Cost Patrol Cruiser - or how to increase seakeeping?

[Nobody]

I was playing around in SpringSharp and decided to design a large patrol boat. However despite, what I think is a ridiculous high freeboard, all my approaches have a very low seaboat quality. Any advice would be appreciated.

Design goals:

• fits into a type 1 slip/dock (120 m length)
• 4000 t maximum size
• armament:
  
  • four 6 inch main guns
    
  • at least one "stop-gun" between 75 mm and 3.5 inch
    
  • about four 1 inch AA-guns
    
  • about four .50 machine-guns
    
• light splinter armor only (mercantile standards!)
• lots of misc weight (>500 t)
• as fast as possible, 28+ knots
• a 1.0 better 1.2 seekeeping and 1.1 stability

And this is one of my better attempts:
4000 t Patrol Boat, Orange Sloop laid down 1920

Displacement:
   4.000 t light; 4.140 t standard; 4.418 t normal; 4.640 t full load

Dimensions: Length overall / water x beam x draught
   393,70 ft / 387,14 ft x 62,34 ft x 12,81 ft (normal load)
   120,00 m / 118,00 m x 19,00 m  x 3,91 m

Armament:
      4 - 6,00" / 152 mm guns in single mounts, 108,00lbs / 48,99kg shells, 1920 Model
     Breech loading guns in deck mounts with hoists
     on centreline ends, evenly spread, 2 raised mounts - superfiring
      1 - 3,46" / 88,0 mm guns in single mounts, 20,79lbs / 9,43kg shells, 1920 Model
     Quick firing gun in deck mount
     on centreline amidships, 1 raised gun
      4 - 1,00" / 25,4 mm guns in single mounts, 0,50lbs / 0,23kg shells, 1920 Model
     Anti-aircraft guns in deck mounts
     on side, all amidships
      4 - 0,50" / 12,7 mm guns in single mounts, 0,06lbs / 0,03kg shells, 1920 Model
     Machine guns in deck mounts
     on side ends, evenly spread, all raised mounts - superfiring
   Weight of broadside 455 lbs / 206 kg
   Shells per gun, main battery: 200

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1,18" / 30 mm   0,79" / 20 mm      0,98" / 25 mm
   2nd:   0,59" / 15 mm         -               -
   3rd:   0,59" / 15 mm         -               -

   - Conning tower: 1,18" / 30 mm

Machinery:
   Oil fired boilers, steam turbines,
   Electric motors, 2 shafts, 39.069 shp / 29.145 Kw = 28,00 kts
   Range 5.000nm at 12,00 kts
   Bunker at max displacement = 500 tons

Complement:
   270 - 352

Cost:
   £0,896 million / $3,584 million

Distribution of weights at normal displacement:
   Armament: 57 tons, 1,3%
   Armour: 28 tons, 0,6%
      - Belts: 0 tons, 0,0%
      - Torpedo bulkhead: 0 tons, 0,0%
      - Armament: 21 tons, 0,5%
      - Armour Deck: 0 tons, 0,0%
      - Conning Tower: 7 tons, 0,2%
   Machinery: 1.366 tons, 30,9%
   Hull, fittings & equipment: 1.930 tons, 43,7%
   Fuel, ammunition & stores: 418 tons, 9,5%
   Miscellaneous weights: 620 tons, 14,0%

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     4.673 lbs / 2.120 Kg = 43,3 x 6,0 " / 152 mm shells or 1,0 torpedoes
   Stability (Unstable if below 1.00): 1,22
   Metacentric height 3,5 ft / 1,1 m
   Roll period: 14,0 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0,13
   Seaboat quality  (Average = 1.00): 0,90

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0,500
   Length to Beam Ratio: 6,21 : 1
   'Natural speed' for length: 19,68 kts
   Power going to wave formation at top speed: 65 %
   Trim (Max stability = 0, Max steadiness = 100): 55
   Bow angle (Positive = bow angles forward): 12,00 degrees
   Stern overhang: 0,98 ft / 0,30 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      26,25 ft / 8,00 m
      - Forecastle (25%):   22,31 ft / 6,80 m
      - Mid (60%):      22,31 ft / 6,80 m (14,76 ft / 4,50 m aft of break)
      - Quarterdeck (20%):   14,76 ft / 4,50 m
      - Stern:      18,04 ft / 5,50 m
      - Average freeboard:   20,01 ft / 6,10 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 125,7%
      - Above water (accommodation/working, high = better): 221,9%
   Waterplane Area: 16.079 Square feet or 1.494 Square metres
   Displacement factor (Displacement / loading): 115%
   Structure weight / hull surface area: 83 lbs/sq ft or 405 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,91
      - Longitudinal: 2,53
      - Overall: 1,00
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is excellent
   Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

