily

200 tons Mines
25 tons long range wireless

This work?

[Jefgte]

26kts is not fast in 1920.

Update tro 30-32kts...


Jef

[Sachmle]

26kts is not fast in 1920.

Update tro 30-32kts...


Jef

It's a minelayer, not a destroyer Jef.

[Jefgte]

High speed is better for discret action in enemy water...


Jef

[Carthaginian]

There are two kinds of minelayers:
Fast - for getting into and out of enemy choke points
Slow - for mining your own choke points

If they are fast, they need to have destroyer-like speed.
If they are slow, they need to have a lot of capacity.

That's about the only requirements.

[Jefgte]

I agree with Cart


Jef

[snip]

Hmmmm. To me this seems like it would mainly be for mining domestic areas. On the other hand, I would like it to be faster, right now it falls between the two classes I have right now.