Minesweeper

[Kaiser Kirk]

I kinda feel like the Norse and Iberians need more up to date Minesweepers.

I could take the existing ones and give them an updated engine...build some of those.
Or I could go with a somewhat generic design that would suit both.

This one would cost 115t to build, so they could afford a decent build without stretching the budget.
I stuck a 105mm on it, but it could be built with smaller.
I did stick basic hydrophones on it, as the Brits would use MS trawlers as listening posts aiding the ASW ships.
There's plenty of reserve to upgrade them later.

MSW-1, Iberia-Norse Minesweeper laid down 1917

Displacement:
   460 t light; 475 t standard; 508 t normal; 535 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (158.33 ft / 155.84 ft) x 31.17 ft x (6.56 / 6.84 ft)
   (48.26 m / 47.50 m) x 9.50 m  x (2.00 / 2.09 m)

Armament:
      1 - 4.13" / 105 mm 45.0 cal gun - 35.62lbs / 16.16kg shells, 150 per gun
     Quick firing gun in deck mount, 1917 Model
     1 x Single mount on sides, forward deck centre
      2 - 2.36" / 60.0 mm 50.0 cal guns - 6.98lbs / 3.16kg shells, 250 per gun
     Quick firing guns in deck mounts, 1917 Model
     2 x Single mounts on sides amidships
      Weight of broadside 50 lbs / 22 kg

Machinery:
   Coal and oil fired boilers, complex reciprocating steam engines,
   Direct drive, 1 shaft, 2,708 ihp / 2,020 Kw = 18.00 kts
   Range 3,000nm at 8.00 kts
   Bunker at max displacement = 60 tons (90% coal)

Complement:
   53 - 69

Cost:
   £0.078 million / $0.313 million

Distribution of weights at normal displacement:
   Armament: 9 tons, 1.9 %
      - Guns: 9 tons, 1.9 %
   Machinery: 175 tons, 34.4 %
   Hull, fittings & equipment: 184 tons, 36.3 %
   Fuel, ammunition & stores: 49 tons, 9.6 %
   Miscellaneous weights: 91 tons, 17.9 %
      - Hull below water: 5 tons
      - Hull void weights: 55 tons
      - Hull above water: 25 tons
      - On freeboard deck: 5 tons
      - Above deck: 1 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     665 lbs / 302 Kg = 18.8 x 4.1 " / 105 mm shells or 0.4 torpedoes
   Stability (Unstable if below 1.00): 1.64
   Metacentric height 2.0 ft / 0.6 m
   Roll period: 9.3 seconds
   Steadiness   - As gun platform (Average = 50 %): 54 %
         - Recoil effect (Restricted arc if above 1.00): 0.05
   Seaboat quality  (Average = 1.00): 1.09

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.558 / 0.563
   Length to Beam Ratio: 5.00 : 1
   'Natural speed' for length: 12.48 kts
   Power going to wave formation at top speed: 68 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 10.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  14.11 ft / 4.30 m,  13.12 ft / 4.00 m
      - Forward deck:   30.00 %,  13.12 ft / 4.00 m,  10.83 ft / 3.30 m
      - Aft deck:   35.00 %,  10.83 ft / 3.30 m,  10.83 ft / 3.30 m
      - Quarter deck:   15.00 %,  10.83 ft / 3.30 m,  10.83 ft / 3.30 m
      - Average freeboard:      11.71 ft / 3.57 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 123.2 %
      - Above water (accommodation/working, high = better): 135.4 %
   Waterplane Area: 3,317 Square feet or 308 Square metres
   Displacement factor (Displacement / loading): 109 %
   Structure weight / hull surface area: 36 lbs/sq ft or 176 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.83
      - Longitudinal: 5.10
      - Overall: 1.00
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room

Warning: Beam between bulkheads too wide

Designed as an AUX minesweeper
capable of easy Oceanic transit.




55t Reserve

1t  FC
0t  SR radio
5t  Paravanes
25t Minesweeping gear
5t  Basic Hydrophones

[The Rock Doctor]

The Iberian variant might benefit from another 1,000 nm of range but generally looks fine to me.

[Kaiser Kirk]

With the 55 tons reserve I can boost the range easily enough.
I will then have to up the BC slightly to get displacement back to 460
so it continues to qualify as AUX.

Hmm, or I can move to a more mixed 75% oil/25% coal.
That would probably do it as well

[The Rock Doctor]

I suppose the weight reserve could simply work for bagged coal when extended ferry range is necessary to move from station to station.  Which is mainly what I'm thinking about for the Iberians.  The Norse have a pretty condensed operating area for the moment.