[Tanthalas]

Try making it a bit deaper, I know that helps.  If I have some time later ill take a shot at it.

[Jefgte]

IMO, too high freeboard
& no superfiring guns give certainly better stability.

Start with a 1000t DD good springsharp.


Jef

[Jefgte]

here is Protector, with some similar choices

Protector, Peru Squadron Gunboat laid down 1918 (Engine 1916)

Displacement:
   2 000 t light; 2 113 t standard; 2 410 t normal; 2 647 t full load

Dimensions: Length overall / water x beam x draught
   393.70 ft / 393.70 ft x 42.65 ft x 11.96 ft (normal load)
   120.00 m / 120.00 m x 13.00 m  x 3.65 m

Armament:
      2 - 5.98" / 152 mm guns in single mounts, 107.15lbs / 48.60kg shells, 1918 Model
     Breech loading guns in casemate mounts
     on centreline, evenly spread
      4 - 5.98" / 152 mm guns in single mounts, 107.15lbs / 48.60kg shells, 1918 Model
     Breech loading guns in casemate mounts
     on side, evenly spread
      4 - 1.57" / 40.0 mm guns (2x2 guns), 1.95lbs / 0.88kg shells, 1918 Model
     Anti-aircraft guns in deck mounts
     on side, evenly spread, all raised mounts
      4 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1918 Model
     Machine guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 651 lbs / 295 kg
   Shells per gun, main battery: 160
   12 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.79" / 20 mm         -               -
   2nd:   0.79" / 20 mm         -               -
   3rd:   0.79" / 20 mm         -               -
   4th:   0.50" / 13 mm         -               -

   - Conning tower: 3.15" / 80 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 4 shafts, 20 538 shp / 15 321 Kw = 27.09 kts
   Range 7 000nm at 12.00 kts
   Bunker at max displacement = 534 tons

Complement:
   171 - 223

Cost:
   £0.491 million / $1.964 million

Distribution of weights at normal displacement:
   Armament: 81 tons, 3.4 %
   Armour: 30 tons, 1.2 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 17 tons, 0.7 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 12 tons, 0.5 %
   Machinery: 765 tons, 31.8 %
   Hull, fittings & equipment: 1 024 tons, 42.5 %
   Fuel, ammunition & stores: 409 tons, 17.0 %
   Miscellaneous weights: 100 tons, 4.1 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     1 951 lbs / 885 Kg = 18.2 x 6.0 " / 152 mm shells or 0.6 torpedoes
   Stability (Unstable if below 1.00): 1.32
   Metacentric height 2.3 ft / 0.7 m
   Roll period: 11.8 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.21
   Seaboat quality  (Average = 1.00): 1.14

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.420
   Length to Beam Ratio: 9.23 : 1
   'Natural speed' for length: 19.84 kts
   Power going to wave formation at top speed: 55 %
   Trim (Max stability = 0, Max steadiness = 100): 62
   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:      18.04 ft / 5.50 m
      - Forecastle (22 %):   14.76 ft / 4.50 m
      - Mid (50 %):      11.48 ft / 3.50 m
      - Quarterdeck (18 %):   11.48 ft / 3.50 m
      - Stern:      11.48 ft / 3.50 m
      - Average freeboard:   12.95 ft / 3.95 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 133.7 %
      - Above water (accommodation/working, high = better): 72.5 %
   Waterplane Area: 10 469 Square feet or 973 Square metres
   Displacement factor (Displacement / loading): 104 %
   Structure weight / hull surface area: 64 lbs/sq ft or 314 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.98
      - Longitudinal: 1.45
      - Overall: 1.02
   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

[Sachmle]

Too wide (beam hurts seakeeping), ditch hoists for single 6" guns (saves weight so making her narrower won't hurt as much), other than that and what Tan said about depth (which is kinda shallow at <4m, I'd shoot for 5 at least) IDK.

