Colonial Cruisers...

[The Rock Doctor]

If you're building a flagship for a distant colonial location - something modest like Coquimbo, with a class one port and drydock handy - what features would you emphasize in the design?

Would it be a protected/light cruiser, a small armored cruiser, a monitor, or what?

Would you provide for an ability to do additional tasks such as minelaying?

I've just thrown together a notional design - basically a shortened Galapagos class ship, so she fits a class one dock.  Traditional protected cruiser roles - trade defence, scouting, strikes - would be the emphasis.  Weight is assigned for ~60 mines, flag facilities, and wireless, plus a growth margin.  Layout of the main battery is similar to Gapapagos, but with fewer torps and a 65mm anti-airship gun replacing one of the midships 14 cm guns.

The speed takes a bit of a hit, not quite 26 knots, but with a high freeboard, she ought to be able to maintain that speed in heavy weather.  Range, at 8000 nm, is high for a GC cruiser. I've retained all-coal firing for now...

I'm rejecting a small AC, as the lower speed would make it more difficult to respond to raiders, work with torpedo-craft, or evade big nasties if, for example, Peru were to attack in force.

Here's the springstyle - will play in springsharp tonight.


pc09a, laid down 1909

     Length, 120.0 m x Beam, 13.5 m x Depth, 5.7 m
          4004 tonnes normal displacement (3403 tonnes standard)

     Main battery:       4 x 14.0-cm
     Secondary battery:  1 x  6.5-cm
     QF battery:         4 x  4.7-cm
     Light battery:      4 x  0.8-cm

          Weight of broadside: 162 kg

     4 TT, 45.7 cm

     Main belt, 7.5 cm; bow and stern, 2.5 cm
     Armor deck, average 2.5 cm
     Conning tower, 7.5 cm

     Battery armor:
          Main, 2.5 cm shields / secondary, 2.5 cm shields
          QF, 2.5 cm shields / light guns, 1.0 cm shields 

     Maximum speed for 18004 shaft kw = 25.98 knots
          Approximate cruising radius, 8000 nm / 10 knots

     Typical complement: 252-327


                    Estimated cost, $1.286 million (£322,000)

          Remarks:

     Relative extent of belt armor, 112 percent of 'typical' coverage.

     Ship has slow, easy roll; a good, steady gun platform.

     Excellent seaboat; comfortable and able to fight her guns
     in the heaviest weather.


          Distribution of weights:
                                                       Percent
                                                       normal
                                                    displacement:

          Armament .........................     45 tonnes =   1 pct
          Armor, total .....................    532 tonnes =  13 pct

               Belt                             325 tonnes =   8 pct
               Deck                             180 tonnes =   4 pct
               C.T.                              16 tonnes =   0 pct
               Armament                          11 tonnes =   0 pct

          Machinery ........................   1206 tonnes =  30 pct
          Hull and fittings; equipment .....   1351 tonnes =  34 pct
          Fuel, ammunition, stores .........    711 tonnes =  18 pct
          Miscellaneous weights ............    160 tonnes =   4 pct
                                              -----
                                               4004 tonnes = 100 pct

          Estimated metacentric height, 0.7 m

     Displacement summary:

          Light ship:              3293 tonnes
          Standard displacement:   3403 tonnes
          Normal service:          4004 tonnes
          Full load:               4469 tonnes

          Loading submergence 928 tonnes/metre

     +++++++++++++++++++++++++


     Estimated overall survivability and seakeeping ability:

          Relative margin of stability: 1.24

          Shellfire needed to sink: 1796 kg = 47.2 x 14.0-cm shells
               (Approximates weight of penetrating
               shell hits needed to sink ship,
               not counting critical hits)

          Torpedoes needed to sink: 0.9
               (Approximates number of 'typical'
               torpedo hits needed to sink ship)

          Relative steadiness as gun platform, 80 percent
               (50 percent is 'average')

          Relative rocking effect from firing to beam, 0.14

          Relative quality as a seaboat: 1.59

     +++++++++++++++++++++++++


     Hull form characteristics:

          Block coefficient: 0.43
          Sharpness coefficient: 0.32
          Hull speed coefficient 'M' = 7.58
          'Natural speed' for length = 19.8 knots
          Power going to wave formation
               at top speed: 55 percent


     Estimated hull characteristics and strength:

          Relative underwater volume absorbed by
               magazines and engineering spaces: 111 percent

          Relative accommodation and working space: 111 percent


          Displacement factor: 116 percent
               (Displacement relative to loading factors)


          Relative cross-sectional hull strength: 0.92
               (Structure weight per square
               metre of hull surface: 344 kg)

          Relative longitudinal hull strength: 2.20
               (for 5.10 m average freeboard;
               freeboard adjustment +1.26 m)

          Relative composite hull strength: 1.00

     +++++++++++++++++++++++++


[Machine-readable parameters: Spring Style v. 1.2.1]

393.60 x 44.28 x 18.70; 16.73 -- Dimensions
0.43 -- Block coefficient
1909 -- Year laid down
25.98 / 8000 / 10.00; Turbine, coal fired -- Speed / radius / cruise
160 tons -- Miscellaneous weights
++++++++++
4 x 5.51; 0 -- Main battery; turrets
  Central positioning of guns
  Gun-shields
   :
1 x 2.56; 0 -- Secondary battery; turrets
  Gun-shields
   :
4 x 1.85 -- Tertiary (QF/AA) battery
  Gun-shields
   :
4 x 0.31 -- Fourth (light) battery
4 / 0 / 17.99 -- TT / submerged / size
++++++++++
2.95 / 0.98 / 0.00 / 0.00; 112 -- Belt armor; relative extent
0.98 / 2.95 -- Deck / CT
0.98 / 0.98 / 0.98 / 0.39 -- Battery armor


     (Note: For portability, values are stored in Anglo-American units)


     +++++++++++++++++++++++++++++++++++++++++++++++++++++++

[Borys]

Ahoj!
Very nice. Maybe even too good for the task.
But I also "overdid it" with my avisos.
Borys

[The Rock Doctor]

If the design is "too good", where would you make cuts?

[P3D]

Block coefficent 0.43?

[Borys]

Ahoj!
I was wondering about the belt - maybe 2 inches enough?, and the speed.
As to the speed and powerplant - I gave my avisos VTE's.
As to armour - I ladled the sides with 4 inch thick armour plates :), so ... "let him who be without sin cast the first stone ... "
:D

Borys

[The Rock Doctor]

I thought a 0.43 BC was reasonable for a small, fast-ish cruiser.  I can reduce the beam and increase to ~0.45, no doubt.