[Desertfox]

I would suggest seeing if you can fit it into 400t even if it means loosing some gun armament. 100t is a nice round number that will make your work with the reports a lot easier.

[Kaiser Kirk]

heh, I was just trying to get something divisible by 4.
I wanted 1 mid and 2 light gun 'spots', and that armament weight drove the minimum tonnage.
I'll play with it some this evening.

[Kaiser Kirk]

Ok Fox/Rocky

Tinkered with the design.
changed to mixed Oil/Coal +1000nm range.

Took a close look at the Norse/Iberian weapons
and designed for a slimmed down set,
which meant I could hit Fox's 400t advice

MSW-1, Iberia-Norse Minesweeper laid down 1917

Displacement:
   400 t light; 413 t standard; 446 t normal; 471 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (159.97 ft / 157.48 ft) x 26.25 ft x (6.56 / 6.87 ft)
   (48.76 m / 48.00 m) x 8.00 m  x (2.00 / 2.10 m)

Armament:
      1 - 2.95" / 75.0 mm 45.0 cal gun - 12.98lbs / 5.89kg shells, 150 per gun
     Quick firing gun in deck mount, 1917 Model
     1 x Single mount on sides, forward deck centre
      2 - 2.95" / 75.0 mm 45.0 cal guns - 12.98lbs / 5.89kg shells, 250 per gun
     Quick firing guns in deck mounts, 1917 Model
     2 x Single mounts on sides amidships
      Weight of broadside 39 lbs / 18 kg

Machinery:
   Coal and oil fired boilers, complex reciprocating steam engines,
   Direct drive, 1 shaft, 2,399 ihp / 1,790 Kw = 18.00 kts
   Range 4,000nm at 8.00 kts
   Bunker at max displacement = 58 tons (23% coal)

Complement:
   48 - 63

Cost:
   £0.066 million / $0.264 million

Distribution of weights at normal displacement:
   Armament: 7 tons, 1.7 %
      - Guns: 7 tons, 1.7 %
   Machinery: 145 tons, 32.6 %
   Hull, fittings & equipment: 169 tons, 38.0 %
   Fuel, ammunition & stores: 46 tons, 10.3 %
   Miscellaneous weights: 78 tons, 17.6 %
      - Hull below water: 5 tons
      - Hull void weights: 42 tons
      - Hull above water: 25 tons
      - On freeboard deck: 5 tons
      - Above deck: 1 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     592 lbs / 268 Kg = 46.0 x 3.0 " / 75 mm shells or 0.4 torpedoes
   Stability (Unstable if below 1.00): 1.38
   Metacentric height 1.2 ft / 0.4 m
   Roll period: 10.1 seconds
   Steadiness   - As gun platform (Average = 50 %): 76 %
         - Recoil effect (Restricted arc if above 1.00): 0.09
   Seaboat quality  (Average = 1.00): 1.52

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.575 / 0.581
   Length to Beam Ratio: 6.00 : 1
   'Natural speed' for length: 12.55 kts
   Power going to wave formation at top speed: 67 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 10.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  14.11 ft / 4.30 m,  13.45 ft / 4.10 m
      - Forward deck:   30.00 %,  13.45 ft / 4.10 m,  11.15 ft / 3.40 m
      - Aft deck:   35.00 %,  11.15 ft / 3.40 m,  11.15 ft / 3.40 m
      - Quarter deck:   15.00 %,  11.15 ft / 3.40 m,  11.15 ft / 3.40 m
      - Average freeboard:      12.01 ft / 3.66 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 117.9 %
      - Above water (accommodation/working, high = better): 133.4 %
   Waterplane Area: 2,876 Square feet or 267 Square metres
   Displacement factor (Displacement / loading): 115 %
   Structure weight / hull surface area: 32 lbs/sq ft or 156 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.80
      - Longitudinal: 7.08
      - Overall: 1.00
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform
   Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Warning: Beam between bulkheads too wide

Designed as an AUX minesweeper
capable of easy Oceanic transit.

4 boilers, 1 oil-sprayed coal, 3 oil burning.

Norse use 100L45 and 2x 47L45
Iberians use 3x  75L45

Both combinations are 7 tons, and a minimum aux Disp of 360t.


42t Reserve

1.2t  FC
0t  SR radio
5t  Paravanes
25t Minesweeping gear
5t  Basic Hydrophones