[Borys]

Ahoj!
I'd put part of the blame on the high miscelenous weight. Another is the ridiculously high speed for a patrol ship.
Have a look at my effort of similar size. I used enclosed turrets for the Antarctic and Artic patrols, but I might use open mounts at the corners of the superstructure in the final version.
http://www.navalism.org/index.php?topic=4480.msg51118#msg51118

[P3D]

Either build a repeat of 1000t sloops or plain cruisers frigates imho. As Orange invested a lot in such ships, an intermediate class does not make much sense.

[Kaiser Kirk]

This is as close to the specs as Bavaria's shipwrights can get.
A 29kt, 1.01 seakeeping, 200misc wt version is also possible....I know because getting from that to the current version took a bit of work. :)

Marshall, Various Patrol Cruiser laid down 1916

Displacement:
   3,095 t light; 3,225 t standard; 3,629 t normal; 3,953 t full load

Dimensions: Length overall / water x beam x draught
   393.27 ft / 383.86 ft x 40.39 ft x 14.76 ft (normal load)
   119.87 m / 117.00 m x 12.31 m  x 4.50 m

Armament:
      4 - 5.98" / 152 mm guns in single mounts, 110.23lbs / 50.00kg shells, 1916 Model
     Quick firing guns in deck mounts with hoists
     on centreline ends, evenly spread, 2 raised mounts - superfiring
      4 - 2.95" / 75.0 mm guns in single mounts, 13.23lbs / 6.00kg shells, 1916 Model
     Anti-aircraft guns in deck mounts
     on side, all amidships
      4 - 0.98" / 25.0 mm guns in single mounts, 0.48lbs / 0.22kg shells, 1916 Model
     Anti-aircraft guns in deck mounts
     on side ends, evenly spread, all raised mounts - superfiring
   Weight of broadside 496 lbs / 225 kg
   Shells per gun, main battery: 200
   3 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.98" / 25 mm   0.98" / 25 mm      0.98" / 25 mm
   2nd:   0.39" / 10 mm         -               -
   3rd:   0.39" / 10 mm         -               -

   - Conning tower: 0.98" / 25 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 32,720 shp / 24,409 Kw = 28.00 kts
   Range 7,500nm at 12.00 kts
   Bunker at max displacement = 727 tons

Complement:
   233 - 303

Cost:
   £0.539 million / $2.157 million

Distribution of weights at normal displacement:
   Armament: 60 tons, 1.7 %
   Armour: 27 tons, 0.7 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 22 tons, 0.6 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 5 tons, 0.1 %
   Machinery: 1,219 tons, 33.6 %
   Hull, fittings & equipment: 1,289 tons, 35.5 %
   Fuel, ammunition & stores: 534 tons, 14.7 %
   Miscellaneous weights: 500 tons, 13.8 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     2,332 lbs / 1,058 Kg = 21.8 x 6.0 " / 152 mm shells or 0.6 torpedoes
   Stability (Unstable if below 1.00): 1.12
   Metacentric height 1.6 ft / 0.5 m
   Roll period: 13.4 seconds
   Steadiness   - As gun platform (Average = 50 %): 52 %
         - Recoil effect (Restricted arc if above 1.00): 0.46
   Seaboat quality  (Average = 1.00): 1.04

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.555
   Length to Beam Ratio: 9.50 : 1
   'Natural speed' for length: 19.59 kts
   Power going to wave formation at top speed: 62 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 22.00 degrees
   Stern overhang: -3.28 ft / -1.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      23.29 ft / 7.10 m
      - Forecastle (20 %):   19.29 ft / 5.88 m
      - Mid (50 %):      19.29 ft / 5.88 m (11.29 ft / 3.44 m aft of break)
      - Quarterdeck (15 %):   11.29 ft / 3.44 m
      - Stern:      11.29 ft / 3.44 m
      - Average freeboard:   15.61 ft / 4.76 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 137.0 %
      - Above water (accommodation/working, high = better): 115.4 %
   Waterplane Area: 10,870 Square feet or 1,010 Square metres
   Displacement factor (Displacement / loading): 105 %
   Structure weight / hull surface area: 67 lbs/sq ft or 328 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.92
      - Longitudinal: 2.06
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is adequate

[Kaiser Kirk]

one more try

Marshall, Various Patrol Cruiser laid down 1916

Displacement:
   3,000 t light; 3,130 t standard; 3,501 t normal; 3,798 t full load

Dimensions: Length overall / water x beam x draught
   393.27 ft / 383.86 ft x 38.39 ft x 16.77 ft (normal load)
   119.87 m / 117.00 m x 11.70 m  x 5.11 m

Armament:
      4 - 5.98" / 152 mm guns in single mounts, 110.23lbs / 50.00kg shells, 1916 Model
     Quick firing guns in deck mounts with hoists
     on centreline ends, evenly spread, 2 raised mounts - superfiring
      4 - 2.95" / 75.0 mm guns in single mounts, 13.23lbs / 6.00kg shells, 1916 Model
     Anti-aircraft guns in deck mounts
     on centreline, all amidships
      4 - 0.98" / 25.0 mm guns in single mounts, 0.48lbs / 0.22kg shells, 1916 Model
     Anti-aircraft guns in deck mounts
     on side ends, evenly spread, all raised mounts - superfiring
   Weight of broadside 496 lbs / 225 kg
   Shells per gun, main battery: 208
   3 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.98" / 25 mm   0.98" / 25 mm      0.98" / 25 mm
   2nd:   0.39" / 10 mm         -               -
   3rd:   0.39" / 10 mm         -               -

   - Conning tower: 0.98" / 25 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 30,839 shp / 23,006 Kw = 28.00 kts
   Range 7,000nm at 12.00 kts
   Bunker at max displacement = 668 tons

Complement:
   226 - 295

Cost:
   £0.518 million / $2.071 million

Distribution of weights at normal displacement:
   Armament: 60 tons, 1.7 %
   Armour: 27 tons, 0.8 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 22 tons, 0.6 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 5 tons, 0.1 %
   Machinery: 1,149 tons, 32.8 %
   Hull, fittings & equipment: 1,264 tons, 36.1 %
   Fuel, ammunition & stores: 501 tons, 14.3 %
   Miscellaneous weights: 500 tons, 14.3 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     2,179 lbs / 988 Kg = 20.3 x 6.0 " / 152 mm shells or 0.6 torpedoes
   Stability (Unstable if below 1.00): 1.09
   Metacentric height 1.4 ft / 0.4 m
   Roll period: 13.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 52 %
         - Recoil effect (Restricted arc if above 1.00): 0.55
   Seaboat quality  (Average = 1.00): 1.21

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.496
   Length to Beam Ratio: 10.00 : 1
   'Natural speed' for length: 19.59 kts
   Power going to wave formation at top speed: 60 %
   Trim (Max stability = 0, Max steadiness = 100): 43
   Bow angle (Positive = bow angles forward): 22.00 degrees
   Stern overhang: -3.28 ft / -1.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      23.29 ft / 7.10 m
      - Forecastle (20 %):   19.29 ft / 5.88 m
      - Mid (50 %):      19.29 ft / 5.88 m (11.29 ft / 3.44 m aft of break)
      - Quarterdeck (15 %):   11.29 ft / 3.44 m
      - Stern:      11.29 ft / 3.44 m
      - Average freeboard:   15.61 ft / 4.76 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 135.6 %
      - Above water (accommodation/working, high = better): 106.2 %
   Waterplane Area: 9,782 Square feet or 909 Square metres
   Displacement factor (Displacement / loading): 106 %
   Structure weight / hull surface area: 66 lbs/sq ft or 324 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.90
      - Longitudinal: 2.49
      - 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

[Jefgte]

A good ship with probably many possibility of work.

Interresting.

In Armada, they are "Squadron Gunboat".


Jef  ;)

[Tanthalas]

Here I said I would have a go at it, that misc. Weight realy messes the stats up.

Just for Fun, Sure not Rohan Patrol Boat laid down 1920

Displacement:
   3,600 t light; 3,726 t standard; 3,980 t normal; 4,184 t full load

Dimensions: Length overall / water x beam x draught
   393.00 ft / 393.00 ft x 45.00 ft x 16.00 ft (normal load)
   119.79 m / 119.79 m x 13.72 m  x 4.88 m

Armament:
      4 - 6.00" / 152 mm guns (2x2 guns), 108.00lbs / 48.99kg shells, 1920 Model
     Breech loading guns in deck mounts with hoists
     on centreline ends, evenly spread
      2 - 4.50" / 114 mm guns in single mounts, 45.56lbs / 20.67kg shells, 1920 Model
     Quick firing guns in deck mounts
     on centreline ends, evenly spread, all raised mounts
      4 - 1.00" / 25.4 mm guns in single mounts, 0.50lbs / 0.23kg shells, 1920 Model
     Anti-aircraft guns in deck mounts
     on side, evenly spread
      4 - 0.75" / 19.1 mm guns in single mounts, 0.21lbs / 0.10kg shells, 1920 Model
     Machine guns in deck mounts
     on side, evenly spread
   Weight of broadside 526 lbs / 239 kg
   Shells per gun, main battery: 150

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1.50" / 38 mm   0.75" / 19 mm      0.75" / 19 mm
   2nd:   1.00" / 25 mm   0.75" / 19 mm            -
   3rd:   1.00" / 25 mm   0.75" / 19 mm            -
   4th:   1.00" / 25 mm         -               -

   - Conning tower: 1.50" / 38 mm

Machinery:
   Oil fired boilers, steam turbines,
   Electric motors, 2 shafts, 39,000 shp / 29,094 Kw = 29.01 kts
   Range 5,000nm at 12.00 kts
   Bunker at max displacement = 458 tons

Complement:
   249 - 325

Cost:
   £0.880 million / $3.518 million

Distribution of weights at normal displacement:
   Armament: 66 tons, 1.7 %
   Armour: 34 tons, 0.8 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 26 tons, 0.6 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 8 tons, 0.2 %
   Machinery: 1,364 tons, 34.3 %
   Hull, fittings & equipment: 1,637 tons, 41.1 %
   Fuel, ammunition & stores: 380 tons, 9.5 %
   Miscellaneous weights: 500 tons, 12.6 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     2,966 lbs / 1,345 Kg = 27.5 x 6.0 " / 152 mm shells or 0.7 torpedoes
   Stability (Unstable if below 1.00): 1.10
   Metacentric height 1.8 ft / 0.6 m
   Roll period: 14.0 seconds
   Steadiness   - As gun platform (Average = 50 %): 62 %
         - Recoil effect (Restricted arc if above 1.00): 0.42
   Seaboat quality  (Average = 1.00): 1.30

Hull form characteristics:
   Hull has low quarterdeck
   Block coefficient: 0.492
   Length to Beam Ratio: 8.73 : 1
   'Natural speed' for length: 19.82 kts
   Power going to wave formation at top speed: 63 %
   Trim (Max stability = 0, Max steadiness = 100): 48
   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:      20.00 ft / 6.10 m
      - Forecastle (20 %):   20.00 ft / 6.10 m
      - Mid (50 %):      20.00 ft / 6.10 m
      - Quarterdeck (15 %):   12.00 ft / 3.66 m (20.00 ft / 6.10 m before break)
      - Stern:      12.00 ft / 3.66 m
      - Average freeboard:   18.80 ft / 5.73 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 137.3 %
      - Above water (accommodation/working, high = better): 179.0 %
   Waterplane Area: 11,701 Square feet or 1,087 Square metres
   Displacement factor (Displacement / loading): 105 %
   Structure weight / hull surface area: 74 lbs/sq ft or 361 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.87
      - Longitudinal: 3.37
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is excellent
   Good seaboat, rides out heavy weather easily

[Nobody]

I thank you for your input, this was helpful for me.
It seems to be indeed the L to B ratio which increases the seekeeping, while increasing the draft actually hurts.
Anyway, it's just a study and only worth considering if build to mercantile standard for 1 BP.


Patrol Cruiser, Orange large Sloop laid down 1920

Displacement:
   4.000 t light; 4.159 t standard; 4.752 t normal; 5.226 t full load

Dimensions: Length overall / water x beam x draught
   393,70 ft / 387,14 ft x 49,93 ft x 17,06 ft (normal load)
   120,00 m / 118,00 m x 15,22 m  x 5,20 m

Armament:
      4 - 6,00" / 152 mm guns in single mounts, 108,00lbs / 48,99kg shells, 1920 Model
     Breech loading guns in deck mounts with hoists
     on centreline ends, evenly spread, 2 raised mounts - superfiring
      1 - 3,46" / 88,0 mm guns in single mounts, 20,79lbs / 9,43kg shells, 1920 Model
     Quick firing gun in deck mount
     on centreline amidships
      4 - 1,00" / 25,4 mm guns in single mounts, 0,50lbs / 0,23kg shells, 1920 Model
     Anti-aircraft guns in deck mounts
     on side, all amidships
      4 - 0,50" / 12,7 mm guns in single mounts, 0,06lbs / 0,03kg shells, 1920 Model
     Machine guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 455 lbs / 206 kg
   Shells per gun, main battery: 250
   6 - 0,0" / 0 mm above water torpedoes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1,18" / 30 mm   0,39" / 10 mm      1,18" / 30 mm
   2nd:   0,39" / 10 mm         -               -
   3rd:   0,39" / 10 mm         -               -

   - Conning tower: 1,18" / 30 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 45.079 shp / 33.629 Kw = 29,00 kts
   Range 4.000nm at 18,00 kts
   Bunker at max displacement = 1.067 tons

Complement:
   286 - 372

Cost:
   £0,965 million / $3,862 million

Distribution of weights at normal displacement:
   Armament: 57 tons, 1,2%
   Armour: 22 tons, 0,5%
      - Belts: 0 tons, 0,0%
      - Torpedo bulkhead: 0 tons, 0,0%
      - Armament: 15 tons, 0,3%
      - Armour Deck: 0 tons, 0,0%
      - Conning Tower: 7 tons, 0,2%
   Machinery: 1.576 tons, 33,2%
   Hull, fittings & equipment: 1.785 tons, 37,6%
   Fuel, ammunition & stores: 752 tons, 15,8%
   Miscellaneous weights: 560 tons, 11,8%

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     3.942 lbs / 1.788 Kg = 36,5 x 6,0 " / 152 mm shells or 0,8 torpedoes
   Stability (Unstable if below 1.00): 1,22
   Metacentric height 2,5 ft / 0,8 m
   Roll period: 13,1 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0,25
   Seaboat quality  (Average = 1.00): 1,21

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0,504
   Length to Beam Ratio: 7,75 : 1
   'Natural speed' for length: 19,68 kts
   Power going to wave formation at top speed: 65 %
   Trim (Max stability = 0, Max steadiness = 100): 41
   Bow angle (Positive = bow angles forward): 12,00 degrees
   Stern overhang: 0,98 ft / 0,30 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      26,25 ft / 8,00 m
      - Forecastle (20%):   22,97 ft / 7,00 m
      - Mid (65%):      21,65 ft / 6,60 m (14,44 ft / 4,40 m aft of break)
      - Quarterdeck (15%):   14,76 ft / 4,50 m
      - Stern:      16,40 ft / 5,00 m
      - Average freeboard:   20,15 ft / 6,14 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 130,1%
      - Above water (accommodation/working, high = better): 171,7%
   Waterplane Area: 12.931 Square feet or 1.201 Square metres
   Displacement factor (Displacement / loading): 113%
   Structure weight / hull surface area: 76 lbs/sq ft or 370 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,87
      - Longitudinal: 3,49
      - Overall: 1,00
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is excellent
   Good seaboat, rides out heavy weather easily

[Jefgte]

 ???

6 - 0.00" torpedoes ...


;)

[TexanCowboy]

I'm not sure that should classify as a civilian ship, Nobody.

[ctwaterman]

It looks alot like an Un Armored - Armed Merchant Cruiser - It sertainly doesnt want to fight anybodies PC of Frigates as it is completely unarmored.  Of course its Tonnage is light compared to most of the historical AMC and its speed is really very high.   

Over all it could prove to be an effective raider IF it is built to merchant standards????  The problem I see is its a disposable warship because while it might out gun some of the smaller 4" armed CL just as the Historical British AMC outgunned them what it lacks is the ability to take damage.

Charles